Collaborative Research: Coring Seymour Island (CSI) Antarctica: Evaluating Causes and Effects of the End Cretaceous Mass Extinction

非技术描述：这个为期4年的项目正在评估在南极半岛西部塞莫尔岛发现的南纬白垩纪-古近纪(K-PG)高纬度露头剖面的灭绝模式和沉积条件的证据。该团队正在使用在风化层以下收集的沉积物样本来评估目标地层间隔中详细的沉积结构、地球化学和微化石。这项研究将有助于确定K-PG大灭绝是单阶段事件还是双阶段事件，以及西摩岛地区过去的地质历史是受限的、亚缺氧的海洋环境还是开阔的混合陆架。该奖项包括一项各级学生培训的综合计划，重点加强了与一名高中地球科学教师的合作伙伴关系，该教师在一所为代表性不足的学生提供服务的学校工作。技术描述：这项拟议中的研究正在应用多种技术来解决一个最主要的研究问题，最近的研究对此存在分歧：来自南极洲西摩岛独特露头的化石证据是否与单阶段或双阶段灭绝一致？在两个阶段的模型中，第一次物种灭绝将主要影响底栖生物，并将发生在K-PG边界的另一次物种灭绝之前约150000年。然而，这种早期的灭绝可以合理地解释为一种未被识别的相控，它被表面风化所掩盖。这个团队正在利用微化石证据和详细的沉积岩石学和地球化学数据来评估西摩岛的化石证据是否符合单阶段或双阶段的灭绝过程。该团队正在使用详细的沉积岩石学和地球化学方法来测试K-PG区间的相变化，这将解释明显的早期灭绝。正在对岩心沉积有孔虫、硅质微体化石和钙质超微化石的样品进行评估，以提供高分辨率的地层分辨率，并评估是否存在早期灭绝的证据。此外，该小组正在使用多种地球化学方法来评估是否有证据表明塞莫尔地区盆地存在间歇性缺氧或缺氧和/或物理限制。来自这一分析的数据将表明这一地区是一个受限的、亚缺氧的海洋环境还是一个开放的良好混合的陆架。这一裁决反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Non-technical description:This 4-year project is evaluating evidence of extinction patterns and depositional conditions from a high southern latitude Cretaceous-Paleogene (K-Pg) outcrop section found on Seymore Island, in the Western Antarctic Peninsula. The team is using sediment samples collected below the weathering horizon to evaluate detailed sedimentary structures, geochemistry, and microfossils in targeted stratigraphic intervals. The study will help determine if the K-Pg mass extinction was a single or double phased event and whether Seymour Island region in the geological past was a restricted, suboxic marine environment or an open well-mixed shelf. The award includes an integrated plan for student training at all levels, enhanced by a highlighted partnership with a high school earth sciences teacher working in a school serving underrepresented students. Technical description: The proposed research is applying multiple techniques to address an overarching research question for which recent studies are in disagreement: Is the fossil evidence from a unique outcropping on Seymour Island, Antarctica consistent with a single or double phased extinction? In a two-phased model, the first extinction would affect primarily benthic organisms and would have occurred ~150 kiloyears prior to a separate extinction at the K-Pg boundary. However, this early extinction could plausibly be explained by an unrecognized facies control that is obscured by surficial weathering. This team is using microfossil evidence with detailed sedimentary petrology and geochemistry data to evaluate if the fossil evidence from Seymour Island is consistent with a single or double phased extinction process. The team is using detailed sedimentary petrology and geochemistry methods to test for facies changes across the K-PG interval that would explain the apparent early extinction. Samples of core sedimentary foraminifera, siliceous microfossils, and calcareous nannofossils are being evaluated to provide a high-resolution stratigraphic resolution and to evaluate whether evidence for an early extinction is present. Additionally, the team is using multiple geochemical methods to evaluate whether there is evidence for intermittent anoxia or euxinia and/or physical restriction of the Seymore region basin. Data from this analysis will indicate if this region was a restricted, suboxic marine environment or an open well-mixed shelf.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.