对全球寒武系-奥陶系界线精确划分对比问题的思考  

COMMENTS ON THE PRECISE SUBDIVISION AND CORRELATION OF THE GLOBAL CAMBRIAN-ORDOVICIAN BOUNDARY

作　　者：汪啸风[1] Svend Stouge 王传尚[1] Jorg Maletz 闫春波 Gabriella Bagnoli WANG Xiao Feng;Svend STOUGE;WANG Chuan Shang;Jorg MALETZ;YAN Chun Bo;Gabriella BAGNOLI(Wuhan Center of China Geological Survey(Wuhan Institute of Geology&MineralResources),Wuhan 430000;Natural History Museum of Denmark,University of Copenhagen,Copenhagen 999017;Institute of Geology,FreeUniversity of Berlin,Berlin999035;Dipartimento di Scienze della Terra,Via S.Maria 53,I-56126 Pisa,Italy)

机构地区：[1]中国地质调查局武汉中心,武汉430000 [2]哥本哈根大学,自然历史博物馆,丹麦哥本哈根999017 [3]柏林自由大学地质研究所,德国柏林999035 [4]比萨大学地球科学系,意大利比萨1-56126

出　　处：《地层学杂志》2023年第2期201-224,共24页Journal of Stratigraphy

基　　金：国科学技术部和中国地质调查局基础研究项目(2015FY310100-7、DD20160120-04)共同资助。

摘　　要：基于吉林白山大阳岔小阳桥剖面高精度多学科交叉研究,综合高分辨率生物、层序、化学和磁性地层学的再研究成果,国际奥陶系分会于2019年5月表决通过了中国北方小阳桥剖面为奥陶系底界的全球辅助层型剖面和点(ASSP),即新修的标准辅助界线层型(SABS)(Martinetal.,2022a,2022b),从而为国内外其他区块寒武系-奥陶系界线的精确划分和对比提供了新依据。据此,本文讨论了以下剖面的寒武系-奥陶系界线精确划分与对比问题:位于华夏地块大陆边缘岛弧或弧后盆地相的广东台山新厂阶命名剖面,分别位于扬子地块台地、陆棚-斜坡和斜坡-盆地相的湖北宜昌黄花场两河口剖面、江西修水武宁剖面和湖南常德瓦尔岗剖面,分别位于中朝地块台地和台缘的河北唐山赵阁庄剖面和山东青州饶王山剖面,位于新疆塔里木地块巴楚—西边大板塔格一带寒武系-奥陶系界线所在剖面,位于加拿大纽芬兰绿岬GSSP剖面,以及位于美国犹他州劳森湾的ASSP剖面。值得注意的是,新建立的小阳桥ASSP剖面位于陆棚-斜坡过渡地带,在古地理位置上正好处于浅水碳酸盐台地(如美国劳森湾ASSP)与深水下斜坡(如加拿大绿岬GSSP)和深水下斜坡-盆地(如中国湖南瓦尔岗(Wargang或Wa’ergan))剖面之间的关键位置,从而成为连接他们之间的纽带和对比标志,并据此提高国内外相关界线划分与对比的准确性。此外,小阳桥ASSP详细的生物、沉积、化学和磁性地层分析揭示了绿岬GSSP剖面所指定的GSSP生物和地球化学标志,说明绿岬GSSP剖面的寒武系-奥陶系界线应对比于小阳桥ASSP剖面的标志性块状叠层石石灰岩(0m)之上的第24层(BD24)底部(19.9±0.2m);生物地层学上,该界线位于牙形石Cordylodusintermedius带上部(Cordyloduslindstromi带底界之下1.5m),在最早的浮游笔石(Rhabdinoporaproparabola)首现(FAD)层位(BD26)之下1 m处。层序地层、海平面变Based on intensive multidisciplinary restudies(including high-resolution biostratigraphy,sea-level changes and sequence-,chemo-and magneto-stratigraphy)of the Xiaoyangqiao Section near Dayangcha Village,Baishan,Jilin,the ISOS ratified the Xiaoyangqiao Section in North China as the new Global Auxiliary Stratotype Section and Point(ASSP)for the base of the Ordovician System,after a voting in May,2019,thus providing a new reference for precise regional and/or global subdivision and correlation of the Cambrian-Ordovician boundary.The correlation of the Xiaoyangqiao Section to some other relevant sections in South China are discussed,including the type section of the Xinchangian Stage at Xinchang,Taishan of Guangdong Province,which was regarded to represent continental marginal island arc or back-arc basin facies of the Cathaysia Block;the Lianghekou Section(platform facies)at Huanghuachang,Yichang,Hubei Province;the Wuning Section(shelf-slope facies)in Xiushui,Jiangxi Province;and the Wargang Section(slope-basin facies)in Changde,Hunan Province.,The Xiaoyangqiao ASSP Section is also correlated to a few representive sections of Sino-Korean Block,including the Zhaogezhuang Section(platform facies)in Tangshan,Hebei Province,and the Raowangshan Section(marginal platform)in Qingzhou,Shandong Province;and to the Cambrian-Ordovician boundary(shelf-slope facies)in Dabantage area,West Bachu of Tarim block.Specifically,the correlation of the Xiaoyangqiao ASSP Section to the Green Point GSSP Section in Newfoundland,Canada,and the Lawson Cove ASSP Section in Lawson Bay,Utah,USA are discussed in details.Significantly,the newly ratified Xiaoyangqiao ASSP Section represents a facies of shelf-slope transition,and thus provides a critical connection and correlation between successions of the shallow-water carbonate platform(e.g.,Lawson Cove ASSP,USA),the lower slope facies(e.g.,Green Point GSSP,Canada)and the lower slope-basin facies deposits[e.g.,Wargang(=Wa'ergan)Section,Hunan,China].Furthermore,biostratigraphy and depositional seq

关 键 词：小阳桥剖面 全球辅助界线层型剖面和点 寒武系-奥陶系界线 高分辨率地层学 牙形石 笔石 

分 类 号：P534.41[天文地球—古生物学与地层学] P534.42[天文地球—地质学]