PETROGENESIS OF DALHOUSIE GRANITE, DALHOUSIE, HIMACHALPRADESH

Abstract

(iranitoid belt of I-Iirna1ayas are known to decipher the orogenic history of the particular region. Daihousie granite is one such rock which tries to give an interesting insight about the tectonic, orogenic and metamorphic history of the region. Daihousie granite is present in semi-lensoid shape of dimensions almost equivalent to that of batholiths. It is emplaced around a limb of the nappe zone of the NW Himalayas in the NW-SE direction. Two different phases of magmatic activity can be seen in the region. The field work and mineralogical study provide a qualitative idea about the structural and tectonic setting of the region to an extent. Various microstructures can be understood through them although the composition is monotonous. By using various analytical tools, a quantitative idea is derived about the composition and the geochemistry of the region. The tight width of variation in composition shows the homogeneity of the source. Various discrimination diagrams show a relation among various mineral phases. The characteristics of the trace elements such as less amount of Sr and more Rb conforms the abundance of feldspars which can also be seen in the field study. The ASI value shows the source to be of S-type. The Eu anomaly further gives an idea about the source. The normative value calculations help to get the exact concentration of various minerals.