Geochemical and pressure-temperature evolution of the continental lithosphere

大陆岩石圈的地球化学和压力-温度演化

• 批准号: 4379-2009
• 负责人: Ghent, Edward
• 金额: $ 1.46万
• 依托单位: University of Calgary
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2010
• 资助国家: 加拿大
• 起止时间: 2010-01-01 至 2011-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=449660
• 关键词: Geochemical; pressure; temperature; evolution; continental

The history of the Earth's interior involves transfer of energy and matter between the interior and the surface. Some of the evidence for this history is found in metamorphic rocks that formed at the margins of the continents where the plates collide, e.g, eclogites and blueschists. Other sources of evidence include pieces of rock (xenoliths) brought up from depth by volcanic eruptions and large scale granitic intrusions. My studies in the Canadian Cordillera and elsewhere involve field mapping and sampling of these rocks with laboratory studies including microscopy and chemical analyses of the rocks and minerals. The data are used in combination with calculations based upon experimental data to estimate the pressure and temperature at which the rocks formed. The estimation of the pressure and temperature at which these rocks form provides information on: (1) the depth in the Earth at which the rocks formed; (2) the amount of uplift and erosion required to get the rocks to the surface; and (3) the variation of temperature with depth in the Earth at the time of metamorphism. Some of the matter transferred from the interior includes hot, water-rich fluids and igneous melts. Estimation of the composition of these fluids and melts is part of the study. Thermodynamic calculations and stable isotope studies can be used to estimate the composition of these fluids and melts. Another important part of this study is the timing of the metamorphic and igneous events and this is accomplished by dating the minerals using radioactive isotopes. All of these studies can be integrated and produce a comprehensive interpretation of the geologic history of large volumes of the Earth's crust and upper mantle.

地球内部的历史涉及内部和表面之间的能量和物质转移。这段历史的一些证据是在板块碰撞的大陆边缘形成的变质岩中发现的，例如榴辉岩和蓝片岩。其他证据来源包括火山爆发和大规模花岗岩侵入体从深处带来的岩石碎片（捕虏体）。我在加拿大科迪勒拉山脉和其他地方的研究涉及实地测绘和采样这些岩石与实验室研究，包括显微镜和化学分析的岩石和矿物。这些数据与基于实验数据的计算结合使用，以估计岩石形成时的压力和温度。对这些岩石形成时的压力和温度的估计提供了以下方面的信息：（1）岩石形成时地球的深度;（2）将岩石带到地表所需的隆起和侵蚀量;以及（3）变质作用时地球温度随深度的变化。一些从内部转移的物质包括热的、富含水的流体和火成岩熔体。估计这些流体和熔体的成分是这项研究的一部分。热力学计算和稳定同位素研究可以用来估计这些流体和熔体的组成。这项研究的另一个重要部分是变质和火成岩事件的时间，这是通过使用放射性同位素测年矿物来完成的。所有这些研究可以综合起来，对大量地壳和上地幔的地质历史作出全面的解释。