Structural and geochronologic data from the Shin Jinst area, eastern Gobi Altai, Mongolia: Implications for Phanerozoic intracontinental deformation in Asia

Abstract

The complex geology of central Asia records significant Phanerozoic growth and deformation of continental lithosphere, yet many questions about the timing and mechanisms of these processes remain. The Gobi Altai of southwestern Mongolia preserves much of this history in exposed mountain ranges and sedimentary basins. The Shin Jinst area (near latitude 44 21' to 44° 32', longitude 99°35' to 99° 25') contains important evidence of Paleozoic growth and accretion as well as subsequent Mesozoic and Cenozoic deformation. Detailed mapping and structural data, including data sets on folds and cross-cutting faults, point to repeated episodes of deformation and add to recent work that documents Triassic and Jurassic compression as well as Cenozoic tectonic activity in this region. New 40Ar/ 39Ar data are interpreted to record Permian to Jurassic convergent margin processes. In particular, these data, in combination with previous studies, suggest that southern Mongolia records protracted deformation throughout the Jurassic that likely resulted from compression associated with the subduction zone at the southern margin of Asia at that time.