SOURCE AND SEDIMENTARY ENVIRONMENT OF JURASSIC TOUTUNHE FORMATION IN SOUTHERN CHANGJI, XINJIANG

The methods of particle analysis, carbon-oxygen isotope and polyclastic triangular end member analysis are used to study the Jurassic Toutunhe Formation in southern Changji of Xinjiang based on field survey and section measuring. It is considered that the braided river delta front subfacies and shore shallow lake subfacies are mainly developed in Toutunhe Formation. The analysis results of carbon and oxygen isotope samples indicate that the sandstones of Toutunhe Formation were formed in meteoric freshwater diagenetic environment, with the compaction temperature of 99.26-114.1℃ and burial depth of 4.34-5.23 km (averagely 4.87 km). The provenance analysis reflects the tectonic setting of uplifted basement and island arc orogenic belt, showing mixed source in the late sedimentary stage. The Jurassic sedimentary environment changed from moist to arid climate, and alternated between weak reduction-weak oxidation and strong oxidation environment repeatedly during the sedimentary period of Toutunhe Formation.