川北广元须家河组一段沉积相与沉积环境演化分析  

Sedimentary Facies and Sedimentary Environment Evolution of First Member of the Xujiahe Formation in Guangyuan Area,Northern Sichuan Province

作　　者：谢小平[1,2] 李姝臻 鲁宁 王永栋 席书娜 XIE XiaoPing;LI ShuZhen;LU Ning;WANG YongDong;XI ShuNa(School of Geography and Tourism,Qufu Normal University,Rizhao,Shandong 276826,China;State Key Laboratory of Palaeobiology and Stratigraphy(Nanjing Institute of Geology and Palaeontology,CAS),Nanjing 210008,China;Institute of Geological Relics,No.137 Geological Team of Sichuan Coalfield Geological Bureau,Chengdu 610000,China)

机构地区：[1]曲阜师范大学地理与旅游学院,山东日照276826 [2]现代古生物学和地层学国家重点实验室中国科学院南京地质古生物研究所,南京210008 [3]四川省煤田地质局一三七队地质遗迹研究院,成都610000

出　　处：《沉积学报》2021年第2期493-505,共13页Acta Sedimentologica Sinica

基　　金：现代古生物学和地层学国家重点实验室(中国科学院南京地质古生物研究所)开放基金(183126,20191103);国家自然科学基金项目(41072164,41572014);中科院战略先导科技专项B类项目子课题(XDB26000000);日照市国土空间规划与生态建设重点实验室。

摘　　要：四川盆地北部三叠系—侏罗纪发育,出露良好,是三叠纪—侏罗纪转换时期古气候与古环境变化的良好物质记录。其中,晚三叠世诺利期是四川盆地海陆转换的重要过渡期,尤其是对陆地生态系统的影响更加显著。以川北广元剖面为研究对象,对晚三叠世诺利期末须家河组须一段进行沉积相及沉积环境演化的分析,结果表明:研究剖面发育潟湖沼泽—三角洲平原—辫状河流亚相沉积,为海陆过渡相—陆相沉积体系;受甘孜—阿坝弧后盆地发育影响,始自卡尼期的海侵自诺利中后期到达广元地区;在秦岭造山带及龙门山的隆升背景下,广元地区较早结束海陆过渡相沉积,于须一段中后期向河流相沉积转变。结合对古生物化石组合研究和岩性特征及沉积相,恢复了广元地区晚三叠世诺利期须一段的古气候特征,广元地区须一段处于近海亚热带潮湿气候,这种潮湿气候从须一段一直延续至诺利期末期。The Norian stage of the Upper Triassic was an important transitional episode from marine to terrestrial environment in the development of the Sichuan Basin.The Late Triassic environment and climate became more complex following the mass extinctions at the turn of the Triassic-Jurassic periods,with the most significant impact being on terrestrial ecosystems.The well developed and exposed Triassic-Jurassic strata in the northern Sichuan Basin,which comprise continuous deposits of the Upper Triassic Xujiahe Formation and the Lower Jurassic Zhenzhuchong Formation,represents an excellent record of the paleoclimatic and paleoenvironmental changes.In particular,in the Sichuan Basin the Norian and Rhaetian stages were crucial in the transition of the marine and terrestrial environmental changes.We investigated the first member of the Xujiahe Formation in Guangyuan,northern Sichuan Basin,focusing on analysis of the sedimentary facies and environmental evolution.The results show that lagoon marshes,delta plains and braided rivers facies developed in the section in the Guangyuan region,which is a remarkable continental transitional-continental facies sedimentary system.Through the influence of the formation and development of the GanziAba back-arc basin,the transgression that had begun in the Carnian stage at the beginning of the Upper Triassic affected the Guangyuan region during the late Norian.The uplift of the Qinling orogenic belt and Longmen Mountain ended the production of marine facies in the Guangyuan area,and terrestrial facies are then seen in the first member of Xujiahe Formation.We have reconstructed the paleoclimate in the later Norian stage in the Guangyuan area by analyzing the plant fossil assemblage combined with the sedimentary cycle and facies characteristics.We suggest that the Guangyuan area experienced a humid,subtropical coastal climate from the depositional stage of the first member of the Xujiahe Formation until the late Norian in the Upper Triassic.

关 键 词：须家河组一段 沉积相 沉积环境 广元 川北 

分 类 号：P512.2[天文地球—地质学]