Probing connections between deep earth and surface processes in a land-locked ocean basin transformed into a giant saline basin: the Mediterranean DREAM-GOLD project

Abstract

During the last decade, the interaction of deep processes in the lithosphere and mantle with surface processes (erosion, climate, sea-level, subsidence, glacio-isostatic readjustment) has been the subject of heated discussion. The use of a multidisciplinary approach linking geology, geophysics, geodesy, modelling, and geotechnology has led to the awareness of coupled deep and surface processes. Deep earth dynamics (topography, erosion, tectonics) are strongly connected to natural hazards such as earthquakes, landslides, and tsunamis; sedimentary mass transfers have important consequences on isostatic movements and on georesources, geothermal energy repartitions The ability to read and understand the link between deep Earth dynamics and surface processes has therefore important societal impacts. Ground-truthing at carefully-selected sites of investigation are imperative to better understand these connections.

Due to its youth (<30 Ma) and its history of strong subsidence, the almost land-locked Gulf of Lion-Sardinia continental margins system provides a unique record of sedimentary deposition from the Miocene to present. Palaeoclimatic variations, tectonic events, and subsidence history are all recorded here at very high resolution. The late Miocene isolation and desiccation of the Mediterranean, the youngest and most catastrophic event, the Messinian Salinity Crisis (MSC), induced drastic changes in marine environments: widespread deposition of evaporite (gypsum, anhydrite and halite) in the central basin, and intense subaerial erosion along its periphery. These extraordinary mass transfers from land to sea induced strong isostatic re-adjustments that are archived in the sedimentary record and represent a window to the lithospheric rheology and the deep processes.

The GOLD project, submitted as Pre-857 in 2014, is also part of the DREAM (Deep-sea Record of Mediterranean Messinian Events Drilling) and Umbrella proposal “Uncovering a Salt Giant” focused on the MSC. GOLD proposes to explore this unique sedimentary record as well as the nature of the deep crustal structure, providing valuable information about the mechanisms underlying vertical motions in basins and their margins. The pre-Proposal submitted as Pre-857 in 2014, was approved by SEP-CIB panel, and will be submitted as a Full-Proposal on 1st April 2015.

AAPG Datapages/Search and Discovery Article #90226 © 2015 European Regional Conference and Exhibition, Lisbon, Portugal, May 18-19, 2015