Monsoon climate and Arabian Sea coastal upwelling recorded in massive corals from southern Oman

Corals living in the coastal waters of southern Oman experience the influence of the seasonally reversing Asian monsoon system. The objective of the research reported here is to assess the potential for using the skeletal chemistry of these corals to investigate past variability in the monsoon climate. To this end, 20-year long, monthly resolution geochemical records are presented for cores from two massive Porites corals, located 20 km apart near Marbat on the Arabian Sea coast of southern Oman. We consider four aspects of skeletal chemistry: oxygen and carbon isotopic composition, barium content and the nature and occurrence of annual fluorescent bands within the coral skeletons. Coral skeletal 180 documents variations in sea surface temperature which have regional and basin-wide significance. In particular, the 80 of coral skeleton precipitated during the period of the NE monsoon is strongly correlated with annual rainfall anomalies in India, whilst that precipitated during the period of the SW monsoon appears to provide information on variability in the strength of coastal upwelling. The stable carbon isotope composition and barium content of these particular corals display strong annual cycles,