RUI: Collaborative Research: Evaluation of Hybridization Mechanisms in Calc-Alkaline Granites

了解花岗岩的成因是重建地球历史的重要组成部分。可能有几个过程(分步结晶、重铁矿混合和岩浆混合)是重要的。同位素和化学数据表明，镁铁质和长英质岩浆的混合很普遍，产生混合岩石到更彻底的混合岩石，这取决于相互作用的岩浆的成分、温度和相对比例。流变学模拟预测混杂作用占主导地位，小型复合堤防支持这一预测。然而，在较大的钚中，杂化显然是在模型显示的禁止混合的条件下发生的。这种二分法表明，除了两种流体混合之外，其他机制可能在大型深成岩中起作用。Murray和Reid将对约塞米蒂国家公园的地点进行现场、岩相学、地球化学和同位素的协调研究，以测试另外两种杂交机制的可行性，这两种杂交机制是：冷冻球体的解体和玄武岩与围岩的污染，以更容易混合中间成分。遗址包括El Capitan和Tuolumne花岗岩中的一套部分解体的枕头，以及北美墙El Capitan中的一系列受污染的玄武岩。该项目将通过让学生参与研究的所有方面来加强两所大学的地质学教育：实地和分析工作，参加研究研讨会和专业会议。

Understanding the origin of granitic rocks is an essential part of reconstructing earth history. It is likely that several processes (fractional crystallization, restite unmixing, and magma mixing) are important. Isotopic and chemical data have suggested that mixing of mafic and felsic magmas is widespread, producing commingled rocks to more thoroughly hybridized rocks, depending on compositions, temperatures and relative proportions of the interacting magmas. Rheological modeling predicts that commingling should predominate, and small-scale composites dikes support this prediction. In larger plutons, however, hybridi- zation has apparently occurred under conditions that models suggest are prohibitive of mixing. This dichotomy suggests that mechanisms other than two fluid mixing may be operative in the large plutons. Murray and Reid will perform a coordinated field, petro- graphic, geochemical and isotopic study of localities in Yosemite National Park to test the viability of two additional hybridization mechanisms, disintegration of chilled globules and contamination of basalts with wallrock to more easily mixed intermediate compositions. Sites include a suite of partially disaggregated pillows in the El Capitan and Tuolumne granites and a series of contaminated basalts in the North America Wall, El Capitan. This project will enhance geologic education at both insti- tutions by involving students in all aspects of the study: field and analytical work, participation in research seminars and professional meetings.