Identification of Sedimentary Slope Breaks in the Margin of a Down Warped Lake Basin''''s Ramp Belt:A Case from Triassic Yanchang Formation,Ordos Basin
坳陷型湖盆缓坡边缘沉积坡折带的识别—以鄂尔多斯盆地三叠纪延长期沉积坡折带为例

In Mesozoic,the Ordos basin is a down warped lake basin sediment in a typical stable Craton. In the Triassic Yanchang period,the margin of the lake basin ramp belt (northern of the line Wuqi-Ziwuling) developed sedimentary slope breaks, however,using seismic reflection characteristics and lithological stratum correlation techniques are difficult to identify it. Within a three-sequence-stratigraphic framework, this paper identifies the margin of the ramp belt's sedimentary slope breaks of the Yanchang period's basin from three aspects: sequence stratigraphy filling shape, sedimentary microfacies association types,short-term base-level cycle superposition types,and the corresponding ratio (A / S) of the accommodation space (A) and the supply of sediment flux (S). On this basis, an identification method of the margin of the ramp belt's sedimentary slope breaks of down warped lake basins and its recognition model are established.