石油与天然气地质2026，Vol.47Issue(3)：1002-1017,16.DOI:10.11743/ogg20260319
西秦岭合作地区上二叠统毛毛隆组碎屑流型海底扇发育特征及成因机制
Development characteristics and genetic mechanisms of a debris flow-dominated submarine fan in the Upper Permian Maomaolong Formation,Hezuo region,Western Qinling Orogenic Belt
摘要
Abstract
Debris flow-dominated submarine fans are a critical type of deep-water gravity-flow deposits and constitute a key research target for deep-water hydrocarbon exploration and submarine geohazard assessment.The Upper Permian Maomaolong Formation in the Hezuo region of the Western Qinling Orogenic belt contains well-preserved outcrops of typical debris flow-dominated submarine fan deposits,which record the Late Permian deep-marine sedimentation events.This study focused on the Laoloudi and Cegou sections.Integrating high-resolution three-dimensional(3D)digital outcrop models,field sedimentological investigation,and petrographic microscope analysis in laboratory,we reveal the development characteristics and genetic mechanisms of submarine fans.As indicated by the research results,the Upper Permian Maomaolong Formation in the Hezuo region of the Western Qinling Orogenic belt was divided into seven lithofacies,including two conglomerate lithofacies,four sandstone lithofacies,and one mudstone lithofacies.The gravity-flow deposits include cohesive debris-flow deposits,coarse-grained hybrid event beds,and high-density turbidites.The cohesive debris-flow deposits,among others,were further subdivided into moderate-to low-strength and high-strength cohesive deposits,whereas the coarse-grained hybrid event beds represented the products of fluid transformation from moderate-to low-strength cohesive debris flows.However,the gravity-flow fan bodies in the Maomaolong Formation exhibit sheet-like or tabular geometries and were dominated by lobe deposits,with channels being poorly developed or absent.Based on event-bed thickness,sandstone ratios,and lithofacies associations,the lobe system was further classified into two architectural units:proximal and distal lobes.Furthermore,the debris flow-dominated submarine fan in the Hezuo region is developed in a paleogeomorphic framework of"narrow shelf-steep slope-deep basin",while controlled by a composite transport mechanism involving slope instability and shelf-current reworking.This submarine fan type is characterized by the dominance of multi-type debris-flow deposits and the coexistence of composite flow-transformation products,exhibiting rapid lateral facies transitions and pronounced heterogeneity.These findings provide important insights for the prediction and architectural characterization of deep-water gravity-flow hydrocarbon reservoirs.关键词
成因机制/流体转换/混合事件层/海底扇/水下碎屑流/重力流沉积/毛毛隆组/西秦岭构造带Key words
genetic mechanism/flow transformation/hybrid event bed/submarine fan/subaqueous debris flow/gravity-flow deposits/Maomaolong Formation/Western Qinling Orogenic Belt分类
能源科技引用本文复制引用
袁赛赛,谈明轩,朱宇航,孙浩南,王新烁..西秦岭合作地区上二叠统毛毛隆组碎屑流型海底扇发育特征及成因机制[J].石油与天然气地质,2026,47(3):1002-1017,16.基金项目
国家自然科学基金项目(42372118,42002117). （42372118,42002117）
