AN INVESTIGATION OF CLIMATE HISTORY, SEA-LEVEL CHANGE, AND GEOLOGICAL PROCESSES IN MODERN TROPICAL EPEIRIC SEAS: APPLICATION TO GLOBAL CHANGE AND ANCIENT ANALOGUES

As part of the IODP, we proposed drilling in the shallow epeiric seas of Australasia (Southeast Asia and northern Australia) using a Mission-Specific Platform. Despite the array of scientific opportunities afforded by tropical epeiric seas, a systematic study of these epeiric seas and the adjacent lands has yet to be conducted. The region of shallow cratonic seas spans the range of climates from the rain forests of the equatorial perhumid (everwet) tropics to the savannas of the semiarid tropics (seasonal). There are two goals of this proposal, 1) establish the long-term (Plio-Quaternary) history of climate and sea-level changes and the relation of this history to atmospheric processes where the greatest ocean-atmosphere transfer of heat and moisture occurs, and 2) develop a comparison between the physical and chemical sedimentary processes in modern tropical epeiric seas with the widespread cratonic seas of the pre-Neogene. In addition, a wide spectrum of associated research topics can be addressed, based on well-preserved strata that range from highstand shallow-water marine deposits to lowstand paleosols, riverine, and lacustrine sediments. The key investigative value of these sediments is their potentially complete preservation based on seismic records from the Gulf of Carpentaria and field observations in the epeiric seas of the Carboniferous. The preservation of both lowstand and highstand lithologies results from low energy in broad expanses of advancing and retreating shallow water, such as a tide over a mud flat. The effect is that complete transgressive/regressive cycles occurred without significant erosion or evidence of a lag deposit, thus preserving the marine and nonmarine strata, including paleosols. To fully understand the atmospheric, oceanic, and geologic processes active in an epeiric system, it is recommended that the study also include an onshore component.