Element geochemical characteristics of Mesozoic mudstones in the northern piedmont zone of the Kuqa depression and their implications to sedimentary environments

Abstract

By means of element geochemistry, the characteristics of major elements, trace elements and rare earth elements (REE) for Triassic and Jurassic mudstones from the northern piedmont zone in the Kuqa depression were studied and discussed for the implications fo sedimentry environment.The Mesozoic mudstones from the northern piedmont zone in the Kuqa depression are dominently terrestrial freshwater sedimentary environments.REE are characterized by enrichment of light REE, and reflect the sedimentary characteristics of rapid accumulation of organic matter and slow recharge of terrigenous fine debris.From the Triassic to the Jurassic, the paleosalinity increased slightly while the paleoclimate was mainly humid, and the whole was under dysoxic-anoxic conditions.The warm and humid paleoclimate and lower paleosalinity during the deposition of the Huangshanjie Formation are conducive to the production of organic matter productivity, and the dysoxic-anoxic condition provides preservation conditions.The hot-dry paleoclimate environment began to appear in the period of the Qiakemake Formation, and the higher paleosalinity may promote the formation of organic matter, but the anoxic condition is more conducive to its preservation.

Keywords

• kuqa depression
• mesozoic mudstone
• geochemistry characteristics
• trace elements
• rare earth elements
• sedimentry environment significance