龙门山区中泥盆统养马坝组混积相与混积层序及其控制因素分析  

Analysis of Hybrid Facies,Hybrid Sequence and Its Controlling Factors of the Middle Devonian Yangmaba Formation in Longmenshan Area

作　　者：李佐强 李凤杰[1,2] 赖雪莲 陈政安 倪子尧 LI Zuo-qiang;LI Feng-jie;LAI Xue-lian;CHEN Zheng-an;NI Zi-yao(State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation(Chengdu University of Technology),Chengdu 610059,China;Institute of Sedimentary Geology,Chengdu University of Technology,Chengdu 610059,China)

机构地区：[1]油气藏地质及开发国家重点实验室(成都理工大学),成都610059 [2]成都理工大学沉积地质研究院,成都610059

出　　处：《科学技术与工程》2020年第26期10580-10591,共12页Science Technology and Engineering

基　　金：国家自然科学基金(41172100);国家重点研发计划(2018YFC0604201)。

摘　　要：龙门山地区中泥盆统养马坝组混合沉积较为发育。通过对龙门山地区北川甘溪剖面养马坝组的野外实测,在混合相和混积层序研究的基础上,分析了养马坝组层序体系域中的混合沉积机理及其控制因素。研究表明:龙门山地区中泥盆统养马坝组由下部的以泥质为背景的Ⅰ型混积类型和中、上部以砂、灰为背景的Ⅱ型混积类型组成,混积机理包括间断混合、相混合和原地混合,前两种是主要类型。由陆向海依次发育混积滨岸、碎屑混积陆棚沉积和碳酸盐混积陆棚,建立了混积滨岸-混积陆棚沉积模式。养马坝组发育Ⅱ型混积层序,沉积体系域可划分为4种:陆架边缘体系域(shelf-margin systems tract,SMST)、海侵体系域(transgressive systems tract,TST)、早期高位体系域(early highstand systems tract,EHST)和晚期高位体系域(late highstand systems tract,LHST)。各体系域均有不同程度的混合沉积现象,但混积沉积机理存在差别:SMST和LHST以间断混合为主,相混合为次,TST和EHST以相混合为主;风暴作用是引起龙门山地区中泥盆统养马坝组间断混合的最主要的驱动因素。相对海平面变化、物源供给、碳酸盐生产速率和气候变化是控制和影响混合沉积的因素。SMST和高位体系域(highstand systems tract,HST)主要受相对海平面的变化有关,TST则受控于物源供给,气候变化不同程度地影响各体系域的混合作用。Hybrid deposition is relatively developed in the Middle Devonian Yangmaba Formation in the Longmenshan area.Based on the field measurements of Yangmaba Formation in Ganxi section,Beichuan,Longmenshan area,Sichuan Province,the hybrid sedimentation mechanism and its controlling factors in the sequence system tracts of the Yangmaba Formation were analyzed based on the study of hybrid facies and hybrid sequence.Research results show that the Yangmaba Formation consists of the lower type-I hybrid type with mudstone background by bottom and the middle-up type-II hybrid type with sand and carbonate background.The hybrid mechanism includes punctuated mixing,facies mixing and in situ mixing,and the first two are the main types.The hybrid shore,clastic hybrid shelf and carbonate hybrid shelf develop successively from land to sea,and the hybrid shore-hybrid shelf deposit sedimentary model is established.The Yangmaba Formation is characteristic of type-II hybrid sequence,which can be divided into four sedimentary system tracts of shelf-margin systems tract(SMST),transgressive systems tract(TST),early highstand systems tract(EHST)and late highstand systems tract(LHST).There are hybrid deposition phenomena of different degrees in each system,but the mechanism of hybrid deposition is different.SMST and LHST are mainly punctuated mixing,and the facies mixing is secondary,TST and EHST are mainly facies mixing.Storm action is the most important driving factor of punctuated mixing of Yangmaba Formation.Relative sea level change,terrestrial clastic supply,carbonate productivity and climate change are factors that control and affect hybrid sedimentation.SMST and highstand systems tract(HST)are mainly related to changes in relative sea level,while TST is controlled by sedimentary source recharge,and climate change affects the hybrid action of system tracts in varied degrees.

关 键 词：混合沉积 混合层序 养马坝组 龙门山地区 

分 类 号：P539.2[天文地球—古生物学与地层学]