古地理学报2025，Vol.27Issue(3)：611-624,14.DOI:10.7605/gdlxb.2025.022
高精度层序格架下湖底扇沉积特征及演化:以鄂尔多斯盆地庆北长7段为例
Sedimentary characteristics and evolution of sublacustrine fan in high-resolution sequence stratigraphic framework:a case study of the Chang 7 Member in Qingbei area,Ordos Basin,China
摘要
Abstract
In recent years,sublacustrine fans have emerged as a prime focus for oil and gas explora-tion in the Ordos Basin due to their immense potential.However,their development is influenced by mul-tiple factors,leading to distinct sedimentary evolution patterns under varying geological settings.This study focuses on the sublacustrine fan in the Chang 7 Member of Yanchang Formation in the Ordos Basin.By in-tegrating core,well logs,and seismic data,a detailed analysis of the sedimentary evolution of the Chang 71 sequence unit's sublacustrine fan in the Qingbei area was conducted within a high-resolution sequence framework.The results show that the Chang 71 sequence unit can be systematically divided into five distinct fifth-order sequence units,based on lithological discontinuity surfaces within the fourth-order sequence.Notably,the crucial fifth-order sequence units,71-5 and 71-4,can be further subdivided into 10 sixth-order sequences.The present study successfully distinguished various sedimentary units within the sub-lacustrine fan,including gravity flow channel,channel-levee complex,levee,lobe,and lobe edge.Given the sedimentary background,the sublacustrine fan in the study area is interpreted to be mainly sourced from the braided river delta front.The results indicate that during periods of lake-level fall under warm and humid climatic conditions,increased terrigenous clastic input enhanced sediment suppy from the braided river delta front,and the accommodation space of the lake basin decreased,facilitating northeast-ward progradation of the sublacustrine fan,with expanding depositional lobes showing distinct lateral mi-gration patterns.关键词
长7段/重力流/湖底扇/沉积特征/鄂尔多斯盆地Key words
Chang 7 Member/gravity flow/sublacustrine fan/sedimentary characteristics/Ordos Basin分类
天文与地球科学引用本文复制引用
叶定蓬,张涵,吕德洁,何云龙,侯秀林,周波,王磊飞,张先平,李国顺,刘佳钰,向常龙..高精度层序格架下湖底扇沉积特征及演化:以鄂尔多斯盆地庆北长7段为例[J].古地理学报,2025,27(3):611-624,14.基金项目
国家自然科学基金项目(编号:41502102,42072137)资助.Financially supported by the National Natural Science Foundation of China(Nos.41502102,42072137) （编号:41502102,42072137）
