Digital outcrop modeling and geological analysing on Tanjiahe profile of Yanchang formation, Ordos basin, China

摘要

Using digital outcrop modeling technology, this paper constructed the digital outcrop of the Tanjiahe profile of Yanchang formation, and analysed the sequence stratigraphy and sandbody characteristics of the upper triassic Yanchang formation, Ordos basin, China. Through establishing sequence stratigraphic identification marks, identifying and tracking sequence interface on digital outcrop, a fourth grade base level cycle interface is identified. Upward coarsening regressive sequence and upward fining transgressive sequence are respectively located above and below the interface. Through the establishment of sandbody interpretation marks, the stratigraphic and sandbody boundary are extracted and calibrated. A greater-thickness of incised distributary channel sandbody and isolated-type terminal subaqueous distributary channel sandbody are identified respectively at the bottom and conversion surface of the fourth grade base level cycle. Statistics of stratigraphic sand ratio along the profile shows that the sand ratio of the development area of the distributary channel and subaqueous distributary channel sandbody is relatively large, indicating that the sandbody development is controlled by the sedimentary environment.