FROM MANGROVES TO PETROLEUM PRECURSORS: AN EXAMPLE FROM TROPICAL NORTHEAST AUSTRALIA.

Missionary Bay, north Queensland, is an example of a tropical modern depositional environment dominated by mangrove swamps. Several major sedimentary facies are represented. Large amounts of mangrove litter are carried in nearly anoxic creeks to the bay. Bay-bottom sediments have only a shallow upper oxidized layer, and are strongly reducing at depth. Total lipid content of the bay-bottom sediments is very high. Sedimentation rates for the bay-bottom sediments are high, about 1 cm/year. Progradation rates are also high, about 1 m/year. Anoxic conditions of transport and deposition, plus the high sedimentation rates, suggest that the low-tide muds and bay-bottom muds are excellent source rock analogs.