A link between rift-related volcanism and end-Ediacaran extinction? Integrated chemostratigraphy, biostratigraphy, and U-Pb geochronology from Sonora, Mexico
A link between rift-related volcanism and end-Ediacaran extinction? Integrated chemostratigraphy, biostratigraphy, and U-Pb geochronology from Sonora, Mexico
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DOI：
10.1130/geol.s.12915629
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发表时间：
2020-09
期刊：
影响因子：
5.8
通讯作者：
E. Hodgin;L. Nelson;C. Wall;A. J. Barron-Diaz;L. C. Webb;M. Schmitz;D. Fike;J. Hagadorn;E. F. Smith
中科院分区：
文献类型：
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作者：
E. Hodgin;L. Nelson;C. Wall;A. J. Barron-Diaz;L. C. Webb;M. Schmitz;D. Fike;J. Hagadorn;E. F. Smith
我们提出了化学地层学、生物地层学和地质年代学，从一个演替跨越埃迪卡拉-寒武纪边界在墨西哥索诺拉。利用U-Pb化学磨损-同位素稀释-热电离质谱法对一群切面鲜明的火山锆石晶体进行分析，得出了一层位于La ciacimunga组基底寒武系碳同位素偏移最低点的富含赤铁矿的砂质白云岩层的最大沉积年龄为539.40±0.23 Ma。这一层被解释为含有重新加工过的凝灰质物质，它位于最后发现的晚埃迪卡拉纪体化石之上，而在第一次发现的寒武纪足迹化石Treptichnus pedum之下，因此它的年龄是埃迪卡拉纪-寒武纪界线的关键标志。Laurentia南部裂谷相关的洪水型玄武岩火山活动（玄武岩面积为250km3）、负碳同位素漂移和生物翻转的时间重合，与大火成岩省的喷发与埃迪卡拉末灭绝之间的机制联系一致。
We present chemostratigraphy, biostratigraphy, and geochronology from a succession that spans the Ediacaran-Cambrian boundary in Sonora, Mexico. A sandy hematite-rich dolostone bed, which occurs 20 m above carbonates that record the nadir of the basal Cambrian carbon isotope excursion within the La Ciénega Formation, yielded a maximum depositional age of 539.40 ± 0.23 Ma using U-Pb chemical abrasion–isotope dilution–thermal ionization mass spectrometry on a population of sharply faceted volcanic zircon crystals. This bed, interpreted to contain reworked tuffaceous material, is above the last occurrences of late Ediacaran body fossils and below the first occurrence of the Cambrian trace fossil Treptichnus pedum, and so the age calibrates key markers of the Ediacaran-Cambrian boundary. The temporal coincidence of rift-related flood basalt volcanism in southern Laurentia (>250,000 km3 of basalt), a negative carbon isotope excursion, and biological turnover is consistent with a mechanistic link between the eruption of a large igneous province and end-Ediacaran extinction.