Geochemical composition and provenance of muddy shelf deposits in the East China Sea

Textural and geochemical compositions of shelf sediments in the East China Sea were measured and compared with those of riverine sediments. The sediments were primarily composed of mud and sandy-mud, with an average mean grain size of 6.1Φ. Contents of CaCO3 varied from 3.9 to 11.5%, averaging 7.6%. Elemental ratios of Sc/Al, Zr/Ti, Cr/Th, and Nb/Co can be treated as powerful geochemical indices for sediment sources because these elements behave conservatively under marine environments, and the ratios show large variations between different end members of potential sediment sources. Comparative analysis between elemental (Sc/Al, Zr/Ti, Cr/Th, Nb/Co) ratios and Sr isotopic (87Sr/86Sr) ratios strongly suggest that sediments in the northern part of the East China Sea primarily originate from the Huanghe River, whereas the muddy deposits in the western part of the East China Sea originate from the Changjiang River. The difference in 87Sr/86Sr ratios between the two regions appears to indicate varied sources.