Collaborative Research: PICASSO: Program to Investigate Convective Alboran Sea System Overturn

阿尔博兰海是在新近纪非洲和欧洲汇合期间横扫地中海西部的年轻俯冲带之后形成的。直布罗陀弧线和阿尔博兰海是该系统最西边的部分，也是最令人困惑的部分之一。向西退缩、伸展、走滑、火山活动、隆起和下沉的混合，使人们无法尝试组成一个一致的情景来解释所有的观测。部分由于数据不足，已经提出了许多涉及俯冲、板片断裂、分层和滴落的模型。有可靠的证据表明，向西俯冲带上覆板块的岩石圈地幔由于弧后伸展和某种类型的对流移动(如滴落、剥离等)而变薄。对流变薄的过程人们知之甚少，但人们认为对流变薄对推动地球表面的隆升和下沉、影响活动造山带的变形速率以及促进大陆物质重新循环回到地幔具有重要作用。该奖项旨在利用被动和主动地震学、大地电磁、地球化学、岩石学/构造地质学和地球动力学模型，对地中海西部的阿尔博兰海、直布罗陀弧形、阿特拉斯山脉和周围地区进行多学科的国际调查。该项目的总体目标是研究导致直布罗陀-阿尔博兰海区域对流变薄的过程。该项目名为毕加索，目前已在西班牙和爱尔兰作为欧盟-美国的一个口头项目获得资助，其他一些欧盟国家提交或正在提交提案。该项目被选为拓扑欧洲的试点实验，拓扑欧洲是欧洲科学基金会最近批准的一个类似地球范围的倡议。很大一部分现场部署将由欧洲科学家完成，包括3D EarthScope类型的滚动阵列(IberArray)，以及由美国调查人员进行的额外有针对性的现场实验。伊比利亚数组已经在进行中，在毕加索地区部署了大约60个测站。

The Alboran Sea was created in the wake of the young subduction zones that swept across the Western Mediterranean in the Neogene during the convergence of Africa and Europe. The Gibraltar Arc and Alboran Sea are the westernmost part of the system and one of the most confusing. The mixture of westward rollback, extension, strike-slip, volcanism, uplift and subsidence has defied attempts to compose a consistent scenario that explains all of the obervations. Partly as a result of inadequate data, there are many models that have been proposed involving subduction, slab breakoff, delamination and drips. There is credible evidence that the lithospheric mantle of the overriding plate of a west-facing subduction zone has been thinned by both back-arc stretching and some type of convective removal (e.g. drips, delamination, etc.). The process of convective thinning is poorly understood but is believed to be important in driving uplift and subsidence of the Earth?s surface, influencing rates of deformation in active orogens, and contributing to recycling of continental materials back into the mantle. This award provides for a multidisciplinary, international investigation of the Alboran Sea, Gibraltar arc, Atlas Mountains and surrounding areas in the western Mediterranean using passive and active seismology, magnetotellurics, geochemistry, petrology/structural geology, and geodynamic modeling. The overall goal of the project is to study the processes responsible for convective thinning in the Gibraltar-Alboran Sea region. The project, known as PICASSO, has now been funded in Spain and Ireland as a colloaborative EU-US program, with proposals from a number of other EU nations submitted or in process. The project was selected as the pilot experiment for TopoEurope, an EarthScope-like initiative recently approved by the European Science Foundation. A large part of the field deployments will be done by European scientists, including a 3D EarthScope-type rolling array (IberArray), with additional targeted field experiments by US investigators. The IberArray is already underway with ~60 stations deployed in the PICASSO field area.