A New Approach to Study Dolomitization Emphasizing Fluid Inclusions, Enewetak Atoll

本文对Enewetak Atoll的白云岩进行了研究，采用新的流体包裹体技术和标准技术，建立了白云化的新模型，并更好地了解了白云化的地球化学触发因素。利用传统的间接技术对Enewetak白云岩进行深入的研究，已经证明在限制白云化的模式和地球化学触发因素方面是不够的。另外，流体包裹体提供了古代白云化流体化学成分的直接记录。冷冻技术将应用于Enewetak流体包裹体，以确定白云化流体的盐度。侦察数据表明，白云石是从一种盐度是白云化流体的两倍的盐水中析出的。侦察数据表明，白云石是从一种盐度是海水两倍的盐水中沉淀出来的。因此，一个新的白云化模型涉及没有沉淀蒸发岩的盐水回流，是有待检验的几个假设之一。激光拉曼微探针工作将首次对低温白云化古流体中的硫酸盐进行分析。流体包裹体提取液将通过DCP和IC分析阳离子和离子，进一步表征白云石化流体。这一新方法将为白云石化的流体演化和地球化学成因提供新的认识。这些信息无法通过标准技术收集到。最后，将采用标准的碳、氧和锶同位素技术对白云岩进行分析，使这项工作与其他白云岩研究直接比较，并进一步评估白云化条件。

This is a study of dolomite from Enewetak Atoll that employs new fluid inclusion techniques and standard techniques to develop a new model for dolomitization and to better understand the geochemical triggers responsible for dolomitization. Thorough study of Enewetak dolomite using traditional indirect techniques has proven less than adequate in constraining the model and geochemical triggers of dolomitization. Alternatively, fluid inclusions provide a direct record of the chemical composition of ancient dolomitizing fluids. Freezing techniques will be applied to the Enewetak fluid inclusions to determine the salinity of dolomitizing fluids. Reconnaissance data indicate that the dolomite precipitated from a brine that was twice the salinity of dolomitizing fluids. Reconnaissance data indicate that the dolomite precipitated from a brine that was twice the salinity of seawater. Thus, a new model for dolomitization involving reflux of brines that have not precipitated evaporites is one of several hypotheses to be tested. Laser Raman microprobe work will provide the first analyses of sulfate in an ancient fluid of low-temperature dolomitization. Extracts from fluid inclusions will be analyzed for cations and ions by DCP and IC to further characterize fluids of dolomitization. This new approach will provide new insight into fluid evolution and geochemical triggers of dolomitization. Such information cannot be gleaned by standard techniques. Lastly, the dolomite will be analyzed by standard carbon, oxygen, and strontium isotopic techniques to make the work directly comparable to other dolomite studies and to further evaluate conditions of dolomitization.