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/g47972.1
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发表时间：
2021-02-01
期刊：
影响因子：
5.8
通讯作者：
Smith, Emily F.
中科院分区：
文献类型：
--
作者：
Hodgin, Eben B.;Nelson, Lyle L.;Smith, Emily F.
我们目前的化学地层学，生物地层学和地质年代学的继承，跨越埃迪卡拉-寒武纪边界在索诺拉，墨西哥。富含桑迪赤铁矿的白云岩层位于碳酸盐岩上方20 m处，记录了拉谢内加组内寒武纪基底碳同位素漂移的最低点，使用U-Pb化学磨蚀-同位素稀释-热电离质谱法对大量锐面状锆石火山晶体进行了测定，得出最大沉积年龄为539.40 +/- 0.23 Ma。该层被解释为含有经过改造的凝灰质物质，位于埃迪卡拉纪晚期身体化石的最后一次出现之上，位于寒武纪痕迹化石Treptichnus pedum的第一次出现之下，因此年龄校准了埃迪卡拉纪-寒武纪边界的关键标志。劳伦蒂亚南部（玄武岩> 250，000 km（3））与裂谷相关的洪水玄武岩火山活动，负碳同位素漂移和生物周转的时间巧合与一个大火成岩省的喷发和埃迪卡拉纪末灭绝之间的机械联系一致。
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 Cienega 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 km(3) 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.