COLLABORATIVE RESEARCH RUI: Testing mechanisms for regional dolomitization of Triassic carbonate platforms across the Nanpanjiang Basin of south China

白云石和方解石是组成沉积岩、石灰岩和白云岩的矿物。石灰岩通过一种名为白云石化的化学过程转化为白云岩，在这种过程中，流经地层的水添加镁，将矿物学从方解石改变为白云石。白云岩形成的环境多种多样，从地球表面的海洋或盐湖，到具有高温热液的深层地下区域。白云石化流体的化学和温度在岩石中留下了不同的标志，这取决于白云石化的环境。这项研究将评估在大片地区造成白云石化的过程。结果将提高对这种岩石形成机制的理解，这种岩石通常含有含水层、能源和矿产资源，并被广泛用于建筑材料。该项目将通过研究项目、教育讲习班和为本科生和高中生出版的教育模块，激发未被充分代表的妇女和少数群体对科学的兴趣。这项研究将对中国南部露头的白云石化作用机制进行验证，为评价表层和深层地下环境的区域分布提供了一个天然的实验室。在这个框架内，将通过矿物相的微观分析、白云石晶体中流体的加热和冻结实验、氧、碳和锶同位素分析以及白云石晶体中微量元素的微量分析来评估白云岩作用的温度和化学。研究结果将有助于理解白云石资源、含水层的空间分布，以及在地球历史上运行的过程。本科生将完成实地和实验室工作、会议报告和高级论文。妇女和少数族裔学生将通过大学讲习班招募。外展将包括参加研究和暑期课程的高中生。课程模块将发布在科学教育资源中心的网站上。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Dolomite and calcite are the minerals that make up the sedimentary rocks limestone and dolostone. Limestone is converted into dolostone by a chemical process called dolomitization in which waters flowing through the strata add magnesium, changing the mineralogy from calcite to dolomite. A wide variety of environments have been proposed for the process of dolomitization, ranging from Earth surface marine or saline lagoons to the deep subsurface realm with high temperature hydrothermal fluids. The chemistry and temperature of the dolomitizing fluids leaves a signature in the rock that differs depending on the environment of dolomitization. This study will evaluate the processes that cause dolomitization over vast areas. Results will improve understanding of mechanisms of formation for a rock that commonly contains aquifers, energy and mineral resources, and is widely used in construction materials. The project will stimulate interest in science for underrepresented women and minority groups through research projects, educational workshops, and published educational modules for undergraduates and high school students. This study will test mechanisms of dolomitization in outcrops of south China that provide a natural laboratory to evaluate regional distribution of both surface and deep subsurface environments. Within this framework, the temperatures and chemistry of dolomitization will be evaluated through microscopic analysis of mineral phases, heating and freezing experiments on fluids trapped within dolomite crystals, analysis of oxygen, carbon and strontium isotopes, and microanalysis of trace elements within dolomite crystals. Results will be valuable for understanding spatial distribution of dolomite resources, aquifers, and processes that operated over Earth’s history. Undergraduate students will complete field and laboratory work, conference presentations and senior theses. Women and minority students will be recruited through university workshops. Outreach will involve high school students from Upward Bound in research and summer courses. Course modules will be published on the Science Education Resource Center website.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.