A record of ductile syn-intrusional fabrics to post solidification cataclasis: Magnetic fabric analysis of neoproterozoic Mirpur and Mt. Abu Granitoids,NW India |
| |
| Authors: | Helga de Wall Stefan Schöbel Manoj K Pandit Kamal K Sharma J Just |
| |
| Institution: | 1.Geozentrum Nordbayern,Universitat Erlangen-Nürnberg,Erlangen,Germany;2.Department of Geology,University of Rajasthan,Jaipur,India;3.Department of Geology,Government Postgraduate College,Sirohi,India |
| |
| Abstract: | The Mirpur granite body represents a relatively small (10 km2) pluton intruded along the northern margin of the adjacent Mt. Abu batholith (∼125 km2) in NW India. It is a visibly undeformed alkali feldspar rich pink granite; in contrast, the Mt. Abu is a composite granitoid
body and variably deformed. Both are intruded by rhyolitic dykes and the terminal magmatic events in both the cases are mafic
dykes. The AMS (Anisotropy of Magnetic Susceptibility) data identify the Mt. Abu with SE-dipping foliations and subvertical
lineations as a single structural domain while the Mirpur granite body shows two domains characterized by predominantly E
— W trend of magnetic foliation in the eastern part (domain I) and N — S orientations in the western part (domain II). The
domain I shows magmatic fabrics, typical for the peraluminous granites of Malani Igneous Suite (MIS). Change in fabric orientation
in the domain II has resulted from cataclasis wherein the samples show destruction of the original E — W fabric and complete
transposition by N — S trends. The foliations in the Mt. Abu granites have been related to SE orientation of maximum horizontal
stress. The same maximum stress direction can be inferred from dyke orientation in the Mirpur granite, which is interpreted
as continuation of the tectonic imprint in this region during emplacement of both the granites. Age of the cataclastic overprint
with a predominant N — S orientation is not yet constrained but corresponds with the trend of the nearby Sindreth basin within
the Malani Igneous Suite. The Neoproterozoic tectonic scenario for the region has been interpreted in terms of an ongoing
crustal convergence and granitic magma emplacement against the back stop offered by the rigid Delhi Fold Belt. |
| |
| Keywords: | |
| 本文献已被 SpringerLink 等数据库收录！ |
|
