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

阿尔博兰海是在新第三纪非洲和欧洲交汇期间席卷西地中海的年轻俯冲带之后形成的。直布罗陀弧和阿尔博兰海是该系统的最西端，也是最令人困惑的部分之一。向西回滚、伸展、走滑、火山作用、隆起和下沉的混合作用，使人们无法形成一个解释所有观测结果的一致情景。部分由于资料不足，人们提出了许多模型，包括俯冲、板块断裂、分层和滴漏。有可靠的证据表明，西向俯冲带上覆板块的岩石圈地幔由于弧后拉伸和某种类型的对流移动（如水滴、分层等）而变薄。人们对对流变薄的过程知之甚少，但人们认为对流变薄在驱动地球的隆起和下沉方面很重要。影响活动造山带的变形速率，并有助于大陆物质回到地幔的再循环。该奖项旨在通过被动和主动地震学、大地电磁学、地球化学、岩石学/构造地质学和地球动力学建模，对地中海西部的Alboran海、直布罗陀弧、阿特拉斯山脉和周边地区进行多学科的国际调查。该项目的总目标是研究导致直布罗陀-阿尔博兰海地区对流变薄的过程。这个名为“毕加索”（PICASSO）的项目目前已得到西班牙和爱尔兰的资助，作为欧盟和美国的合作项目，其他一些欧盟国家也提交了或正在提交提案。该项目被选为TopoEurope的试点实验，TopoEurope是欧洲科学基金会最近批准的一项类似地球镜的计划。大部分现场部署将由欧洲科学家完成，包括3D earthscope型滚动阵列（IberArray），美国研究人员将进行额外的针对性现场实验。IberArray已经在毕加索地区部署了约60个站点。

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.