Interphase boundary misorientation in serpentinized mantle rocks

Seminary by Luiz Morales

Interphase boundaries are planar defects that separate two different phases, which may have different compositions and/or crystalline structures. Depending on the degree of atomic structure matching between the two adjacent phases, the interphase boundaries can be classified in coherent, semicoherent and incoherent phase boundaries. Here we present the recent developments of interphase misorientation boundary analyses calculated from EBSD data in an olivine-antigorite schist from the Val Malenco (Italy). The antigorite schist is strongly foliated and contains about 78% antigorite and 22% olivine, with minor amounts (<1%) of magnetite and chlorite. The antigorite CPO is characterized by a point maxima of poles to (100) parallel to lineation and poles to (001) to the foliation normal. Phase transformation relationships between olivine and antigorite are evident in phase boundary misorientation analysis, (100)ol||(001)atg being more frequent than  [001]ol||[010]atg. From the interphase misorientation analyses, we have described two new phase transformation relationships between olivine and antigorite, namely (100)ol||(010)atg & [001]ol||[100]atg and No.4 (010)ol||(210)atg & [100]ol||[001]atg. We demonstrate the potential of interphase misorientation analysis on the study of phase transformations and metamorphic reactions

Published Jan. 28, 2019 1:45 PM - Last modified Jan. 28, 2019 1:45 PM