Advances in Earth Science ›› 2013, Vol. 28 ›› Issue (7): 737-750. doi: 10.11867/j.issn.1001-8166.2013.07.0737

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Magmatism of Typical Marginal Basins (or Back-Arc Basins) in the West Pacific

Shi Xuefa, Yan Quanshu   

  1. Key Laboratory of Marine Sedimentary and Environmental Geology, The First Institute of Oceanography, State Oceanic Administration, Qingdao266061, China
  • Received:2013-04-18 Revised:2013-06-16 Online:2013-07-10 Published:2013-07-10

Shi Xuefa, Yan Quanshu. Magmatism of Typical Marginal Basins (or Back-Arc Basins) in the West Pacific[J]. Advances in Earth Science, 2013, 28(7): 737-750.

There developed about 75 percent of marginal basins (or back-arc basins) in the west Pacific in which there have built the biggest and most complex trench-arcback-arc system has been built. Based on ages inferred from magnetic anomaly stripes, these marginal basins can be divided into three spreading epochs. This paper, based on drilling results of the Deepsea Drilling Program (DSDP), the Ocean Drilling Program (ODP) and the Integrated Ocean Drilling Program (IODP), combined with other survey results, systematically describes the characteristics of the West Philippine Basin (WPB) (No. 1 spreading epoch), the South China Sea (SCS) and the Shikoku Basin (SKB) (No.2 spreading epoch), and the Okinawa Trough and Mariana Trough (No.3 spreading epoch). Rock types in WPB include NMORB (related to the back-arc spreading process similar to those in mid-ocean ridges), OIB (related to mantle plume) and arc volcanics (related to subduction process), reflecting that WPB has experienced complex tectonic evolution. In SKB, in addition to the occurrence of NMORB-EMORB which may be related to the back-arc spreading process, medium-K and super-K alkali basalts have been obtained from the Kinan seamount chain, and the latter may be produced by intraplate volcanism. In SCS, no oceanic basement rock, but alkali basalts from seamounts have been reported, and the dynamic origin for Cenozoic spreading of the SCS are still in debate. In Mariana trough, from south to north, rock types are transitional, ranging from MORB-like to IAB-like. The Okinawa Trough is a nascent basin, and rock types include MORB-like rock from southwestern segment, basaltic rocks and acidic rocks from the middle segment, and intermediate and acidic rocks from the northeastern segment. This paper also suggests  that it should perform integrated studies of volcanism in the Mariana arc-trough system and the Ryukyu arcOkinawa trough, which will be very helpful to understand the relaitionship between subducting input and arc and back-arc volcanic output and provide some important clues to the tectonic evolution of the West Pacific. We should make full use of upcoming IODP legs 349 to 352 to improve our research skills in deep sea study area.

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