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1、2016年6月,第22卷,第2期,242-253頁高校地質(zhì)學(xué)報(bào)Jun2016,Vol.22,No.2,pp.242-253GeologicalJournalofChinaUniversitiesDOI:10.16108/j.issn1006-7493.2015153南祁連化石溝花崗巖年代學(xué)、地球化學(xué)特征及其構(gòu)造意義11,21*11胡萬龍,賈志磊,王金榮,侯克選,王淑華1.甘肅省西部礦產(chǎn)資源重點(diǎn)實(shí)驗(yàn)室,蘭州大學(xué)地質(zhì)科學(xué)與礦產(chǎn)資源學(xué)院蘭州730000;2.甘肅省地質(zhì)礦產(chǎn)勘查開發(fā)局,蘭州730000摘要:化石溝二長花崗巖呈長
2、條狀侵入于泥盆系-石炭系阿木尼克組。巖石LA-ICP-MS鋯石U-Pb加權(quán)平均年齡為252.0±2.1Ma,形成于晚二疊世。巖石高SiO2(69.8%~72.2%)、Al2O3(14.2%~15.4%),低的TiO2、MgO含量(分別為0.28%~0.36%、0.60%~0.77%),A/CNK=1.08~1.14,富堿(Na2O+K2O=6.57%~8.00%);相對富集Th、K、Pb,虧損Nb、Ta、P、Ti,低Sr(201×10-6~248×10-6),高Y(19.4×10-6~24.0×10-6),富集LREE
3、,(La/Yb)N=10.8~18.4,中等負(fù)Eu異常(δEu=0.55~0.68);全巖(87Sr/86Sr)i為0.7060~0.7061,εNd(t)為1.63~1.84,εHf(t)=8.79。二長花崗巖的全巖Nd和Hf模式年齡分別為780~794Ma和694Ma。綜合研究表明二長花崗巖是新元古代中期形成的玄武質(zhì)下地殼在晚古生代晚期玄武質(zhì)巖漿底侵加熱作用下發(fā)生部分熔融的產(chǎn)物,形成于造山擠壓向后造山伸展轉(zhuǎn)變的構(gòu)造環(huán)境。關(guān)鍵詞:二長花崗巖;地球化學(xué);晚二疊世;構(gòu)造環(huán)境;化石溝;南祁連山中圖分類號:P588.121;
4、P595;P597文獻(xiàn)標(biāo)識碼:A文章編號:1006-7493(2016)02-0242-12GeochronologyandGeochemistryCharacteristicsoftheGranitesfromtheHuashigouArea,SouthQilianandTheirTectonicSignificance11,21*11HUWanlong,JIAZhilei,WANGJinrong,HOUKexuan,WANGShuhua1.KeyLaboratoryofMineralResourcesinWeste
5、rnChina,SchoolofEarthSciences,LanzhouUniversity,Lanzhou730000,China;2.GansuProvincialBureauofGeologyandMineralExploration&Development,Lanzhou730000,ChinaAbstract:ThemonzoniticgranitesintrudedintoDevonian-CarboniferousAmunikeformationinalongstripfashionintheHuash
6、igouarea.AccordingtothezirconU-Pbweightedmeanageof252.0±2.1MadeterminedusingLA-ICP-MS,itwassuggestedthattherockwasformedinlatePermian.MonzoniticgranitescontainrichSiO2(69.8%~72.2%)andAl2O3(14.2%~15.4%),andlowTiO2,MgO(0.28%~0.36%,0.60%~0.77%,respectively),withA/C
7、NK=1.08~1.14,richalkali(Na2O+K2O=6.57%~8.00%),relativelyenrichedTh,K,Pb,depletedNb,Ta,PandTi,lowcontentofSr(201×10-6~248×10-6),highcontentofY(19.4×10-6~24.0×10-6),enrichedLREE,(La/Yb)8786N=10.8~18.4,moderateanomalynegativeEu(δEu=0.55~0.68);whole-rock(Sr/Sr)I=0.7
8、060~0.7061,εNd(t)=1.63~1.84,andεHf(t)=8.79.TheNdandHfmodelagesofwhole-rockofmonzoniticgranitesare780~794Maand694Ma,respectively.Overall,ourstudyshowsthattheHuashigoum