Tropical ocean temperatures and changes in terrigenous flux during the Paleocene-Eocene Thermal Maximum in southern Tibet

Abstract

The Paleocene-Eocene Thermal Maximum (PETM, ∼56 Ma) was an extreme climate warming event of the early Cenozoic. The development and ecology of carbonate platforms are highly sensitive to changes in SSTs, sea level and terrestrial detrital input. However, no record of SST changes during the PETM has yet been reported from a shallow marine carbonate platform. Here, we reconstruct SSTs for two shallow marine carbonate PETM sections in present-day southern Tibet from the distribution of isoprenoid glycerol dialkyl glycerol tetraethers (isoGDGT). Our dataset demonstrates that the temperature of the tropical eastern Tethys likely increased 3 to 5 °C during the PETM (depending on the TEX86 calibration used), and it supports a reduction of 2 °C in the meridional gradient between middle and low latitudes. Elemental data and quartz content imply an increase in terrigenous flux prior to the onset of the CIE, possibly linked to initial PETM warming. However, inconsistent changes in terrigenous flux at other PETM sections in the eastern Tethys suggest a variable response modulated by sea-level change and hinterland weathering, erosion and sediment delivery.