Silica Diagenesis: Deeply Buried Sandstones

深埋石英砂岩的成岩作用在沉积盆地的演化过程中具有重要意义，包括古水文和热史，以及从高级别成岩作用向低级别变质作用的过渡。岩石学研究的主要目的将是定量测量石英和碳酸盐的胶结作用、压力溶液(颗粒接触的几何形状、化学压实的时间和程度)以及孔隙度损失作为压力、温度和综合时间-温度历史的函数。样品将通过岩相显微镜、阴极发光和扫描电子显微镜以及一些化学和原位分析进行检查。成岩历史将在埋藏和热史的背景下重建和设定。压力溶蚀作用将是研究的主要焦点之一，特别是当它涉及到深部埋藏的高级成岩作用与部分变形山带的低级变质作用之间的过渡时。需要取样的砂岩包括格林河盆地的宾夕法尼亚系，阿纳达科盆地的宾夕法尼亚系和奥陶系，以及密歇根和伊利诺伊盆地的寒武系。现在，宾夕法尼亚州宾夕法尼亚州隆起的未变形和变形的部分将与罗德岛宾夕法尼亚和新汉普郡的志留纪Clough石英岩进行比较。最古老的砂岩将是来自斯皮茨卑尔根一个研究充分的地段的元古界石英砂岩。该研究对深部(4~9公里)石英砂岩孔隙度的丧失，影响流体的传质，进而影响油气的产出，具有重要的现实意义。

The diagenesis of deeply buried quartz arenite sandstones is important in the evolution of sedimentary basins, including paleohydrology and thermal history and the transition from high grade diagenesis to low grade matamorphism. The primary aim of petrographic study will be to measure quantitatively cementation by quartz and carbonate, pressure solution (geometry of grain contacts, timing and extent of chemical compaction), and porosity loss as a function of pressure, temperature and integrated time- temperature history. Samples will be examined by petrographic microscopy, cathodo-luminescence and SEM, as well as by some chemical and istotopic analyses. The diagenetic history will be reconstructed and set in the context of burial and thermal history. Pressure solution will be one of the main focuses, especially as it pertains to the transition between the high grade diagenesis of deep burial and the low grade metamorphism of parts of deformed mountain belts. Sandstones to be sampled include the Pennsylvanian of the Green River basin, Pennsylvanian and Ordovician of the Anadarko basin, and Cambrian of the Michigan and Illinois basins. Now uplifted undeformed and deformed sections of the Pennsylvanian of Pennsylvania will be compared with the Rhode Island Pennsylvanian and the Silurian Clough quartzite of New Hampshire. The oldest sandstones will be of Proterozoic quartz arenites from a well-studied section of Spitsbergen. This study has practical significance in the loss of porosity of quartz arenites at great depths (4-9km), which influences the mass transfer of fluids and thus production of oil and, especially, gas.