四川广元清风峡剖面上泥盆统风暴沉积特征及其古环境意义  

Sedimentary characteristics and its palaeoenvironmental significance of the Upper Devonian storm deposits at Qingfengxia section in Guangyuan City,Sichuan Province

作　　者：黄程 沈宇葳 文馨 Huang Cheng;Shen Yu-Wei;Wen Xin(State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Southwest Petroleum University,Chengdu 610500,China;The Laboratory of Carbonate Sedimentary and Diagenetic Geochemistry,Southwest Petroleum University,Chengdu 610500,China;Exploration Division of Petro China Southwest Oil and Gas Field Company,Chengdu 610041,China)

机构地区：[1]西南石油大学油气藏地质及开发工程国家重点实验室,四川成都610500 [2]西南石油大学碳酸盐岩沉积-成岩地球化学实验室,四川成都610500 [3]中国石油西南油气田分公司勘探事业部,四川成都610041

出　　处：《古地理学报》2021年第6期1094-1109,共16页Journal of Palaeogeography：Chinese Edition

基　　金：国家自然科学基金项目(编号:41602027)资助。

摘　　要：泥盆纪吉维特期—弗拉期(G-F)之交的环境突变拉开了晚泥盆世生物大灭绝的序幕。然而,不同学者对于该时期环境变化的认识仍存在争议。为了解泥盆纪G-F之交的环境变化特征,通过对四川广元清风峡剖面泥盆系观雾山组中6套风暴岩的详细沉积学研究,识别出了典型的风暴沉积标志,如底面侵蚀构造、粗粒滞留沉积、粒序层理、丘状交错层理等。根据风暴沉积构造的组合特征,建立了3种近源风暴沉积序列:序列Ⅰ,底部为具侵蚀构造的砾屑灰岩,顶部为块状泥晶灰岩;序列Ⅱ,底部为具侵蚀构造的砾屑灰岩,顶部为具粒序层理的砂屑灰岩;序列Ⅲ,底部为具侵蚀构造的砾屑灰岩,中部为具粒序层理的介壳灰岩,上部为具丘状交错层理的颗粒泥晶灰岩,顶部为具波状层理和水平层理的泥晶灰岩。牙形石生物组合分析显示,风暴岩形成于晚泥盆世弗拉期初期。基于现代风暴成因分析,认为弗拉期初期全球低纬度地区广泛分布的风暴岩与气候变暖和快速海侵密切相关。研究区风暴岩的发现对认识上扬子地区晚泥盆世沉积环境、古地理、古气候均具有重要意义。It is well known that environmental changes during the Devonian Givetian-Frasnian(G-F)transition initiated the beginning of the Late Devonian extinction.However,it is still controversial as to the understanding of environmental changes in this period.For that,this study conducted detailed sedimento-logical study on six sets of tempestites in the Devonian Guanwushan Formation at the Qingfengxia section in Guangyuan City,Sichuan Province,China.Some typical storm depositional indicators,including ero-sional structures,coarse lag deposits,graded bedding,and hummocky cross-stratification were identified.Three proximal storm sedimentary sequences have been established based on the combined characteristics of storm sedimentary structures in the Guanwushan Formation.Storm sequenceⅠconsists of calcirudites with erosional surface at the bottom and homogeneous mudstones at the top.Storm sequenceⅡis charac-terized by calcirudites with erosional surface at the bottom and calcarenites with graded bedding at the top.Storm sequenceⅢis composed of calcirudites with erosional surface at the bottom,coquinas with graded bedding in the middle interval,hummocky cross-stratificated wackestones in the upper part,and mud-stones with wavy and horizontal beddings at the top.The tempestites were formed in the early Frasnian age according to the biochronological analysis of conodont assemblages.Based on the analysis of origin of mo-dern storms,the widely distributed tempestites in early Frasnian age at the low-latitude areas might have resulted from climate warming and rapid transgression.Discovery of tempestites in the study area is of great significance in understanding of the Late Devonian sedimentary environment,palaeogeography,and palaeoclimate in the upper Yangtze region.

关 键 词：风暴岩 沉积环境 古地理 古气候 泥盆纪 龙门山地区 

分 类 号：P531[天文地球—古生物学与地层学]