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The AAPG/Datapages Combined Publications Database
Houston Geological Society Bulletin
Abstract
Abstract: Lithologic Correlations Across the Eastern North Pamir
Suggest a Regionally Extensive Thrust Nappe
Older, widely used, geologic maps of the eastern North Pamir show a collage of Paleozoic lithologies. Recent work has documented that
many of these lithologies are Triassic in age and regional similarities in lithologies and structural relationships suggest a broad continuity
in the tectonic architecture across the region. We compare two regional areas: 1) the Baoziya Thrust and Tanymas Thrust are exposed
north and northwest of the Muztaghata massif, in the hanging wall of the Kongar Shan normal fault. The Baoziya/Tanymas thrust hangingwall
consists of upper greenschist to amphibolite facies schists and quartzites with abundant Triassic igneous intrusions. Detrital zircon
analyses of the hanging wall yield Permo-Triassic maximum depositional ages and Late Triassic metamorphic age signatures (Robinson
et al., 2004; 2012). The footwall of the Baoziya Thrust consists of greenschist facies marbles, phyllites, and quartzites with Triassic
maximum depositional ages, whereas the Tanymas thrust footwall consists of Paleozoic sandstones, limestones, and marls. 2) The Torbashi
Thrust is exposed south of the Muztaghata massif as a large folded klippe in the hanging wall of the Shen-ti fault. Its hanging wall consists
of amphibolite facies schists and gneisses with abundant igneous intrusions. Like the Baoziya/Tanymas hanging-wall, the Torbashi Thrust
hanging-wall yields Permo-Triassic maximum depositional ages and a Late Triassic metamorphic
signature
. The northern exposure of
the footwall consists of greenschist facies marbles, quartzites, phyllites, and metavolcanics with Triassic metamorphic age signatures,
whereas the southern exposure consists of Permian limestones and slates. Based on structural juxtaposition and lithologic similarities we
correlate the north exposure of the Torbashi Thrust with the Boaziya Thrust, and correlate the southwest exposure of the Torbashi thrust
with the Tanymas thrust. We propose the Torbashi and Baoziya/Tanymas faults were a continuous structure which formed a regionally
extensive thrust nappe in the Northern Pamir. The thrust sheet was subsequently cut by the Muztaghata gneiss dome in the Miocene.
