28 D18. Petrology, Igneous/Metamorphic

Monday, 26 October 2020
5:30 PM - 8:00 PM
Meeting Rooms

IDENTIFYING PARAMETERS INFLUENCING TEXTURE AND GROWTH KINEMATICS OF SYN-TECTONIC PHASES: A STUDY ON METAPELITES OF NEEM KA THANA, RAJASTHAN, INDIA

Paper number: 28-8
Program: Technical Sessions
Time: 7:00 PM – 7:10 PM

Authors

Abstract

Syn-tectonic minerals in metapelites of North Delhi fold belt, Rajasthan, India show spectacular inter- and intra- specimen textural variations. Owing to matrix mineral distributions, the rocks were broadly classified into layered and non-layered types. Detailed textural investigation reveals significant variation in staurolite shape, size and grain count between the layers. Phyllosilicate rich zone (PL) shows large number (>2000) of small (<5 μm2) staurolite grains, whereas quartz rich zone (QL) shows fewer (<400) but larger (>100μm2) euhedral grains. The largest grains (>3000 μm2) are hosted in quartz + phyllosilicate zone (QPL). Matrix mineral distribution and staurolite texture in QPL of layered metapelites have a similarity to the non-layered metapelites, but in terms of appearance, size and number they differ drastically from PL and QL. Staurolite area vs. total area plots suggest significantly comparable modal proportions in PL, QL and QPL, although number of grains vary considerably between them. Shape, inclusion density, inclusion distribution, mineral orientation, etc., suggest strong influence of micro-scale physical and/or chemical characters of the zones on the growth and texture of the minerals. Pseudosection analyses indicate similar conditions of formation of both the rock types, suggesting rock/layer rheology as primary controller of the contrasting staurolite texture between layers and rocks.

Geological Society of America Abstracts with Programs. Vol. 52, No. 6

doi: 10.1130/abs/2020AM-357945

© Copyright 2020 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.