Håkon Olav Austrheim

• Malvoisin, Benjamin; Dörfler, Paula; Auzende, Anne Line; Brunet, Fabrice; Cannat, Mathilde & Austrheim, Håkon Olaf [Show all 7 contributors for this article] (2026). Magnetite production in mesh texture during serpentinization, a marker of H<inf>2</inf>diffusion. Journal of Petrology. ISSN 0022-3530. 67(4). doi: 10.1093/petrology/egag021. Full text in Research Archive
• Collet, C.; Cousin, A.; Beyssac, O.; Beck, P.; Forni, O. & Clegg, S. [Show all 15 contributors for this article] (2025). Variably weathered ultramafic rocks: Investigation of their mineralogy with SuperCam-like techniques. Spectrochimica Acta Part B - Atomic Spectroscopy. ISSN 0584-8547. 234. doi: 10.1016/j.sab.2025.107338. Full text in Research Archive Show summary

  The NASA Perseverance rover is exploring Jezero crater on Mars since February 2021. Orbital data from Nili Fossae and Jezero crater show a wide diversity of mineralogical signatures including primary mineral like olivine as well as diverse secondary minerals like clays and serpentines and one of the strongest spectral signatures of carbonate on Mars from orbit. This olivine and carbonate-bearing unit is regionally extensive. Most of the studies interpreted the relationship between olivine and carbonate-bearing units as a result of weathering processes involving fluid–rock interactions such as serpentinization and carbonation. Since February 2021, Perseverance has confirmed this large diversity of primary and secondary minerals. The detection of serpentine is of particular interest in order to better constrain the past environment at Jezero crater. Among the science payload, SuperCam is combining three spectral techniques (Laser-Induced Breakdown Spectroscopy - LIBS, Raman, and Visible and near InfraRed - VISIR) that give access to the elemental composition of the targets but also to their mineral and molecular structure. Here, we use terrestrial ultramafic rocks with various degrees of alteration that were well characterized from previous studies, and we analyze them with SuperCam replicate laboratory setups to investigate the sensitivity of SuperCam to detect olivine and secondary phases, in particular serpentines. Distinguishing serpentine from olivine by LIBS is challenging since they have similar chemistry. On the other hand, Raman spectroscopy is able to detect all the phases present in the analyzed samples, when their content is high enough. Finally, the VISIR technique detected the secondary phases while it did not observe easily the olivine. We found that the synergy between these three techniques is of particular importance to differentiate such specific phases, which occur as intricate mixtures down to the sub-micrometer scale in natural targets.

• Sednev-Lugovets, Anton; Lu, Yang; Vistad, Ørnulv Bjørnsson; Carvalho, Patricia Almeida; Missyul, Alexander & Austrheim, Håkon Olaf [Show all 8 contributors for this article] (2025). The crystal structure of dypingite: understanding the long-range disorder. Journal of Applied Crystallography. ISSN 0021-8898. 58(6), p. 1908–1919. doi: 10.1107/S1600576725007915. Full text in Research Archive Show summary

  Dypingite, a hydrated magnesium carbonate hydroxide mineral [Mg5(CO3)4(OH)2·XH2O, X = 5–6], exhibits promising catalytic and purification properties. Although it was discovered 55 years ago, the crystal structure of this compound has remained unknown due to its aggregated morphology and structural disorder. This work investigates the origin of this phenomenon through a systematic analysis of synthetic and natural mineral samples, using synchrotron powder X-ray diffraction, thermogravimetric analysis and transmission electron microscopy. The findings reveal that ambient humidity significantly influences dypingite's structural properties at room temperature. High humidity (80% relative humidity at 22 °C) causes inhomogeneous expansion of the unit cell along the crystallographic c axis, leading to long-range structural disorder. Conversely, at 20% relative humidity at 22 °C, the mineral structure exhibits a shorter c lattice constant and reduced structural disorder. Chemical analysis reveals that samples kept at 80% and 20% relative humidity for 10 days differ by one molecule of water of hydration, yielding Mg5(CO3)4.5(2)(OH)0.96(3)·6.0(2)H2O and Mg5(CO3)4.5(2)(OH)1.02(4)·5.0(2)H2O, respectively. The results obtained demonstrate that the crystal structure of dehydrated dypingite [Mg5(CO3)4.5(2)(OH)1.02(4)·5.0(2)H2O] derives from hydro­magnesite's unit cell tripled along the a axis. The analysis of the mineral crystal structure provides insight into the role of humidity on the structural properties of dypingite, including unit-cell dimensions and long-range disorder.

• Lu, Yang; Sednev-Lugovets, Anton; Carvalho, Patricia Almeida; Guzik, Matylda N.; Dayaghi, Amir Masoud & Dunkel, Kristina G [Show all 9 contributors for this article] (2025). Dypingite as a hydration series with reversible change of H2O content. American Mineralogist. ISSN 0003-004X. 111(5), p. 746–757. doi: 10.2138/am-2024-9603. Full text in Research Archive Show summary

  Dypingite has recently been found to have promising applications in material and environmental sciences. However, its exploitation is limited due to its ambiguous identification via powder X-ray diffraction (PXRD), which is caused by the occurrence of several phases with similar structures and PXRD patterns to that of dypingite. Multiple dypingite-like phases with partially overlapping X-ray diffraction traces appear to exist. To better understand dypingite, we studied samples from Dypingdal and Feragen Ultramafic Body, Norway. Dypingite sensu stricto (s.s.), several dypingite-like phases, and hydromagnesite were identified by PXRD. Three regions of 2θ (CuKα) were recognized where diffraction peaks are readily observed to transition between dypingite s.s., dypingite-like phases, and hydromagnesite. The position of the peak at around 8.5° 2θ varies with the H2O contents measured by the thermogravimetric and Fourier transform infrared analyses, suggesting that structural and compositional characteristics of dypingite-like phases form a continuum between dypingite s.s. and hydromagnesite. Humidity incubation experiments at room temperature indicated a reversible change of H2O content between dypingite s.s. and dypingite-like phases. High humidity conditions increased H2O contents of dypingite-like phases to dypingite s.s., whereas low humidity conditions reversed the direction towards hydromagnesite, but without complete reaction. Such transition behavior suggests that the structures of dypingite s.s. and the dypingite-like phases are very similar, probably identical in building unit topology but with different degrees of hydration, whereas the structure of hydromagnesite is less closely related. This study draws attention to the sample processing on dypingite hydration series, contributes to the applications of this series in CO2 sequestration, and gives suggestions to the refinement of structures of dypingite and dypingite-like phases.

• Grund, Saskia; John, Timm; Vrijmoed, Johannes Christiaan; Austrheim, Håkon Olaf & Andersen, Torgeir Bjørge (2025). A Mechanistic Look at the Amphibolitization of Mafic Crust: Insights From the Kråkeneset Gabbro Body, Western Gneis Region, Norway. Journal of Metamorphic Geology. ISSN 0263-4929. 43(4), p. 385–405. doi: 10.1111/jmg.12809. Full text in Research Archive Show summary

  ABSTRACT Fluid–rock interactions play a key role in the formation, evolution and recycling of the Earth's crust. For fluids to infiltrate rocks and enable and sustain fluid-mediated mineral transformations, fluid pathways are required. In this study, we examined the potential mechanisms of formation of such pathways via detailed mineralogical, petrophysical and thermodynamic analysis of a dry, essentially ‘non-porous’ gabbro that was hydrated and transformed into an amphibolite under amphibolite-facies conditions. During a previous regional HP eclogite-facies metamorphism, the gabbro did not equilibrate and preserved almost entirely its igneous textures and magmatic minerals. Rock transformation during amphibolitization was triggered by fluid infiltration through a newly opened N–S striking fracture network. An equally spaced fracture network formed by mode I opening related to the formation of an E–W striking shear zone at the northern and southern borders of the gabbro body. The amphibolitization process allowed the fluid to pervasively infiltrate the rock from the fracture into the pristine gabbro. The essentially fully amphibolitized sample exhibits some unaffected gabbroic mineral relicts. Even though the amphibolitization process led to the formation of ~70 vol.% hydrous phases, it was accompanied by densification and related porosity formation. The modes and compositions of minerals within partly amphibolitized rocks indicate that besides the uptake of H2O, no significant mass exchanges were necessary for this transformation, at least on the thin section scale. Thermodynamic modelling and petrological data show that the transition from gabbro to amphibolite favours porosity formation. In the model, the reaction front proceeded as soon as the gabbro at the reactive interfaces of the affected minerals was sufficiently transformed. At this point, fluid was not consumed further but remained as a free fluid phase, which progressed through the newly formed pore space and advanced amphibolitization. Once the gabbro was almost entirely amphibolitized, its mineral content and mineral chemistry no longer changed, so the progress of amphibolitization progress was controlled by fluid availability. This case study shows that fluid–rock interaction leading to hydration of a rock can be efficiently maintained in almost non-permeable, dry and mafic crust and, therefore, strongly affects the petrophysical properties of the Earth's crust.

• Filiberto, Lorena H.; Austrheim, Håkon Olaf; Putnis, Andrew; Padrón-Navarta, José Alberto; Reddy, Steven & Putnis, Christine V. (2025). Mechanisms of shear zone development in Krossøy, the Bergen Arcs, Norway. Lithos. ISSN 0024-4937. 498-499. doi: 10.1016/j.lithos.2025.107977. Full text in Research Archive Show summary

  The island of Krossøy in the Bergen Arcs, southwestern Norway, provides an ideal geological setting to study the mechanisms of grain size reduction in plagioclase during shear zone development. The transition from a granulite facies anorthosite to mylonitic textures under amphibolite facies conditions is investigated through field observations, petrographic analysis, electron microprobe analysis, and electron backscattered diffraction (EBSD) techniques. Initial ductile deformation, evidenced by complex twinning and intragrain misorientation, leads to strain hardening and subsequent brittle fracturing. This results in grain size reduction primarily through fragmentation, forming a bimodal grain size distribution. Syntectonic recrystallization produces compositionally similar neoblasts. Subsequent interactions with fluids induce compositional recrystallization, leading to further grain size reduction and the formation of zoned plagioclase grains. These processes highlight the critical role of fluid-mediated recrystallization in shear zone development and strain localization. The spatial variation in deformation and hydration stages across Krossøy is attributed to both mechanical anisotropy and chemical reequilibration driven by fluid pathways. These findings enhance our understanding of the interplay between mechanical anisotropy, brittle failure and fluid infiltration in the lower crust, providing insights into the conditions that facilitate the formation and evolution of shear zones in the Bergen Arcs.

• Austrheim, Håkon Olaf; Hu, Depan; Ulven, Ole Ivar & Andersen, Niels Højmark (2024). Formation of Natural Magnesium Silica Hydrate (M-S-H) and Magnesium Alumina Silica Hydrate (M-A-S-H) Cement. Materials. 17(5). doi: 10.3390/ma17050994. Full text in Research Archive Show summary

  Occurrences of natural magnesium alumina silicate hydrate (M-(A)-S-H) cement are present in Feragen and Leka, in eastern and western Trøndelag Norway, respectively. Both occurrences are in the subarctic climate zone and form in glacial till and moraine material deposited on ultramafic rock during the Weichselian glaciation. Weathering of serpentinized peridotite dissolves brucite and results in an alkaline fluid with a relatively high pH which subsequently reacts with the felsic minerals of the till (quartz, plagioclase, K-feldspar) to form a cement consisting of an amorphous material or a mixture of nanocrystalline Mg-rich phyllosilicates, including illite. The presence of plagioclase in the till results in the enrichment of alumina in the cement, i.e., forms M-A-S-H instead of the M-S-H cement. Dissolution of quartz results in numerous etch pits and negative quartz crystals filled with M-A-S-H cement. Where the quartz dissolution is faster than the cement precipitation, a honeycomb-like texture is formed. Compositionally, the cemented till (tillite) contains more MgO and has a higher loss of ignition than the till, suggesting that the cement is formed by a MgO fluid that previously reacted with the peridotite. The M-(A)-S-H cemented till represents a new type of duricrust, coined magsilcrete. The study of natural Mg cement provides information on peridotites as a Mg source for Mg cement and as a feedstock for CO2 sequestration.

• Moore, Jo; Piazolo, Sandra; Beinlich, Andreas; Austrheim, Håkon Olaf & Putnis, Andrew (2024). Brittle initiation of dissolution–precipitation creep in plagioclase-rich rocks: insights from the Bergen arcs, Norway. Contributions to Mineralogy and Petrology. ISSN 0010-7999. 179(6). doi: 10.1007/s00410-024-02141-0. Full text in Research Archive Show summary

  The initiation of ductile shear zones commonly occurs spatially associated with fluid-rock reactions along brittle precursors. In many cases the relative timing of fracturing, fluid infiltration, reaction, and recrystallisation is unclear, making it difficult to disentangle mechanisms of shear zone initiation from subsequent deformation and recrystallisation. Here we present the study of the transition from a dry plagioclase-diopside-garnet-scapolite host granulite-facies lithology to (1) a low strain amphibolite-facies rock, and (2) a transition from low strain to high strain amphibolite-facies lithologies. Hydration of the granulite-facies precursor at amphibolite-facies conditions produces an assemblage comprised dominantly of plagioclase-amphibole-zoisite-clinozoisite-kyanite-scapolite-quartz. Detailed study of plagioclase chemistry and microstructures across these two transitions using Electron Backscatter Diffraction (EBSD) and Wavelength Dispersive Spectrometry (WDS) allows us to assess the degree of coupling between deformation and fluid-rock reaction across the outcrop. Plagioclase behaves dominantly in a brittle manner at the hydration interface and so the initial weakening of the rock is attributed to grain size reduction caused by fracture damage and fluid infiltration at amphibolite-facies conditions. Extensive fracturing-induced grain size reduction locally increases permeability and allows for continuing plagioclase and secondary mineral growth during shear. Based on plagioclase microstructures, such as, an inherited but dispersed crystallographic preferred orientation (CPO), truncation of chemical zoning, and the dominance of fine (5–150 µm), slightly elongate, polygonal grains we conclude that deformation is dominantly facilitated by dissolution–precipitation creep assisted by grain boundary sliding in the shear zone.

• Austrheim, Håkon Olaf & Andersen, Torgeir Bjørge (2023). Extreme enrichment of arsenic and antimony during alteration of serpentinized peridotites to form listvenite-like dolomite–quartz rocks and Ni–Cr-rich jasper and quartzites in the Highland Border Complex of Scotland. Journal of the Geological Society. ISSN 0016-7649. 180(5). doi: 10.1144/jgs2023-054. Full text in Research Archive Show summary

  Alteration of serpentinised peridotitesof Highland Border Complex in Scotland took place in two steps. Listvenite-like dolomite-quartz rocks formed by addition of CaO, Sr and CO2 at constant MgO and SiO2 involving a mass increase of ca. 140 %. Stage-two involved the dissolution of dolomite evinced by the abundant pores and rhombohedral-shaped grains of quartz to form Cr- and Ni-rich jasper and quartzites. Formation of the jasper-quartzites involve a mass reduction of ca. 80%. The listvenite-like and jasper-quartzite rocks have enrichment in ACCEPTED MANUSCRIPT the fluid mobile elements Ba, Sr, Cs, As and Sb. The As is present in the Aluminium- Phosphate-Sulphate group of minerals formed during alteration of Cr-spinel. Cr-spinel also alters to porous hematite and ferrihydrite with patches containing up to 5.5 wt% As2O3. Enrichment of As, related to alteration of chromite, is previously unknown from natural rocks, but strongly resembles efficient methods used for remediation of this toxic element. Formation of quartzite and jasper from peridotite and their common presence as pebbles both in the Devonian Old Red conglomerates, in the Highland Border Complex and in Devonian Basins in the Scandinavian Caledonides, highlights their importance and potential for provenance- and tectono-stratigraphic correlations.

• Engvik, Ane; Trepmann, C.A. & Austrheim, Håkon Olaf (2023). Microfabric evolution during metasomatism and deformation, exemplified by the nodular sillimanite gneisses (Bamble lithotectonic domain, South Norway). Lithos. ISSN 0024-4937. 456-457. doi: 10.1016/j.lithos.2023.107317. Full text in Research Archive Show summary

  Proterozoic foliated and nodular sillimanite gneisses from the Bamble lithotectonic domain, South Norway, are analysed to unravel their microfabric evolution with mineral reactions during metasomatism and associated deformation. The nodules form cm-scaled spherical to ellipsoidal sillimanite-quartz aggregates that locally grade into foliated sillimanite gneisses. Independent on their fabric, they record incomplete breakdown reactions of biotite and K-feldspar recorded by muscovite lamellae and associated Fe-oxide needles in biotite and by muscovite-quartz aggregates after K-feldspar. Muscovite is partly replaced by sillimanite. Based on immobile Al, the nodular gneiss forming reactions give excess K, Mg and H2O that may leave the nodular gneiss to form a metasomatic agent and caused regional metasomatism (scapolitisation) in the surrounding rocks. Quartz in the foliated gneisses shows a pronounced shape but no marked crystallographic preferred orientation. There is no indication of major strain accumulation by quartz dislocation creep. Muscovite shows lobate phase boundaries to quartz, which is interpreted as reaction fabric, from the breakdown reactions of K-feldspar and biotite. The nodular and sillimanite gneisses formed during metasomatic mineral reactions, where major elements K, Mg and H2O leave the rock and an Al-rich metasomatic restite remains. We suggest that the metasomatism involved a molar volume loss, where reactions forming muscovite, quartz and sillimanite occurred by incongruent dissolution-precipitation creep at low stresses forming the nodular and foliated gneisses. Our study demonstrates that metasomatism with chemical rock changes and mass transfer associated with incongruent dissolution-precipitation contributed to the observed reaction and deformation microfabric.

• Austrheim, Håkon Olaf; Engvik, Ane; Ganerød, Morgan; Dunkel, Kristina G & Velo, Mari Roen (2022). Low-grade prehnite-pumpellyite facies metamorphism and metasomatism in basement rocks adjacent to the Permian Oslo rift: The importance of displacive reactions. Journal of Metamorphic Geology. ISSN 0263-4929. 40(9), p. 1467–1492. doi: 10.1111/jmg.12682. Full text in Research Archive Show summary

  The Kongsberg and Bamble lithotectonic domains of SE-Norway are known as classical Precambrian high-grade metamorphic terrains. The area has undergone extensive metasomatism with formation of albitites and scapolite-rich rocks and numbers of previously economically important deposits including the Kongsberg Silver and the Modum Cobalt mines. We demonstrate here that the central part of the Bamble lithotectonic domain (Kragerø area) has locally developed low-grade metamorphic minerals (prehnite, pumpellyite, analcime, stilpnomelane and thomsonite) belonging to the prehnite-pumpellyite and zeolite facies. Structurally, the low-grade minerals occur as fracture fills, in the alteration selvages around fractures where the rock is albitized, and along shear zones and cataclastic zones. The fracture fill and the alteration selvages vary from millimetres scale to 1 m in thickness. The fractures with low-grade minerals are part of larger fracture systems. The low-grade minerals typically formed by both displacive (swelling) and replacive reactions and in a combination of these. Prehnite together with albite, K-feldspar, quartz, epidote and hydrogarnet form lenses along (001) faces in biotite and chlorite leading to bending of the sheet silicates through a displacive reaction mechanism. Numerous replacement reactions including the earlier minerals as well as the low-grade minerals occur. As albite, K-feldspar, talc, quartz, actinolite, titanite, calcite and hydrogrossular form in the same veins and in the same biotite grain as the classical low-grade minerals, they probably belong to the low-grade assemblage and some of the albitization in the region presumably occurred at low-grade conditions. Alteration of olivine (Fo69) at low-grade conditions results in the formation of clay minerals including ferroan saponite. Reconnaissance studies at the east (Idefjord lithotectonic domain) and the northwest (Kongsberg lithotectonic domain) sides of the Oslo rift together with reports of low-grade assemblages in south-western Sweden along the continuation of the rift into Skagerrak suggest that the low grade assembles occur in rocks adjacent to the Oslo rift along its full extent. Ar-Ar dating of K-feldspar from the low-grade assemblages gave an age of 265.2 ± 0.4 Ma (MSWD = 0.514 and P = 0.766), suggesting that the low-grade metamorphism and some of the metasomatism is induced by fluids and heat from the magmatic activity of the Permian Oslo rift, which requires transport of fluid over distances of several kilometres. The metamorphic conditions are constrained by stability fields of prehnite, pumpellyite and analcime to be less than 250°C and at a pressure less than 5 kbars. The displacive reactions created micro-fractures and porosity in the adjacent minerals that enhance fluid flow and low-grade mineral formation on a local scale. On a thin section scale, the displacive growth of albite in biotite results in a local volume increase of several 100%. Whether the opening of the larger, horizontally oriented fracture systems needed to transport the fluid over a distance of several kilometres was also the results of displacive reactions remains unknown. The low-grade metamorphism and metasomatism formed in the shoulder of the Oslo rift and may have contributed to its uplift.

• Ruiter, Lisa de; Gunnæs, Anette Eleonora; Dysthe, Dag Kristian & Austrheim, Håkon Olaf (2021). Quartz dissolution associated with magnesium silicate hydrate cement precipitation. Solid Earth (SE). ISSN 1869-9510. 12(2), p. 389–404. doi: 10.5194/se-12-389-2021. Full text in Research Archive
• Putnis, Andrew; Moore, Josephine; Prent, Alexander M.; Beinlich, Andreas Michael & Austrheim, Håkon Olaf (2021). Preservation of granulite in a partially eclogitized terrane: Metastable phenomena or local pressure variations? Lithos. ISSN 0024-4937. 400-401. doi: 10.1016/j.lithos.2021.106413. Full text in Research Archive
• Austrheim, Håkon Olaf; Corfu, Fernando & Renggli, Christian J. (2021). From peridotite to fuchsite bearing quartzite via carbonation and weathering: with implications for the Pb budget of continental crust. Contributions to Mineralogy and Petrology. ISSN 0010-7999. 176. doi: 10.1007/s00410-021-01851-z. Full text in Research Archive Show summary

  Abstract Extensive carbonation of peridotite results in listvenite, a rock composed of magnesite and quartz. At Gråberget, Røros, SE-Norway, a variably serpentinized peridotite body, surrounded by the Røros schists, a former abyssal sediment displays all stages of transformation of peridotite to quartzite. In this paper we record the sequence of steps in this process by combining the observation of mineral assemblages, textural relationships and geochemistry, and variations in Pb isotopic compositions. Initial serpentinization, a stage that also involved an enrichment in fluid-mobile elements (Pb, Sb and As), was followed by carbonation through CO 2 fluids that formed soapstone, and eventually listvenite. The listvenite grades by decreasing amounts of carbonates into fuchsite bearing quartzite. The carbonates dissolved during supergene alteration and formed pores coated with oxides of Fe, Mn and Ni resulting in a brown rock color. The quartzite displays porous stylolites enriched in Pb, As and Sb and fuchsite with porous chromite grains as the only relicts of the original mineralogy in the peridotite. The dissolution of the carbonate occurred at oxidizing conditions at temperatures below 150 °C, where the solubility of magnesite is higher than that of quartz. Formation of quartzite from peridotite is supported by low REE contents and lack of zircons in the two rock types. The transformation involved enrichment of Pb, coupled with the elimination of Mg and enrichment of Si. This chemical fractionation and selective transfer of elements to the continents is an important mechanism and needs to be taken into account in models of continental evolution.

• Jamtveit, Bjørn; Dunkel, Kristina G; Petley-Ragan, Arianne Juliette; Austrheim, Håkon Olaf; Corfu, Fernando & Schmid, Daniel Walter (2021). Rapid fluid-driven transformation of lower continental crust associated with thrust-induced shear heating. Lithos. ISSN 0024-4937. 396-397. doi: 10.1016/j.lithos.2021.106216. Full text in Research Archive
• Engvik, Ane; Gautneb, Håvard; Baranwal, Vikas Chand; Rønning, Jan-Steinar; Solberg, Janja Knezevic & Liu, Yunhe [Show all 7 contributors for this article] (2021). The control of shear-zone development and electric conductivity by graphite in granulite: An example from the Proterozoic Lofoten-Vesterålen Complex of northern Norway. Terra Nova. ISSN 0954-4879. 33(5), p. 529–539. doi: 10.1111/ter.12545. Full text in Research Archive Show summary

  Graphite impacts crustal rheology and electric conductivity in the lower crust. In a combined geophysical and geological study from the Proterozoic Lofoten-Vesterålen Complex, Norway, we show the enrichment of graphite resulted in zones with strong schistosity and a sharp strain gradient towards host massive granulite gneiss. Increased graphite content resulted in high-conductivity zones with true resistivity values <10 Ωm compared with a resistivity of >3,000 Ωm in the low-conductive crust. The regionally distributed graphite zones contain up to 39% graphite with variable amounts of quartz, feldspars, biotite and pyroxenes and where graphite is present in stable assemblage to orthopyroxene. High-ordered graphite and biotite with a strong-preferred orientation define the well-developed foliation. Our results demonstrate that graphite accounts for the high electric conductivity of this former Proterozoic lower-crustal segment. The presence of graphite causes strain localisation in the granulite facies crust, reducing crustal strength and may thereby influence continental architecture and evolution of collision zones.

• Jung, Sejin; Jung, Haemyeong & Austrheim, Håkon Olaf (2020). Microstructural Evolution of Amphibole Peridotites in Åheim, Norway, and the Implications for Seismic Anisotropy in the Mantle Wedge. Minerals. 10(4). doi: 10.3390/min10040345. Full text in Research Archive Show summary

  The microstructure of amphibole peridotites from Åheim, Norway were analyzed to understand the evolution of the lattice-preferred orientation (LPO) of olivine throughout the Scandian Orogeny and its implication for the seismic anisotropy of the subduction zone. The Åheim peridotites had a porphyroclastic texture and some samples contained an abundant amount of hydrous minerals such as tremolite. Detailed microstructural analysis on the Åheim peridotites revealed multiple stages of deformation. The coarse grains showed an A-type LPO of olivine, which can be interpreted as the initial stage of deformation. The spinel-bearing samples showed a mixture of B-type and C-type LPOs of olivine, which is considered to represent the deformation under water-rich conditions. The recrystallized fine-grained olivine displays a B-type LPO, which can be interpreted as the final stage of deformation. Microstructures and water content of olivine indicate that the dominant deformation mechanism of olivine showing a B-type LPO is a dislocation creep under water-rich condition. The observation of the B-type LPO of olivine is important for an interpretation of trench-parallel seismic anisotropy in the mantle wedge. The calculated seismic anisotropy of the tremolite showed that tremolite can contribute to the trench-parallel seismic anisotropy in the mantle wedge.

• Gussone, Nikolaus; Austrheim, Håkon Olaf; Westhues, Anne & Mezger, Klaus (2020). Origin of Rodingite Forming Fluids Constrained by Calcium and Strontium Isotope Ratios in the Leka Ophiolite Complex. Chemical Geology. ISSN 0009-2541. 542. doi: 10.1016/j.chemgeo.2020.119598. Full text in Research Archive
• Malvoisin, Benjamin; Austrheim, Håkon Olaf; Hetényi, György; Reynes, Julien; Hermann, Jörg & Baumgartner, Lukas [Show all 7 contributors for this article] (2020). Sustainable densification of the deep crust. Geology. ISSN 0091-7613. 48(7), p. 673–677. doi: 10.1130/G47201.1. Full text in Research Archive
• Moore, Jo; Beinlich, Andreas; Piazolo, Sandra; Austrheim, Håkon Olaf & Putnis, Andrew (2020). Metamorphic Differentiation via Enhanced Dissolution along High Permeability Zones. Journal of Petrology. ISSN 0022-3530. 61(10). doi: 10.1093/petrology/egaa096. Full text in Research Archive
• Cao, Yi; Du, Jinxue; Park, Munjae; Jung, Sejin; Park, Yong & Kim, Dohyun [Show all 9 contributors for this article] (2020). Metastability and Nondislocation-Based Deformation Mechanisms of the Flem Eclogite in the Western Gneiss Region, Norway. Journal of Geophysical Research (JGR): Solid Earth. ISSN 2169-9313. 125(5). doi: 10.1029/2020JB019375. Full text in Research Archive Show summary

  The eclogite in the Flem Gabbro from Flemsøya Island of the Western Gneiss Region in Norway contains atypical eclogitic minerals, such as olivine and orthopyroxene, and can be texturally divided into weakly deformed massive eclogite (MEC) and strongly deformed foliated eclogite (FEC). Based on phase equilibria modeling, peak metamorphic pressure‐temperature conditions of ~600–750 °C and ~1.0–2.5 GPa and ~700–820 °C and ~2.7–3.7 GPa are recorded in MEC and FEC, respectively. These different pressure‐temperature conditions between MEC (high‐pressure, HP) and FEC (ultrahigh‐pressure, UHP) in the same outcrop reflect deformation‐enhanced eclogitization metamorphism (HP to UHP transition) via the addition of external water during subduction/burial to early exhumation stages and metastable preservation of the HP MEC assemblage at UHP condition due to the local lack of deformation and fluid access at the deep subduction interface or around Moho beneath continental collision zone. Based on the mineral microstructures, nondislocation‐based creep mechanisms—such as diffusion creep, grain and phase boundary sliding, and rigid‐body‐like rotation—play dominant roles in governing the deformation features of FEC and developing the crystal preferred orientations of its major constituent minerals. These deformation mechanisms could considerably affect the interplate coupling at the subduction interface or the rheological strength of Moho beneath continental collision zones. Therefore, the effects of metastability‐based (i.e., preservation of low‐pressure assemblages at HP conditions) and contributions of nondislocation‐based creep mechanisms should be included in the future geodynamic and petrological simulations of subduction and collision processes.

• Moore, Jo; Beinlich, Andreas; Porter, Jennifer K.; Talavera, Cristina; Berndt, Jasper & Piazolo, Sandra [Show all 8 contributors for this article] (2020). Microstructurally controlled trace element (Zr, U–Pb) concentrations in metamorphic rutile: An example from the amphibolites of the Bergen Arcs. Journal of Metamorphic Geology. ISSN 0263-4929. 38(1), p. 103–127. doi: 10.1111/jmg.12514. Full text in Research Archive
• Petley-Ragan, Arianne Juliette; Ben-Zion, Yehuda; Austrheim, Håkon Olaf; Ildefonse, Benoit; Renard, Francois & Jamtveit, Bjørn (2019). Dynamic earthquake rupture in the lower crust. Science Advances. 5(7). doi: 10.1126/sciadv.aaw0913. Full text in Research Archive Show summary

  Earthquakes in the continental crust commonly occur in the upper 15 to 20 km. Recent studies demonstrate that earthquakes also occur in the lower crust of collision zones and play a key role in metamorphic processes that modify its physical properties. However, details of the failure process and sequence of events that lead to seismic slip in the lower crust remain uncertain. Here, we present observations of a fault zone from the Bergen Arcs, western Norway, which constrain the deformation processes of lower crustal earthquakes. We show that seismic slip and associated melting are preceded by fracturing, asymmetric fragmentation, and comminution of the wall rock caused by a dynamically propagating rupture. The succession of deformation processes reported here emphasize brittle failure mechanisms in a portion of the crust that until recently was assumed to be characterized by ductile deformation.

• Ruiter, Lisa de; Putnis, Christine V; Hovelmann, Jörn; King, Helen E. & Austrheim, Håkon Olaf (2019). Direct Observations of the Coupling between Quartz Dissolution and Mg-Silicate Formation. ACS Earth and Space Chemistry. 3(4), p. 617–625. doi: 10.1021/acsearthspacechem.8b00197. Full text in Research Archive
• Moore, Jo; Beinlich, Andreas; Austrheim, Håkon Olaf & Putnis, Andrew (2019). Stress orientation-dependent reactions during metamorphism. Geology. ISSN 0091-7613. 47(2), p. 151–154. doi: 10.1130/G45632.1. Full text in Research Archive
• Jamtveit, Bjørn; Petley-Ragan, Arianne Juliette; Incel, Sarah; Dunkel, Kristina G; Aupart, Claire Olga Maryse & Austrheim, Håkon Olaf [Show all 9 contributors for this article] (2019). The effects of earthquakes and fluids on the metamorphism of the lower continental crust. Journal of Geophysical Research (JGR): Solid Earth. ISSN 2169-9313. 124(8), p. 7725–7755. doi: 10.1029/2018JB016461. Full text in Research Archive Show summary

  Rock rheology and density have first‐order effects on the lithosphere's response to plate tectonic forces at plate boundaries. Changes in these rock properties are controlled by metamorphic transformation processes that are critically dependent on the presence of fluids. At the onset of a continental collision, the lower crust is in most cases dry and strong. However, if exposed to internally produced or externally supplied fluids, the thickened crust will react and be converted into a mechanically weaker lithology by fluid‐driven metamorphic reactions. Fluid introduction is often associated with deep crustal earthquakes. Microstructural evidence, suggest that in strong highly stressed rocks, seismic slip may be initiated by brittle deformation and that wall‐rock damage caused by dynamic ruptures plays a very important role in allowing fluids to enter into contact with dry and highly reactive lower crustal rocks. The resulting metamorphism produces weaker rocks which subsequently deform by viscous creep. Volumes of weak rocks contained in a highly stressed environment of strong rocks may experience significant excursions toward higher pressure without any associated burial. Slow and highly localized creep processes in a velocity strengthening regime may produce mylonitic shear zones along faults initially characterized by earthquake‐generated frictional melting and wall rock damage. However, stress pulses from earthquakes in the shallower brittle regime may kick start new episodes of seismic slip at velocity weakening conditions. These processes indicate that the evolution of the lower crust during continental collisions is controlled by the transient interplay between brittle deformation, fluid‐rock interactions, and creep flow.

• Dunkel, Kristina G; Jamtveit, Bjørn & Austrheim, Håkon Olaf (2019). Ophicarbonates of the Feragen Ultramafic Body, central Norway. Norwegian Journal of Geology. ISSN 2387-5844. 99(3), p. 1–18. doi: 10.17850/njg99-3-3. Full text in Research Archive Show summary

  The carbonation of ultramafic rocks is a common alteration process in ophiolites and can occur in various settings. We provide the first detailed description of the carbonated peridotites (ophicarbonates) of the Feragen Ultramafic Body, central Norway, which have unusually variable compositions and microstructures. Lithologies range from pervasively carbonated serpentinites through carbonated serpentinite breccias to carbonated ultramafic conglomerates. Carbonate phases are Ca-carbonate, magnesite and dolomite. Some breccias are also cemented by coarsegrained brucite. This variability records strong variations in fluid chemistry and/or pressure and temperature conditions, both spatially and temporally. By analysing these altered ultramafic rocks using field relationships, optical microscopy, electron microprobe analysis and oxygen and carbon isotope compositions, we elucidate the history of the Feragen Ultramafic Body in more detail and emphasise the importance of deformation for the extent and type of alteration.

• Halpaap, Felix; Rondenay, Stéphane; Perrin, Alexander; Goes, Saskia; Ottemöller, Lars & Austrheim, Håkon Olaf [Show all 8 contributors for this article] (2019). Earthquakes track subduction fluids from slab source to mantle wedge sink. Science Advances. 5(4). doi: 10.1126/sciadv.aav7369. Full text in Research Archive Show summary

  Subducting plates release fluids as they plunge into Earth’s mantle and occasionally rupture to produce intraslab earthquakes. It is debated whether fluids and earthquakes are directly related. By combining seismic observations and geodynamic models from western Greece, and comparing across other subduction zones, we find that earthquakes effectively track the flow of fluids from their slab source at >80 km depth to their sink at shallow (<40 km) depth. Between source and sink, the fluids flow updip under a sealed plate interface, facilitating intraslab earthquakes. In some locations, the seal breaks and fluids escape through vents into the mantle wedge, thereby reducing the fluid supply and seismicity updip in the slab. The vents themselves may represent nucleation sites for larger damaging earthquakes.

• Engvik, Ane; Taublad, H.; Solli, Arne; Grenne, Tor & Austrheim, Håkon Olaf (2018). Dynamic metamorphism: stable isotopes, fluid evolution, and deformation of albitite and sapolite metagabbro. Geofluids. ISSN 1468-8115. 2018. doi: 10.1155/2018/9325809. Full text in Research Archive
• Aupart, Claire Olga Maryse; Dunkel, Kristina G; Angheluta, Luiza; Austrheim, Håkon Olaf; Ildefonse, Beniot & Malthe-Sørenssen, Anders [Show all 7 contributors for this article] (2018). Olivine Grain Size Distributions in Faults and Shear Zones: Evidence for Nonsteady State Deformation. Journal of Geophysical Research (JGR): Solid Earth. ISSN 2169-9313. 123(9), p. 7421–7443. doi: 10.1029/2018JB015836. Full text in Research Archive Show summary

  The grain size distribution of deformed rocks may provide valuable information about their deformation history and the associated mechanisms. Here we present a unique set of olivine grain size distributions from ultramafic rocks deformed under a wide range of stress and strain rate conditions. Both experimentally deformed and naturally deformed samples are included. We observe a surprisingly uniform behavior, and most samples show power law grain size distributions. Convincing lognormal distributions across all scales were only observed for samples experimentally deformed at high temperature (1200 °C) and for some mantle‐deformed natural samples. Single power law distributions were observed for natural samples deformed by brittle mechanisms and by samples deformed experimentally in the regime of low‐temperature plasticity. Most natural samples show a crossover in power law scaling behavior near the median grain size from a steep slope for the larger grain fraction to a more gentle slope for the smaller grains. The small grain fraction shows a good data collapse when normalized to the crossover length scale. The associated power law slope indicates a common grain size controlling process. We propose a model that explains how such a scaling behavior may arise in the dislocation creep regime from the competition between the rate involved in the dislocation dynamics and the imposed strain rate. The common departure from lognormal distributions suggests that naturally deformed samples often have a deformation history that is far from a steady state scenario and probably reflects deformation under highly variable stress and strain rates. ©2018. American Geophysical Union. All Rights Reserved.

• Clerc, Adriane; Renard, Francois; Austrheim, Håkon Olaf & Jamtveit, Bjørn (2018). Spatial and size distributions of garnets grown in a pseudotachylyte generated during a lower crust earthquake. Tectonophysics. ISSN 0040-1951. 733, p. 159–170. doi: 10.1016/j.tecto.2018.02.014. Full text in Research Archive Show summary

  In the Bergen Arc, western Norway, rocks exhumed from the lower crust record earthquakes that formed during the Caledonian collision. These earthquakes occurred at about 30–50 km depth under granulite or amphibolite facies metamorphic conditions. Coseismic frictional heating produced pseudotachylytes in this area. We describe pseudotachylytes using field data to infer earthquake magnitude (M ≥ ~6.6), low dynamic friction during rupture propagation (μd < 0.1) and laboratory analyses to infer fast crystallization of microlites in the pseudotachylyte, within seconds of the earthquake arrest. High resolution 3D X-ray microtomography imaging reveals the microstructure of a pseudotachylyte sample, including numerous garnets and their corona of plagioclase that we infer have crystallized in the pseudotachylyte. These garnets 1) have dendritic shapes and are surrounded by plagioclase coronae almost fully depleted in iron, 2) have a log-normal volume distribution, 3) increase in volume with increasing distance away from the pseudotachylyte-host rock boundary, and 4) decrease in number with increasing distance away from the pseudotachylyte -host rock boundary. These characteristics indicate fast mineral growth, likely within seconds. We propose that these new quantitative criteria may assist in the unambiguous identification of pseudotachylytes in the field.

• Petley-Ragan, Arianne Juliette; Dunkel, Kristina G; Austrheim, Håkon Olaf; Ildefonse, Benoit & Jamtveit, Bjørn (2018). Microstructural Records of Earthquakes in the Lower Crust and Associated Fluid-Driven Metamorphism in Plagioclase-Rich Granulites. Journal of Geophysical Research (JGR): Solid Earth. ISSN 2169-9313. 123(5), p. 3729–3746. doi: 10.1029/2017JB015348. Full text in Research Archive Show summary

  Coseismic damage associated with earthquakes in the lower continental crust is accompanied by postseismic annealing and fluid‐mediated metamorphism that influence the physical and chemical development of the continental crust on regional scales. A transition from brittle deformation to crystal‐plastic recrystallization is a recurring characteristic of rocks affected by lower crustal earthquakes and is observed in plagioclase adjacent to pseudotachylytes in granulite facies anorthosites from the Bergen Arcs, western Norway. The microstructural and petrological records of this transition were investigated using electron microscopy, electron microprobe analysis, and electron backscatter diffraction analysis. Microfractures associated with mechanical twins are abundant within plagioclase and contain fine‐grained aggregates that formed by fragmentation with minor shear deformation. The presence of feather features, which are described for the first time in feldspar, suggests that fractures propagate at near the shear wave velocity into the wall rock of earthquake slip planes. Grain size insensitive recrystallization took place within the time frame of pseudotachylyte formation, forming high‐angle grain boundaries required for shear zone initiation. Fluid infiltration synfracture to postfracture facilitated the epitactic replacement of plagioclase by alkali feldspar and the nucleation of clinozoisite, kyanite, and quartz. The grain size reduction and crystallization associated with the microfractures create rheologically weak areas that have the potential to localize strain within the plagioclase‐rich lower crust. ©2018. American Geophysical Union. All Rights Reserved.

• Beinlich, Andreas; Austrheim, Håkon Olaf; Mavromatis, Vasileios; Grguric, Ben; Putnis, Christine V & Putnis, Andrew (2018). Peridotite weathering is the missing ingredient of Earth's continental crust composition. Nature Communications. 9(1). doi: 10.1038/s41467-018-03039-9. Full text in Research Archive Show summary

  The chemical composition of the continental crust cannot be adequately explained by current models for its formation, because it is too rich in Ni and Cr compared to that which can be generated by any of the proposed mechanisms. Estimates of the crust composition are derived from average sediment, while crustal growth is ascribed to amalgamation of differentiated magmatic rocks at continental margins. Here we show that chemical weathering of Ni- and Cr-rich, undifferentiated ultramafic rock equivalent to ~1.3 wt% of today’s continental crust compensates for low Ni and Cr in formation models of the continental crust. Ultramafic rock weathering produces a residual that is enriched in Ni and also silica. In the light of potentially large volumes of ultramafic rock and high atmospheric CO2 concentrations during the Archean, chemical weathering must therefore have played a major role in forming compositionally evolved components of the early Earth’s crust.

• Janots, Emilie; Austrheim, Håkon Olaf; Spandler, C; Hammerli, Johannes; Trepmann, Claudia A. & Berndt, Jasper [Show all 8 contributors for this article] (2018). Rare earth elements and Sm-Nd isotope redistribution in apatite and accessory minerals in retrogressed lower crust material (Bergen Arcs, Norway). Chemical Geology. ISSN 0009-2541. 484, p. 120–135. doi: 10.1016/j.chemgeo.2017.10.007. Full text in Research Archive
• Jamtveit, Bjørn; Ben-Zion, Yehuda; Renard, Francois & Austrheim, Håkon Olaf (2018). Earthquake-induced transformation of the lower crust. Nature. ISSN 0028-0836. 556(7702), p. 487–491. doi: 10.1038/s41586-018-0045-y. Full text in Research Archive Show summary

  The structural and metamorphic evolution of the lower crust has direct effects on the lithospheric response to plate tectonic processes involved in orogeny, including subsidence of sedimentary basins, stability of deep mountain roots and extension of high-topography regions. Recent research shows that before orogeny most of the lower crust is dry, impermeable and mechanically strong1. During an orogenic event, the evolution of the lower crust is controlled by infiltration of fluids along localized shear or fracture zones. In the Bergen Arcs of Western Norway, shear zones initiate as faults generated by lower-crustal earthquakes. Seismic slip in the dry lower crust requires stresses at a level that can only be sustained over short timescales or local weakening mechanisms. However, normal earthquake activity in the seismogenic zone produces stress pulses that drive aftershocks in the lower crust2. Here we show that the volume of lower crust affected by such aftershocks is substantial and that fluid-driven associated metamorphic and structural transformations of the lower crust follow these earthquakes. This provides a ‘top-down’ effect on crustal geodynamics and connects processes operating at very different timescales.

• Jamtveit, Bjørn; Moulas, Evangelos; Andersen, Torgeir Bjørge; Austrheim, Håkon Olaf; Corfu, Fernando & Petley-Ragan, Arianne Juliette [Show all 7 contributors for this article] (2018). High Pressure Metamorphism Caused by Fluid Induced Weakening of Deep ontinental Crust. Scientific Reports. 8. doi: 10.1038/s41598-018-35200-1. Full text in Research Archive Show summary

  Studies of mineral equilibria in metamorphic rocks have given valuable insights into the tectonic processes operating at convergent plate margins during an orogeny. Geodynamic models simulating orogenesis and crustal thickening have been constrained by temperature and pressure estimates inferred from the mineral assemblages of the various lithologies involved along with age constrains from increasingly precise geochronological techniques. During such studies it is assumed that the pressure experienced by a given rock is uniquely related to its depth of burial. This assumption has been challenged by recent studies of high pressure (HP) and ultrahigh pressure (UHP) rocks. Here, we describe an example of Caledonian HP metamorphism from the Bergen Arcs in western Norway, and show that the associated formation of Caledonian eclogites at the expense of Proterozoic granulites was related to local pressure perturbations rather than burial, and that the HP metamorphism resulted from fluid-induced weakening of an initially dry and highly stressed lower crust when thrust upon the hyperextended margin of the Baltic shield.

• Centrella, Stephen; Putnis, Andrew; Lanari, Pierre & Austrheim, Håkon Olaf (2018). Textural and chemical evolution of pyroxene during hydration and deformation: A consequence of retrograde metamorphism. Lithos. ISSN 0024-4937. 296-299, p. 245–264. doi: 10.1016/j.lithos.2017.11.002. Full text in Research Archive
• Austrheim, Håkon Olaf; Dunkel, Kristina G; Plümper, Oliver; Ildefonse, Benoit; Liu, Yang & Jamtveit, Bjørn (2017). Fragmentation of wall rock garnets during deep crustal earthquakes. Science Advances. 3(2). doi: 10.1126/sciadv.1602067. Full text in Research Archive Show summary

  Fractures and faults riddle the Earth’s crust on all scales, and the deformation associated with them is presumed to have had significant effects on its petrological and structural evolution. However, despite the abundance of directly observable earthquake activity, unequivocal evidence for seismic slip rates along ancient faults is rare and usually related to frictional melting and the formation of pseudotachylites. We report novel microstructures from garnet crystals in the immediate vicinity of seismic slip planes that transected lower crustal granulites during intermediate-depth earthquakes in the Bergen Arcs area, western Norway, some 420 million years ago. Seismic loading caused massive dislocation formations and fragmentation of wall rock garnets. Microfracturing and the injection of sulfide melts occurred during an early stage of loading. Subsequent dilation caused pervasive transport of fluids into the garnets along a network of microfractures, dislocations, and subgrain and grain boundaries, leading to the growth of abundant mineral inclusions inside the fragmented garnets. Recrystallization by grain boundary migration closed most of the pores and fractures generated by the seismic event. This wall rock alteration represents the initial stages of an earthquake-triggered metamorphic transformation process that ultimately led to reworking of the lower crust on a regional scale.

• Dunkel, Kristina G; Austrheim, Håkon Olav; Renard, Francois; Cordonnier, Benoit & Jamtveit, Bjørn (2017). Localized slip controlled by dehydration embrittlement of partly serpentinized dunites, Leka Ophiolite Complex, Norway. Earth and Planetary Science Letters. ISSN 0012-821X. 463, p. 277–285. doi: 10.1016/j.epsl.2017.01.047. Full text in Research Archive Show summary

  Dehydration of partly or completely serpentinized ultramafic rocks can increase the pore fluid pressure and induce brittle failure, a process referred to as dehydration embrittlement. However the extents of strain localization and unstable frictional sliding during deserpentinization are still under debate. In the layered ultramafic sections of the Leka Ophiolite Complex in the Central Norwegian Caledonides, prograde metamorphism of serpentinite veins led to local fluid production and to the growth of Mg-rich and coarse-grained olivine with abundant magnetite inclusions and δ18O values ‰ below the host rock. Embrittlement associated with the dehydration caused faulting along highly localized (<10 μm-wide) slip planes near the centers of the original serpentinite veins and pulverization of wall rock olivine. These features along with an earthquake-like size distribution of fault offsets suggest unstable frictional sliding rather than slower creep. Structural heterogeneities in the form of serpentinite veins clearly have first-order controls on strain localization and frictional sliding during dehydration. As most of the oceanic lithosphere is incompletely serpentinized, heterogeneities represented by a non-uniform distribution of serpentinite are common and may increase the likelihood that dehydration embrittlement triggers earthquakes.

• Putnis, Andrew; Jamtveit, Bjørn & Austrheim, Håkon Olaf (2017). Metamorphic processes and seismicity: The Bergen Arcs as a natural laboratory. Journal of Petrology. ISSN 0022-3530. 58(10), p. 1871–1898. doi: 10.1093/petrology/egx076. Full text in Research Archive
• Porter, Jennifer & Austrheim, Håkon Olav (2017). Sulphide formation from granulite-facies S-rich scapolite breakdown. Terra Nova. ISSN 0954-4879. 29(1), p. 29–35. doi: 10.1111/ter.12242. Full text in Research Archive
• Dunkel, Kristina G; Austrheim, Håkon Olaf; Ildefonse, Benoit & Jamtveit, Bjørn (2017). Transfer of olivine crystallographic orientation through a cycle of serpentinisation and dehydration. Contributions to Mineralogy and Petrology. ISSN 0010-7999. 172(8). doi: 10.1007/s00410-017-1378-5. Full text in Research Archive Show summary

  Our ability to decipher the mechanisms behind metamorphic transformation processes depends in a major way on the extent to which crystallographic and microstructural information is transferred from one stage to another. Within the Leka Ophiolite Complex in the Central Norwegian Caledonides, prograde olivine veins that formed by dehydration of serpentinite veins in dunites exhibit a characteristic distribution of microstructures: The outer part of the veins comprises coarse-grained olivine that forms an unusual, brick-like microstructure. The inner part of the veins, surrounding a central fault, is composed of fine-grained olivine. Where the fault movement included a dilational component, optically clear, equant olivine occurs in the centre. Electron backscatter diffraction mapping reveals that the vein olivine has inherited its crystallographic preferred orientation (CPO) from the olivine in the porphyroclastic host rock; however, misorientation is weaker and associated to different rotation axes. We propose that prograde olivine grew epitaxially on relics of mantle olivine and thereby acquired its CPO. Growth towards pre-existing microfractures along which serpentinisation had occurred led to straight grain boundaries and a brick-like microstructure in the veins. When dehydration embrittlement induced slip, a strong strain localisation on discrete fault planes prevented distortion of the CPO due to cataclastic deformation; grain size reduction did not significantly modify the olivine CPO. This illustrates how a CPO can be preserved though an entire metamorphic cycle, including hydration, dehydration, and deformation processes, and that the CPO and the microstructures (e.g. grain shape) of one phase do not necessarily record the same event. © 2017 Springer Verlag

• Engvik, Ane; Corfu, Fernando; Solli, Arne & Austrheim, Håkon Olav (2017). Sequence and timing of mineral replacement reactions during albitisation in the high-grade Bamble lithotectonic domain, S-Norway. Precambrian Research. ISSN 0301-9268. 291, p. 1–16. doi: 10.1016/j.precamres.2017.01.010. Full text in Research Archive
• Kovaleva, Elizaveta; Austrheim, Håkon Olaf & Klötzli, Urs Stefan (2017). Interpretation of zircon coronae textures from metapelitic granulites of the Ivrea-Verbano Zone, northern Italy: Two-stage decomposition of Fe-Ti oxides. Solid Earth (SE). ISSN 1869-9510. 8(4), p. 789–804. doi: 10.5194/se-8-789-2017. Full text in Research Archive
• Ruiter, Lisa de & Austrheim, Håkon Olav (2017). Formation of magnesium silicate hydrate cement in nature. Journal of the Geological Society. ISSN 0016-7649. 175(2), p. 308–320. doi: 10.1144/jgs2017-089. Full text in Research Archive
• Ulven, Ole Ivar; Beinlich, Andreas; Hövelmann, Jörn-Erik; Austrheim, Håkon Olav & Jamtveit, Bjørn (2017). Subarctic physicochemical weathering of serpentinized peridotite. Earth and Planetary Science Letters. ISSN 0012-821X. 468, p. 11–26. doi: 10.1016/j.epsl.2017.03.030. Full text in Research Archive Show summary

  Frost weathering is effective in arctic and subarctic climate zones where chemical reactions are limited by the reduced availability of liquid water and the prevailing low temperature. However, small scale mineral dissolution reactions are nevertheless important for the generation of porosity by allowing infiltration of surface water with subsequent fracturing due to growth of ice and carbonate minerals. Here we combine textural and mineralogical observations in natural samples of partly serpentinized ultramafic rocks with a discrete element model describing the fracture mechanics of a solid when subject to pressure from the growth of ice and carbonate minerals in surface-near fractures. The mechanical model is coupled with a reaction–diffusion model that describes an initial stage of brucite dissolution as observed during weathering of serpentinized harzburgites and dunites from the Feragen Ultramafic Body (FUB), SE-Norway. Olivine and serpentine are effectively inert at relevant conditions and time scales, whereas brucite dissolution produces well-defined cm to dm thick weathering rinds with elevated porosity that allows influx of water. Brucite dissolution also increases the water saturation state with respect to hydrous Mg carbonate minerals, which are commonly found as infill in fractures in the fresh rock. This suggests that fracture propagation is at least partly driven by carbonate precipitation. Dissolution of secondary carbonate minerals during favorable climatic conditions provides open space available for ice crystallization that drives fracturing during winter. Our model reproduces the observed cm-scale meandering fractures that propagate into the fresh part of the rock, as well as dm-scale fractures that initiate the breakup of larger domains. Rock disintegration increases the reactive surface area and hence the rate of chemical weathering, enhances transport of dissolved and particulate matter in the weathering fluid, and facilitates CO2 uptake by carbonate precipitation. Our observations have implications for element cycling and CO2 sequestration in natural gravel and mine tailings.

• Centrella, Stephen; Austrheim, Håkon Olav & Putnis, Andrew (2016). Mass transfer and trace element redistribution during hydration of granulites in the Bergen Arcs, Norway. Lithos. ISSN 0024-4937. 262, p. 1–10. doi: 10.1016/j.lithos.2016.06.019. Full text in Research Archive
• Jamtveit, Bjørn; Austrheim, Håkon Olav & Putnis, Andrew (2016). Disequilibrium metamorphism of stressed lithosphere. Earth-Science Reviews. ISSN 0012-8252. 154, p. 1–13. doi: 10.1016/j.earscirev.2015.12.002. Full text in Research Archive Show summary

  Most changes in mineralogy, density, and rheology of the Earth's lithosphere take place by metamorphism, whereby rocks evolve through interactions between minerals and fluids. These changes are coupled with geodynamic processes and have first order effects on the global geochemical cycles of a large number of elements. In the presence of fluids, metamorphic reactions are fast compared to tectonically induced changes in pressure and temperature. Hence, rocks evolve through near-equilibrium states during fluid-producing metamorphism. However, much of the Earth's lower crust, and a significant fraction of the upper mantle do not contain free fluids. These parts of the lithosphere exist in a metastable state and are mechanically strong. When subject to changing temperature and pressure conditions at plate boundaries or elsewhere, these rocks do not react until exposed to externally derived fluids. Metamorphism of such rocks consumes fluids, and takes place far from equilibrium through a complex coupling between fluid migration, chemical reactions, and deformation processes. This disequilibrium metamorphism is characterized by fast reaction rates, dissipation of large amounts of energy as heat and work, and the generation of a range of emergent pore structures and fracture patterns that often control transport properties and thus further reaction progress. Fluid-consuming metamorphism leads to mechanical weakening due to grain size reduction, the formation of sheet silicates, and local heat production. Strain localization in the lower crust and upper mantle is therefore likely to be controlled by the availability of fluids. Fault-controlled migration of meteoric fluids from the brittle crust to the underlying ductile region in areas of compressive stress may provide a spatial and temporal link between localized strain and seismic activity in the upper crust and shear zone controlled deformation below. In a similar way, channelized fluid migration from areas undergoing prograde metamorphism in the lower plate of a subduction zone, may control the distribution of retrograde metamorphism and strain localization in the lower parts of the upper plate.

• Kusebauch, Christof; John, Timm; Barnes, Jaime D.; Klügel, Andreas & Austrheim, Håkon Olav (2015). Halogen element and stable chlorine isotope fractionation caused by fluid-rock interaction (Bamble sector, SE Norway). Journal of Petrology. ISSN 0022-3530. 56(2), p. 299–324. doi: 10.1093/petrology/egv001. Full text in Research Archive
• Centrella, Stephen; Austrheim, Håkon Olav & Putnis, Andrew (2015). Coupled mass transfer through a fluid phase and volume preservation during the hydration of granulite: An example from the Bergen Arcs, Norway. Lithos. ISSN 0024-4937. 236-237, p. 245–255. doi: 10.1016/j.lithos.2015.09.010. Full text in Research Archive
• Jung, Sejin; Jung, Haemyeong & Austrheim, Håkon Olav (2014). Characterization of olivine fabrics and mylonite in the presence of fluid and implications for seismic anisotropy and shear localization. Earth, Planets and Space. ISSN 1343-8832. 66(1). doi: 10.1186/1880-5981-66-46. Full text in Research Archive Show summary

  The Lindås Nappe, Bergen Arc, is located in western Norway and displays two high-grade metamorphic structures. A Precambrian granulite facies foliation is transected by Caledonian fluid-induced eclogite-facies shear zones and pseudotachylytes. To understand how a superimposed tectonic event may influence olivine fabric and change seismic anisotropy, two lenses of spinel lherzolite were studied by scanning electron microscope (SEM) and electron back-scattered diffraction (EBSD) techniques. The granulite foliation of the surrounding anorthosite complex is displayed in ultramafic lenses as a modal variation in olivine, pyroxenes, and spinel, and the Caledonian eclogite-facies structure in the surrounding anorthosite gabbro is represented by thin (<1 cm) garnet-bearing ultramylonite zones. The olivine fabrics in the spinel bearing assemblage were E-type and B-type and a combination of A- and B-type lattice preferred orientations (LPOs). There was a change in olivine fabric from a combination of A- and B-type LPOs in the spinel bearing assemblage to B- and E-type LPOs in the garnet lherzolite mylonite zones. Fourier transform infrared (FTIR) spectroscopy analyses reveal that the water content of olivine in mylonite is much higher (approximately 600 ppm H/Si) than that in spinel lherzolite (approximately 350 ppm H/Si), indicating that water caused the difference in olivine fabric. Fabric strength of olivine gets weaker as the grain size reduced, and as a result, calculated seismic properties for the two deformation stages reveal that P- and S-velocity anisotropies are significantly weaker in the mylonite. Microtextures and LPO data indicate that the deformation mechanism changed from dominant dislocation creep in spinel lherzolite to dislocation creep accompanied by grain-boundary sliding in mylonite. Shear localization in the mylonite appears to be originated from the grain size reduction through (1) enhanced dynamic recrystallization of olivine in the presence of water and (2) Zener pinning of clinopyroxene or (3) by ultracomminution during the pseudotachylyte stage.

• Bast, R.; Scherer, Erik E.; Mezger, Klaus; Austrheim, Håkon Olav; Ludwig, Thomas Hartmut & Marschall, Horst [Show all 8 contributors for this article] (2014). Boron isotopes in tourmaline as a tracer of metasomatic processes in the Bamble sector of Southern Norway. Contributions to Mineralogy and Petrology. ISSN 0010-7999. 168(4). doi: 10.1007/s00410-014-1069-4. Full text in Research Archive
• Corfu, Fernando; Austrheim, Håkon Olav & Ganzhorn, A-C (2014). Localized granulite and eclogite facies metamorphism at Flatraket and Kråkeneset, Western Gneiss Region: U-Pb data and tectonic implications. Geological Society Special Publication. ISSN 0305-8719. 390, p. 425–442. doi: 10.1144/SP390.22. Full text in Research Archive
• Beinlich, Andreas; Mavromatis, Vasileios; Austrheim, Håkon Olav & Oelkers, Eric H. (2014). Inter-mineral Mg isotope fractionation during hydrothermal ultramafic rock alteration - Implications for the global Mg-cycle. Earth and Planetary Science Letters. ISSN 0012-821X. 392, p. 166–176. doi: 10.1016/j.epsl.2014.02.028. Full text in Research Archive
• Hövelmann, Jörn-Erik; Austrheim, Håkon Olav & Putnis, A. (2014). Cordierite formation during the experimental reaction of plagioclase with Mg-rich aqueous solutions. Contributions to Mineralogy and Petrology. ISSN 0010-7999. 168(3). doi: 10.1007/s00410-014-1063-x. Full text in Research Archive
• Ulven, Ole Ivar; Storheim, Håkon; Austrheim, Håkon Olav & Malthe-Sørenssen, Anders (2014). Fracture initiation during volume increasing reactions in rocks and applications for CO2 sequestration. Earth and Planetary Science Letters. ISSN 0012-821X. 389, p. 132–142. doi: 10.1016/j.epsl.2013.12.039. Full text in Research Archive
• Mukai, Hiroki; Austrheim, Håkon Olav; Putnis, Christine V & Putnis, Andrew (2014). Textural evolution of plagioclase feldspar across a shear zone: Implications for deformation mechanism and rock strength. Journal of Petrology. ISSN 0022-3530. 55(8), p. 1457–1477. doi: 10.1093/petrology/egu030. Full text in Research Archive
• Plümper, Oliver; Beinlich, Andreas; Bach, Wolfgang; Janots, Emilie & Austrheim, Håkon Olav (2014). Garnets within geode-like serpentinite veins: Implications for element transport, hydrogen production and life-supporting environment formation. Geochimica et Cosmochimica Acta. ISSN 0016-7037. 141, p. 454–471. doi: 10.1016/j.gca.2014.07.002. Full text in Research Archive
• Andersen, Torgeir Bjørge; Austrheim, Håkon Olav; Deseta, Natalie; Silkoset, Petter & Ashwal, Lewis D. (2014). Large subduction earthquakes along the fossil Moho in Alpine Corsica. Geology. ISSN 0091-7613. 42(5), p. 395–398. doi: 10.1130/G35345.1. Full text in Research Archive Show summary

  ABSTRACT Subduction earthquakes release vast amounts of energy to crust and mantle lithosphere. The products of such drastic events are rarely observed in the field because they are mostly lost by subduction. We present new observations of deformation products formed by a few very large and numerous small intermediate-depth Alpine subduction earthquakes that are pre- served along the exhumed gabbro–mantle peridotite contact of the Piemont-Liguria oceanic basin in Corsica. The abrupt release of energy resulted in shear heating events that completely melted both gabbro and peridotite. The large volumes of melt that were generated can be stud- ied in the fault and injection vein breccia complex along the fault zone. The energy required for wholesale melting of a large volume of peridotite along the fault combined with previous esti- mates of stress drops show that very large earthquakes took place along the Moho of the sub- ducting plate. Because these fault rocks formed by intraplate seismicity, we suggest, by analogy with present-day subduction, that they represent a proxy for the lower seismogenic zone.

• Engvik, Ane; Ihlen, Peter Marcus & Austrheim, Håkon Olav (2014). Characterisation of Na-metasomatism in the Sveconorwegian Bamble Sector of South Norway. Geoscience Frontiers (GSF). ISSN 1674-9871. 5(5), p. 659–672. doi: 10.1016/j.gsf.2014.03.008. Full text in Research Archive
• Vrijmoed, Johannes Christiaan; Austrheim, Håkon Olav; John, T; Hin, R.C.; Corfu, Fernando & Davies, G.R. (2013). Metasomatism in the Ultrahigh-pressure Svartberget Garnet-peridotite (Western Gneiss Region, Norway): Implications for the Transport of Crust-derived Fluids within the Mantle. Journal of Petrology. ISSN 0022-3530. 54(9), p. 1815–1848. doi: 10.1093/petrology/egt032. Full text in Research Archive
• Austrheim, Håkon Olav (2013). Fluid and deformation induced metamorphic processes around Moho beneath continent collision zones: Examples from the exposed root zone of the Caledonian mountain belt, W-Norway. Tectonophysics. ISSN 0040-1951. 609, p. 620–635. doi: 10.1016/j.tecto.2013.08.030. Full text in Research Archive
• Beinlich, Andreas; Plümper, Oliver; Hövelmann, Jörn-Erik; Austrheim, Håkon Olav & Jamtveit, Bjørn (2012). Massive serpentinite carbonation at Linnajavri, N-Norway. Terra Nova. ISSN 0954-4879. 24(6), p. 446–455. doi: 10.1111/j.1365-3121.2012.01083.x. Full text in Research Archive
• Plümper, Oliver; Piazolo, Sandra & Austrheim, Håkon Olav (2012). Olivine Pseudomorphs after Serpentinized Orthopyroxene Record Transient Oceanic Lithospheric Mantle Dehydration (Leka Ophiolite Complex, Norway). Journal of Petrology. ISSN 0022-3530. 53(9), p. 1943–1968. doi: 10.1093/petrology/egs039. Full text in Research Archive
• Lundmark, Anders Mattias; Gabrielsen, Roy H.; Austrheim, Håkon Olav; Flaat, Kjersti; Strand, Tor & Ohm, Sverre Ekrene (2012). Late Devonian rifting in the central North Sea: evidence from altered felsic volcanic rocks in the Embla oil field. Marine and Petroleum Geology. ISSN 0264-8172. 29(1), p. 204–218. doi: 10.1016/j.marpetgeo.2011.06.002. Full text in Research Archive
• Malvoisin, Benjamin; Austrheim, Håkon Olav; Malthe-Sørenssen, Anders & Glodny, Johannes (2012). Deformation-related alteration of basaltic clasts during deep burial in sedimentary basins. Chemical Geology. ISSN 0009-2541. 322-323, p. 47–67. doi: 10.1016/j.chemgeo.2012.06.011. Full text in Research Archive
• Roffeis, Cornelia; Corfu, Fernando & Austrheim, Håkon Olav (2012). Evidence for a Caledonian amphibolite to eclogite facies pressure gradient in the Middle Allochthon Lindas Nappe, SW-Norway. Contributions to Mineralogy and Petrology. ISSN 0010-7999. 164(1), p. 81–99. doi: 10.1007/s00410-012-0727-7. Full text in Research Archive
• Plümper, Oliver; King, Helen E.; Vollmer, Christian; Ramasse, Quentin; Jung, Haemyeong & Austrheim, Håkon Olav (2012). The legacy of crystal-plastic deformation in olivine: high-diffusivity pathways during serpentinization. Contributions to Mineralogy and Petrology. ISSN 0010-7999. 163(4), p. 701–724. doi: 10.1007/s00410-011-0695-3. Full text in Research Archive

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• Harlov, Dan & Austrheim, Håkon Olav (2013). Metasomatism and the Chemical Transformation of Rock. Springer. ISBN 9783642283932. 806 p. Full text in Research Archive

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• Andersen, Torgeir Bjørge & Austrheim, Håkon Olaf (2024). Discovery and significance of pseudotachylytes in the Corsican Subduction Complex. Full text in Research Archive
• Austrheim, Håkon Olaf & Andersen, Torgeir Bjørge (2024). Extreme enrichment of Arsenic and Antimony during formation of Ni-Cr- rich jasper and quartzite from serpentinized peridotite. Full text in Research Archive Show summary

  Extreme enrichment of Arsenic and Antimony during formation of Ni-Cr- rich jasper and quartzite from serpentinized peridotite Håkon Austrheima and Torgeir B. Andersenb aDepartment of Geosciences, University of Oslo,Oslo, Norway, e-mail: h.o.austrheim@geo.uio.no bDepartment of Geosciences, University of Oslo, Oslo, Norway, e-mail: t.b.andersen@geo.uio.no Alteration of serpentinised peridotites of Highland Border Complex in Scotland take place in two steps. Listvenite-like dolomite-quartz rocks are formed by addition CaO and CO2 at constant MgO and SiO2 involving a mass-increase of ca 140 %. Stage-two involves dissolution of dolomite evinced by the abundant pores and rhombohedral-shaped grains of quartz to form Cr- and Ni-rich jasper and quartzites. Formation of the jasper-quartzites involve a mass-reduction of ca 80%. The listvenite-like and jasper-quartzite rocks have enrichment in the fluid mobile elements Ba, Sr, Cs, As and Sb. The As is present in the Aluminium Phosphate-Sulphate group of minerals formed during alteration of Cr- spinel. Cr-spinel also alters to porous hematite and ferrihydrite with patches containing up to 5 wt% As2O3. Enrichment of As, related to alteration of chromite, is previously unknown from natural rocks, but strongly resembles efficient methods used for remediation of this potential toxic element. Formation of quartzite and jasper from peridotite and their common presence as pebbles both in the Devonian Old Red conglomerates, in the Highland Border Complex and in Devonian Basins in the Scandinavian Caledonides, highlights their importance and potential for provenance- and tectono- stratigraphic correlations.

• Austrheim, Håkon Olaf & Andersen, Torgeir Bjørge (2023). Extreme enrichment of Arsenic and Antimony in altered peridotite; mechanism and consequences. Full text in Research Archive
• Lu, Yang; Sednev-Lugovets, Anton; Carvalho, Patricia Almeida; Guzik, Matylda N.; Dunkel, Kristina G & Austrheim, Håkon Olaf [Show all 7 contributors for this article] (2023). Dypingite revisited. Norsk Mineralsymposium. 2023, p. 23–30. Full text in Research Archive
• Friis, Henrik; Lu, Yang; Sednev-Lugovets, Anton; Carvalho, Patricia Almeida; Guzik, Matylda N. & Dunkel, Kristina G [Show all 7 contributors for this article] (2023). Dypingitt - Nytt 'liv' i gamle gruver. Full text in Research Archive
• Andersen, Torgeir Bjørge & Austrheim, Håkon Olaf (2023). Scotland revisited: Ekstreme enrichment of Arsenic and Antimon in alteret peridotites in The Highland Border Complex. Full text in Research Archive
• Lu, Yang; Sednev-Lugovets, Anton; Carvalho, Patricia Almeida; Guzik, Matylda N.; Dunkel, Kristina G & Austrheim, Håkon Olaf [Show all 7 contributors for this article] (2023). Dypingite series defined by the content of molecular H2O. Full text in Research Archive
• Guzik, Matylda N.; Sednev-Lugovets, Anton; Carvalho, Patricia Almeida; Friis, Henrik; Lu, Yang & Vistad, Ørnulv Bjørnsson [Show all 7 contributors for this article] (2023). Sustainable materials & green technologies for renewable energy systems / Nature-inspired filters for sequestration of heavy metals. Full text in Research Archive
• Engvik, Ane; Gautneb, Håvard; Mørkved, Pål Tore; Solberg, Janja Knezevic; Erambert, Muriel & Austrheim, Håkon Olaf (2022). Graphite in granulite - characterization, origin, role of fluids and consequences for rheology. Full text in Research Archive
• Sednev-Lugovets, Anton; Lu, Yang; Carvalho, Patricia Almeida; Vistad, Ørnulv Bjørnsson; Friis, Henrik & Austrheim, Håkon Olaf [Show all 7 contributors for this article] (2022). Dypingite: The phase identification and transformation. Full text in Research Archive Show summary

  Dypingite is a naturally occurring mineral, with an empirical formula Mg₅(CO₃)₄(OH)₂·5H₂O, and a member of the hydrocarbonate mineral group. It was named in 1970 by Gunnar Raade, after the Dypingdal serpentine-magnesite deposit in Norway ( ). Recently, it was reported that this mineral can effectively remove heavy metals (e.g., Cr, Cd, Cu, Pb, Ni ( )) from water and cause their long-term immobilisation ( ). It is expected that the unique desert rose morphology of the compound or/and peculiarities of its crystal structure (Figure 1) are the reasons of the dypingite remarkable sorption properties. Despite the fact that this mineral has been known for 50 years, the information about its unit cell parameters, or even Bragg peak positions, is inconsistent and surprisingly limited. To partly fill this gap, we have been performing comprehensive structural and microstructural studies on the natural and synthetic dypingite powder samples to: i) identify a crystalline phase called dypingite; ii) correctly index powder X-ray diffraction (PXD) patterns so as to determine the compound unit cell parameters and to solve its crystal structure; iii) investigate the dypingite phase transformation occurring upon the compound hydration/dehydration.

• Sednev-Lugovets, Anton; Lu, Yang; Carvalho, Patricia Almeida; Vistad, Ørnulv Bjørnsson; Friis, Henrik & Austrheim, Håkon Olaf [Show all 7 contributors for this article] (2022). Dypingite: The phase identification and transformation. Full text in Research Archive Show summary

  Dypingite is a naturally occurring mineral, with an empirical formula Mg₅(CO₃)₄(OH)₂·5H₂O, and a member of the hydrocarbonate mineral group. It was named in 1970 by Gunnar Raade, after the Dypingdal serpentine-magnesite deposit in Norway ( ). Recently, it was reported that this mineral can effectively remove heavy metals (e.g., Cr, Cd, Cu, Pb, Ni ( )) from water and cause their long-term immobilisation ( ). It is expected that the unique desert rose morphology of the compound or/and peculiarities of its crystal structure (Figure 1) are the reasons of the dypingite remarkable sorption properties. Despite the fact that this mineral has been known for 50 years, the information about its unit cell parameters, or even Bragg peak positions, is inconsistent and surprisingly limited. To partly fill this gap, we have been performing comprehensive structural and microstructural studies on the natural and synthetic dypingite powder samples to: i) identify a crystalline phase called dypingite; ii) correctly index powder X-ray diffraction (PXD) patterns so as to determine the compound unit cell parameters and to solve its crystal structure; iii) investigate the dypingite phase transformation occurring upon the compound hydration/dehydration.

• Engvik, Ane; Gautneb, Håvard; Mørkved, Pål Tore; Solberg, Janja Knezevic; Erambert, Muriel & Austrheim, Håkon Olaf (2021). Proterozoic deep carbon - The graphite bearing rocks of the Lofoten-Vesterålen area, North Norway; Characterisation, origin and the role of fluids. Full text in Research Archive
• Engvik, Ane; Gautneb, Håvard; Solberg, Janja Knezevic; Rønning, Jan Steinar & Austrheim, Håkon Olaf (2020). High-grade formation of graphite in Vesterålen, northern Norway, and its consequences for petrophysical properties of the lower continental crust. Full text in Research Archive
• Austrheim, Håkon Olaf (2018). Fluids, Metamorphism and Seismicity. Full text in Research Archive
• Ulven, Ole Ivar; Austrheim, Håkon Olaf & Jamtveit, Bjørn (2018). Self-induced serpentine deformation and its effect on weathering. Full text in Research Archive
• Halpaap, Felix; Rondenay, Stéphane; Ottemöller, Lars; Perrin, Alexander; Goes, Saskia & Austrheim, Håkon Olaf (2018). Seismicity, Metamorphism & Fluid Migration in the Western Hellenic Subduction Zone. Full text in Research Archive
• Ruiter, Lisa de; Austrheim, Håkon Olaf; Gunnæs, Anette Eleonora & Dysthe, Dag Kristian (2018). Quartz dissolution and M-S-H cement precipitation in a high pH ultramafic system. Full text in Research Archive
• Ruiter, Lisa de; Austrheim, Håkon Olaf; Dysthe, Dag Kristian & Gunnæs, Anette Eleonora (2018). Quartz weathering associated with magnesium silicate hydrate cement precipitation. Full text in Research Archive
• Ruiter, Lisa De; Austrheim, Håkon Olav & Dysthe, Dag Kristian (2017). Formation of magnesium silicate hydrate cement during lithification of ultramafic-rich glacial deposits. Full text in Research Archive
• Ruiter, Lisa De; Austrheim, Håkon Olav & Dysthe, Dag Kristian (2017). Formation of magnesium silicate hydrate cement in the weathering zone of ultramafites. Full text in Research Archive
• Ruiter, Lisa De; Austrheim, Håkon Olav & Dysthe, Dag Kristian (2016). The lithification of ultramafic dominated till with magnesium silicate hydrate: a new green concrete. Full text in Research Archive
• Dysthe, Dag Kristian & Austrheim, Håkon Olav (2015). Beyond research based teaching: Teaching interdisciplinary research and pushing students beyond their training. Full text in Research Archive
• Dysthe, Dag Kristian & Austrheim, Håkon Olav (2015). Beyond research based teaching: Teaching interdisciplinary research and pushing students beyond their training. Full text in Research Archive
• Ulven, Ole Ivar; Austrheim, Håkon Olav; Beinlich, Andreas; Hövelmann, Jörn-Erik & Jamtveit, Bjørn (2015). Subarctic physicochemical weathering of serpentinized peridotite. Full text in Research Archive
• Ulven, Ole Ivar; Beinlich, Andreas; Sun, WaiChing; Malthe-Sørenssen, Anders & Austrheim, Håkon Olav (2015). Fracture Formation due to Growth of Hydrous Carbonates. Full text in Research Archive
• Ulven, Ole Ivar; Austrheim, Håkon Olav; Hövelmann, Jörn-Erik; Beinlich, Andreas & Malthe-Sørenssen, Anders (2014). Fragmentation and Carbonation of Serpentinized Dunites. Full text in Research Archive
• Dunkel, Kristina G.; Drivdal, Kerstin; Austrheim, Håkon Olav; Andersen, Torgeir Bjørge & Jamtveit, Bjørn (2014). Faulting and Serpentinisation of Peridotites in the Leka Ophiolite. Full text in Research Archive
• Andersen, Torgeir Bjørge; Deseta, Natalie; Silkoset, Petter; Austrheim, Håkon Olav & Ashwal, Lewis D. (2014). Large Subduction Earthquakes along the fossil MOHO in Alpine Corsica: what was the role of fluids? Full text in Research Archive
• Silkoset, Petter; Andersen, Torgeir Bjørge; Austrheim, Håkon Olav; Magraso, Anna & Wheeler, John (2013). Microstructure of ultramafic pseudotachylyte from Alpine Corsica – insights into earthquakes in mantle lithosphere. Full text in Research Archive
• Drivdal, Kerstin; Austrheim, Håkon Olav & Andersen, Torgeir Bjørge (2013). Mineral reactions and structural evolution of deformation zones transecting the layered sequence of the Leka Ophiolite Complex (LOC). Full text in Research Archive
• Aasen, Hedda S; Andersen, Torgeir Bjørge & Austrheim, Håkon Olav (2013). Eclogite facies pseudotachylytes in the Lindås Nappe, Bergen Arcs: field observations, textures and fault dynamics. Full text in Research Archive

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