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Seismotectonic range-front segmentation and mountain-belt growth in the Pamir-Alai region, Kyrgyzstan (India-Eurasia collision zone)

J. R. Arrowsmith and M. R. Strecker
Seismotectonic range-front segmentation and mountain-belt growth in the Pamir-Alai region, Kyrgyzstan (India-Eurasia collision zone)
Geological Society of America Bulletin (November 1999) 111 (11): 1665-1683

Abstract

The Trans Alai Range along the northern perimeter of the Pamir region of Kyrgyzstan is at the northern edge of the India-Eurasia collision zone. The range defines a section of Main Pamir thrust, which is divided into eastern, central, and western segments that record differential absorption of plate convergence. The 50-km-long, east-west-striking, central fault segment of the Main Pamir thrust has dip-slip thrust fault offsets (with a minimum Holocene dip-slip rate of approximately 6 mm/yr) and is linked to the other segments via northwest-striking dextral transfer. The western transfer faults are well characterized geomorphically, and the westernmost records the predominant transition to north-vergent thrusting along the western segment via north-vergent, low-angle thrust faults rooted in a steeply south-dipping dextral shear zone. In contrast, the eastern segment deformation is widely distributed and geomorphically less evident, but the transfer also takes place in a structurally complex zone. Asymmetric offset of a regionally correlated terrace, geomorphic zonation, and the distribution of historic earthquakes suggest that the central segment is mechanically linked with the western segment, but not with the eastern segment. The progressive closure of the Alai Valley by the northward advance of thrusting exemplifies the annihilation of an intramontane basin. If the high surface uplift rates implied by these geologic observations have been maintained for the last few million years, they attest to the high level of tectonic activity and the recency of construction of the Trans Alai Range.


ISSN: 0016-7606
EISSN: 1943-2674
Coden: BUGMAF
Serial Title: Geological Society of America Bulletin
Serial Volume: 111
Serial Issue: 11
Title: Seismotectonic range-front segmentation and mountain-belt growth in the Pamir-Alai region, Kyrgyzstan (India-Eurasia collision zone)
Affiliation: Arizona State University, Department of Geology, Tempe, AZ, United States
Pages: 1665-1683
Published: 199911
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 32
Accession Number: 1999-070115
Categories: Structural geology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. geol. sketch map
N39°15'00" - N40°19'60", E70°55'00" - E74°30'00"
N39°00'00" - N42°00'00", E69°00'00" - E80°00'00"
Secondary Affiliation: Universitaet Potsdam, DEU, Federal Republic of Germany
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2019, American Geosciences Institute. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 199924
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