Active surface salt structures of the western Kuqa fold-thrust belt, northwestern China

Abstract

The western Kuqa fold-thrust belt of Xinjiang Province, China, hosts a series of surface salt structures. Here we present preliminary analysis of the geometry, kinematics, and surface processes of three of these structures: the Quele open-toed salt thrust sheet, Tuzimazha salt wall, and Awate salt fountain. The first two are line-sourced, the third appears to be point-sourced, and all are active. The ∼35-km-long, 200-m-thick Quele open-toed salt thrust sheet features internal folding, salt-lined transfer structures, dissolution topography, flanking growth strata, and alluvial fan/stream-network interactions. The ∼10-km-long, 50-m-wide Tuzimazha salt wall marks a local topographic high, such that fluvial stream networks are deflected by the rising weak tabular salt body. The salt wall is also flanked by growth strata and normal faults. The ∼2-km-long Awate salt fountain represents salt exhumation coincident with the intersection of multiple structures and a river. Therefore this salt body may respond to local structural and/or erosional variations, or it may play a key role determining such variations—or both. Activity along all three structures confirms that active deformation occurs from foreland to hinterland across the western Kuqa fold-thrust belt. Gradual lateral transition from bedded strata to flow-banded halite observed within the Quele open-toed salt thrust sheet implies that similar transitions observed in seismic reflection data do not require interpretation as diapiric cut-off relationships. The surface salt structures of the western Kuqa fold-thrust belt display a variety of erosion-tectonics interactions, with nuances reflecting the low viscosity and high erodibility of salt, including stream deflections, potential tectonic aneurysm development, and even an upper-crustal test site for channel flow–focused denudation models.