High‐resolution evolution of terrigenous sediment yields in the Provence Basin during the last 6 Ma: relation with climate and tectonics

Abstract

Basin-wide correlation of Messinian units and Plio-Quaternary chronostratigraphic markers (5.3 Ma, 2.6 Ma, 0.9 Ma and 0.45 Ma), the mapping of total sediment thickness and the determination of overall sedimentary volumes enabled us to provide a high-resolution quantitative history of sediment volumes for the last 6 Ma along the Gulf of Lions margin. The results point to (i) a dramatic increase in terrigenous sediment input during the Messinian Salinity Crisis. This increased sedimentation reflects enhanced regional fluvial erosion related to the dramatic fall of Mediterranean base-level. Stronger weathering due to a regional wetter climate probably also increased erosional fluxes. (ii) A sediment input three times higher during the Plio-Quaternary compared to the Miocene seems in agreement with published measurements from World's ocean. However, the timing of this increase being uncertain, it implies that the trigger(s) also remain(s) uncertain. (iii) A decrease in detrital volume around 2.6 Ma is attributed to a regional change in the drainage pattern of rivers in the northwestern Alps. (iv) This study also highlights the Mid-Pleistocene Revolution around 0.9 Ma, which resulted in an almost doubling of sediment input in the Provencal Basin.

Organic matter isotopes reveal enhanced rainfall activity in Northwestern Mediterranean borderland during warm substages of the last 200 kyr

“…Seismic investigations and dated sediment cores allowed a detailed reconstruction of sedimentary accumulation since the Messinian (ca. 6 Myr; Leroux et al, 2017;Rabineau et al, 2006 among others), which is described as a superposition of 100 kyr seismic sequences separated by major discontinuities formed in response to glacio-eustatic sea level changes. In the GoL, seaward migration of the shoreline close to our study site (~90/100 mbsf; Rabineau et al, 2006) induced high to very high sedimentation rates during glacial times (averaging ~1 to 2 m ka -1 )…”

On the termination of deep-sea fan channels: Examples from the Rhône Fan (Gulf of Lion, Western Mediterranean Sea)

“…Due to the wealth of geophysical and sedimentological data acquired in the Gulf of Lion since 1965 (Menard et al, 1965), the Plio-Quaternary architecture of the margin and the sediment sources to the basin are well known (Lofi et al, 2003;Leroux et al, 2014;Rabineau et al, 2014;Leroux et al, 2017). Deep-sea sedimentation since the Pliocene was dominated by gravity processes, i.e.…”

“…com.). The fan was fed mainly by alpine inputs of the Rhône River (Molliex et al, 2016;Leroux et al, 2017).…”

The late Messinian event: A worldwide tectonic revolution

“…It started 5.97 Ma ago, when vast amounts of evaporites began to be deposited in the Mediterranean area, leading to a significant drop in Global Ocean salinity (Adams, Benson, Kidd, Ryan, & Wright, ). This event left indelible signs in the present terrestrial and marine landscapes through intense erosion associated with a Mediterranean >1000 m sea‐level drop (Bache et al., ; Clauzon, ) and the accumulation of large volumes of detritic (Gorini et al., ; Leroux et al., ; Lofi et al., ) and evaporitic rocks, mainly gypsum and halite (CIESM, ; Hsü et al., ).…”