Site U1500

Abstract

International Ocean Discovery Program (IODP) Expedition 367 Site U1500 is located on basement Ridge B and is the most seaward site that Expedition 367 drilled within the South China Sea (SCS) continent–ocean transition (COT) zone. Ridge B is located ~80 km seaward of the outer margin high and ~20 km seaward of Ridge A, where Site U1499 was drilled. The goal of drilling here was to sample and log the lowermost sediment and underlying basement rocks to determine basement age and lithology of the COT or embryonic oceanic crust, thus providing a test of different possible models for the processes and rheology controlling the breakup of the continent. Ridge B was expected to have basement of either upper continental crust, lower continental crust, mantle rocks, or oceanic crust. The coring and logging would also constrain the history of the region after rifting by determining the age, water depth, and subsidence rates of the overlying sedimentary packages.