| Abstrakt: |
The overlying shallow meandering river delta sedimentary system developed in the Chang 6 sedimentary period of the upper Triassic in Ordos Basin. Based on core observation, logging data, analysis of testing data and modern sedimentary viewpoints, the sedimentary architectural characteristics, evolution and pattern are studied. The results show that the Chang 6 sedimentary period is accompanied by short-term lake level fluctuation. Based on this, three main facies are divided: the lower delta plain, the inner delta front and the outer delta front. After the establishment of the graded crevasse system, it is found that the architectural elements mainly consist of distributary channel and estuary dam, the lower plain is mainly composed of broad-band meander channel, the distributary channel delta of "river on dam" is developed in the inner delta front, and the distributary sand dam delta of "river in dam" is developed in the outer delta front. During the evolution process of sedimentary architecture, the type of architectural elements, geometry, combination mode and spatial distribution have changed gradually, and the sedimentary pattern has also changed. After considering the influence of various control factors such as sedimentary background, base level cycle, graded crevasse and lake wave control, a sedimentary architectural model of shallow meandering river with pan-connectivity is established. From the perspective of sedimentary architecture, this paper discusses the key points left in the study of shallow water delta, hoping to provide reference for the further exploration in this field. [ABSTRACT FROM AUTHOR] |
