摘要
TheNeotethysplaysanimportantroleinshapingtheGangdesemagmaticbelt,southernTibet.However,theinitialtimeofspreadingandsubductionoftheNeotethysremainscontentious.Inthisstudy,asuiteoflateTriassiccumulatehornblendegabbrowasidentifiedinthesouthernmarginoftheGangdesemagmaticbelt.Thegabbroexhibitscumulatestructure,withhornblendeandplagioclaseastheprimarymineralphases.Isotopicdataindicateahydrousmagmasourcederivedfromadepletedmantlewedgethathasbeenmodifiedbyslabdehydration.Geochemicaldiscriminationssuggestthatthegabbrowasformedinanintraoceanicarcsetting,withcrystallizationagesofca.220-213Ma.Hornblende,hornblendelagioclaseandilmenitethermometersrevealthatthecrystallizationtemperatureof900-750°Cforthegabbro.Hornblendeandhornblende-plagioclasegeobarometersyieldanemplacementdepthatca.14.5-19.5km.ThisgabbroconstitutesalineofevidenceforanintraoceanicarcmagmatismthatiscoevalwiththecounterpartsinthesouthernTurkey,revealinganintraoceanicsubductionsystemwithintheNeotethysfromwesttoeastintheLateTriassicandthattheoceanizationoftheNeotethyswasmuchearlierthanpreviousexpectation.
出版日期
2017年01月17日(中国期刊网平台首次上网日期,不代表论文的发表时间)