Collaborative Research: The Evolution of Extremely Acid Lakes and Groundwaters in Western Australia

西澳大利亚南部伊尔加恩克拉通的酸性和中性盐湖和地下水系统代表了一种罕见的现代极端环境类型。这些自然系统的特点是酸碱值在1.5至10.5之间的水域和不同的化学成分，以及不寻常的沉积和成岩矿物组合，以及新的极端微生物。PIS将进行一个钻探项目，从这些极端环境中提供第一批完整的第四纪和晚第三纪沉积物样本。过去的地表和地下历史将从这些岩心的沉积学、矿物学和孢粉学研究中得到解释。过去地表水和地下水的温度、酸碱度和化学成分将由层状和置换盐岩和石膏中的流体包裹体以及石膏、明矾石和黄钾铁矾土中的稳定同位素决定。孢粉形态的鉴定以及富含有机硅质碎屑和成岩矿物的测年将限制年龄。任何可疑的微生物遗骸都将被描述并进行初步研究。来自整个伊尔加恩克拉通的10个岩芯的数据将产生：(1)过去的沉积环境；(2)过去的湖水和地下水的化学和pH；(3)过去的地表水温，作为西澳大利亚南部的第四纪地表气温的替代指标。这项研究将记录这些酸性咸水的演化以及它们对当地、区域和全球地质过程的响应。这项工作将评估地球和火星岩石记录中对过去极端环境的认识。最后，PI将利用这些结果来预测西澳大利亚酸性咸水的未来演变，在那里它威胁到农业、牧场，甚至人类居住。这项研究是与NSF的国际科学与工程办公室联合资助的。

Acid and neutral saline lake and groundwater systems on the Yilgarn Craton in southern Western Australia represent a rare modern extreme environment type. These natural systems are characterized by waters with a pH range from 1.5 to 10.5 and diverse chemical composition, as well as by an unusual assemblage of depositional and diagenetic minerals, and novel extremophilic microorganisms. PIs will conduct a drilling project that will provide the first intact and complete samples of Quaternary and late Tertiary sediments from these extreme environments. Past surface and subsurface histories will be interpreted from sedimentological, mineralogical, and palynological studies of these cores. Temperatures, pHs, and chemical compositions of past surface water and groundwater will be determined by fluid inclusions in bedded and displacive halite and gypsum and stable isotopes in gypsum, alunite, and jarosite. Identification of palynomorphs and dating of organic-rich siliciclastics and diagenetic minerals will constrain ages. Any suspect microbial remains will be described and will undergo preliminary study. Data from ten cores from throughout the Yilgarn Craton will yield: (1) past depositional environments; (2) past lake water and groundwater chemistry and pH; and (3) past surface water temperatures, which serve as surface air temperature proxies, through the Quaternary for southern Western Australia. This research will document the evolution of these acid saline waters and their response to and from local, regional, and global geological processes. The recognition of past extreme environments in the rock record of Earth and Mars will be evaluated with this work. Finally, PIs will use these results to make predictions about the future evolution of acid saline waters in Western Australia, where it threatens farming, ranching, and even human habitation.This research is jointly funded with NSF's Office of International Science and Engineering.