Environmental Impacts of Caribbean Plateau Volcanism: Timing and Composition of Magmatic Activity Related to Ocean Anoxic Event 2

海洋高原是异常厚的海洋地壳，据信是由于地幔部分熔融增强而迅速形成的。如此大规模的海底火山活动的一个自然后果是，在地质上短暂的间隔内，向海洋释放了大量的热量和富含金属的液体，这很可能导致海洋化学变化，导致海洋缺氧事件和海洋生物的选择性灭绝。白垩纪是一个极端气候条件的时期，伴随着海洋-大气生物地球化学循环的重大扰动。最有趣的特征之一是在缺氧条件下（oae）沉积的富有机物沉积物对正常海洋上层沉积物沉积的零星中断。目前关于这些事件的突然发生和结论的一个模型是，在与海洋高原建设有关的大规模火山活动期间，生物限制性微量金属（营养物质）向海洋表面的输送，增加了浮游植物的产量，并导致深海中氧气的最终枯竭和富有机物沉积物的沉积。认为微量金属是在脱气岩浆流体和以水岩交换为主的热液流出物中释放的。本研究将具体评价加勒比高原构造与Cenomanian-Turonian （C/T）边界（~93.5 Ma） OAE2之间的联系。这将通过(1)从完整的中央高原北部和南部边缘（在海地和库拉帕拉索/阿鲁巴）暴露的厚地壳剖面为加勒比海高原岩浆活动的初始、体积占主导地位的阶段建立一个更牢固的时间尺度，以及(2)通过分析橄榄石和辉石中的熔体包裹体来确定海底熔岩母岩浆中选定痕量金属的丰度。与同一岩石玻璃状枕缘的元素丰度进行比较。在记录OAE2的近场和远场海相沉积剖面中，已经发现了微量金属丰度异常，以及Pb、Os和Nd的同位素偏移。这些发现与加勒比海高原熔岩的释放一致。更广泛的影响我们将为一名研究生提供支持和指导，包括实地采样、辐射测年和微观分析方法方面的培训。本科学生将从我们与大学荣誉学院的合作项目中招收，该项目要求毕业论文http://oregonstate.edu/dept/honors/research/coasreu)。这个项目也是由COAS和地球科学（EarthSystem5）联合提供的新的5年制荣誉地球系统科学学士学位+硕士学位的资助项目。这些学生的资金将通过大学研究办公室对本科生研究的支持来利用。我们还参与了nsf资助的COAS夏季站点REU，并与分析设施有限的本科学院（雷德兰兹和波莫纳）合作。邓肯和肯特将在俄勒冈州立大学指导学生的研究方法和撰写高级论文/项目报告。调查结果将通过正在进行的外展活动（如史密森学会）传达给更广泛的受众。请问邓肯在哪里？他在lip上的工作被包括在视频采访中。以及海洋学等流行期刊[Coffin et al., 2007]。

Intellectual MeritOceanic plateaus are anomalously thick oceanic crust, believed to have formed rapidly by enhanced partial melting of the mantle. A natural consequence of such massive submarine volcanism is the release of extraordinary amounts of heat and metal-rich fluids to the ocean over geologically brief intervals, which are likely to have produced changes in ocean chemistry that lead to ocean anoxic events (OAEs) and selective extinctions of marine organisms. The Cretaceous was a period of extreme climatic conditions accompanied by major perturbations in ocean-atmosphere biogeochemical cycles. One of the most intriguing features is the sporadic interruption of normal marine pelagic sediment deposition by organic-rich sediments deposited during oxygen-deficient conditions (OAEs). A current model for the abrupt onset and conclusion of these events relates delivery of biolimiting trace metals (nutrients) to the surface ocean during massive volcanic activity associated with ocean plateau construction, that increased phytoplankton production and lead to the eventual depletion of oxygen in the deep ocean and deposition of organic-rich sediments. It is proposed that the trace metals were releasedin degassed magmatic fluids plus hydrothermal effluents dominated by water/rock exchange. This study will specifically evaluate the proposed link between metal release associated with the construction of the Caribbean plateau and OAE2 at the Cenomanian-Turonian (C/T) boundary (~93.5 Ma). This will be done by (1) establishing a firmer time scale for the initial,volumetrically dominant phase of Caribbean plateau magmatic activity from thick crustal sections exposed on the northern and southern margins of the intact central plateau (in Haiti and Curaçao/Aruba), and by (2) determining the abundances of select trace metals in parental magmas for submarine lavas through analysis of melt inclusions in olivines and pyroxenes, for comparison with elemental abundances in glassy pillow margins of the same rocks. Trace metal abundance anomalies, as well as isotopic excursions in Pb, Os and Nd, have already been identified in near-field and far-field marine sedimentary sections that record OAE2. These findings are consistent with release from Caribbean plateau lavas.Broader ImpactsWe will support and mentor a graduate student, including training in field sampling, in radiometric dating and micro-analytical methods. Undergraduate students will be recruited from our cooperative program with the University Honors College that requires a senior thesis for graduation http://oregonstate.edu/dept/honors/research/coasreu). This program is also a feeder for a new 5-yr honors B.S. + M.S. in Earth System science, offered jointly by COAS and Geosciences (EarthSystem5). Funding for these students will be leveraged through University research office support for undergraduate research. We also participate in an NSF-funded COAS summer site REU, and with undergraduate-oriented colleges with limited analytical facilities (Redlands and Pomona). Duncan and Kent will supervise students in research methods andwriting of senior theses/project reports at OSU. Findings will be conveyed to broader audiences through ongoing outreach activities, such as the Smithsonian Institution?s Ocean Hall, where Duncan?s work on LIPs is included as a video ?interview?, and in popular journals such as Oceanography [Coffin et al., 2007].