西秦岭TTG质脉岩地球化学特征及其与金矿化的关系
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摘要
选取西秦岭夏河-合作断裂以南广泛发育的中酸性脉岩进行岩石学、岩石地球化学分析研究:研究区脉岩具有低硅低镁(SiO_2占55.14%～68.42%,平均64.13%;MgO占0.101%～1.02%,平均0.633%);高钠低钾(Na_2O/K_2O=0.63～2.92>0.5);高铝高钛(Al_2O_3含量大于15%;TiO_2占0.462%～0.806%,平均0.566%)特征。轻稀土元素(LREE)富集(LREE为195.89×10~(-6)～223.95×10~(-6),平均215.85×10~(-6)),重稀土元素(HREE)严重亏损(HREE为10.45×10~(-6)～14.56×10~(-6),平均11.86×10~(-6)),轻重稀土元素分馏明显,具弱的负铕异常(δ_(Eu))(δ_(Eu)=0.61～0.97,平均0.75);微量元素组成与埃达克岩类似,高Sr、低Y,高场强元素Th、U、Zr、Hf正异常,大离子亲石元素K、Ba、Sr负异常。脉岩具有奥长花岗岩-英云闪长岩-花岗闪长岩(TTG)岩套的性质,脉岩产生于晚三叠世洋壳俯冲消减活动大陆边缘弧环境。脉岩与金矿化是同一构造-岩浆旋回内区域壳幔相互作用的系列产物,金成矿与脉岩不仅在时空上密切伴生,而且物质成分上具有相同的来源和继承演化的成因联系。
The petrology and petro-geochemical analysis of the widely developed intermediate-acid dike rocks in the south of Xiahe-Hezuo fault in the West Qinling was investigated.The result shows that the dike rocks in the study area are characterized by low silicon and low magnesium(SiO_2=55.14%～68.42%,average is 64.13%;MgO=0.101%～1.02%,average is 0.633%),high sodium and low potassium(Na_2O/K_2O=0.63～2.92),high aluminum and high titanium(Al_2O_3>15%;TiO_2=0.462%～0.806%,average is 0.566%).The light rare earth elements(LREE)are enriched(LREE=195.89×10~(-6)～223.95×10~(-6),average is 215.85×10~(-6)),and the heavy rare earth elements(HREE)are severely depleted(HREE=10.45×10~(-6)～14.56×10~(-6),average is11.86×10~(-6)),and there is an obvious fractionation between HREE and LREE and a weak negative uranium anomaly(δEu)(δEu=0.61～0.97,average is 0.75).The composition of trace elements of the dike rocks is similar to that of adakite,which has a high Sr content and low Y content and a high field intensity element anomaly and a large lithophile element negative anomaly.The dike rocks have a property of trondhjemite-tonalite-granodiorite(TTG)rocks suite,and are originated in the late Triassic oceanic crust subduction active continental margin arc environment.Dike rocks and gold mineralization are the products of the interaction between crust and mantle in the same tectonic-magmatic cycle.Gold mineralization and dike rocks are not only closely associated in time and space,but also have the same origin and genetic relationship of inheritance and evolution in material composition.
The petrology and petro-geochemical analysis of the widely developed intermediate-acid dike rocks in the south of Xiahe-Hezuo fault in the West Qinling was investigated.The result shows that the dike rocks in the study area are characterized by low silicon and low magnesium(SiO_2=55.14%～68.42%,average is 64.13%;MgO=0.101%～1.02%,average is 0.633%),high sodium and low potassium(Na_2O/K_2O=0.63～2.92),high aluminum and high titanium(Al_2O_3>15%;TiO_2=0.462%～0.806%,average is 0.566%).The light rare earth elements(LREE)are enriched(LREE=195.89×10~(-6)～223.95×10~(-6),average is 215.85×10~(-6)),and the heavy rare earth elements(HREE)are severely depleted(HREE=10.45×10~(-6)～14.56×10~(-6),average is11.86×10~(-6)),and there is an obvious fractionation between HREE and LREE and a weak negative uranium anomaly(δEu)(δEu=0.61～0.97,average is 0.75).The composition of trace elements of the dike rocks is similar to that of adakite,which has a high Sr content and low Y content and a high field intensity element anomaly and a large lithophile element negative anomaly.The dike rocks have a property of trondhjemite-tonalite-granodiorite(TTG)rocks suite,and are originated in the late Triassic oceanic crust subduction active continental margin arc environment.Dike rocks and gold mineralization are the products of the interaction between crust and mantle in the same tectonic-magmatic cycle.Gold mineralization and dike rocks are not only closely associated in time and space,but also have the same origin and genetic relationship of inheritance and evolution in material composition.
引文
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21李康宁,刘伯崇,狄永军.三叠纪西秦岭西北部洋俯冲的记录:来自镁安山岩/高镁安山岩的证据[J].中国地质,2019,46(1):473-484Li Kangning,Liu Bochong,Di Yongjun.Triassic subduction of oceanic in northwestern of West Qinling Mountain:The evidence from MA/HMA[J].Chinese Geology,2019,46(1):473-484
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24吴鸣谦,左梦璐,张德会,等.TTG岩套的成因及其形成环境[J].地质论评,2015,60(3):503-514Wu Mingqian,Zuo Menglu,Zhang Dehui,et al.Genesis and diagenetic environment of TTG Suite[J].Geological Review,2015,60(3):503-514
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27邓晋福,刘翠,冯艳芳,等.高镁安山岩/闪长岩类(HMA)和镁安山岩/闪长岩类(MA):与洋俯冲作用相关的两类典型的火成岩类[J].中国地质,2010,37(4):1112-1118Deng Jinfu,Liu Cui,Feng Yanfang,et al.High magnesian andesite/diorite(HMA)and magnesian andesite/diorite(MA):Two typical igneous rocks related to oceanic subduction[J].Chinese Geology,2010,37(4):1112-1118
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30 Pearce J A,Harris N B W,Tindle A G.Trace element discrimination diagrams for the tectonic interpretation of granitic rocks[J].Journal of Petrology,1984,25:956-983
31 Harris N B,Pearce J A,Yindle A G.Geochemical characteristics of collision-zone magmatism[C]//Coward M P,Reis A C.Collision Tectonics.London:Special Publications Geological Society,1986,19:67-81
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35殷勇.西秦岭地区脉岩与金矿化的关系[J].甘肃地质,2011,20(1):28-51Yin Yong.Relation of dike rock and gold and gold mineretion in west Qinling Region[J].Gansu Geology,2011,20(1):28-51
2闫臻.西秦岭晚古生代弧前盆地沉积与成矿作用[D].北京:中国科学院地质与地球物理研究所,2002Yan Zhen.Deposition and mineralization of the late Paleozoic arc basin in West Qinling Mountains[D].Beijing:Institute of Geology and Geophysics,Chinese Academy of Sciences,2002
3张国伟,郭安林,姚安平.中国大陆构造中的西秦岭-松潘大陆构造结[J].地学前缘,2004,11(3):23-32Zhang Guowei,Guo Anlin,Yao Anping.Western Qinling-Songpan continental tectonic nodein China's continental tectonics[J].Earth Science Frontiers,2004,11(3):23-32
4张国伟,张宗清,董云鹏,等.秦岭造山带主要构造岩石地层单元的构造性质及其大地构造意义[J].岩石学报,1995,11(2):101-113Zhang Guowei,Zhang Zongqing,Dong Yunpeng,et al.Tectonic characteristics and tectonic significance of the main tectonic lithostratigraphic units in the Qinling Mountains orogenic belt[J].Acta Petrologica Sinica,1995,11(2):101-113
5甘肃省地质矿产勘查开发局.甘肃省地质图(1∶500000)[M].北京:地质出版社,2015Gansu Provincial Bureau of Geology and Mineral Resources.Geological map of Gansu Province(1∶500000)[M].Beijing:Geological Publishing House,2015
6刘伯崇,李康宁,史海龙,等.西秦岭甘青交界一带晚三叠世火山岩岩石成因及构造指示意义[J].现代地质,2018,32(4):704-717Liu Bochong,Li Kangning,Shi Hailong,et al.Petrogenesis and tectonic implication of volcanic rocks during the late Triassic period at the junction of Gansu and Qinghai in west Qinling Mountains[J].Geoscience,2018,32(4):704-717
7张克信,朱云海,林启祥,等.青海同仁县隆务峡地区首次发现镁铁质-超镁铁质岩带[J].地质通报,2007,26(6):661-667Zhang Kexin,Zhu Yunhai,Lin Qixiang,et al.The discovery of the mafic ultramafic zone for the first time in the long valley area of Tongren County,Qinghai[J].Geological Bulletin,2007,26(6):661-667
8秦江锋.秦岭造山带晚三叠世花岗岩类成因机制及深部动力学背景[D].西安:西北大学,2010Qin Jiangfeng.Petrogenesis and geodynamic implications of the LateTriassic granitoids from the Qinling orogenic belt[D].Xi'an:Northwestern University,2010
9高婷.西秦岭西段北部重要侵入体年代学、地质地球化学、形成构造环境及与成矿作用关系[D].西安:长安大学,2011Gao Ting.The zircon dating,geology and geochemistry,tectonic setting of several important intrusions from the north part of the western stage of West Qinling and their relationship with mineralization[D].Xi'an:Chang'an University,2011
10张宏飞,靳兰兰,张利.等.西秦岭花岗岩岩类地球化学和Pb-Sr-Nd同位素组成对基底性质及其构造属性的限制[J].中国科学(D辑),2005,35:914-926Zhang Hongfei,Jin Lanlan,Zhangli,et al.The limitation of rock geochemistry and Pb-Sr-Nd isotopic composition on the properties and tectonic properties of the base in the Western Qinling granites[J].Chinese Science(Series D),2005,35:914-926
11邓晋福,冯艳芳,狄永军,等.中国侵入岩大地构造图(1∶250 000 0)[M].北京:地质出版社,2016Deng Jinfu,Feng Yanfang,Di Yongjun,et al.Intrusive tectonic map of China(1∶250 000 0)[M].Beijing:Geological Publishing House,2016
12邓晋福,路凤香,鄂莫岚.汉诺坝玄武岩岩浆起源及上升的p-t路线[J].地质论评,1987,33(4):317-332Deng Jinfu,Lu Fengxiang,E Molan.Hannuoba basalt magma origin and the rise of the p-t route[J].Geological Review,1987,33(4):317-332
13 Middlemost E A K.Naming materials in the magma/igneous rocksystem[J].Earth-Science Reviews,1994,37(3-4):215-224
14 O'Connor J T.A classification for quartz-rich igneous rocks based on feld spar ratios[J].Geological Survey,1965,525(B):79-84
15 Wright J B A.Simple alkalinity ratio and its application to questions of non-orogenic granite genesis[J].Geological Magazine,1969,106(4):370-384
16 Pecerillo A,Taylor S R.Geochemistry of Eocene calc-alkaline volcanic rocks from the Kastamonu Area,Northern Turkey[J].Contributions to Mineralogy and Petrology,1976,58(1):63-81
17 Maniar P D,Piccoli P M.Tectonic discrimination of granitoids[J].Geological Society of America Bulletin,1989,101:635-643
18 Sun S S,Mcdonough W F.Chemical and isotope systematic of oceanic basalts:Implications for mantle composition and processes[J].Geological Society of London Special Publication,1989,42:313-345
19黄雄飞.西秦岭印支期花岗质岩浆作用与造山带演化[D].北京:中国地质大学(北京),2016Huang Xiongfei.Petrogenesis of the indosinian granitic magmatism and tectonic evolution of the West Qinling orogenic belt[D].Beijing:China University of Geosciences(Beijing),2016
20陈明辉,郭素雄,徐军伟,等.德乌鲁岩体内外接触带金多金属成矿区成岩成矿地质地球化学特征及成因探讨[J].矿产与地质,2016,30(4):517-530Chen Minghui,Guo Suxiong,Xu Junwei,et al.Diagenetic,metallogenic,geological and geochemical characteristics of gold polymetallic metallogenic province inside inner and outer contact zone of Dewulu rock mass[J].Mineral Resources and Geology,2016,30(4):517-530
21李康宁,刘伯崇,狄永军.三叠纪西秦岭西北部洋俯冲的记录:来自镁安山岩/高镁安山岩的证据[J].中国地质,2019,46(1):473-484Li Kangning,Liu Bochong,Di Yongjun.Triassic subduction of oceanic in northwestern of West Qinling Mountain:The evidence from MA/HMA[J].Chinese Geology,2019,46(1):473-484
22 Li X W,Mo X X,Yu X H,et al.Petrology and geochemistry of the early Mesozoic pyroxene andesites in the Maixiu Area,West Qinling,China:Products of subduction or syn-collision?[J].Lithos,2013,172(173):158-174
23邓晋福,冯艳芳,狄永军,等.岩浆弧火成岩构造组合与洋陆转换[J].地质论评,2015,61(3):473-484Deng Jinfu,Feng Yanfang,Di Yongjun,et al.Igneous tectonic assemblage of magmatic arc and ocean land transition[J].Geological Review,2015,61(3):473-484
24吴鸣谦,左梦璐,张德会,等.TTG岩套的成因及其形成环境[J].地质论评,2015,60(3):503-514Wu Mingqian,Zuo Menglu,Zhang Dehui,et al.Genesis and diagenetic environment of TTG Suite[J].Geological Review,2015,60(3):503-514
25 Stern R J.Evidence from ophiolites,blueschists,and ultrahighpressure metamorphic terranes that the modern episode of subductiontectonics began in Neoproterozoic time[J].Geology,2005,33(7):557-560
26 Moyen J F,Stevens G.Experimental constraints on TTG petrogenesis:Implications for Archean geodynamics[J].Archean Geodynamics and Environments,2006,164:149-175
27邓晋福,刘翠,冯艳芳,等.高镁安山岩/闪长岩类(HMA)和镁安山岩/闪长岩类(MA):与洋俯冲作用相关的两类典型的火成岩类[J].中国地质,2010,37(4):1112-1118Deng Jinfu,Liu Cui,Feng Yanfang,et al.High magnesian andesite/diorite(HMA)and magnesian andesite/diorite(MA):Two typical igneous rocks related to oceanic subduction[J].Chinese Geology,2010,37(4):1112-1118
28 Weaver B L.The origin of ocean island basalt end-member compositions:Trace element and isotopic constraints[J].Earth and Planetary Science Letters,1991,104:3810
29 Lassiter J C,De Paolo D J.Plume/lithosphere interaction in thegeneration of continental and oceanic flood basalts:Chemical andisotopic constraints[C]//Mahoney J J,Coffin M F.Large igneous provinces:Continental,oceanic,and planetary flood volcanism,geophysics.Monograph.Washington,D.C.:American Geophysical Union,1997:335-355
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