Rare Earth Elements and Nd Isotopes in Hydrothermal Metalliferous Sediments: Pleistocene and Cenozoic Paleoceanography

在这项研究中，PI将测试和开发一个新的古气候代理-碳酸盐沉积物的稀土元素（REE）丰度，其中包含来自热液羽流的含金属沉积物。结合起来，PI将使用Nd同位素值（？Nd）作为替代，以帮助解开风化速率的差异和海水稀土元素丰度的变化，由于其他原因的来源。REE的短停留时间（1-4 Ka）意味着这些代理可能提供高分辨率数据。初步数据表明，含金属沉积物记录底层水稀土元素模式和稀土元素模式几乎是相同的大西洋和太平洋。整个稀土模式反映在Nd/Er的差异上。初步数据的核心为过去135 Ka表明，Nd/Er和？O具有良好的相关性，显示出良好的代理潜力。额外的初步数据较长时期（过去28马）显示有趣的模式和大的变化？Nd和Nd/Er的这一时期，再次认为，这些组合代理有可能确定不断变化的风化输入到海洋。为了进一步评估这一代用指标，研究人员将分析来自EPR北方和南方其他热液喷口的热液羽流材料，进行体外稀土元素吸收的实验室实验，使用SEPR岩心的全新世岩心顶部校准Nd/Er代用指标，使用具有已知和不同成岩历史的岩心评估可能的成岩作用对代用指标信号保存的影响，并探讨这两个代理的行为Ma至10 Ka时间尺度的大气候变化在渐新世和中新世。

In this study, the PIs will test and develop a new paleoclimate proxy- Rare Earth Element (REE) abundances of carbonate sediments that contain metalliferous sediment originating from hydrothermal plumes. In combination, the PIs will use Nd isotope values (?Nd) as a proxy to help unravel differences in weathering rates and sources from variations in seawater REE abundances due to other causes. The short residence times of the REE (1-4 Ka) mean that potentially, these proxies could provide high resolution data. Preliminary data show that metalliferous sediment records bottom water REE patterns and that the REE patterns are virtually identical for the Atlantic and Pacific. The entire REE pattern is reflected in differences in Nd/Er. Preliminary data for a core for the last 135 Ka indicate that Nd/Er and ???O are well correlated, showing good potential for the proxy. Additional preliminary data for a longer period (last 28Ma) show interesting patterns and large changes in ?Nd and Nd/Er for this period, again arguing that these combined proxies have potential to identify changing weathering inputs to the ocean. In order to further evaluate this proxy, the PIs will analyze hydrothermal plume material from additional hydrothermal vents in the northern and southern EPR, carry out lab experiments of REE uptake in vitro, calibrate the Nd/Er proxy using Holocene core tops from SEPR cores, evaluate possible diagenetic effects on the preservation of the proxy signals using cores with known and diverse diagenetic histories, and explore the behavior of both proxies on Ma to 10 Ka time scales for large climatic variations in the Oligocene and Miocene.