Origin of Granite and Mafic-felsic Magma Interaction in the Lower Crust: Athabasca Granulite Terrane, CA

“这项奖励是根据2009年美国复苏和再投资法案（公法111-5）资助的。”知识价值。加拿大萨斯喀彻温省的阿萨巴斯卡麻粒岩地是地球上最大的完整的下大陆地壳之一，它提供了一个机会，可以亲眼看到岩浆过程的复杂性，这些岩浆过程有助于形成深部地壳。在这个地体中，有独特的非均质下地壳暴露，包括从基性到长英质成分不等的火成岩。与人们普遍认为的下地壳含水量很低相反，这些岩石中有许多含有丰富的含水相。地体东部以3.3 Ga Chipman闪长岩和2.6 Ga Fehr花岗岩/花岗闪长岩为主。在1.9 Ga之前，这些岩石构成了Rae省稳定的深部地壳。在1.9 Ga时，奇普曼基性岩脉群侵入了云母岩和花岗岩。钠长石和部分已结晶的基性岩脉发生了小程度的熔融。Fehr花岗岩经历了广泛的部分熔融，产生了真正的花岗岩岩浆。在几十平方公里的范围内，被刷火的清洁路面暴露在地表，记录了部分融化的过程，以及Fehr花岗岩和Chipman岩脉基性岩浆之间令人惊叹的混合和混合纹理。据推测，深部地壳的非均质性使其成为各种熔体成分的丰富来源，并且在其他地方的浅层地壳暴露中得到充分记录的岩浆相互作用过程在近地幔深度也很常见。需要资金对这些岩石进行全面的岩石学表征。现场关系、纹理和织物将沿着从北向南的梯度/样带从最小到广泛的部分熔化进行描述。主要、痕量和同位素分析将确定端元岩和混合岩的起源，以及在下地壳中发现的烃源岩和熔化物的中地壳等价物。更广泛的影响。这笔资金将用于培养一名博士生，并丰富矿物学、岩石学和构造地质学的本科课程。此外，实地工作将提供一个机会，通过介绍和讨论，向生活在非常偏远地区，但其生计一般以该地区的自然资源为基础的人民进行宣传。这项工作将有助于为地质学家和地球物理学家讨论非均匀下地壳的含义的计划现场论坛奠定基础，最后，该项目将涉及为教师和研究人员开发有关这种特殊的大陆地壳深层暴露的网络资源。

"This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5)."Intellectual Merit. The Athabasca granulite terrane, Saskatchewan, Canada is one of Earth's largest exposures of intact lower continental crust, and offers the opportunity to see first-hand the complexity of magmatic processes that contributed to formation of the deep crust. In this terrane are unique exposures of heterogeneous lower crust comprising igneous rocks ranging from mafic to felsic compositions. Contrary to common belief that the lower crust is very poor in H2O, many of these rocks host abundant hydrous phases. The eastern part of the terrane is dominated by the 3.3 Ga Chipman tonalite and the 2.6 Ga Fehr granite/granodiorite. Prior to 1.9 Ga, these rocks made up the stable deep crust of the Rae Province. At 1.9 Ga, the Chipman mafic dike swarm intruded both the tonalite and the granite. The tonalite and some of the already crystallized mafic dikes were melted to a small extent. The Fehr granite underwent extensive partial melting, producing true granitic magmas. Over an area of tens of km2, brush-fired cleaned pavement exposures record the partial melting process and a stunning array of mixing and mingling textures between partial melt of Fehr granite and the Chipman dike mafic magma. It is hypothesized that the heterogeneity of the deep crust makes it a fertile source for a variety of melt compositions and that magma interaction processes so well documented in shallow crustal exposures elsewhere are also common at near-mantle depths as well. Funds are requested to carry out comprehensive petrologic characterization of these rocks. Field relationships, textures, and fabrics will be described along a north to south gradient/transect from minimal to extensive partial melting. Major, trace and isotopic analyses will establish the origin of end-member and hybrid rocks as well as source rocks and mid-crustal equivalents of melts identified in the lower crust.Broader Impacts. This grant will support the training of a Ph.D. student and the enrichment of the undergraduate mineralogy, petrology, and structural geology courses. In addition, the field work will provide an opportunity for outreach, through presentations and discussions, to a people who live in a very remote area, but whose livelihoods are generally based on the natural resources of the area. The work will help to lay the groundwork for a planned field forum for geologists and geophysicists to discuss the implications of the heterogeneous lower crust, and finally the project will involve the development of web resources for teachers and researchers about this special exposure of deep continental crust.