Tectonic evolution of the NW-Himalayan thrust front:

مرکز و کتابخانه مطالعات اسلامی به زبان های اروپایی

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" Tectonic evolution of the NW-Himalayan thrust front: "
P. M. Blisniuk L. J. Sonder

Document Type	:	Latin Dissertation
Language of Document	:	English
Record Number	:	1112943
Doc. No	:	TLpq304305614
Main Entry	:	L. J. Sonder
	:	P. M. Blisniuk
Title & Author	:	Tectonic evolution of the NW-Himalayan thrust front:\ P. M. BlisniukL. J. Sonder
College	:	Dartmouth College
Date	:	1996
student score	:	1996
Degree	:	Ph.D.
Page No	:	193
Abstract	:	The results of structural, stratigraphic and paleomagnetic work in the Trans-Indus Ranges of northern Pakistan are presented. The Trans-Indus Ranges form the western part of the NW-Himalayan frontal thrust system, which comprises structural re-entrants and promontories with wave-lengths between 50 and 150 km. The structure of the Trans-Indus Ranges is characterized by abrupt lateral variations in tectonic style, between mainly compressive deformation along the central parts of re-entrants and promontories, and transpressive deformation along their lateral flanks. This complex geometry of the thrust front seems to be largely controlled by a system of frontal and lateral structural ramps, formed by north-dipping flexures and normal faults offsetting the basement. Balanced cross-sections, based on the integration of stratigraphic and structural mapping with seismic reflection data and well logs, show that the amount of convergence along the Trans-Indus Ranges is on the order of 10 km. The history of deformation along the Trans-Indus Ranges is constrained by sedimentological and magnetostratigraphic studies of synorogenic foreland basin deposits, which contain evidence for two main phases of tectonic activity. Locally derived conglomerates in usd \simusd3.5-4 Ma old deposits are interpreted as evidence for Early Pliocene extension along north-dipping flexures and normal faults on the northern flank of a peripheral bulge south of the NW-Himalayan foreland basin. Locally derived conglomerates in usd\leusd1.2 Ma deposits are related to the ongoing convergence along the Trans-Indus Ranges, during which normal faults and flexures formed during the earlier extension were used as thrust ramps. The rate of shortening along the frontal thrust system in the Trans-Indus thus is usd\geusd8 mm/a, similar to shortening rates previously reported in the Salt Range in the eastern part of the frontal thrust system.
Subject	:	Earth sciences
	:	Geology
	:	Geophysics