Late Cretaceous changes in oceanic currents and sediment sources in the eastern Tethys: insights from Nd isotopes and clay mineralogy

The Late Cretaceous is marked by geodynamical changes including Africa-Eurasia convergence that resulted in the narrowing of Tethys Ocean and ophiolite obduction along southern margin various continental blocks eastern Tethys. Geochemical mineralogical analyses were performed on Shahneshin section (Zagros Basin - Tethys), to explore consequences this evolution oceanic circulation, estimate role weathering can impact climate through atmospheric CO2 drawdown. [Ni] [Cr] sharply increase uppermost Campanian – Maastrichtian interval are not coeval with an Nd isotope composition (ɛNd) detrital fraction sediments. This interpreted as reflecting mantellic, ultramafic part sequence at time, implying ophiolites exposed continents soon Coniacian vicinity Zagros Basin. Hence their could have contributed climatic cooling. Clay mineralogy reveals alternation kaolinite-rich humid periods (Coniacian/Santonian late early latest Campanian) kaolinite-depleted arid (early Maastrichtian). ɛNd(t) bathyal waters (carbonate leached fraction) appears quite radiogenic, range -3.4 -5.2 ɛ-units, about 2 4 ɛ-units higher than fraction. Changes material delivered appear control local bottom from middle Campanian. By contrast, decoupling points increasing fluxes westward flowing Pacific radiogenic water masses into time. These results support intensification Tethyan Circumglobal Current, likely related seaway.