SGER: Exploring Intracrystalline Boron Isotope Variations

硼取代铝在粘土矿物中具有较大的同位素分馏。伊利石/蒙脱石（I/S）粘土比其他类型的粘土含硼量更多，在沉积盆地中也最常见。我们想要验证这样一个假设，即这些粘土的硼含量和同位素比率代表了它们在埋藏到生烃深度期间生长的古流体的温度和组成的有价值的监测。沉积物中B的研究主要集中在吸附-B的行为及其随温度和ph的变化。然而，当温度超过100℃时，吸附-B的分布系数接近于0。因此，在成岩条件下，了解B在粘土矿物晶格取代过程中的分馏作用更为重要。在R1排序过程中，层间b在I/S中的含量大量增加，层电荷导致蒙脱石部分坍塌形成伊利石。使用甘露醇洗涤，然后进行碱阳离子饱和，我们能够分离吸附层，层间层和四面体层b。不同结晶位置的种群b同位素比值不同。利用这种技术，我们将研究B在低温条件下作为单矿物地温计的潜力。

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.