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

这是对来自埃尼韦塔克环礁的白云岩进行的一项研究，该研究采用了新的流体包裹体技术和标准技术，以开发一种新的白云石化模式，并更好地了解导致白云石化的地球化学触发因素。用传统的间接技术对埃尼韦塔克白云岩进行了深入的研究，已证明不足以约束白云石化的模式和地球化学触发因素。或者，流体包裹体提供了古代白云石化流体化学成分的直接记录。冰冻技术将应用于Enewetak流体包裹体，以确定白云石化流体的盐度。勘察数据表明，白云石是从一种盐度是白云化流体盐度两倍的卤水中沉淀出来的。勘测数据表明，白云石是从海水盐度两倍的卤水中沉淀出来的。因此，一个新的白云石化模型，包括没有沉淀的蒸发岩的卤水回流，是需要检验的几个假设之一。激光拉曼显微探针的工作将首次提供低温白云岩化古老流体中硫酸盐的分析。流体包裹体的萃取物将通过DCP和IC分析阳离子和离子，以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触发因素提供新的见解。这样的信息不能通过标准技术收集。最后，将用标准的碳、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相比较，并进一步评价白云岩的成岩条件。

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.