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.

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与裂谷有关的火山活动与埃迪卡拉末灭绝之间有联系吗？来自墨西哥索诺拉的综合化学地层学，生物地层学和U-Pb地球年代学

我们介绍了跨越墨西哥索诺拉（Sonora）的Ediacaran-Cambrian边界的一系列地热地层学，生物地层学和地球年代学。富含赤铁矿的砂质白云岩床，发生在碳酸盐上方20 m处，记录了LaCiénega组内基性寒武纪碳同位素偏移的最低点，使用U-Pb化学磨损-同位素稀释法得出的最大沉积年龄为539.40±0.23 Ma。 -热电离质谱分析大量尖锐的火山锆石晶体。该床层被解释为包含重做的凝灰质材料，位于最后一次出现的爱迪卡拉动物体化石的上方，而低于第一次出现的寒武纪微量化石Treptichnus pedum的所在地，因此该年龄标定了爱迪卡拉坎-寒武纪边界的主要标志。³的玄武岩），负的碳同位素偏移和生物更新与大火成岩省的爆发和埃迪卡拉car灭绝之间的机械联系相一致。