Ichnological evidence for bottom water oxygenation during organic rich layer deposition in the westernmost Mediterranean over the Last Glacial Cycle

Organic rich layers (ORLs), deposited in the westernmost Mediterranean over Last Glacial Cycle, have been studied integrating sedimentological and ichnological information from sediment records recovered at Ocean Drilling Program Leg 161 Sites 976 977. The conducted study has served to redefine ORLs initially differentiated 977 976, with seven new recognized, as well extensions subtraction of some parts previously defined. In addition, three different ORL types are distinguished according features. Type 1 intermediate thickness is highly bioturbated, mainly consisting abundant Scolicia Planolites, frequent Chondrites, possible Thalassinoides base, which interpreted supporting dysoxic conditions during deposition. 2, corresponding thicker intervals, shows alternance moderately bioturbated parts, revealing variable oxygen —from moderate extreme or even suboxic. 3 consists short, laminated intervals characterized by absence bioturbation, indicating anoxic suboxic determining unfavourable macro benthic habitat. amended show a correlation between Sea Surface Temperatures established climatic events Cycle Western Mediterranean.