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

白云石和方解石是构成沉积岩石灰岩和白云岩的矿物。石灰岩通过一种叫做白云化的化学过程转化为白云石，在这种化学过程中，流经地层的水加入了镁，将矿物从方解石转变为白云石。白云化过程的环境范围广泛，从地球表面的海洋或咸水泻湖到具有高温热液流体的深层地下领域。白云化流体的化学性质和温度在岩石中留下的特征因白云化环境的不同而不同。这项研究将评估在广大地区造成白云化的过程。研究结果将提高对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。本研究将对华南露头白云化机制进行研究，为评价地表和深层地下环境的区域分布提供一个天然实验室。在这一框架内，将通过对矿物相的微观分析、对白云石晶体中捕获的流体的加热和冷冻实验、对氧、碳和锶同位素的分析以及对白云石晶体中微量元素的微观分析来评价白云化的温度和化学作用。研究结果将有助于了解白云岩资源的空间分布、含水层和地球历史上运行的过程。本科生将完成实地和实验室工作、会议报告和毕业论文。将通过大学讲习班招募妇女和少数民族学生。拓展活动将包括来自“向上跳跃”的高中生参加研究和暑期课程。课程模块将在科学教育资源中心网站上公布。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值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.