Leandro Cesar Gallo

• Domeier, Mathew Michael; Gallo, Leandro C.; Marcilly, Chloé M. & Torsvik, Trond H. (2026). Quadrupolar sea level fluctuations reveal episodes of rapid polar wander. Science. ISSN 0036-8075. 394(6819), p. 87–90. doi: 10.1126/science.aec8423. Full text in Research Archive Show summary

  True polar wander (TPW) is presently occurring at a rate of ~10 centimeters per year, exceeding the mean rate of differential plate motion. Whether this rate is transient and negligible on geological timescales or whether Earth has experienced rapid TPW lasting millions of years is unclear. Paleomagnetic evidence has been used to propose fast episodes of TPW, but limitations of the paleomagnetic record have precluded definitive results. Rapid TPW will induce global sea level fluctuations associated with relative changes in centrifugal potential, offering an independent test. We evaluated this prediction using continental flooding reconstructions and identified multiple robust quadrupolar patterns since 320 million years ago, confirming that protracted rapid TPW has occurred on Earth and that couplings among Earth’s rotational dynamics, mantle processes, and surface environments can be strongly episodic.

• Giannicor, Guido M.; Gianni, Conrado; Gallo, Leandro C.; Sippl, Christian; Arvizu, Harim & Ramos, Victor (2026). Mid-ocean ridge extinctions as amplifiers of plate-tectonic change. Earth-Science Reviews. ISSN 0012-8252. p. 105685–105685. doi: 10.1016/j.earscirev.2026.105685. Full text in Research Archive Show summary

  Plate-tectonic reorganizations involve rapid shifts in plate motions, boundary forces, and tectonic regimes, yet the role of mid-ocean ridge extinctions (MOREs) remains unclear. Here we show that MOREs can amplify reorganizations by removing divergent boundaries, coupling formerly independent plate domains, and enabling stress transmission across extinct ridges. We illustrate this mechanism through four Cenozoic examples closely associated with plate reorganizations: the Wharton, Pacific–Farallon, Shikoku, and Sandra–Malpelo ridges. These cases indicate that, when extinct ridges are incorporated into larger plate circuits undergoing reorganization, they can transmit stresses generated elsewhere in the network toward neighboring margins, consistent with cascading plate-to-plate reorganizations. Strength-profile calculations show that substantial post-MORE strengthening can develop within a few million years after extinction. However, the early coupling inferred from the natural examples is best explained if this strengthening acts on ridge systems already mechanically preconditioned before shutdown, particularly by terminal slow- to ultraslow-spreading that produces a relatively thick axial brittle lithosphere. We therefore propose that inherited preconditioning enables early stress transmission, while subsequent thermo-mechanical strengthening progressively consolidates the extinct boundary. MOREs thus represent evolving mechanical structures that influence how plate-boundary forces are transmitted during plate-network reorganization.

• Zhang, Yiming; Swanson‐Hysell, Nicholas L.; Domeier, Mathew Michael; Gallo, Leandro; Sapienza, Facundo & Afanador, Diego Alberto Osorio (2026). Enriching Paleogeographic Reconstruction Through the Integration of Bayesian Age Models Into Site‐Based Apparent Polar Wander Paths. Journal of Geophysical Research (JGR): Solid Earth. ISSN 2169-9313. 131(9). doi: 10.1029/2026jb034561. Full text in Research Archive Show summary

  Apparent polar wander paths (APWPs) synthesized from paleomagnetic data are foundational to our understanding of the long‐term motions of lithospheric plates. Recent progress has highlighted the advantages of developing such paths from paleomagnetic sites that provide individual snapshots of the ancient geomagnetic field. This approach contrasts with traditional methods that rely on study‐level mean poles—through which it is challenging to incorporate positional and temporal uncertainty. A benefit of the site‐based approach is the flexibility in incorporating temporal information. Rather than relying on a single age assigned to a mean paleomagnetic pole that groups sites together, varied ages can be assigned to individual sites. It also allows the incorporation of stratigraphic superposition constraints, which would otherwise be discarded. We show how probabilistic stratigraphic age models can be integrated into the development of site‐based APWPs. Through resampling from the posterior distributions of such age models, temporal uncertainty can be incorporated while honoring stratigraphic superposition. We illustrate this approach using volcanic and sedimentary successions with U‐Pb age constraints from the late Mesoproterozoic Midcontinent Rift of North America combined with contemporaneous lavas and intrusions from southwestern Laurentia. The result is a site‐based APWP of the Keweenawan Track with significantly higher temporal resolution than a traditional running mean. The high‐resolution path gives insights into motion rates and constrains the timing of change in path direction without requiring additional assumptions. This framework demonstrates how probabilistic treatment of age and positional uncertainties can strengthen quantitative tests of tectonic models.

• Tonti‐Filippini, Justin A. D.; Antonio, Paul Y. J.; Dahlgren, Sven; Boer, Rosa de; Gallo, Leandro & Silkoset, Petter [Show all 9 contributors for this article] (2026). Ediacara Obscura: Unveiling Hidden Magnetisations in the Fen Complex, Southern Norway. Geochemistry Geophysics Geosystems. 27(5). doi: 10.1029/2025gc012881. Full text in Research Archive Show summary

  Paleomagnetic directions found in Ediacaran (635–539 Ma) rocks are widely dispersed, which has led to conflicting hypotheses about tectonic regimes and geomagnetic field behavior during this period, and raised doubts about the fidelity of the paleomagnetic record. In particular, data from eastern and western Baltica show large and rapid changes in paleopole positions which are difficult to explain if we assume a geocentric axial dipole field operated in the Ediacaran. We present new paleomagnetic data from 214 samples across 18 sites of the Fen carbonatite‐alkaline rock complex (583 15 Ma) in southern Norway, coupled with detailed petrographic observations using transmitted and reflected light, scanning electron and quantum diamond microscopy, alongside conventional rock magnetic and mineralogical analyses. Our results indicate that the Fen complex and its associated intrusions were pervasively overprinted in the Permian (ca. 270 Ma), during tectono‐magmatic activity of the nearby Oslo Rift, which complicated previous paleomagnetic interpretations. However, after removing secondary overprints, we find that 7% of our specimens preserve weak, shallow paleodirections interpreted as primary. The outlier directions are found in rock types not previously studied, mainly damtjernites (ultramafic lamprophyre intrusions). Based on specimen directions from these preserved units, we define a new paleopole at 266.6E, −1.7N ( = 4.5, K  = 77.4, N  = 15), which places Baltica at low/equatorial latitudes during the mid‐Ediacaran (ca. 583 Ma). Our findings have significant implications for understanding the nature of the geomagnetic field and Baltica's paleogeography in the late Neoproterozoic.

• Xue, Yi; Domeier, Mathew Michael; Silkoset, Petter; Gallo, Leandro Cesar; Tonti-Filippini, Justin Antony Dean & Walderhaug, Harald James (2026). Cryptic Paleomagnetic Complexity in the Ediacaran Egersund Dikes. Geochemistry Geophysics Geosystems. 27(5). doi: 10.1029/2025GC012730. Full text in Research Archive Show summary

  The Ediacaran Period (∼635–539 Ma) represents a critical interval in Earth's evolution, yet its paleomagnetic record remains complex and contentious. One of the few Ediacaran paleomagnetic results from Baltica considered robust is a pole from the ca. 616 Ma Egersund dikes in southwest Norway, which is interpreted to represent a primary thermoremanent magnetization. However, we report on a new paleomagnetic and rock magnetic investigation of these dikes that suggests that their paleomagnetic record is more complex than previously recognized. Our results reveal a multicomponent remanence structure, and we identify a new high-temperature component that positive baked contact tests suggest to be the primary thermoremanent magnetization. Together with microscopic and geochemical analyses, we demonstrate that another distinct component represents a remagnetization acquired during Caledonian orogenesis. Although we also identified a stable direction similar to that interpreted as the primary component in earlier studies, our analysis suggests this component may be an artifact resulting from vector overlap of the other components. The origins of two additional directions, which deviate markedly from the other components and known Phanerozoic reference directions, remain uncertain. They may reflect transitional geomagnetic states, hinting at the possibility of a more dynamic and unstable Ediacaran geomagnetic field. Our revised pole position (20.8°N, 89.0°E) differs from earlier results by more than 40°, with important implications for Baltica's paleogeographic evolution. This study underscores the value of integrated approaches and highlights the importance of reinvestigating key paleomagnetic results, particularly from data-poor intervals of time and space.

• Sapienza, F.; Gallo, L. C.; Bolibar, J.; Pérez, F. & Taylor, J. (2025). Spherical Path Regression Through Universal Differential Equations With Applications to Paleomagnetism. Journal of Geophysical Research (JGR): Machine Learning and Computation. 2(4). doi: 10.1029/2025jh000626. Full text in Research Archive Show summary

  Directional data analysis plays a central role in paleomagnetism, where observations lie on a spherical surface. Existing methods for analyzing directional data often fail to incorporate prior physical knowledge about plate geodynamics, significantly constraining their potential. To address this limitation, we developed a hybrid, physics‐informed machine learning model that uses a neural network to learn the underlying rotations responsible for generating directional data. Our method robustly captures the time‐dependent variability of directional data in both synthetic and real paleomagnetic data sets. Additionally, by leveraging in the differentiable programming paradigm, we can incorporate physical constraints in the form of regularizations. These results have the potential to improve future estimations of apparent polar wander paths, advancing the reconstruction of past tectonic plate motions.

• Antonio, Paul Yves Jean; Rossignol, S; Gallo, Leandro Cesar; Trindade, Ricardo I.F.; Almeida, R De Souza & Lana, Cristiano [Show all 14 contributors for this article] (2025). Amazonia in Cambrian times: reconciling discordantpaleomagnetic dataset with a geocentric axial dipole? Journal of the Geological Society. ISSN 0016-7649. 182(6). doi: 10.1144/jgs2025-026. Full text in Research Archive Show summary

  Palaeomagnetic behaviour during the Ediacaran–Cambrian is problematic, with many discordant directions, suggesting a non-uniform magnetic field during the development of the first complex life on Earth c. 540 Myr ago. To better understand the global nature of such discrepancies, we provide new geochronological and palaeomagnetic data from the Parauapebas dyke swarm (6.10° S, 49.76° W), located in the southeastern Amazonian Craton (Carajás Province), Brazil. U–Pb dating on apatite and Ar–Ar whole-rock ages from different dykes give an emplacement date for this mafic dyke swarm of c. 522 Ma. Most of the sites revealed a stable characteristic remanent magnetization with Dm = 290.6° and Im = −42.4° (N = 15, k = 8, a95 = 14.4°), yielding a palaeomagnetic pole for Amazonia at 21.8° S, 14.4° E (K = 8.3, A95 = 14.1°). The primary origin of this pole is confirmed by a positive baked contact, the petrography and magnetic mineralogy experiments. Yielding an R criterion of 6, this is the first reliable pole for Amazonia during the Cambrian. Although a persistent anomalous magnetic field since the Ediacaran cannot be dismissed with the available dataset, such discrepancies could be attributed to uncertainties in global reconstructions or data-related issues. Without additional constraints, a Cambrian geocentric axial dipole may be considered.

• Gallo, Leandro Cesar; Domeier, Mathew Michael; Antonio, Paul Yves Jean; sapienza, facundo; Rapalini, Augusto & Font, Eric [Show all 12 contributors for this article] (2025). Unraveling remagnetization sources using statistical learning. Earth and Planetary Science Letters. ISSN 0012-821X. 662. doi: 10.1016/j.epsl.2025.119390. Full text in Research Archive Show summary

  The paleomagnetic archive provides invaluable insights into Earth's history, but its records are often obscured by various geological processes. A prime example is remagnetization, which can replace the original natural remanent magnetization. Although magnetic overprints can be detected by traditional paleomagnetic tests, the mechanisms responsible for them often remain elusive because linking bulk magnetic properties to their microscopic sources is inherently challenging. Here, we bridge this gap by pairing an extensive rock magnetic and geochemical dataset with statistical learning techniques for the first time. Using a Random Forest regressor trained on geochemical data, we accurately predict the growth of fine-grained magnetite in an undeformed late Ediacaran section of remagnetized carbonate rocks from Paraguay. Our modeling results identify the K/Al ratio—alongside K and Sr contents—as key predictors of this remagnetization mechanism. Notably, clay mineralogy analyses further link the K/Al ratio to enhanced clay authigenesis (illitization) driven by K-feldspar dissolution and albitization—processes that also release iron. Together, these findings indicate that remagnetization occurred via authigenic magnetite formation under isochemical diagenesis—without the involvement of external fluids. This novel application of statistical learning to uncover the geochemical drivers of chemical remagnetizations provides a robust framework to investigate and understand these events. It could also open new avenues for their direct dating, thereby significantly enriching the global paleomagnetic record.

• Gianni, Guido; Gallo, Leandro Cesar; Likerman, Jeremias; Echaurren, Andrés; Gianni, Conrado R. & Faccenna, Claudio (2025). Slab underthrusting is the primary control on flat-slab size. Science Advances. 11(28). doi: 10.1126/sciadv.adv8872. Full text in Research Archive Show summary

  Flat subduction, an intermittent phenomenon along active margins, arises from well-known causes, yet the mechanisms driving its expansion remain poorly understood. The prevailing view suggests that trenchward continental motion drives slab overthrusting, causing the flat slab to expand oceanward. Here, we explore an alternative mechanism: underthrusting of the subducting plate through forward propagation of the flat-slab hinge. We directly evaluate both hypotheses through a kinematic analysis of trench and flat-slab motions using a global flat subduction database cast into multiple absolute plate motion models. Our results indicate that flat-slab expansion reflects distinct end-member processes, with forward propagation emerging as the dominant mode. We present a framework for flat-slab propagation that emphasizes the dynamic interaction between lower-plate motion and slab pull from adjacent subduction zones, an interplay validated through numerical modeling. These findings challenge conventional assumptions and underscore the need to reconsider the role of lower-plate kinematics in flat-slab dynamics.

• Vaes, Bram; Hinsbergen, Douwe Van; Lagemaat, Suzanna H.A. van de; Wiel, Erik van der; Lom, Nalan & Advokaat, Eldert L. [Show all 15 contributors for this article] (2023). A global apparent polar wander path for the last 320 Ma calculated from site-level paleomagnetic data. Earth-Science Reviews. ISSN 0012-8252. 245. doi: 10.1016/j.earscirev.2023.104547. Full text in Research Archive Show summary

  Apparent polar wander paths (APWPs) calculated from paleomagnetic data describe the motion of tectonic plates relative to the Earth's rotation axis through geological time, providing a quantitative paleogeographic framework for studying the evolution of Earth's interior, surface, and atmosphere. Previous APWPs were typically calculated from collections of paleomagnetic poles, with each pole computed from collections of paleomagnetic sites, and each site representing a spot reading of the paleomagnetic field. It was recently shown that the choice of how sites are distributed over poles strongly determines the confidence region around APWPs and possibly the APWP itself, and that the number of paleomagnetic data used to compute a single paleomagnetic pole varies widely and is essentially arbitrary. Here, we use a recently proposed method to overcome this problem and provide a new global APWP for the last 320 million years that is calculated from simulated site-level paleomagnetic data instead of from paleopoles, in which spatial and temporal uncertainties of the original datasets are incorporated. We provide an updated global paleomagnetic database scrutinized against quantitative, stringent quality criteria, and use an updated global plate motion model. The new global APWP follows the same trend as the most recent pole-based APWP but has smaller uncertainties. This demonstrates that the first-order geometry of the global APWP is robust and reproducible. Moreover, we find that previously identified peaks in APW rate disappear when calculating the APWP from site-level data and correcting for a temporal bias in the underlying data. Finally, we show that a higher-resolution global APWP frame may be determined for time intervals with high data density, but that this is not yet feasible for the entire 320–0 Ma time span. Calculating polar wander from site-level data provides opportunities to significantly improve the quality and resolution of the global APWP by collecting large and well-dated paleomagnetic datasets from stable plate interiors, which may contribute to solving detailed Earth scientific problems that rely on a paleomagnetic reference frame.

• Sapienza, F.; Gallo, Leandro Cesar; Zhang, Yiming; Vaes, Bram; Domeier, Mathew Michael & Swanson-Hysell, Nicholas L. (2023). Quantitative Analysis of Paleomagnetic Sampling Strategies. Journal of Geophysical Research (JGR): Solid Earth. ISSN 2169-9313. 128(11). doi: 10.1029/2023JB027211. Full text in Research Archive Show summary

  Abstract Sampling strategies used in paleomagnetic studies play a crucial role in dictating the accuracy of our estimates of properties of the ancient geomagnetic field. However, there has been little quantitative analysis of optimal paleomagnetic sampling strategies and the community has instead defaulted to traditional practices that vary between laboratories. In this paper, we quantitatively evaluate the accuracy of alternative paleomagnetic sampling strategies through numerical experiments and an associated analytical framework. Our findings demonstrate a strong correspondence between the accuracy of an estimated paleopole position and the number of sites or independent readings of the time‐varying paleomagnetic field, whereas larger numbers of in‐site samples have a dwindling effect. This remains true even when a large proportion of the sample directions are spurious. This approach can be readily achieved in sedimentary sequences by distributing samples stratigraphically, considering each sample as an individual site. However, where the number of potential independent sites is inherently limited the collection of additional in‐site samples can improve the accuracy of the paleopole estimate (although with diminishing returns with increasing samples per site). Where an estimate of the magnitude of paleosecular variation is sought, multiple in‐site samples should be taken, but the optimal number is dependent on the expected fraction of outliers. The use of filters based on angular distance helps the accuracy of paleopole estimation, but leads to inaccurate estimates of paleosecular variation. We provide both analytical formulas and a series of interactive Jupyter notebooks allowing optimal sampling strategies to be developed from user‐informed expectations.

• Gallo, Leandro Cesar; Domeier, Mathew Michael; Sapienza, F.; Swanson-Hysell, N. L.; Vaes, B. & Zhang, Y. [Show all 14 contributors for this article] (2023). Embracing Uncertainty to Resolve Polar Wander: A Case Study of Cenozoic North America. Geophysical Research Letters. ISSN 0094-8276. 50(11). doi: 10.1029/2023GL103436. Full text in Research Archive Show summary

  Abstract Our understanding of Earth's paleogeography relies heavily on paleomagnetic apparent polar wander paths (APWPs), which represent the time‐dependent position of Earth's spin axis relative to a given block of lithosphere. However, conventional approaches to APWP construction have significant limitations. First, the paleomagnetic record contains substantial noise that is not integrated into APWPs. Second, parametric assumptions are adopted to represent spatial and temporal uncertainties even where the underlying data do not conform to the assumed distributions. The consequences of these limitations remain largely unknown. Here, we address these challenges with a bottom‐up Monte Carlo uncertainty propagation scheme that operates on site‐level paleomagnetic data. To demonstrate our methodology, we present an extensive compilation of site‐level Cenozoic paleomagnetic data from North America, which we use to generate a high‐resolution APWP. Our results demonstrate that even in the presence of substantial noise, polar wandering can be assessed with unprecedented temporal and spatial resolution.

• Vaes, Bram; Gallo, Leandro Cesar & Hinsbergen, Douwe Van (2022). On Pole Position: Causes of Dispersion of the Paleomagnetic Poles Behind Apparent Polar Wander Paths. Journal of Geophysical Research (JGR): Solid Earth. ISSN 2169-9313. 127(4). doi: 10.1029/2022JB023953. Full text in Research Archive Show summary

  Paleomagnetic poles used to compute apparent polar wander paths (APWPs) are strongly dispersed, which was recently shown to cause a large fraction (>50%) of these poles to be statistically distinct from the APWP to which they contributed, suggesting that current statistical approaches overestimate paleomagnetic resolution. Here, we analyze why coeval paleopoles are so dispersed, using the paleopoles behind the most recent global APWP and a compilation of paleomagnetic data obtained from <10 Ma volcanic rocks (PSV10). We find that paleopoles derived from sedimentary rocks, or from data sets underrepresenting paleosecular variation (PSV), are more dispersed and more frequently displaced. We show that paleopoles based on a smaller number of paleomagnetic sites are more dispersed than poles based on larger data sets, revealing that the degree to which PSV is averaged is an important contributor to the pole dispersion. We identify as a fundamental problem, however, that the number of sites used to calculate a paleopole, and thus the dispersion of coeval paleopoles, is essentially arbitrary. We therefore explore a different approach in which reference poles of APWPs are calculated from site-level data instead of paleopoles, thereby assigning larger weight to larger data sets. We introduce a bootstrap-based method for comparing a collection of paleomagnetic data with a reference data set on the same hierarchical level, whereby the uncertainty is weighted against the number of paleomagnetic sites. Finally, our study highlights that demonstrating smaller tectonic displacements requires larger paleomagnetic data sets, and that such data sets can strongly improve future APWPs.

• Gallo, Leandro Cesar; Sapienza, Facundo & Domeier, Mathew Michael (2022). An optimization method for paleomagnetic Euler pole analysis. Computers & Geosciences. ISSN 0098-3004. 166. doi: 10.1016/j.cageo.2022.105150. Full text in Research Archive Show summary

  Owing to the axial symmetry of the Earth’s magnetic field, paleomagnetic data only directly record the latitudinal and azimuthal positions of crustal blocks in the past, and paleolongitude cannot be constrained. An ability to overcome this obstacle is thus of fundamental importance to paleogeographic reconstruction. Paleomagnetic Euler pole (PEP) analysis presents a unique means to recover such information, but prior implementations of the PEP method have incorporated subjective decisions into its execution, undercutting its fidelity and rigor. Here we present an optimization approach to PEP analysis that addresses some of these deficiencies—namely the objective identification of change-points and small-circle arcs that together approximate an apparent polar wander path. We elaborate on our novel methodology and conduct some experiments with synthetic data to demonstrate its performance. We furthermore present implementations of our methods both as adaptable, stand-alone scripts in Python and as a streamlined interactive workflow that can be operated through a web browser.

• Gallo, Leandro Cesar; Cristallini, Ernesto O. & Svarc, Marcela (2018). A Nonparametric Approach for Assessing Precision in Georeferenced Point Clouds Best Fit Planes: Toward More Reliable Thresholds. Journal of Geophysical Research (JGR): Solid Earth. ISSN 2169-9313. doi: 10.1029/2018JB016319. Full text in Research Archive
• Gallo, Leandro Cesar; Tomezzoli, Renata Nela & Cristallini, Ernesto O. (2017). A pure dipole analysis of the Gondwana apparent polar wander path: Paleogeographic implications in the evolution of Pangea. Geochemistry Geophysics Geosystems. doi: 10.1002/2016GC006692. Full text in Research Archive

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• Domeier, Mathew Michael; Gallo, Leandro C. & Tonti-Filippini, Justin Antony Dean (2026). Mechanistic linkages between remagnetizations and superchrons. Full text in Research Archive
• Tonti-Filippini, Justin Antony Dean; Antonio, Paul Yves Jean; Dahlgren, Sven Harald; Boer, R. de; Gallo, Leandro C. & Silkoset, Petter [Show all 9 contributors for this article] (2026). Ediacara obscura: Unveiling hidden magnetisations in the Fen complex, southern Norway. Full text in Research Archive
• Tonti-Filippini, Justin Antony Dean; Antonio, Paul Yves Jean; Dahlgren, Sven Harald; Boer, R. de; Gallo, Leandro C. & Silkoset, Petter [Show all 9 contributors for this article] (2026). Ediacara obscura: Unveiling hidden magnetisations in the Fen complex, southern Norway. Full text in Research Archive
• Gallo, Leandro Cesar; Domeier, Mathew Michael; Antonio, Paul Yves Jean; Trindade, Ricardo I.F.; Temporim, Filipe Altoé & Tonti-Filippini, Justin Antony Dean [Show all 8 contributors for this article] (2024). Using Statistical Learning to Identify Remagnetization Sources in Carbonate Rocks. Full text in Research Archive
• Xue, Yi; Domeier, Mathew Michael; Silkoset, Petter; Gallo, Leandro C.; Kulakov, Evgeniy & Boer, Rosa de [Show all 7 contributors for this article] (2024). Revisiting the paleomagnetism of the Egersund dikes. Full text in Research Archive
• Gallo, Leandro Cesar; Domeier, Mathew Michael; Trindade, Ricardo I.F.; Antonio, Paul Yves Jean; Temporim, Filipe Altoé & Warren, Lucas V. (2023). Rock Magnetic Cyclostratigraphy of the Ediacaran-Cambrian Tagatiya-guazu formation, Paraguay. Full text in Research Archive
• Xue, Yi; Domeier, Mathew Michael; Silkoset, Petter; Kulakov, Evgeniy; Gallo, Leandro C. & Boer, Rosa de [Show all 7 contributors for this article] (2023). Revisiting the paleomagnetism of the Egersund dikes. Full text in Research Archive

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