冀西北怀安地区中性辉石麻粒岩的锆石U-Pb、Lu-Hf及微量元素组成对区域退变质时代的制约.pdf

《冀西北怀安地区中性辉石麻粒岩的锆石U-Pb、Lu-Hf及微量元素组成对区域退变质时代的制约.pdf》由会员上传分享，免费在线阅读，更多相关内容在行业资料-天天文库。

1、1000-0569／2012／028(11)-3721-38ActaPetrologicaSinica岩石学报冀西北怀安地区中性辉石麻粒岩的锆石U—Pb、Lu-Hf及微量元素组成对区域退变质时代的制约罗志波张华锋第五春荣张红LUOZhiB0，ZHANGHuaFeng’，DIWUChunRong2andZHANGH0ng21．中国地质大学地球科学与资源学院，北京1000832．西北大学大陆动力学国家重点实验室，西安7100691．DepartmentofGeoscieneesandResources，ChineseUnive~ityofGeosciences，Beijing1

2、00083，China2．StateKeyLaboratoryofContinentalDynami~，DepartmentofGeology，Northw~tUnivemity，Xi’a／z710069，China2012-05—10收稿．2012-08-l8改回．LuoZB。ZhangHF，DiwuCRandZhangIL2012．ZirconU-Pb，Lu-HfisotopeandtraceelementcompositionsofintermediatpyroxenegranuliteintheHuai’anarea。NorthwestHebeiProvince：C

3、onstraintsonthetimingofretrogrademetamorphism．ActaPetrologicaSinica，28(11)：3721-3738AbstractTheHuai’anareaofNorthwestHebeistandsonthecentral—northoftheNoahChinaCraton(NCC)．Intermediatpyroxene．granuliteinthisareacanprovideimpo~antcluesforthetimingofregionalmetamorphism．Themineralassemblages

4、indicatethatitwasundergonemid．pressuregranulitemetamorphismandoverlappedbyamphibolitefaciesretrograde．ZirconU—Pb．Lu-Hfisotopeandtraceelementscompositionsareanalyzed．Asaresult．zirconcoreswitIloscillatoryzoningexhibitvariousPb／Pbagesinrangeof2542—19O2Ma(hr)．TheyshowapositivetelationswithTlU(

5、0．10—1．92)ratios，三HREE(59．1×10～452×10-6)andsHf()values，indicatingtheirdiferentdegreesoflatticerecrystallizationduetothepostdatedmetamorphism．Zircongrainsththemostconcordantandoldagesyieldamean207Pb／Pbageof2471±18Ma(2o-，MSwD=6．7)．isageisinterpretedtobetheemplacementageoftheprotolithrocks．ei

6、rdepletedHfmodelagesoftDMandtDMvaryinrangeof2550～2621Ma(peakat2586Ma)，and2596—27l6Ma(peakat2665Ma)，respectively．Whereas，theyhavegHf(t)ValUesof4．1—6．7，indicatingthattheprotolithrocksisdominatelyderivedfromtheLateArcheaniuvenilecrust．Themetamorphicovergrowthzirconsoccurringasmetamorphicnew．s

7、inglegrainsoraszirconmantlesovergrowtharoundthemagmaticzirconcores．yieldU-Pbagesvaryingfrom1865Mat01782Ma．withrelativelylowTh／U(<0．10)，Lu／’Ⅲ(<0．0oo1)，andHREEabundance．Theyyieldamean2o7Pb／2o6Pbageof1831±7Ma(20-，MSWD=2．5)．Weinterpretthisagetobetheageofgranulitet