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

在阿肯色州和俄克拉何马州的瓦希托山脉中发现的密西西比斯坦利页岩显示出令人惊讶的整体化学特征，可能与变质过程或热液蚀变有关。自西向东的变质品位递增与Mg、Ca、Na、K、Ba等元素的富集和Al、Li等元素的富集相对应。铝含量的增加反映在类绿石和叶蜡石等铝相丰度的增加上。体积化学的变化表明斯坦利可能向周围的地形输出了物质。有必要评估可能导致在瓦希塔记录的化学和矿物学变化的过程。要做到这一点，需要研究西部瓦希塔斯的成岩斯坦利和东部瓦希塔斯的绿片岩相斯坦利之间的总体化学、矿物学和结构差异。特别是，这项研究将记录结构、体化学和同位素示踪剂的变化，这些变化可能有助于估计体积损失，并评估斯坦利在成岩/变质作用期间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.