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Crustal Structure Beneath the Nanao Forearc Basin from TAICRUST MCS/OBS Line 14
叢TAICRUST海底地震儀第十四號測缐資料探討南澳海盆下之地殼構造
並列摘要
The ongoing orogeny in Taiwan is a result of the collision of the PhilippineSea and the Eurasian plates.While the structure of the continentalcrust on the Eurasian plate(EP)is now mostly known,that of the oceaniccrust on the Philippine Sea plate(PSP)is not well mapped.Using offshore-onshore refraction data,collected during the R/V Ewing cruise of 1995,weinvestigate the nature of the transition between the EP and the PSP in thevicinity of the southern Coastal Range of Taiwan.The data were producedby the air-gun array of the R/V Ewing along a WNW-ESE trending line offthe coast of central Taiwan(MCS/OBS line 23).The refracted P waveswere collected by 19 RefTek recorders with L-28 sensors placed along thesouthern cross-island highway of Taiwan,which is the onshore extension ofline 23.Because of high noise levels in the Coastal Plain,we were only ableto retrieve usable data from 11 stations located from the east coast throughthe Central Range.We performed forward modeling of the first arrivingwaves at these stations;our strategy was to search for the simplest modelthat fitted all the data.Our results indicate that the crust thickens graduallytoward Taiwan,from about 9-12km thick in the Huatung basin to 15-18km thick off the eastern coast of Taiwan,with a 4-8 degree dip of theMoho.Continuing westward,the crust thickens more rapidly to 27-32kmthick under the east coast of Taiwan,with a 26-32 degree dip of the Moho.