西秦岭秦岭梁环斑花岗岩锆石U-Pb年龄及地球化学特征
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摘要
对秦岭梁岩体进行了地质学、岩石学、地球化学及年代学研究。秦岭梁岩体主要岩石类型有似斑状黑云环斑花岗岩、似斑状角闪黑云环斑花岗岩、中粒黑云二长花岗岩,普遍发育环斑结构,LA-ICP-MS锆石U-Pb测年结果为215.1±2.5Ma(MSWD=0.29,n=17),显示秦岭梁环斑花岗岩形成于晚三叠世。秦岭梁环斑花岗岩属于高钾钙碱性系列,具有准铝质-弱过铝质的特点,富集Rb、Th、K、Pb、Nd等,贫Ba、Nb、Ta、La、P、Eu等,明显亏损Nb、Ta、P。稀土元素含量中等偏低,轻、重稀土元素分异程度高,稀土元素标准化配分曲线呈明显的右倾模式。秦岭梁环斑花岗岩岩浆主要来源于地壳熔融,同时具有壳幔混合特点。结合区域地质背景,认为秦岭梁环斑花岗岩形成于造山后伸展环境。
Based on geological, petrological and geochemical studies, the authors investigated Qinlingliang rapakiwi granite intrusion,porphyritic biotite rapakivi granite, porphyritic hornblende biotite rapakivi granite and medium-grained biotite monzonitic granite.LA-ICP-MS zircon U-Pb analysis suggests that Qinlingliang rapakiwi granite intrusion was formed in late Triassic(215.1±2.5 Ma).Qinlingliang rapakiwi granite belongs to high-K calc-alkaline series with aluminous-peraluminous nature, and is characterized by enrichment of Rb, Th, K, Pb and Nd, depletion of Ba, Nb, Ta, La, P and Eu, and significant loss of Nb, Ta and P. In addition, this intrusion has moderate-low REE concentration and right-inclined distribution curve. The magma probably mainly originated from partial melting of the crust, and also had the characteristics of crust-mantle mixing. In combination with regional geological background, the authors hold that Qinlingliang rapakiwi granite intrusion probably originated from a post orogenic extension environment.
Based on geological, petrological and geochemical studies, the authors investigated Qinlingliang rapakiwi granite intrusion,porphyritic biotite rapakivi granite, porphyritic hornblende biotite rapakivi granite and medium-grained biotite monzonitic granite.LA-ICP-MS zircon U-Pb analysis suggests that Qinlingliang rapakiwi granite intrusion was formed in late Triassic(215.1±2.5 Ma).Qinlingliang rapakiwi granite belongs to high-K calc-alkaline series with aluminous-peraluminous nature, and is characterized by enrichment of Rb, Th, K, Pb and Nd, depletion of Ba, Nb, Ta, La, P and Eu, and significant loss of Nb, Ta and P. In addition, this intrusion has moderate-low REE concentration and right-inclined distribution curve. The magma probably mainly originated from partial melting of the crust, and also had the characteristics of crust-mantle mixing. In combination with regional geological background, the authors hold that Qinlingliang rapakiwi granite intrusion probably originated from a post orogenic extension environment.
引文
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[17]刘春花,吴才来,郜源红,等.南秦岭东江口、柞水和梨园堂花岗岩类锆石LA-ICP-MS U-Pb年代学与锆石Lu-Hf同位素组成[J].岩石学报,2014,30(8):2402-2420.
[18]卢欣祥,尉向东,肖庆辉,等.西秦岭发现奥长环斑花岗岩带[J].地质论评,1998,14(5):535.
[19]R?m?O T,Haapala I.One hundred years of rapakivi granite[J].Mineralogy and Petrology,1995,52(3):129-185.
[20]Haapala I,R?m?O T.Rapakivi granites and related rocks:an introduction[J].Precambrian Research,1999,95(1/2):1-7.
[21]卢欣祥,尉向东,肖庆辉,等.秦岭环斑花岗岩的年代学研究及意义[J].高校地质学报,1999,5(4):373-377.
[22]王晓霞,王涛,卢欣祥.环斑花岗岩研究及存在的问题[J].地质科技情报,2001,20(4):19-23.
[23]赵太平.对秦岭奥长环斑花岗岩的质疑[J].地质论评,2001,17(5):487-491.
[24]张静,陈衍景,舒桂明,等.陕西西南部秦岭梁花岗岩体的矿物成分研究和相关问题讨论[J].中国科学(D辑),2002,2:113-120.
[25]王晓霞,王涛,卢欣祥,等.北秦岭老君山、秦岭梁环斑结构花岗岩岩浆混合的岩相学证据及其意义[J].地质通报,2002,21(8):523-529.
[26]雷泓晏,张占武,赵选社,等.北秦岭老君山环斑花岗岩的成因及大地构造意义[J].陕西地质,2003,21(2):49-56.
[27]王晓霞,王涛,卢欣祥,等.北秦岭老君山和秦岭梁环斑结构花岗岩及构造环境--一种可能的造山带型环斑花岗岩[J].岩石学报,2003,19(4):650-660.
[28]卢欣祥,王晓霞,肖庆辉,等.答“对秦岭奥长环斑花岗岩质疑”[J].地质论评,2003,49(2):146-154.
[29]Anderson T.Correction of common lead in U-Pb analyses that do not report204Pb[J].Chemical Geology,2002,192(1):59-79.
[30]Ludwig,K R.User’s Manual for Isoplot 3.00.A Geochronological Toolkit for Microsoft Excel[J].Berkeley Geochronology Center,2003:1-70.
[31]Wu Y B,Zheng Y F.Genesis of zircon and its constraints on interpretation of U-Pb age[J].Chinese Science Bulletin,2004,49(15):1554-1569.
[32]Siebel W,Blaha U,Chen F K,et al.Geochronology and geochemistry of a dyke-host rock association and implications for the formation of the Bavarian Pfahl shear zone,Bohemian Massif[J].International Journal of Earth Sciences,2005,94(1):8-23.
[33]Sun S S,McDonough W F.Chemical and isotopic systematics of oceanic basalts:Implications for mantle composition and processed.Magmatism in Ocean Basins,Geological Society of London Special Publication,1989,42:313-345.
[34]Rapp R P,Watson E B.Dehydration melting of metabasalts at 8~32 kbar:Implications for continental growth and crust-mantle recycling[J].Journal of Petrology,1995,36:891-931.
[35]Rapp R P.Heterogeneous source regions for Archean granitoids.[C]//Wit M J,Ashwal L D.Greenstone Belts.Oxford:Oxford University Press,1997:35-37.
[2]王涛.花岗岩混合成因研究及大陆动力学意义[J].岩石学报,2000,16(2):161-168.
[3]肖庆辉,邢作云,张星,等.当代花岗岩研究的几个重要前沿[J].地学前缘,2003,10(3):222-229.
[4]张国伟,袁学诚,张本仁,等.秦岭造山带与大陆动力学[M].北京:科学出版社,2001:1-806.
[5]张本仁,骆庭川,高山.秦巴岩石圈构造及成矿规律地球化学研究[M].武汉:中国地质大学出版社,1994:1-446.
[6]张成立,王涛,王晓霞.秦岭造山带早中生代花岗岩成因及其构造环境[J].高校地质学报,2008,14(3):304-316.
[7]张宏飞,靳兰兰,张利,等.西秦岭花岗岩类地球化学和Pb-SrNd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(10):914-926.
[8]卢欣祥,董有,常秋玲,等.秦岭印支期沙河湾奥长环斑花岗岩及动力学意义[J].中国科学(D辑),1996,26(3):244-248.
[9]张宗清,张国伟,唐索寒,等.秦岭沙河湾奥长环斑花岗岩的年龄及其对秦岭造山带主造山期时间的限制[J].科学通报,1999,44(9):981-984.
[10]王晓霞,王涛,卢欣祥.北秦岭沙河湾岩体环斑结构特征及有关问题的讨论[J].地球学报,2002,23(1):30-36.
[11]张成立,王晓霞,王涛,等.东秦岭沙河湾岩体成因--来自锆石U-Pb定年及其Hf同位素的证据[J].西北大学学报(自然科学版),2009,39(3):453-465.
[12]胡建民,崔建堂,孟庆任,等.秦岭柞水岩体锆石U-Pb年龄及其地质意义[J].地质论评,2004,50(3):323-329.
[13]杨恺,刘树文,李秋根,等.秦岭柞水岩体和东江口岩体的锆石U-Pb年代学及其意义[J].北京大学学报(自然科学版),2009,45(5):841-847.
[14]弓虎军,朱赖民,孙博亚,等.南秦岭地体东江口花岗岩及其基性包体的锆石U-Pb年龄和Hf同位素组成[J].岩石学报,2009,25(11):337-350.
[15]Jiang Y H,Jin G D,Liao S Y,et al.Geochemical and Sr-Nd-Hf isotopic constraints on the origin of Late Triassic granitoids from the Qinling orogen,central China:Implications for a continental arc to continent-continent collision[J].Lithos,2010,117(s1/4):183-197.
[16]刘春花,吴才来,郜源红,等.南秦岭麻池河乡和沙河湾花岗岩体锆石LA-ICP-MS U-Pb年代学及Lu-Hf同位素组成[J].地学前缘,2013,20(5):36-56.
[17]刘春花,吴才来,郜源红,等.南秦岭东江口、柞水和梨园堂花岗岩类锆石LA-ICP-MS U-Pb年代学与锆石Lu-Hf同位素组成[J].岩石学报,2014,30(8):2402-2420.
[18]卢欣祥,尉向东,肖庆辉,等.西秦岭发现奥长环斑花岗岩带[J].地质论评,1998,14(5):535.
[19]R?m?O T,Haapala I.One hundred years of rapakivi granite[J].Mineralogy and Petrology,1995,52(3):129-185.
[20]Haapala I,R?m?O T.Rapakivi granites and related rocks:an introduction[J].Precambrian Research,1999,95(1/2):1-7.
[21]卢欣祥,尉向东,肖庆辉,等.秦岭环斑花岗岩的年代学研究及意义[J].高校地质学报,1999,5(4):373-377.
[22]王晓霞,王涛,卢欣祥.环斑花岗岩研究及存在的问题[J].地质科技情报,2001,20(4):19-23.
[23]赵太平.对秦岭奥长环斑花岗岩的质疑[J].地质论评,2001,17(5):487-491.
[24]张静,陈衍景,舒桂明,等.陕西西南部秦岭梁花岗岩体的矿物成分研究和相关问题讨论[J].中国科学(D辑),2002,2:113-120.
[25]王晓霞,王涛,卢欣祥,等.北秦岭老君山、秦岭梁环斑结构花岗岩岩浆混合的岩相学证据及其意义[J].地质通报,2002,21(8):523-529.
[26]雷泓晏,张占武,赵选社,等.北秦岭老君山环斑花岗岩的成因及大地构造意义[J].陕西地质,2003,21(2):49-56.
[27]王晓霞,王涛,卢欣祥,等.北秦岭老君山和秦岭梁环斑结构花岗岩及构造环境--一种可能的造山带型环斑花岗岩[J].岩石学报,2003,19(4):650-660.
[28]卢欣祥,王晓霞,肖庆辉,等.答“对秦岭奥长环斑花岗岩质疑”[J].地质论评,2003,49(2):146-154.
[29]Anderson T.Correction of common lead in U-Pb analyses that do not report204Pb[J].Chemical Geology,2002,192(1):59-79.
[30]Ludwig,K R.User’s Manual for Isoplot 3.00.A Geochronological Toolkit for Microsoft Excel[J].Berkeley Geochronology Center,2003:1-70.
[31]Wu Y B,Zheng Y F.Genesis of zircon and its constraints on interpretation of U-Pb age[J].Chinese Science Bulletin,2004,49(15):1554-1569.
[32]Siebel W,Blaha U,Chen F K,et al.Geochronology and geochemistry of a dyke-host rock association and implications for the formation of the Bavarian Pfahl shear zone,Bohemian Massif[J].International Journal of Earth Sciences,2005,94(1):8-23.
[33]Sun S S,McDonough W F.Chemical and isotopic systematics of oceanic basalts:Implications for mantle composition and processed.Magmatism in Ocean Basins,Geological Society of London Special Publication,1989,42:313-345.
[34]Rapp R P,Watson E B.Dehydration melting of metabasalts at 8~32 kbar:Implications for continental growth and crust-mantle recycling[J].Journal of Petrology,1995,36:891-931.
[35]Rapp R P.Heterogeneous source regions for Archean granitoids.[C]//Wit M J,Ashwal L D.Greenstone Belts.Oxford:Oxford University Press,1997:35-37.
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