Quantifying subsidence and isostatic readjustment using sedimentary paleomarkers, example from the Gulf of Lion
|Author(s)||Rabineau Marina1, Leroux Estelle1, 2, Aslanian Daniel2, Bache F.3, Gorini Christian4, Moulin Maryline2, Molliex Stephane1, 2, Droz Laurence1, Dos Reis Antonio5, Rubino J. L.6, Guillocheau Francois7, Olivet Jean-Louis2|
|Affiliation(s)||1 : UBO, CNRS, IUEM, UMR 6538,Domaines Ocean, F-29280 Plouzane, France.
2 : IFREMER, Ctr Brest, GM, F-29280 Plouzane, France.
3 : GNS Sci, Lower Hutt 5040, New Zealand.
4 : Univ Paris 06, ISTEP, UMR 7193, F-75005 Paris, France.
5 : UERJ Brazil, Dept Oceanog Geol, BR-20550900 Rio De Janeiro, RJ, Brazil.
6 : CSTJF, TOTAL, TG, ISS, F-64018 Pau, France.
7 : Univ Rennes 1, Geosci Rennes, UMR 6118, F-35042 Rennes, France.
|Source||Earth And Planetary Science Letters (0012-821X) (Elsevier Science Bv), 2014-02 , Vol. 388 , P. 353-366|
|WOS© Times Cited||20|
|Keyword(s)||subsidence, pliocene-quaternary, messinian salinity crisis, isostasy, Mediterranean Sea, Gulf of Lion|
|Abstract||Passive margins are characterised by an important tectonic and thermal subsidence, which favours a good preservation of sedimentary sequences. This sedimentation in turn enhances the subsidence because of loading effects. We present here a direct method based on sedimentary markers seen on seismic data, to evaluate total subsidence rates from the coast to the outer shelf and to the deep basin in the Gulf of Lion, from the beginning of massive salt deposition up to present day (the last circa 6 Ma) with minimal theoretical assumptions.On the shelf, the Pliocene-Quaternary subsidence shows a seaward tilt reaching a rate of 240 m/Ma (±15 m/Ma) at the shelf break (70 km from the present day coastline) (i.e. a total angle of rotation of 0.88° (0.16°/Ma)). We were also able to measure and quantify for the first time the isostatic rebound of the outer shelf due to the Messinian salinity crisis (MSC). This value is very high and reaches up to 1.3 km of uplift during the crisis around the Herault–Sète canyon heads (around 1.8 km/Ma). On the slope, we also find a seaward tilting subsidence from Km 90 to Km 180 with a measured angle of 1.41°. From 180 km to the deepest part of the basin, the total subsidence is then almost vertical and reaches 960 m/Ma (±40 m/Ma) during the last 5.7 Ma (±0.25 Ma) in the deepest part of the basin.The subsidence is organised in three compartments that seem related to the very deep structure of the margin during the opening of the Liguro-provencal basin. These very high total subsidence rates enable high sedimentation rates along the margin with sediments provided by the Rhône river flowing from the Alps, which in turn enable the detailed record of climate evolution during Pliocene-Quaternary that make of the Gulf of Lion a unique archive.|