摘要
黔西北遵义丁台剖面下寒武统龙王庙阶清虚洞组的底部和中部发育两套具有不同沉积特征的风暴沉积,与同时期风暴沉积多发现于黔东湘西台缘区不同,研究在黔西北台地内部发现该时期风暴沉积。其底部风暴沉积段发育侵蚀底面、粗粒滞留沉积、丘—洼状交错层理、沙纹层理和泥晶灰岩背景沉积,共识别出三种类型的风暴沉积序列,其沉积特征指示其形成于正常浪基面与风暴浪基面之间的中缓坡环境,而中部风暴沉积段则发育粗粒滞留沉积、粒序层理、沙纹层理和具鸟眼构造的藻屑灰岩背景沉积,可识别出四种类型的风暴沉积序列,其沉积特征指示其形成于浪基面之上的浅水潮坪环境。本剖面上下两段形成于不同沉积背景的风暴沉积的发现不仅丰富了我们对风暴沉积的认识,更为重要的是为研究早寒武世龙王庙期扬子地台的古纬度及古板块演化、地层等时对比和古地理演化提供了极有价值的资料。
Two sets of storm deposits,with different sedimentary characteristics,were found at the bottom and the middle of Qingxudong Formation（ Lungwangmiaoan Stage,Lower Cambrian） of the Dingtai section,Zunyi,northwestern Guizhou province,which are different from the discovery of the storm deposits that were found mostly at the platform margin in eastern Hunan and western Guizhou. It was the first time that we found storm deposits at the interior of the Yangtze platform in northwestern Guizhou at the same stage. At the bottom,we found erosion surface,coarse lag deposit,hummocky-sunken cross-stratification,ripple bedding,and micrite limestone,which represents the background deposit,and we can recognize three types of storm deposit sequences,and its sedimentary characteristics indicate that it was deposited at middle ramp,between the wave base and the storm wave base. At the middle,we found coarse lag deposit,graded bedding and ripple bedding,and the background deposit is algal clast limestone which develops bird-eye structure,and there are four types of storm deposit sequences that we can recognize,and its sedimentary characteristics indicate that it was deposited at shallow water tidal flat,above the wave base. The discovery of this two sets of storm deposits,which deposited at different settings,not only enrich our understanding of storm deposit,but more impotant is that it can provide us valuable infomation for our study on the evolution of paleolatitude and paleoplate,the isochronostratigraphic correlation and the evolution of paleogeography of the Yangtze platform in the Lungwangmiaoan Stage,Lower Cambrian.
出处
《沉积学报》
CAS
CSCD
北大核心
2016年第3期478-486,共9页
Acta Sedimentologica Sinica
基金
国家科技重大专项(2008ZX05043-005)
中国地质调查局项目(1212010916060
12120115004301)
国家自然科学基金项目(41302093)~~
关键词
黔西北
丁台剖面
下寒武统
清虚洞组
风暴沉积
northwestern Guizhou
Dingtai section
Lower Cambrian
Qingxudong Formation
storm deposit
