Muhammad Asif Khan

Geochemistry and petrogenesis of Oligocene volcaniclastic rocks from the Chagai arc: implications for the emplacement of porphyry copper deposits

The Chagai–Raskoh arc is an east–west trending subduction-related magmatic belt in the western part of Pakistan. The initial Cretaceous to Paleocene volcanism in the arc is tholeiitic, and from the Eocene onwards, it becomes calc-alkaline in nature. The Oligocene volcaniclastic rocks are found in the western part of the Chagai–Raskoh arc. These rocks and are mainly andesitic tuffs and belong to the calc-alkaline series. Normalized trace element patterns with negative Nb anomalies and moderate enrichments in K, Sr, Rb and light rare earth elements (LREE) confirm a composition consistent with a continental margin (Andean)-type arc environment. The LREE enriched chondrite-normalized REE patterns with negative Eu anomalies are consistent with their calc-alkaline signature and suggest plagioclase fractionation during differentiation. The Oligocene volcaniclastic rocks from the Chagai–Raskoh arc are more enriched in large ion lithophile elements (LILE) and LREE than the older rocks of the arc. This enrichment in LILEs and LREEs suggests that during the Oligocene–Miocene, more subduction-related fluids were added to the sub-arc mantle source from the subducting Arabian slab and may have been responsible for the porphyry copper deposits in the arc.

Copy detection in urdu language documents using n-grams model

In this paper we present our work on copy detection in short Urdu text passages. Given two passages one as the source text and another as the copied text it is determined whether the second passage is plagiarized version of the source text? We have developed an algorithm for plagiarism detection. We have used the n-gram model for word retrieval and found tri-grams as the best model for comparing the Urdu text passages. Based on probability and the resemblance measures calculated from the bi-gram comparison we categorize the passages on a threshold. In the Algorithm the connecting words are considered in computing and matching trigram. We have developed a software system in C# for both the algorithms. This system can be used to detect copy in students assignments in Urdu language.

Interrelationships between Deformation and Metamorphic Events across the Western Hinterland Zone, NW Pakistan

Microscopic to mesoscopic structural investigations and foliation intersection axes (FIAs) preserved in porphyroblasts reveal a very complex history of deformation and tectonism within the southwestern part of the western hinterland zone along the northern margin of the Indian plate, NW Pakistan. D1, D2, and D3 related structures in the southwestern part resemble the F1/F2, F3, and F4 related structures in the northeastern part of the western hinterland zone. These structures developed at the same time through the same changes in the direction of bulk shortening in southwestern and northeastern parts of the western hinterland zone. FIA set 1 indicates NW-SE shortening. The D2 fabrics, mineral lineations and fold axes indicate E-W shortening. FIA set 2, D3 fold axes and mineral lineations indicate NNE-SSW shortening. D3 deformation event is equivalent to the F4 deformation event in the northeastern part of the western hinterland zone. D4 fold axes, mineral stretching lineations and axial plane foliation suggest ENE-WSW shortening. The D4 NNW-SSE fabrics, which formed in the region after the formation of the MMT (main mantle thrust), Khairabad-Panjal thrust fault, Hissartang thrust fault and MBT (main boundary thrust), likely resulted from ENE-WSW bulk shortening related to development of the Hazara-Kashmir syntaxis.