Th and U isotopes composition of Mn nodule 44 TKD and Mn crust 40 TKD retrieved in the South China sea during expedition SO23/2 (R/V Sonne)

During the campaign SO23/2 (R/V Sonne) in the South China sea various manganese deposits were retrieved by dredging. Two representative samples were selected for chemical analysis: one Mn crust (0.4 cm thick) attached to a vesicular olivine basalt fragment for station 40KD and one irregular spheroidal shaped Mn nodule with rough surface and a Miocene chalk core for station 44KD. In order to study the distribution of Th and U with distance, samples were drilled and the result was divided in equal parts. Liquid chromatography was used to separate and purify the Th isotopes. U and Th concentrations were determined using alpha spectrometry and 232Th isotope using atomic absorption spectroscopy.