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

在这项研究中，pi将测试和开发一种新的古气候代理-含有源自热液柱的含金属沉积物的碳酸盐沉积物的稀土元素（REE）丰度。结合使用，pi将使用Nd同位素值(？Nd)作为代理来帮助揭示风化速率的差异和海水REE丰度变化的来源，这些变化是由其他原因引起的。稀土元素停留时间短（1 ~ 4 Ka），意味着这些代用品有可能提供高分辨率的数据。初步数据表明，含金属沉积物记录了底水稀土元素模式，大西洋和太平洋的稀土元素模式几乎相同。整个稀土模式反映在Nd/Er的差异上。过去135ka的核的初步数据表明，Nd/Er和？？O的相关性很好，显示出代理的良好潜力。额外的较长时期（最近28Ma）的初步数据显示出有趣的模式和大的变化？Nd和Nd/Er，再次认为这些组合的代用物有可能识别海洋中不断变化的风化输入。为了进一步评估这一代理，pi将分析EPR北部和南部其他热液喷口的热液羽流物质，开展体外稀土吸收的实验室实验，使用SEPR岩心的全新世岩心顶部校准Nd/Er代理，使用具有已知和多样化成岩历史的岩心评估可能的成岩作用对代理信号保存的影响。探讨渐新世和中新世大气候变化在Ma - 10ka时间尺度上的表现。

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.