摘要
TheregularvariationsinmagmaticactivitiesalongtheNorthwestPacificplatehavebeenlittlestudiedinspiteoftheirimportance.Inthiscontribution,systematicanalyseswereconductedontholeiiticbasaltsfromthreeOceanDrillingProgramsites(Sites304,1149,and801),includingthepetrographicfeatures,majorandtraceelements,Ndisotopiccompositions,andmineralstructureandcompositionsofwholerocks.VolcanicrocksfromSites304,1149,and801belongtotholeiitesandexhibitdepletedlightrareearthelements(LREE),largeionlithophileelementalcontents(LILE),andrelativelydepletedNdisotopicratios(143Nd/144Nd=0.513139-0.513211),similartothoseofnormalmid-oceanridgebasalts(N-MORB).Comprehensivedataonmineralcompositions,whole-rockgeochemistry,andgeochronologydemonstratethataregularvariationtrendexistsinthenorth-southdirectionalongtheNorthwestPacificplate.The143Nd/144Ndvalues(0.513139-0.513211)andtrace-elementratiosforwholerocks(Sm/Th=15.35-30.00;Zr/Hf=28.53-35.76;Zr/Y=2.58-3.67;Th/La=0.04-0.06;Th/Y=0.33-0.70),aswellasthetrace-elementratios(Zr/Hf,La/Yb,Ti/Zr)ofclinopyroxenesfromSites1149and801tholeiitesshowlargervariationscomparedtothosefromSite304tholeiites(143Nd/144Nd=0.513185-0.513195;Sm/Th=18.19-20.58;Zr/Hf=31.07-33.26;Zr/Y=2.62-3.03;Th/La=0.05-0.06;Th/Y=0.48-0.57).MineralzoningtextureswereobviousintholeiitesfromSites1149and801butwererarelyobservedinSite304.Theseregularfeatureswerelikelyattributedtothedifferencesintheheterogeneityofthemagmasource,theprocessofmagmatieevolution,theplate-spreadingrate,andtheeffectiveandineffectivemixing.
出版日期
2018年03月13日(中国期刊网平台首次上网日期,不代表论文的发表时间)