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|Title: ||Overview and early highlights of the TAIGER project marine, active-source seismic program|
|Authors: ||K. D. Mcintosh;H. J. Van Avendonk;C. Liu;S. Hsu;C. Lee;T. K. Wang;F. T. Wu|
|Contributors: ||NTOU:Institute of Applied Geosciences|
|Issue Date: ||2011-10-20T08:19:00Z
|Abstract: ||The marine active-source portion of the TAIGER (TAIwan GEodynamic Research) project took place during April-July 2009 using the R/V Marcus Langseth with support from a variety of Taiwanese ships used to deploy and recover ocean bottom seismographs (OBSs). Due to Taiwanese shiptime (Langseth) contribution, the active-source program was doubled from our original proposal. Over the course of three, ~month-long cruises, the Langseth produced seismic source points along >13,000 km of track line. This includes > 11,000 km of deep-penetration multichannel seismic reflection data (MCS), shots to ~269 OBS stations (Taiwanese and U.S.), and shots to ~280 temporary land seismic stations across Taiwan. During this comprehensive project the Langseth circled Taiwan and ventured far to the south and east. TAIGER data cover the passive margin SW of Taiwan to provide a “pre-collision” structural configuration of the subducting plate, while TAIGER MCS and OBS data acquired on transects south of Taiwan will provide an idea of the “pre-collision” structural configuration of the Manila trench subduction zone. We will compare these areas to the evolving crustal structure of the Taiwan collision, which will be analyzed with onshore/offshore seismic data recorded during TAIGER legs 1 and 2. These TAIGER crustal transects will elucidate crucial components and stages of the southwestward advancing collision. We were able to process all the MCS data during the acquisition cruises to preliminary stack and FK migration. In much of the area SW of Taiwan we observe deep reflections, likely marking Moho. Surprisingly, even at distances > 250 km south of the shelf edge, apparent basement crustal thickness is frequently 3+ s (two-way travel time) or about 9-11 km. We also obtained exciting results across both the Manila/Luzon and Ryukyu arc-trench systems. These subduction systems are primarily characterized by ample sediment supply and relatively fast convergence leading to young, rapidly-accreting, sedimentary prisms. However, we were able to cross the Ryukyu trench several times well east of Taiwan where sediment supply is much reduced. This area of the forearc, east of the Gagua ridge, has a much smaller prism and may also be truncated by a nearly margin-parallel transcurrent fault system. Although the shipboard data processing provides an excellent initial look at many important tectonic features around Taiwan, we need to attenuate multiples and re-migrate the MCS data before doing further interpretation. An ongoing, concurrent effort to process and model the OBS data along the key TAIGER transects has been initiated; the preliminary results are very exciting.|
|Appears in Collections:||[應用地球科學研究所] 演講及研討會|
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