SGER: Exploring Intracrystalline Boron Isotope Variations

SGER：探索晶内硼同位素变化

• 批准号: 0108852
• 负责人: Lynda Williams
• 金额: $ 3万
• 依托单位: Arizona State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-03-15 至 2002-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0108852&HistoricalAwards=false
• 关键词: SGER; Exploring; Intracrystalline; Boron; Isotope

WilliamsEAR-0108852Boron substitutes for Al in clay minerals with a relatively large isotope fractionation. Illite/smectite (I/S) clays incorporate more boron than other clay types and they are also most common in sedimentary basins. We want to test the hypothesis that the boron contents and isotopic ratios of these clays represent valuable monitors of the temperature and composition of the paleofluids from which they grew during burial to depths of hydrocarbon generation. Research on B in sediments has primarily focussed on the behavior of adsorbed-B and its variations as a function of T and pH. As temperatures exceed 100 degrees C, however, the distribution coefficient for adsorbed-B approaches 0. Therefore, under diagenetic conditions it is more important to understand the fractionation of B during substitution in the clay mineral lattice. There is a large increase in the amount of interlayer-B in I/S during R1 ordering, when the layer charges cause partial collapse of smectite to form illite. Using a mannitol wash, followed by alkali cation saturation we were able to separate adsorbed, interlayer, and tetrahedral layer-B. Each population from different crystallographic sites had a different B-isotope ratio. Using this technique we will study the potential of B as a single-mineral geothermometer under low temperature conditions.

Williamsons-0108852硼在粘土矿物中替代铝，具有相对较大的同位素分馏。伊利石/蒙皂石（I/S）粘土比其他粘土类型包含更多的硼，它们也是沉积盆地中最常见的。我们要测试的假设，这些粘土的硼含量和同位素比值代表的温度和组成的古流体，他们从埋藏到深度的烃生成过程中生长的宝贵的监控器。沉积物中B的研究主要集中在吸附态B的行为及其随温度和pH值的变化。然而，当温度超过100 ℃时，吸附态B的分配系数接近0。因此，在成岩条件下，更重要的是要了解B在粘土矿物晶格中的替代过程中的分馏。有一个很大的增加，在I/S的层间-B的量在R1有序，当层电荷导致部分的蒙脱石崩溃，形成伊利石。使用甘露醇洗涤，然后通过碱阳离子饱和，我们能够分离吸附，夹层，和四面体层-B。来自不同晶体学位点的每个群体具有不同的B-同位素比率。利用这种技术，我们将研究B在低温条件下作为单矿物地质温度计的潜力。