Science Objective

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 observations. 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.

PICASSO is 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. A companion project has been funded in Spain and Ireland as a collaborative 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.