Research Projects

Psuedotachylites are indicators of paleoseismic earthquakes and are produced by frictional melting during seismic slip along subduction zones. They may provide information on the physical properties of the fault and the thermodynamics of the slip process (Sibson, 1975, Maddock, 1983, Spray, 1995, Wenk et al., 2000, Di Toro et al., 2009, Spray, 2010). Pseudotachylites commonly occur in shear zones, where they are often spatially associated with ductile fabrics (Pittarello et al., 2012). To provide insight into this topic, we will conduct a case study in the mylonitic granitoid in the Ambaji, South Delhi terrane, Aravalli Delhi Mobile belt (NW India), which records both ductile (mylonites (deformed psuedotachylites)) and brittle deformation feature pseudotachylites. This coexistence of pseudotachylites and foliated psuedotachylite suggests that there may be a relation between brittle deformation and ductile deformation: because seismic slip commonly occurs along pre-existing anisotropic planes, such as mica rich phyllosilicate-defined fabrics (Niemeijer et al., 2010). Here we explore how the field, lab, and geochemistry of deformation products provides insight into the localization and thermodynamics of brittle deformation along brittle-ductile shear zone in a late Paleoproterozoic Ambaji, South Delhi terrane, Aravalli-Delhi mobile belt, NW India. The duration and temperature of pseudotachylite and deformed pseudotachylite development will be tracked by the geochemical signature of major minerals in both ductile and brittle deformation products. The objective of the project is to illustrate more accurate elemental variations in fault rocks, which provides new insights into the element migration in the pseudotachylites due to frictional melting and fluid-rock interaction afterward. This research will supply important information that will improve our understanding of seismic faulting mechanisms and fault behavior in seismogenic fault zones. The formation of microlites is a very slow process that is driven by the interaction of glass with external forces like water, hydrothermal fluid, or thermal effect. The timing of the formation of microlites in the study area pseudotachylyte needs more study to be explained. Detailed geochemical and age dating is required to infer the exact nature of the shear zone and upto what duration it has been active. The duration of the shear zone upto what time it has been active can be determined by Ar-Ar dating in the future. This study can also be applicable to the present seismic zones where we are finding both brittle and ductile shear structures.