Keywords: 
• sedimentary facies /
• delta /
• turbidity /
• fault subsidence basin /
• Baiyinchagan Depression

Abstract: Based on cores’ description, electric log, mud logging, cores’ analysis data, seismic survey, etc., the sedimentary facies’ types and their characteristics of early Cretaceous Tenggeer Formation, Baiyinchagan (BYCG) Depression, were studied, as well as their distribution rule. The research showed that fan delta, braided channel delta, lacustrine facies, and turbidities were present in the formation, of which fan delta was located along the steep north border and braided channel delta in the gently south slope. In addition, from the margin to the depocenter of the depression, the sedimentary environments gradually changed from fan delta or braided channel delta to middle depth lacus and deep lacus, and on the flank of fan delta or braided channel delta were deposited shore sediments and meare sediments. The turbidities were distributed in the delta front zone as well as in the prodelta and middle depth lacustrine zone. Generally speaking, the sedimentary facies were different from the east to the west of the depression and differentiated between the south and the north, which were controlled by the neighboring faults and the basin palaeotopography. The fronts of fan delta and braided channel delta are still the important hydrocarbon accumulation area, and the faultsrelated turbidities in them are the potential targets of exploring the lithological hydrocarbon reservoirs.