Collaborative Research: The Rosario Segment of the Cretaceous Alisitos Oceanic Arc (Baja California, Mexico): An Outstanding Field Analog to the Izu Bonin Arc

该合作研究项目将与ibmarc的IODP项目紧密结合，全面描述可能是地球上最好的油田模拟：Alisitos弧的Rosario段。德巴里一直深入参与IBM的提案，巴斯比是IODP远征350的联合首席科学家。从弧形地壳剖面中挖掘出来的岩石具有独特的能力，可以通过“地面真实化”模型、实验和解释地球物理和地球化学的假设，为活跃俯冲带的研究提供信息。我们将提出的一些问题，与IBM的工作高度互补，包括：弧形中地壳是如何构造的？幼年弧壳中火山岩与深成岩的关系和比例如何？构造弧壳的速度是多少？弧壳成分如何随时间变化？是否有更古老的地壳构成了阿利西托弧的重要部分？通过比较阿尔西托斯弧和伊豆波宁弧，我们可以了解到什么关于收敛边缘矿化的信息？阿利西托斯弧的地壳结构与现代弧的地震速度剖面如何比较？现代弧的地表和钻孔热流测量是否与古代弧的地质记录中保存的特征有关？这项研究进一步推动了两位女科学家（WWU的DeBari和UCSB的Busby）及其各自研究生的职业生涯。这些研究生的培训是合作的，这样两名学生都能熟练地整合野外地质学、岩石学和地质年代学。世界大学和加州大学圣迭戈分校的美国科学家与墨西哥国立墨西哥大学的国际同事之间的科学互动将拓宽所有参与者的视野，并提高研究和培训成果。拟议中的项目引起了更广泛的科学界的兴趣，因为它解决了NSF GeoPRISMS科学计划中的一些最重要的问题，即通过研究岛弧来研究大陆地壳的生长和演化（http://www.geoprisms.org/science-plan.html#science-plan），以及GeoPRISMS ExTerra计划（http://www.geoprisms.org/scd/exterra.html）设想的研究。其中一个主要产品是基于web的？岛弧地壳虚场模型？，将被科学家用作IBM钻井成果的参考模型，并被纳入本科生和研究生的课程。Alisitos弧线的现场研讨会，最好与远征350-352的远征后会议以及IBM-4钻井开始之前一起举行，将为IBM钻井参与者提供宝贵的背景。下加利福尼亚州白垩纪Alisitos弧的Rosario段是Izu-Bonin-Mariana （IBM）火山弧的杰出野外模拟。国际海洋钻探计划（IODP）正在对IBM弧进行深入研究，将其作为现今新生大陆地壳形成的现场实例。地球是太阳系中唯一一个拥有广泛的长硅（富硅，贫镁）大陆地壳的行星。岩石行星和月球都有玄武岩（富含镁元素）的地壳，形成于太阳系历史的早期。由于板块构造过程，地球上大陆地壳的体积随着时间的推移而增长，主要是由于在会聚边缘的长英质至中间火山弧的增生。然而，形成这种长英质到中间地壳的过程并没有很好的就地表征。罗萨里奥段具有通过伸展洋弧的上至中地壳剖面的优越三维暴露。之前对阿里西托斯弧线这段60公里长的地图绘制于20世纪90年代。s (Busby et al., 2006)，将为拟议的研究提供框架；然而，这项研究主要集中在对火山岩的实地描述上，只有有限的地质年代学，没有地球化学。拟议的研究将利用野外、地球化学和地质年代学数据，详细确定弧内所有地层水平上岩石类型之间的关系。该合作研究项目将与IODP 350-352（2014年）和第四个雄心勃勃的计划（IODP提案698，地点在IBM-4，等待调度）紧密对接。这些数据将用于构建一个？岛弧地壳虚场模型？科学家将其作为IBM钻井结果的参考模型。

This collaborative research project will interface closely with the IODP projects in the Izu-Bonin-Mariana (IBM) arc by fully characterizing what is probably its best field analog on Earth: the Rosario segment of the Alisitos arc. DeBari has been deeply involved in the IBM proposals, and Busby is co-chief scientist on IODP Expedition 350. Exhumed rocks from arc crustal sections have the unique ability to inform studies of active subduction zones by "ground-truthing" the assumptions that go into models, experiments, and interpretive geophysics and geochemistry. Some of the questions we will ask, highly complementary to the IBM work, are: How is arc middle crust constructed? What is the relationship and proportion between volcanic and plutonic rocks in juvenile arc crust? What is the tempo of constructing arc crust? How does arc crust composition change with time? Is there any older crust that makes up significant parts of the Alisitos arc? What can we learn about convergent margin mineralization by comparing the Alsitos arc to the Izu Bonin arc? How does the crustal structure of the Alisitos arc compare with seismic velocity profiles in modern arcs? Can surface and borehole heat flow measurements in modern arcs be related to features preserved in the geologic record of ancient arcs?This research furthers the careers of two female scientists (DeBari at WWU and Busby at UCSB) and their respective graduate students. Training of these graduate students is collaborative so that both students will become skilled at the integration of field geology, petrology and geochronology. Scientific interaction between US scientists at WWU and UCSB and international colleagues at UNAM in Mexico will broaden the perspectives of all participants, and enhance research and training outcomes. The proposed project is of interest to the broader science community, as it addresses some of the foremost questions in the NSF GeoPRISMS science plan on the growth and evolution of continental crust through study of island arcs (http://www.geoprisms.org/science-plan.html#science-plan), as well as research envisioned by the GeoPRISMS ExTerra initiative (http://www.geoprisms.org/scd/exterra.html). One of the main products, a web-based ?Island Arc Crust Virtual Field Model?, will be used by scientists as a reference model for IBM drilling outcomes, and in curriculum for both undergraduate and graduate students. A field workshop in the Alisitos arc, ideally held in conjunction with Expeditions 350-352 post-expedition meetings and before IBM-4 drilling begins, will provide invaluable context for IBM drilling participants.The Rosario segment of the Cretaceous Alisitos arc in Baja California is an outstanding field analog for the Izu-Bonin-Mariana (IBM) volcanic arc. The IBM arc is under intense study by the International Ocean Drilling Program (IODP) as an in-situ example of present-day formation of nascent continental crust. Earth is the only planet in the solar system with extensive felsic (Si-rich, Mg-poor) continental crust. The rocky planets and the Moon have basaltic (Mg-rich) crusts formed early in the history of the solar system. The volume of continental crust on Earth has grown over time due to plate tectonic processes, dominantly because of accretion of felsic to intermediate volcanic arcs at convergent margins. However, the processes that produce this felsic to intermediate crust are not well characterized in situ. The Rosario segment has superior three-dimensional exposures of an upper- to middle-crustal section through an extensional oceanic arc. Previous mapping of this 60-km-long segment of the Alisitos arc, done in the 1990?s (Busby et al., 2006), will provide a framework for the proposed study; however, that study focused mainly on field descriptions of the volcanic rocks, with limited geochronology, and no geochemistry. The proposed study will determine in detail the relationships between rock types at all stratigraphic levels in the arc, using field, geochemical, and geochronological data. This collaborative research project will interface closely with IODP Expeditions 350-352 (in 2014) and a fourth ambitious proposal to drill to the arc middle crust (IODP Proposal 698 at site IBM-4, awaiting scheduling. These data will be used to construct an ?Island Arc Crust Virtual Field Model? to be used by scientists as a reference model for IBM drilling outcomes.