泰国难府-程逸缝合带中灰岩块的虫筳类生物地层学

Thestudyarea,NanProvince,northernThailandisgeotectonicallysituatedwithintheNan-UttaraditSuture,theonceback-arcbasinbetweentheSukhothaiZoneandIndochinaBlock.PermianFusulinaceanfaunafromlimestoneblockswithinthesuturehasbeeninvestigatedandtheNanareahasbeenmappedindetail.Thesemayprovidetheusefulinformationforunderstandingthefaunalassemblageandoverallge-ometryofstratigraphicsuccessionsinthebasin.Thestratawereintenselyfoldedandthrust.ScatteredPer-mianlimestonesfoundinNanareaareblockswithinshaleinterbeddedwithtuffaceousrock.Thecontactbetweenthisunitandtheadjacentunits,thestronglyfoliatedshaleandtuffaceoussedimentarystratathataremildlymetamorphosedandgivingphyllitictex-tures,hasbeeninterpretedasawest-dippingnormalfault,namelythePhaSingFault.Thisfaultrunspar-alleltotheHighwayno.1080(Nan-ThaWangPha).MiddleandearlyLatePermianfusulinaceanfaunafoundintheNanareacontainsNeoschwagerina,Pseudodoliolina,Colania,Lepidolina,andColaniella.Additionally,lateEarlyPermianfusulinaceanandMiddleTriassicradiolarianfaunahavebeenreportedinthisarea(e.g.,Fontaine,2002;Saesaengseerungetal.2008).ThesepaleontologicaldatashowtheexistenceofNanBack-arcBasinduringlateEarlyPermian(Artin-skian)toMiddleTriassic.Moreover,thesimilarityoffusulinaceanassemblageyieldingPermianlimestoneblocksoftheNanBack-arcBasinandtheonesoftheIndochinaBlockhasbeeninterpretedthatthePermianlimestoneblocksintheNanBack-arcBasinwerepartofthecontinentalshelfwithintheIndochinaBlock.