Abstract Rich small skeletal fossil assemblages are described from the Yanjiahe Formation and Tianzhushan Member of southern Huangling Anticline. The Anabarites trisulcatus– Protohertzina anabarica Assemblage Zone (Small Skeletal Fossil Zone 1) is recognized in the middle to upper Yanjiahe Formation, while the thin topmost conglomeratic limestone unit yielded a mixed assemblage resulting from reworking and redeposition of source material of Small Skeletal Fossil Zones 1 to 3 (including Anabarites trisulcatus, Protohertzina anabarica, P. unguliformis, Watsonella crosbyi, Aldanella attleborensis, Anabarella plana). Our revised biostratigraphic correlation indicates the existence of longer hiatuses in the Yanjiahe Formation and between the Yanjiahe and Shuijingtuo formations. The obtained δ13Ccarb values in our profile deviate in some details from those of some previous reports. Based on the new biostratigraphic correlation, the δ13Ccarb trend records values oscillating between −3 to +4.4‰ in the upper Anabarites trisulcatus - Protohertzina anabarica Assemblage Zone, which is unusual for the Yangtze Platform. This interval of positive δ13Ccarb values in the upper Yanjiahe Formation and the Dahai Member of eastern Yunnan are here interpreted to reflect the impact of a local aquafacies. Moreover, it is here argued that the selection of a carbon isotope peak as a primary index tool in the Laolin section for defining the Cambrian Stage 2 must be treated with caution, as this isotope excursion is influenced by a regional water mass and does not reflect an open marine seawater signature, underlining other technical and theoretic concerns on the general application of chemostratigraphy in Cambrian shallow-water carbonate platforms. Overall we suggest that chemostratigraphic correlations need to be supported by biostratigraphic tools.

中文翻译：

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湖北黄陵背斜南部寒武纪小骨骼化石和碳同位素记录及对扬子地台化学地层的意义

摘要 黄陵背斜南部燕家河组和天柱山段发育丰富的小型骨骼化石组合。燕家河组中上部为Anabarites trisulcatus-Protohertzina anabarica组合带（小骨骼化石带1），而顶部薄的砾岩灰岩单元由于小骨骼化石带的源材料再加工和再沉积而产生混合组合1至 3 种（包括三沟 Anabarites trisulcatus、Protohertzina anabarica、P. unguliformis、Watsonella crosbyi、Aldanella attleborensis、Anabarella plana）。我们修正后的生物地层对比表明，燕家河组以及燕家河组和水井沱组之间存在更长的间断。在我们的配置文件中获得的 δ13Ccarb 值在一些细节上与之前的一些报告有所不同。根据新的生物地层相关性，δ13Ccarb 趋势记录的值在上层 Anabarites trisulcatus - Protohertzina anabarica 组合带中在 -3 至 +4.4‰ 之间振荡，这在扬子地台是不寻常的。在此解释了滇东鄢家河组上部和大海段δ13Ccarb 正值区间，以反映当地水相的影响。此外，这里认为选择碳同位素峰作为定义寒武纪第 2 阶段的老林剖面的主要指标工具必须谨慎对待，因为这种同位素偏移受区域水团的影响，并不能反映一个开放的海洋海水签名，强调了化学地层学在寒武系浅水碳酸盐岩平台中的一般应用的其他技术和理论问题。总的来说，我们建议化学地层相关性需要得到生物地层工具的支持。