Tectono-Paleogeographic Impact on the Permian Depositional Environment and Provenance around the Chaiwopu Depression in the Southern Junggar Basin, NW China

Shasha Liu,Michael Wagreich,Eun Young Lee,Jinliang Zhang,Leqiang Zhao,Hui Liu

doi:10.3390/min11111237

Abstract

The Chaiwopu Depression in the southern Junggar Basin is located between the West Bogda Mountains and the northeastern Tian Shan Mountains in northwest China. The intracontinental basin–mountain system was formed in the Central Asian Orogenic Belt during the Late Paleozoic. The Permian strata around the depression exhibits distinct variations, which provide significant information to understand its tectonic and depositional evolution. This study investigated six outcrop sites using lithological, sedimentological, and geochemical analyses. The representative lithology of the Lower Permian is submarine lava and pyroclastic flows on the northern margins and alluvial deposits near the southern margins. In the Middle Permian sequence, the extensive distribution of alternating shale and silt/sandstone with oil shale and carbonate indicates a lacustrine setting. The sediments are composed of felsic rock-forming minerals derived mainly from island arc settings. The source rock properties correspond to the Carboniferous volcanic terrain of northeastern Tian Shan. The Lower to Middle Permian source-to-sink system occurred in an incipient level of weathering and maturation, a simple recycling process, and arid to semi-arid climatic conditions. The characteristics and changes of the depositional environment and provenance can be understood in terms of implications of tectono-paleogeographic evolution associated with the West Bogda rifting and uplift.

Highlights

The Chaiwopu Depression is a sub-basin on the southern margin of the Junggar Basin in northwest China, which is about 115 km long from east to west and 35 km wide from south to north (Figure 1)
Paleozoic has been considered as a significant period in the evolution of the intracontinental basin–mountain system
The other 3 sites are in the Erenharbirga Mountains near the southern margin of the Chaiwopu Depression, as follows: Aiwergou outcrop (AWG; 43◦ 000 5200 N, 87◦ 340 500 E), Hougou outcrop (HOUG; 43◦ 110 1600 N, 88◦ 280 4100 E), and Tarlang outcrop (TAR; 43◦ 170 1500 N, 89◦ 20 4700 E), from west to east

Summary

Introduction

The Chaiwopu Depression is a sub-basin on the southern margin of the Junggar Basin in northwest China, which is about 115 km long from east to west and 35 km wide from south to north (Figure 1). It lies between the West Bogda Mountains, the Erenhabirga. The series of intracontinental basins and mountains was formed by the amalgamation of multiple micro-continents, island arcs, and accretionary wedges, as part of the Central Asia Orogenic Belt (CAOB) (Figure 1a)—the largest accretionary orogen on Earth.

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