Ed Hathorne
Ed Hathorne was born in Maryland USA before moving to England aged 8 where he grew up in the East and West Midlands. He studied Physical Geography at the University of Wales in Aberystwyth where he first learnt about sediment cores and mass spectrometers. He obtained a PhD in isotope geochemistry at the Department of Earth Sciences at the Open University, UK. He was lucky to sail on the JOIDES resolution 3 times as an inorganic geochemist (ODP 208, IODP 321, IODP 353) and also joined 2 mission specific platform expeditions (IODP 310 & IODP 389) which took him to Bremen in Germany. He was a postdoc in Bremen at the Marum, Center for Marine Environmental Sciences until 2009 when he moved to GEOMAR Helmholtz Centre for Ocean Research Kiel. Since 2014 he has been a senior scientist at GEOMAR.
South Asian Monsoon climate control of Neogene to Pleistocene silicate weathering
The weathering of silicate rocks removes CO2 from the atmosphere-ocean system on geological timescales but where exactly these reactions occur and the role of the monsoon climate is poorly constrained. Here we examine the coupled Nd-Hf isotope signatures of clays deposited along the Ganges River sediment cascade by comparing a core from the floodplain, surface sediment samples from the Bay of Bengal shelf, and a marine sediment core from near the mouth of the Ganga-Brahmaputra. For a longer-term perspective of the evolution of silicate weathering under the monsoon climate, samples from International Ocean Discovery Program Site U1443 were measured at orbital resolution across the middle Miocene. The radiogenic isotopes of hafnium and neodymium are decoupled during silicate weathering with deviations of clay Hf isotope compositions from the global average (ΔεHf clay) reflecting silicate weathering intensity. The middle Miocene sediments exhibit some of the highest ΔεHf clay values measured to date suggesting the prevalence of extremely intense chemical weathering during the mid-Miocene climatic optimum. The ΔεHf clay values decrease during the late Miocene, signalling a decrease in weathering intensity and monsoon precipitation. Pleistocene ΔεHf clay values from both terrestrial and marine sediment cores display a temporal pattern of variability similar to the record of South Asian Monsoon intensity inferred from seawater d18O and dD of leaf waxes from the marine core. This demonstrates a strong link between hydroclimate and silicate weathering across this region, where monsoon seasonality and intensity, erodes and delivers a large proportion of sediments to the oceans.
