Stable isotope systematics in complex carbonates: Decoding geochemical processes and environmental conditions on Earth and other planets

碳酸盐，如珊瑚和洞穴沉积物，在整个地质历史中一直是地球表面最丰富的矿物之一。在一些火星陨石中也发现了不同化学成分的碳酸盐。因此，碳酸盐岩作为重建地球和其他星球环境历史的自然档案，一直受到地球科学家的广泛研究。我的研究项目集中在研究碳酸盐矿物的稳定同位素系统学，以准确解码隐藏在碳酸盐矿物中的地球化学和环境信号。我的发现研究计划的主要目标是详细了解结构复杂的碳酸盐矿物的稳定同位素系统学，例如具有两个不同阳离子层的白云石（CaMg（CO 3）2）和晶体结构中含水的ikaite（CaCO 3·6 H2O）。尽管在地球表面条件下，它们的丰度不如众所周知的碳酸盐或方解石，但这些结构复杂的碳酸盐仍然具有地质重要性，并且具有很高的潜力，可以作为地球化学替代物，用于探测陆地和地外环境的地球化学过程和气候/环境条件，包括南极洲和火星。我的研究团队将通过改进我实验室完善的合成方法和专业设备，在各种实验室条件下合成白云石和伊卡伊特两种复杂的碳酸盐。这些碳酸盐岩的矿物学和稳定同位素特征将被仔细检查，其形成机制和条件，以更好地解释从碳酸盐岩的地球化学或环境信息。在不牺牲现有分析精度的情况下，还将探索具有成本效益或时间效益的分析技术，用于对两种目标碳酸盐进行准确的稳定同位素分析，这不仅是为了我拟议的研究，也是为了更广泛的科学界的利益。我还将检查通过国家/国际合作获得的天然样品（例如，南极洲的ikaite），以验证我们的实验结果，并解释天然碳酸盐的地球化学数据，以准确揭示地球和其他星球的气候/环境历史。我提议的研究结果将为利用陆地或地外碳酸盐开辟一个新的机会，这些碳酸盐由于缺乏科学理解和分析挑战而被科学界忽视或未被探索，以揭示地球和其他行星的气候/环境历史。这对于预测地球未来的气候变率具有重要意义，为我国政府和公众制定相关的指导方针和法规提供了依据。我提议的研究还将为高素质人员（HQP）提供尖端的研究经验，并帮助他们发展未来职业所需的基本分析和研究技能。

Carbonates, such as corals and cave deposits, have been one of the most abundant minerals on Earth's surface throughout its geological history. Carbonates of varying chemical compositions were also found in some Martian meteorites. Therefore, carbonates have been extensively studied by earth scientists as a natural archive from which Earth and other planet's environmental history can be reconstructed. My research program has focused on studying stable isotope systematics of carbonate minerals to accurately decode geochemical and environmental signals hidden in the carbonate minerals. The main objective of my Discovery research proposal is to gain a detailed understanding of stable isotope systematics of structurally complex carbonate minerals, such as dolomite (CaMg(CO3)2) with two distinct cation layers and ikaite (CaCO3·6H2O) containing water in its crystal structure. Although they are less abundant than the well-known carbonate, or calcite, under Earth's surface condition, these structurally complex carbonates are still of geological importance and have high potential as geochemical proxies for probing geochemical processes and climatic/environmental conditions from terrestrial and extraterrestrial environments, including Antarctica and Mars. My research team will synthesize two complex carbonates, dolomite and ikaite, under various laboratory conditions by refining my laboratory's well-established synthesis methods and specialized facilities. These carbonates will then be examined carefully for their mineralogical and stable isotope characteristics with respective to their formation mechanisms and conditions to better interpret geochemical or environmental information from the carbonates. Cost-effective or time-efficient analytical techniques, without sacrificing the existing analytical precision, will also be explored for accurate stable isotopic analyses of the two target carbonates not only for my proposed research, but also for the benefit of a broader scientific community. I will also examine natural samples, obtained through national/international collaborations (e.g., ikaite from Antarctica), to validate our experimental findings and interpret geochemical data from natural carbonates to accurately uncover Earth and other planet's climate/environmental history. The outcome of my proposed research will open a new opportunity to use terrestrial or extraterrestrial carbonates that have been neglected or unexplored by the scientific community due to lack of scientific understanding and analytical challenges to uncover Earth and other planet's climate/environmental history. This is important to predict Earth's future climate variability, providing our government and public to prepare for relevant guidelines and regulations. My proposed research will also provide highly qualified personnel (HQP) with cutting-edge research experience and help them to develop essential analytical and research skills required for their future careers.