Early diagenetic remineralization of sedimentary organic C in the Gulf of Papua deltaic complex (Papua New Guinea): Net loss of terrestrial C and diagenetic fractionation of C isotopes

Oceania supplies similar to40% of the global riverine flux of organic carbon, approximately half of which is injected onto broad continental shelves and processed in shallow deltaic systems. The Gulf of Papua, on the south coast of the large island of New Guinea, is one such deltaic clinoform complex. It receives similar to4 Mt yr(-1) particulate terrestrial organic carbon with initial particle C-org loading similar to0.7 mg m(-2). C-org loading is reduced to similar to0.3 mg m(-2) in the topset-upper foreset zones of the delta despite additional inputs of mangrove and planktonic detritus, and high net sediment accumulation rates of 1-4 cm yr(-1) . Carbon isotopic analyses (delta(3)C, Delta(14)C) of SigmaCO(2) and C-org demonstrate rapid (