Neogene Sources and Sinks of Carbonates and Siliciclastics in the Gulf of Papua, Papua New Guinea

Evgueni N. Tcherepanov¹, André W. Droxler¹, Gerald R. Dickens¹, Sam J. Bentley², Larry C. Peterson³, and Luc Beaufort^4
1 Rice University, Houston, TX
² Louisiana State University, Baton Rouge, LA
³ University of Miami, Rosenstiel School of Marine and Atmospheric Science, Miami, FL
⁴ CEREGE - Université Aix-Marseille III, France

This study is based on the interpretation of a series of industrial seismic lines and existing wells acquired by different companies on the shelf of the Gulf of Papua. Sediment production and accumulation in the Gulf of Papua have evolved during the Neogene from a pure carbonate to a mixed siliciclastic/carbonate system in which the siliciclastic sedimentation dramatically increased since the Messinian and became prevalent in particular since the late Pliocene and early Pleistocene. Several isolated carbonate platforms were established and thrived during the early Miocene on topographic highs separated by 1- 2 km deep troughs. Some of the platforms drowned and quickly subsided as early as the upper most part of the early Miocene but were not buried until the late Pliocene and the early Pleistocene by siliciclastic sediments prograding southeastward and reaching 2-3 km in thickness. This immensely large flux of siliciclastic sediments coming from the northwest had its origin from the rapid uplift and exhumation of the PNG high mountains associated to the equatorial warm and wet climatic conditions of the area. The siliciclastic sediments first filled the troughs between already drowned carbonate platforms and covered the platform tops with about 2 km of sediments. In particular in the southern part of the Gulf, other platforms have remained active until today. The acquired surveys of the modern Ashmore, Pandora, and Moresby troughs by the 2004 R/V Melville and 2005 R/V Marion Dufresne, used as analogues, greatly help our understanding of the paleo-trough and platform evolution buried under the wide shelf of the Gulf of Papua.