Vol. 5 No. 2 (2021)
Articles

To Study the Petrography and Provenance of the Upper Siwalik Sub Group Sandstones of Boulder Conglomerate, Nagrota and, Purmandal Sandstone Formation, Jammu and Kashmir Sub Himalaya

Published 2021-06-30

Abstract

Mechanical and physical characteristics of rocks generally depend on their composition and texture, because they are reflective of their environments during sedimentation, digenesis and weathering in each location. To understand this, relationships between mechanical and physical indices and composition and texture have been analyzed using several rock samples obtained from Mio-Pleistocene sandstone sequence of the Siwalik Group, widely distributed in foothills Jammu and Kashmir Himalayas. Sandstones are quartz-Feldspathic to quartz-lithic and quartz-feldspathilithic. Cement, matrix and void vary from 6 to 41%, 0 to 18% and 1 to 12%, respectively. Clasts are loosely to closely packed and are weakly to strongly bounded by cement. Results of correlation analyses show that sandstones strongly depend on several indices, that are percent of voids, strong cement over total cement, strong over weak contacts, concavo–convex contacts and packing density, most of which are measured on thin sections. Contrarily, they depend little on grain size, shape, mineralogical maturity index and the other Petrographic indices. Increased interlocking and strong cementing with reduced void tends to possess high densities, low porosity and offer good resistance against deformation. Therefore, proportion of strong cement over total cement, void content, strong over weak contacts, grain-to-void contact, concavo–convex contact and packing density are meaningful indices considering the sandstones of the Siwalik Group. Based on the multiple regression, correlation analyses and then stepwise multiple regression analysis, some regression equations with significant explanatory indices are indicated for estimating mechanical and physical properties. In other words, such relationships may be useful in estimating mechanical and physical properties using the significant Petrographic indices.