Tracing the origin of subduction components beneath the South East rift in the Manus Basin,Papua New Guinea |
| |
| Authors: | Sung-Hyun Park Sang-Mook Lee George D Kamenov Sung-Tack Kwon Kyeong-Yong Lee |
| |
| Institution: | 1. Korea Polar Research Institute, Incheon, Republic of Korea;2. School of Earth and Environmental Sciences, Seoul National University, Seoul, Republic of Korea;3. Department of Geological Sciences, University of Florida, Gainesville, FL32611, USA;4. Department of Earth System Sciences, Yonsei University, Seoul, Republic of Korea;5. Deep-Sea Research Program, Korea Ocean Research and Development Institute, Ansan, P.O. Box 29, Seoul, Republic of Korea;1. Department of Geology, University of California, One Shields Avenue, Davis, CA 95616, United States;2. Department of Chemistry, University of California, One Shields Avenue, Davis, CA 95616, United States;1. Department of Earth and Planetary Sciences, University of California, Davis, CA 95616, USA;2. Department of Geoscience, Aarhus University, DK-8000 Aarhus C, Denmark;3. Graduate School of Engineering, Tohoku University, Aoba-ku, Sendai, 980-8579, Japan;4. Department of Chemical Engineering and Materials Science, University of California, Davis, CA 95616, USA;1. MLR Key Laboratory of Metallogeny and Mineral Assessment, Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037, China;2. Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China |
| |
| Abstract: | The Manus Basin to the northeast of Papua New Guinea is an actively spreading/rifting back-arc basin in the Bismarck Sea located between the inactive Manus-Kilinailau trench on the Pacific-plate side and the active New Britain trench on the Solomon-plate side. Spreading/rifting in the Manus Basin takes place in the last 0.78 Myr or so. We present major and trace elements, and Sr–Nd–Pb isotope compositions of rock samples taken from the South East Rift (SER) at the eastern end of the Manus Basin. The strong enrichment of Pb and LILE (large ion lithophile elements) relative to HFSE (high field strength elements) and REE (rare earth elements) in the SER lava is also quite similar to other island arc lavas, suggesting that substantial amount of subduction components were present in its source mantle. To investigate the origin of the subduction components in SER lavas, we compare the geochemical data of SER lavas to published data from New Britain Arc (NBA) and Tabar–Lihir–Tanga–Feni (TLTF) island chain. The volcanism in NBA is related to presently active subduction of the Solomon slab, whereas the TLTF volcanism is located in the forearc area of New Ireland arc which was formed during a former subduction of the Pacific slab. In other words, the NBA and TLTF lavas were influenced by subduction components from the present and former subduction, respectively. We argue that the subduction components in SER lava were incorporated in the mantle lithosphere during the active arc volcanism on New Ireland because the amount of the subduction component in SER decreases with increasing in distance from New Ireland. On the other hand, no relationships are found with respect to New Britain. The Sr–Nd–Pb isotopes indicate that SER lavas contain little sediment component and less amount of fluid component derived from altered oceanic crust compared to the TLTF lavas. This is probably due to the fact that SER is located in backarc settings in contrast to TLTF which is located in forearc setting with respect to the Pacific slab. Thus it is likely that the sediment was removed from the slab in the forearc and/or arc areas, and therefore little or none was introduced in the backarc mantle, which is the source region for SER magmas at present. Fluid derived from altered oceanic crust also may have made its way into the sub-forearc region more effectively than backare region by shallow dehydration process. |
| |
| Keywords: | |
| 本文献已被 ScienceDirect 等数据库收录！ |
|
