Boron Isotopic Studies of Hydrothermal Fluids and AssociatedVein Mineralization

此次SGER奖的目的是发起一项合作研究，在Salton Sea、Coso和Geysers地热田的热液盐水和相关矿脉矿化样品之间进行B同位素分馏。本研究将用于评价几种常见蚀变矿物及其沉淀流体之间的B元素和同位素分配。利用为这些油田的商业地热井建立的储层特征，也可以对温度对这种划分的影响进行经验校准。从本质上讲，计划使用自然系统作为实验校准的一种形式。这种方法将提供对各种热液矿物中B浓度的重要调查（以及对每种矿物进行B同位素分析的可行性），从而将随后的详细实验重点放在具有最大实际应用潜力的矿物上。同位素测量将在国家标准与技术研究所与R. Vocke合作进行，后者的研究小组最近开发了一种改进的B同位素质谱法。建议首先分析M.A. McKibben先前收集的流体样本，以改进同位素分析方法，然后访问每个地热田的代表性井，进一步采样流体和脉矿化（从岩心和岩屑）。

The purpose of this SGER award is to initiate a collaborative investigation of B isotopic fractionation between well characterized samples of hydrothermal brines and associated vein mineralization at the Salton Sea, Coso, and Geysers geothermal fields. This study will serve to evaluate both B elemental and isotopic partitioning between several common alteration minerals and the fluids from which they precipitated. Empirical calibration of temperature effects on such partitioning is also possible using reservoir characteristics established for commercial geothermal wells in these fields. Essentially, it is planned to use the natural systems as a form of experimental calibration. This approach will provide an important survey of B concentrations in a variety of hydrothermal minerals(and of the feasibility of B isotopic analysis in each) that will focus subsequent detailed experimentation on those mineral species having the greatest potential for practical applications. Isotopic measurements will be carried out at the National Institute for Standards and Technology in collaboration with R. Vocke whose research group has recently developed an improved method for B isotopic mass spectrometry. It is proposed to first analyze selected fluid samples previously collected by M.A. McKibben to refine methods for isotopic analysis, then to visit representative wells from each of the geothermal fields for further sampling of fluids and vein mineralization (from core and cuttings).