Oxygen and Hydrogen Isotope Studies of Igneous Rocks and Associated Hydrothermal Metamorphism

我们开发了矿物和热液流体之间18O/16O交换动力学方程，可以用作“氧同位素时钟”。共存矿物的18个值代表了等时线，可以测量化石热液系统的“寿命”和水/岩石比，而无需进行冗长的计算机模拟。我们希望将这些概念应用于各种裂谷带环境，在这些环境中，增强的裂缝渗透率允许地表水的深层循环。浅层的、短暂的系统已经得到了很好的研究，但是更深的、更长的、更热的系统向地壳融化过渡却知之甚少。我们拟在以下地区研究这类“热液-深海相”岩浆：(1)欧洲海西期变质体系，包括西德黑森林的典型混杂岩区。(2)裂谷带环境下的火山活动，特别是冰岛、内华达州大盆地和爱达荷州斯内克河平原。(3)扩散中心在阿拉伯，包括一个22 Ma的海底热液系统（红海的开口）和一个95 Ma的海底系统（阿曼蛇绿岩复合体）。(4)不同类型和变质等级的碎屑沉积岩，以更好地确定成岩、变质和熔融过程中18O/16O和D/H的地球化学旋回。意大利北部的伊夫雷亚带，可能是穿过大陆地壳最底层的最佳区域。(6)意大利第四纪火成岩。(7)榴辉岩和长橄榄岩捕虏体，以更好地确定上地幔的流体-岩石相互作用，并试图在这些次大陆岩石圈中识别古俯冲洋壳。

We have developed equations for the kinetics of 18O/16O exchange between minerals and hydrothermal fluids that can be used as an "oxygen isotope clock". The 18 values of coexisting minerals represent isochrons that can measure the "life-times" and water/rock ratios of fossil hydrothermal systems without doing lengthy computer simulations. We wish to apply these concepts to various rift-zone environments, where enhanced fracture permeability allows deep circulation of surface waters. Shallow, short-lived systems have been well studied, but deeper, longer-lived, and hotter systems transitional to crustal melting are poorly understood. We intend to study such "hydrothermal- anatetic" magmas in: (1) Hercynian-age Metamorphic Systems in Europe, including the classic area of migmatites in the Black Forest, West Germany. (2) Volcanism in Rift-Zone Environments, notably in Iceland, the Great Basin in Nevada, and the Snake River Plain, Idaho. (3) Spreading Centers in Arabia, including a 22 Ma subaerial hydrothermal system (opening of the Red Sea), and a 95 Ma submarine system (Oman ophiolite complex). Also, we need to improve our understanding of the 18O/16O geochemistry of the continental crust and upper mantle, notably in: (4) Detrital Sedimentary Rocks of different types and metamorphic grades to better define the geochemical cycles of 18O/16O and D/H during digeneses, metamorphism and melting. (5) The Ivrea Zone, Northern Italy, perhaps the best available section through the lowermost continental crust. (6) Quaternary- Age Igneous Rocks of Italy. (7) Eclogite and Periodotite Xenoliths to better define fluid-rock interactions in the upper mantle, and to try to identify ancient subducted oceanic crust in these sub-continental lithosphere.