Mineral Transformations in Low Grade Rocks

透射电子显微镜和其他电子 微束技术在研究 通过黑云母级变质作用的成岩作用 碎屑沉积物和火成岩。 重点是charac- 粘土矿物，其中高分辨率 技术允许直接的结构，化学和纹理 特征化 表征样品的比较， 给定过程的范围允许过渡机制， 被定义。 这项研究强调了以下因素的平行影响： 改变温度、水岩比和应力， 在亚稳态阶段的反应，其中过渡是在 可预测的Ostwald步骤规则样变化的平衡 一般达到绿片岩相的状态。 具体项目包括：（1）墨西哥湾沿岸泥质 沉积物，重点是伊利石/蒙皂石关系（2）定量- 伊利石结晶度变化原因初探 (3)通过黑云母级变质作用的成岩作用， 在新西兰南部造成纹理变化的过程 岩石，主要是杂砂岩（4）低级变质， 威尔士泥质岩中的接触变质叠加（5） 海相玄武岩，在DSDP中强调三八面体粘土矿物 核心540 B。 这些研究有助于更好地了解 富含粘土的岩石中的成岩作用， 对油气勘探的影响。

Transmission electron microscope and other electron microbeam techniques are being emphasized in studies of diagenesis through biotite-grade metamorphism of fine-grained clastic sediments and igneous rocks. The focus is on charac- terization of clay minerals, for which the high resolution techniques permit direct structural, chemical and textural characterization. Comparison of characterized samples that cover the range of a given process permit mechanisms of transitions to be defined. This research emphasizes the parallel effects of changing temperature, water/rock ratio and stress in promoting reactions in metastable phases, for which transitions are in predictable Ostwald-step-rule-like changes toward the equilibrium state generally reached at greenschist facies conditions. Specific projects include: (1) Gulf Coast argillaceous sediments, with emphasis on illite/smectite relations (2) quanti- tative studies of the causes of variation in illite crystallinity (3) diagenesis through biotite-grade metamorphism, with emphasis on processes causing textural changes in southern New Zealand rocks, principally greywackes (4) low grade metamorphism with contact metamorphic overprint in Welsh pelites (5) alteration of marine basalts, emphasizing trioctahedral clay minerals in DSDP core 540B. Such studies lead to a better understanding of diagenesis in clay-rich rocks which will have important implications to oil and gas exploration.