SEDIMENTARY EVOLUTION MODELS OF LOWER TRIASSIC DEEP-WATER CARBONATE ROCKS OF WEST QINLING MTS

Based on the study of Lower Triassic deep-water carbonate rock sequenc e of west Qinling Mts.; deep-water carbonate rock sequence is divided into lower fine-grain euxinic deposits of a carbonate gentle slope typ e and upper bathyal and abyssal sediments of carbonate steep slope typ e. The upper member is emphatically analysed and synthesized into five facies associations. They comprise four fining- and thinning-upward m egacycles, each of them representing a sedimentary column which accumu lated after a tensional fault subsidence event, which recorded a whole rifting process of west Qinling ocean trough during Lower Triassic.