EAGER: Do Mass Extinctions Have Diagenetic Consequences? Investigating Unique Early Diagenesis at the Triassic-Jurassic Boundary

生物大灭绝会导致成岩作用吗？在三叠系-侏罗系交界处研究独特的早期成岩作用当软沉积物变成硬岩时，成岩作用就发生在地质过程中。成岩特征通常被认为是次生特征？因为它们发生在沉淀物被埋藏之后，大多与地表条件隔离。作为次要特征，它们在研究古代环境时通常被忽视。相比之下，PI最近的发现表明，在大规模灭绝期间，在海底或略低于海底的成岩作用过程可能确实掌握着以前未被注意到的关于大规模灭绝原因的线索。PIS发现了与三叠系-侏罗系(T-J)界线有关的独特成岩特征--碳酸钙扇层。不列颠哥伦比亚省东部的大灭绝。质地和地球化学证据表明，碳酸钙层直接生长在海底下方，很可能是在大灭绝时受到海洋化学的影响。碳同位素分析和质量平衡计算表明，先前存在的碳酸盐的溶解可能为早期成岩层提供了碳酸钙的来源，潜在地表明了形成过程中的海洋酸化作用和潜在的消亡机制。在这里，PI提出了一个新的概念，即大规模消亡机制可能会影响成岩领域，研究长期被忽视的成岩特征可能会以以前没有开发过的方式来阐明消亡机制。有趣的是，一项文献搜索在世界各地的其他T-J边界遗址发现了不同寻常的碳酸盐成岩特征，但它们的性质和与物种灭绝有关的产状尚不清楚。为了确定这些特征是否与物种灭绝相关，PIS建议进行一项初步研究，在其他地方(如英格兰的圣奥德里？S湾、威尔士的拉弗诺克角和北爱尔兰的拉恩)发现的与物种灭绝相关的成岩作用的新框架内，对不寻常的成岩阶段进行调查。来自多个地区的碳酸盐成岩特征确实与物种灭绝有关，这一发现将为随后对众多其他T-J遗址进行全面研究提供动力，以开拓大规模物种灭绝研究的新窗口--早期成岩领域。

Do Mass Extinctions Have Diagenetic Consequences? Investigating Unique Early Diagenesis at the Triassic-Jurassic BoundaryPI: David J. BottjerCo-PI: Frank A. CorsettiEAR-1017536ABSTRACT The geological process of diagenesis occurs when soft sediments are turned into hard rocks. Diagenetic features are commonly considered ?secondary features? because they occur after the sediments are buried, mostly isolated from surface conditions. As secondary features, they are usually overlooked when investigating ancient environments. In contrast, PIs recent discoveries suggest that diagenetic processes operating at or just below the seafloor during the time of a mass extinction may indeed hold previously unnoticed clues to the causes of mass extinctions. PIs have discovered unique diagenetic features?calcium carbonate fan layers?associated with the Triassic-Jurassic (T-J) boundary, one of the ?Big 5? mass extinctions, in eastern British Columbia. Textural and geochemical evidence suggests that the calcium carbonate layers grew immediately below the seafloor, likely influenced by ocean chemistry at the time of the mass extinction. Carbon isotopic analysis coupled with mass balance calculations suggest dissolution of preexisting carbonate likely provided the source of calcium carbonate for the early diagenetic layers, potentially indicating ocean acidification in their formation and as a potential extinction mechanism.Here, PIs propose the novel concept that mass extinction mechanisms could affect the diagenetic realm and that studying long-ignored diagenetic features might elucidate the extinction mechanisms in ways not previously exploited. Intriguingly, a literature search turned up unusual carbonate diagenetic features at other T-J boundary sites from around the world, but their nature and occurrence with respect to the extinction is unclear. To determine whether the features are relevant to the extinction, PIs propose a pilot study to investigate unusual diagenetic phases found elsewhere (e.g., St. Audrie?s Bay, England; Lavernock Point, Wales; and Larne, Northern Ireland) within their emerging framework of extinction-related diagenetic effects. The discovery that the carbonate diagenetic features from multiple localities are indeed relevant to the extinction will provide the impetus for a subsequent full-scale study of numerous other T-J sites to exploit a new window?the early diagenetic realm?in the study of mass extinctions.