Triassic Chronostratigraphy and Chinese Stages
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摘要: 国际地层委员会三叠系分会(SubcommissiononTriassicStratigraphy,简称STS)成立后的第一件工作就是建立全球统 一的三叠纪年代地层划分方案.以国际地质对比规划项目IGCP-4(特提斯地区的三叠系)所取得的研究成果为基础,经过STS 专家的深入研讨,采用投票表决的方式于1991年确定了将三叠系划分为3统7阶的国际年代地层格架.随后的焦点集中于各 阶界线层型剖面和点位(GlobalStratotypeSectionandPoint,简称GSSP)的选定工作.但时至今日只确定了3个阶的GSSP,而 且只有三叠系底界,即印度阶底界的GSSP获得的研究最多,且应用广泛;另外2个阶(拉丁阶和卡尼阶)底界的GSSP仍以传 统的菊石作为首选定义标志,其推广可应用性还待实践检验.其他4个阶的界线层型选定工作正在推进中,但都存在一些困 难,其中尤以奥伦尼克阶界线层型的选定工作面临重大挑战.鉴于国际年代地层研究工作所面临的困境,全国地层委员会组织 专家于2000年提出了中国的年代地层划分和建阶方案,并在全国范围开展研究和推广应用.由于三叠纪时期中国处于从海向 陆的重要转折时期,海、陆相地层在中国都有广泛发育,因此提出了海、陆相两套中国三叠纪年代地层划分和建阶方案.经过十 多年的建阶研究和应用实践,中国三叠纪年代地层建阶方案逐步得以改进和完善,促进了中国三叠纪地层规范化研究,为相 关科学研究和实践应用奠定了基础,也推动了国际相关领域的科学研究.Abstract: Construction of a g1oba1 scheme of Triassic time scale was the first key task of the Subcommission on Triassic Stra- tigraphy(STS) since its foundation in1971. Based upon the scheme of Triassic time scale resulted from the research of the In- tcrnationa1 Gco1ogica1 Corrclation Programmc IGCP-4 (Triassic of thc Tcthys Rcalm) , thc STS mcmbcrs madc an in-dcpth dis- cussion and fina11y voted in1991 for the scheme that the Triassic is divided into3 series and7 stages. STS has been working on the selection of the G1oba1 Stratotype Section and Point(GSSP) of the stage boundary. However, only3 GSSPs have been de- cided in the Triassic up to the present, and among them only the base of the Triassic, i.e., the base of the Induan Stage, has been we11 studied and widely applied to various areas over the world, whereas the other2 GSSPs, i.e., the bases of the Ladinian and Carnian stages, are defined through the traditiona1 ammonoid indexes and their extension and application need to be con- firmed by further investigation. The selections on the stratotypes of the remaining4 stages have been in progress but they are cha11enged by some issues, especia11y the decision of the Induan-01enekian boundary stratotype. Considering the di価culties in the construction of the Internationa1 Chronostratigraphic Chart, the Stratigraphic Commission of China proposed a Chinese Chronostratigraphic Chart in2000 to meet the demands of the geo1ogica1 survey and researches in China. Since the Triassic was the turning period from marine to terrestria1 facies in the geo1ogica1 history and both marine and terrestria1 Triassic strata are widespread in China, two schemes of Chinese Triassic chronostratigraphic division corresponding respectively to the marine and tcrrcstria1 「acics and rclatcd Chincsc stagcs havc bccn suggcstcd. A11tcr tcn ycars o」1 study and application, thc schcmcs 」1or thc Chinese Triassic chronostratigraphic divisions and stages have been improved and refined, which promotes the standardization of the Triassic studies in China, and facilitates the g1oba1 Triassic stratigraphic and related researches as we11.
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Key words:
- Triassic /
- chronostratigraphy /
- boundary stratotype /
- Chinese stage /
- research advance /
- stratigraphy
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