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

这一合作研究项目将与Izu-Bonin-Mariana(IBM)弧的IODP项目密切合作，全面描述可能是其在地球上最好的野外模拟：Alisitos弧的Rosario段。DeBari深度参与了IBM的提议，巴斯比是IODP Expedition 350的联合首席科学家。从弧形地壳剖面中挖掘出的岩石具有独特的能力，通过“地面求真”来为活动俯冲带的研究提供信息，这些假设进入了模型、实验和解释性的地球物理和地球化学。我们将提出的一些问题是对IBM工作的高度补充，它们是：弧形中地壳是如何构成的？年轻弧壳中火山岩和深成岩的关系和比例是什么？建造弧形地壳的速度是多少？弧壳成分是如何随时间变化的？是否有任何更古老的地壳构成了阿利西托斯弧形的重要部分？通过将阿尔西托斯弧与伊豆博宁弧进行比较，我们可以了解到什么关于会聚边缘成矿作用的信息？Alisitos弧区的地壳结构与现代弧区的地震速度剖面相比如何？现代弧形的地表和钻孔热流测量是否与保存在古代弧形地质记录中的特征有关？这项研究进一步促进了两位女科学家(WWU的DeBari和UCSB的Busby)和她们各自的研究生的职业生涯。对这些研究生的培训是合作的，以便两名学生都能熟练地将野外地质学、岩石学和地质年代学结合起来。WWU和UCSB的美国科学家与墨西哥UNAM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。拟议的项目引起了更广泛的科学界的兴趣，因为它解决了美国国家科学基金会GeoPRISMS科学计划中的一些最重要的问题，即通过研究岛弧(http://www.geoprisms.org/science-plan.html#science-plan)，以及GeoPRISMS ExTerra倡议(http://www.geoprisms.org/scd/exterra.html).)设想的研究来研究大陆地壳的生长和演化其中一个主要产品，基于网络的岛弧地壳虚拟场模型，将被科学家用作IBM钻探结果的参考模型，并将在本科生和研究生的课程中使用。在Alisitos弧的野外研讨会，最好与350-352次探险后会议一起举行，在IBM-4钻探开始之前，将为IBM钻探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。国际大洋钻探计划(IODP)正在对IBM弧进行深入研究，将其作为当今新生大陆地壳形成的原地实例。地球是太阳系中唯一拥有广泛的长英质(富硅，贫镁)大陆壳的行星。这些岩石行星和月球都有早在太阳系历史早期形成的玄武岩(富镁)结壳。由于板块构造过程，地球上的大陆地壳体积随着时间的推移而增加，主要是因为长英质岩石在汇聚边缘的中间火山弧中吸积。然而，产生这种长英质到中间地壳的过程在现场并没有得到很好的描述。罗萨里奥地段通过伸展的大洋弧段具有优越的上到中地壳剖面的三维曝光。上一次对这段60公里长的阿利西托斯弧段的测绘是在1990年？S(巴斯比等人，2006年)完成的，将为拟议的研究提供一个框架；然而，那项研究主要集中在对火山岩的野外描述上，地质年代学有限，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，详细确定弧形所有地层级别的岩石类型之间的关系。这一合作研究项目将与IODP Expeditions 350-352(2014年)和第四个雄心勃勃的钻探弧形中地壳的提案(IODP提案698在IBM-4现场进行，等待安排)密切配合。这些数据将被用来构建岛弧地壳虚拟场模型。供科学家用作IBM钻探结果的参考模型。

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.