台湾东部海域花东盆地的地质特征：位于欧亚板块和太平洋板块之间的新特提斯洋残余?

TheHuatungBasin(20°30’-23°30’N/121°30’-123°E;maximumwaterdepth:5500m)locateseastoffTaiwan.ItisborderedbytheCoastalRangeofTaiwanandtheNorthLuzonArctothewest,theWestPhilippineSeatotheeastandtheRyukyuTrenchtothenorth.TheHuatungBasinwasprevi-ouslyregardedasapartoftheCenozoicPhilippineSeaPlate(<50Ma).However,Ar40/Ar39datingonamphiboleintwodredgedgabbrosamplesretrievedfromthesouthernpartoftheHuatungBasinindi-catedthattheBasinwasearlyCretaceousinage(115-121Ma;Deschampsetal.,2000).Thisageisfurthersupportedbyanindependentmicropaleon-tologystudyonsomeredchertxenolithscontainingEarlyCretaceousradiolarianfossils(115Ma;YehandCheng,2001)intheLatePleistocenevolcanicsequencesoftheLanyuVolcanicIslandoftheNorthLuzonArc.TheNorthLuzonVolcanicArcwasformedduringtheeastwardsubductionoftheSouthChinaSeaoceaniclithospherebeneaththeHuatungBasinsincemiddleMiocene.Accordingly,theMio-ceneLuzonvolcanicarcissittingontheCretaceousoceaniccrustoftheHuatungBasin.