HR: 0800h
AN: OS51B-1302    [Abstracts]
TI: Petrology and Provenance of Turbidite Sands From the Pandora and Moresby Troughs, Source to Sink Papua New Guinea Focus Area
AU: * Patterson, L J
EM: lpatte3@lsu.edu
AF: Coastal Studies Institute-LSU, Louisiana State University, Baton Rouge, La 70803 United States
AU: Bentley, S J
EM: sjb@lsu.edu
AF: Coastal Studies Institute-LSU, Louisiana State University, Baton Rouge, La 70803 United States
AU: Henry, D
EM: dhenry@geol.lsu.edu
AF: Department of Geology and Geophysics-LSU, Louisiana State University, Baton Rouge, La 70803 United States
AU: Droxler, A
EM: andre@rice.edu
AF: Department of Earth Science, Rice University, Houston, Tx 77251 United States
AU: Dickens, G
EM: jerry@rice.edu
AF: Department of Earth Science, Rice University, Houston, Tx 77251 United States
AU: Opdyke, B
EM: bno@ems.anu.edu.au
AF: Dept. of Earth and Marine Science, Australian National University, Canberra, ACT 0200 Australia
AU: Peterson, L
EM: lpaterson@rsmas.miami.edu
AF: Rosenstiel School of Marine and Atmospheric Science - MGG, University of Miami, Miami, Fl 33149 United States
AB: The Moresby and Pandora Troughs of the northern Coral Sea are components of the deep-sea depositional system that is the ultimate sink for the Source to Sink Papua New Guinea Focus Area. Cores collected from the R/V Melville during March-April 2004 reveal abundant and varied turbidites deposited in these troughs during the Quaternary. Constraining the source regions for these terrigenous sands through mineralogical and textural analysis is the primary focus of this study. Two jumbo piston cores were analyzed for this study, MV25-0403-22JPC from the Moresby Trough (southeast of the Gulf of Papua), and MV26-0403-66JPC from the Pandora Trough (south-central slope of the Gulf of Papua). Cores were analyzed using a multi-sensor core logger onboard ship. Point counts of lithic grains as well as standard Quartz-Feldspar-Lithic (QFL) percentages in thin section were prepared for six sand samples from comparable depths in each of these cores. For comparison to terrigenous source areas, identical analyses will be conducted on samples from the Fly and Strickland rivers. Cathodoluminescence (CL), energy dispersive spectroscopy (EDS), and standard petrographic techniques were used for grain identification. Both cores contain thin-bedded sandy turbidite packages, although Moresby Trough core JPC22 appears to be generally finer-grained. QFL percentages from 22JPC are 13%-65%-23%, respectively, and plagioclase/ total feldspar ratios are near .90. These mineralogical characteristics are generally typical of back-arc settings. QFL percentages from Pandora Trough core JPC66 are 69%-14%-17%, and plagioclase / total feldspar ratios are near .47, characteristic of trailing-edge, passive-margin basins. The concentration of brown and green hornblende is 2 to 3 times greater in 22JPC than in 66JPC. Isotropic volcanic glass is present in both cores. Based on these preliminary observations, we suggest that the apparent contrast in sand mineralogy between 66JPC and 22JPC reflects contrasting source areas and fluvial delivery systems. If this is the case, then the Moresby Trough receives turbidite sands derived mostly from volcanic/collision margin highlands of SW PNG, and the Pandora Trough receives more quartzose sands from the Fly/Strickland system, more akin to a trailing-edge margin.
DE: 4863 Sedimentation
DE: 3022 Marine sediments--processes and transport
DE: 3045 Seafloor morphology and bottom photography
DE: 1815 Erosion and sedimentation
DE: 1020 Composition of the crust
SC: Ocean Sciences [OS]
MN: 2004 AGU Fall Meeting