New geological investigations regarding MCT along southwestern part of Malakand granite gneiss, Malakand Agency, N.W. Pakistan

Abstract

The western pan of previously called Malakand granite gneiss and its contact with metasediments was studied at several localities. The objectives were to study the relationship of granite and metasediments and find out the evidences of MCT at the contact, if any does exist. Along contact zone at Baru locality, the granite is fine­ to medium-grained, weakly foliated and shows micro inter-fingering inside metasediments. Backing and chilling effects are clearly visible at contact. Also a band of garnet mica- schist (2-5 m thick) has been developed in metasediments all along the contact zone that looks to be piezothermal in characters and probably have resulted from the granite intrusion. This band disappears away from the contact. Similar observations were made at the northern contact of granite and metasediments at Totai locality. This study indicates that the contact between granite (southwestern part of Malakand granite) and metasediments is intrusive in nature and no indications of MCI' exist as was previously reported by Chaudhry et al. (1991).

A traverse, across strike from Baru area at the southern contact of granite up to Hazanao top covering the area SW of Mekhband, was undertaken to study the nature of so called granite gneiss in its interior parts. During this traverse it was observed that this pan of previously called granite gneiss is not gneissic in nature but comprises fine­ to medium-grained weakly foliated granite that contains patches of granite gneiss. This pan of granite shows close resemblance to the granite occurring at Baru locality.

The granite NE of Mekhband locality, not included in this study, may be comprise granite gneiss but the granite SW of Mekhband is fine- medium in texture and weakly foliated. We consider this part of granite as a phase that miry be older than Malakand proper granite and younger than the granite gneisses lying NE of Mekhband.