Testing the interactions between chemical weathering and glacial cycles using novel isotope tracers.

在整个地质时期，反馈过程防止了失控的温室和冰库状态，将地球气候保持在适宜居住的范围内。硅酸盐岩石的大陆风化被认为在这种气候稳定性中发挥了重要作用，但令人惊讶的是，量化得很差。该项目旨在为气候变化的运作提供新的约束条件，作为气候反馈。实验室实验将用来研究各种岩性和粒度的硅酸盐岩石在化学风化过程中的元素释放和铅(铅)同位素体系。然后，这些结果将被用于检验第四纪冰川-间冰期旋回中硅酸盐风化的变异性。由于海洋是大陆剥蚀的颗粒和溶解产物的最终储存库，海洋沉积物岩芯代表了过去风化变化的独特档案。从海洋沉积物的不同部分提取的同位素示踪剂的新组合将量化风化变化对过去气候扰动的响应。洞穴中的锂同位素记录也有探索的余地，作为与陆地冰盖退缩有关的陆地风化的指标。这项研究将在伦敦大学学院逻辑组内最先进的地球化学实验室进行。将在海洋沉积物提取、化学分离以及利用多收集器电感耦合等离子体质谱分析放射性和非传统稳定同位素方面培养专门知识。

Throughout geological time, feedback processes have prevented runaway greenhouse and icehouse states, keeping Earth's climate within habitable limits. The continental weathering of silicate rocks has been proposed to play an important role in such climate stability but is surprisingly poorly quantified. This project seeks to provide new constraints on the operation of weathering as a climate feedback. Laboratory experiments will be used to investigate element release and lead (Pb) isotope systematics during the chemical weathering of silicate rocks over a range of lithologies and grain sizes. These results will then be applied to examine variability in silicate weathering through Quaternary glacial-interglacial cycles. Because the ocean is the ultimate repository for the particulate and dissolved products of continental denudation, ocean sediment cores represent unique archives of past weathering changes.A novel combination of isotope tracers extracted from different fractions of marine sediments will quantify weathering changes in response to past climate perturbations. There is also scope to explore Li isotope records in speleothems as proxies for terrestrial weathering linked to terrestrial ice sheet retreat. This research will be carried out in state-of-the-art geochemistry labs within the LOGIC group at UCL. Expertise will be developed in marine sediment extractions, chemical separations, and analysis of both radiogenic and non-traditional stable isotopes by multi-collector inductively-coupled plasma mass spectrometry (MC-ICP-MS).