Chemical, Mineralogical and Fabric Evolution of the Lower Stanley Shale, Ouachita Mountains

暴露在阿肯色州和俄克拉何马州瓦奇塔山脉的密西西比州斯坦利页岩显示出令人惊讶的大量化学特征，这些特征可能与变质过程或热液蚀变有关。瓦奇塔斯变质程度自西向东的增加伴随着大量的化学变化，包括亏损镁、钙、钠、钾和巴，相对富集铝和锂。铝含量的增加反映在铝相的丰度增加，如类绿泥石和叶蜡石。大量化学成分的变化表明，斯坦利可能向周围的地形输出了物质。有必要对可能导致瓦奇塔斯记录的化学和矿物学变化的过程进行评估。要做到这一点，需要研究瓦奇塔斯西部的成岩赤柱与东部的绿片岩相赤柱在整体化学、矿物学和组构方面的差异。特别是，这项研究将记录组构、主体化学和同位素示踪的变化，这些变化可能有助于估计体积损失，并评估赤柱在成岩/变质过程中是一个开放系统的程度。

The Mississippian Stanley Shale exposed in the Ouachita Mountains of Arkansas and Oklahoma exhibits surprising bulk chemical characteristics that are probably related either to metamorphic processes or to hydrothermal alteration. The west to east increase in metamorphic grade seen in the Ouachitas is paralleled by bulk chemical changes including depletion in Mg, Ca, Na, K, and Ba, and relative enrichment in Al and Li. The increased Al content is reflected in an increased abundance of aluminous phases such as chloritoid and pyrophyllite. The changes in bulk chemistry suggest that the Stanley may have exported material to surrounding terrains. It is necessary to evaluate the processes that may have led to the chemical and mineralogical changes recorded in the Ouachitas. To do so involves a study of the differences in bulk chemistry, mineralogy, and fabric that exist between diagenetic Stanley in the western Ouachitas and greenschist facies Stanley in the eastern Ouachitas. In particular, this research will document changes in fabric, bulk chemistry and isotopic tracers that may be useful in estimating volume loss and evaluating the extent to which the Stanley was an open system during diagenesis/metamorphism.