The Global Boundary Stratotype Section and Point (GSSP) for the base of Changhsingian Stage (Upper Permian)
The Global Boundary Stratotype Section and Point (GSSP) for the base of Changhsingian Stage (Upper Permian)
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DOI：
10.18814/epiiugs/2006/v29i3/003
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发表时间：
2006-09-01
期刊：
影响因子：
3.1
通讯作者：
Cao, Changqun
中科院分区：
文献类型：
--
作者：
Jin, Yugan;Wang, Yue;Cao, Changqun
长兴阶底界的全球层型剖面和点位（GSSP）定义在浙江省长兴县煤山D剖面第4层下部（4a - 2底部）长兴灰岩底部之上88厘米处，从长刺克拉克刺（Clarkina longicuspidata）到王氏克拉克刺（C. wangi）演化谱系中王氏克拉克刺的首现面（FAD）。该层位与长兴阶的标志性䗴类中华古纺锤䗴（Palaeofusulina sinensis）和塔帕沙尼菊石类（tapashanitid ammonoids）的首次出现一致。从长刺克拉克刺到王氏克拉克刺的物种形成事件恰好发生在长兴灰岩第二个准层序的海泛面之上。此外，通过碳同位素比值的降低以及出现在吴家坪晚期反极性带之上的正极性带，可以清晰地识别该界线层段。D剖面以西约300米的C剖面更多地出露了龙潭组上部。它清晰地展示了龙潭组/长兴组地层界线处沉积的过渡性质，因此被描述为一个辅助参考剖面。
The Global Stratotype Section and Point (GSSP) for the base-Changhsingian Stage is defined at the First Appearance Datum (FAD) of the conodont Clarkina wangi within the lineage from C. longicuspidata to C. wangi at a point 88 cm above the base of the Changxing Limestone in the lower part of Bed 4 (base of 4a-2) at Meishan D section, Changxing County, Zhejiang Province, South China. This level is consistent with the first appearance of Changhsingian index fusulinid Palaeofusulina sinensis and tapashanitid ammonoids. The speciation event from Clarkina longicuspidata to C. wangi occurs just above the flooding surface of the second parasequence in the Changxing Limestone. In addition, the boundary interval is clearly recognizable by the depletion of isotopic carbon ratios and the normal polarity zone appearing above the Late Wuchiapingian reversed polarity zone. Section C, about 300 m to the west of Section D, exposes more of the upper Longtan Formation. It clearly shows the transitional nature of deposition across the Longtan/Changxing formational boundary, and thus is described as a supplementary reference section.