Collaborative Research: Tectonic and Magmatic Implications of a Mid-Crustal, Sheeted Complex in a Tilted Arc Section, California

在加利福尼亚州东部横贯山脉的一个倾斜的中地壳部分，包括约书亚树国家公园(JTNP)，暴露出的一个片状深成复合体将被详细检查。该部分提供了一个极好的机会来分析(1)岩浆管道系统中随深度变化的物理变化和增长；(2)源区不均一性、污染和原位晶体-液体分馏在形成深成系统成分多样性方面的相对重要性；以及(3)中地壳拆离和/或垂直变形分配在形成造山带规模的片状深成杂岩中的作用。野外测绘和详细的构造分析与侵入单元的地质年代学和地球化学相结合，将允许检验一系列假说。一个目标是确定上、下地壳深成岩体和下伏的席状杂岩是否同步形成，从而反映出大陆边缘弧建造过程中岩石成因和侵入样式随深度的突然变化。他们还将测试这样的假设，即该杂岩既代表了一个岩浆转移带，创造了垂直通道，也代表了一个杂交地，形成了与上地壳深成岩浆和爆炸性火山岩亲缘的岩浆。其目的是扩大我们对大陆地壳中部和深层板块边界造山作用的理解。这项研究将极大地影响我们对为火山提供燃料的岩浆管道系统中运行的物理和化学过程的垂直变化的认识。这项研究将集中在日本技术国家方案的范围内，并将通过地球科学宣传和解释活动对公共教育产生重要的积极影响。在过去五年中，私人投资机构与JTNP的公园管理局工作人员及其解释机构沙漠研究所建立了合作关系。他们将与公园和美国地质调查局合作完成地质图，提高对S公园地质的了解，重点关注影响S公园景观形成的火山和构造演化中的重大事件。进一步的外联将通过开展实地考察和讲座来扩大这一承诺，并将把成果转化为协助公园工作人员加强公共教育和课程材料。在南加州大学和南加州理工学院，将通过特殊的实地、课堂和实验室经验，包括为人数不足的学生群体提供绝佳的机会，加强地球科学方面的研究生和本科生教育。

A sheeted plutonic complex exposed within a tilted mid-crustal section in the eastern Transverse Ranges of California, including Joshua Tree National Park (JTNP), will be examined in detail. The section provides a wonderful opportunity for analysis of (1) the depth dependent physical changes in, and growth of, a magma plumbing system; (2) the relative importance of source region heterogeneity, contamination, and in situ crystal-liquid fractionation in forming compositional diversity in plutonic systems, and (3) the role of mid-crustal detachments and/or vertical deformation partitioning in forming orogen-scale sheeted plutonic complexes. Field mapping and detailed structural analyses combined with geochronology and geochemistry of intrusive units will allow testing of a series of hypotheses. One goal is to determine whether upper and lower crustal plutons and the underlying sheeted complex formed synchronously and thus reflect an abrupt depth-dependent change in petrogenesis and intrusive style during continental margin arc construction. They will also test the hypotheses that the complex represents both a zone of magma transfer, with the creation of vertical pathways, and a site for hybridization that formed magmas parental to upper crustal plutons and explosive volcanic rocks. The goal is to expand our understanding of orogenesis along plate boundaries in the middle and deeper parts of continental crust. This study will dramatically affect our knowledge of vertical changes in the physical and chemical processes operating in magmatic plumbing systems that feed volcanoes. The research will be concentrated within the boundaries of JTNP and will have important positive impact on public education through geoscience outreach and interpretive activities. Over the last five years, the PIs have developed collaborations with Park Service staff at JTNP and with its interpretive arm, the Desert Institute. They will work with the Park and the U.S. Geological Survey to complete a geologic map and improve understanding of the Park?s geology, with a focus on major events in the volcanic and structural evolution that influenced formation of the Park?s landscape. Further outreach will extend that commitment through development of field trips and lectures, and will translate the results to assist park staff in enhancing public educational and curriculum materials. At USC and IUPUI graduate and undergraduate education in the geosciences will be strengthened through exceptional field, classroom and laboratory experiences, including excellent opportunities for underrepresented student groups.