南秦岭柞水—山阳矿集区下官坊含铜岩体矿化特征与岩石地球化学
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摘要
柞水—山阳矿集区是南秦岭构造—岩浆活动强烈地区,广泛出露白沙沟等浅成—超浅成的花岗岩类侵入体及与之有关的矽卡岩—斑岩型矿床(化)。文章在对柞水—山阳矿集区下官坊岩体矿化地质特征观测的基础上,对该矿集区内的下官坊含矿岩体进行了详细的岩石学、元素地球化学、锆石U-Pb年代学、LuHf同位素及微量元素分析研究,探讨了该岩体的成因、成岩成矿大地构造环境及成矿潜力。下官坊岩体岩性为准铝质高钾钙碱性—钾玄岩系列的花岗闪长斑岩和石英闪长玢岩。LA-ICP-MS锆石U-Pb测年测定表明,下官坊岩体的岩浆侵位年龄为139～144 Ma。Lu-Hf同位素分析结果显示,下官坊岩体的岩浆源区可能为地壳熔融岩浆与地幔重熔岩浆的混合,并且具有较高的混合均一化程度。下官坊岩体显著富集成矿元素Cu,其成岩成矿大地构造环境、矿化地质特征、围岩蚀变类型、岩石矿物组合与国内外矽卡岩型矿床相似,指示该岩体具有形成矽卡岩型铜矿床的成矿潜力。下官坊岩体形成于晚侏罗世—早白垩世之交,造山带应力状态由挤压转向伸展,引发强烈壳幔相互作用和花岗质岩浆活动,并随之形成了含矿岩体及其矽卡岩型矿化。
The Zhashui-Shanyang ore concentrated area is characterized by serious tectomagmatic activity in the South Qinling.It is widely exposed hypabyssal-super hypabyssal granite intrusions such as Baishagou and related skarn-porphyry deposits.Based on the observation of the mineralization geological characteristics of the Xiaguanfang rock in the Zhashui-Shanyang ore district,the detailed petrology,elemental geochemistry,Zircon U-Pb geochronology,Lu-Hf isotope and trace element analysis of the ore-bearing rock are carried out to discuss the origin of the rock mass,diagenesis and ore-forming tectonic environment and metallogenic potential.The Xiaguanfang intrusions comprise granodioritic porphyry and quartz diorite porphyrite and are typical metaluminous high-K calc-alkaline to shoshonite series.The magma emplacement age of the rock mass obtained from zircon LA-ICP-MS U-Pb dataing is 139 ～144 Ma.The result of Lu-Hf isotope analysis suggests that the magma source of the Xiaguanfang intrusions may be a mixture of crustal melting magma and mantle remelting magma,and they have a high degree of mixed homogenization.The rock mass is significantly enriched with mineralization element Cu.It is similar to skarn deposits at home and abroad in diagenetic ore-forming tectonic environment,mineralization geological characteristics,wall rock alteration type,and rock mineral combination,indicating that the intrusion has the metallogenic potential of forming a skarn type copper deposit.The Xiaguanfang intrusions was formed at the late Jurassic to early Cretaceous.The stress state of the orogenic belt was changed from extrusion to extension,causing strong crust-mantle interaction and granitic magmatism,and ore-bearing rock mass and skarn type mineralization are subsequently formed.
The Zhashui-Shanyang ore concentrated area is characterized by serious tectomagmatic activity in the South Qinling.It is widely exposed hypabyssal-super hypabyssal granite intrusions such as Baishagou and related skarn-porphyry deposits.Based on the observation of the mineralization geological characteristics of the Xiaguanfang rock in the Zhashui-Shanyang ore district,the detailed petrology,elemental geochemistry,Zircon U-Pb geochronology,Lu-Hf isotope and trace element analysis of the ore-bearing rock are carried out to discuss the origin of the rock mass,diagenesis and ore-forming tectonic environment and metallogenic potential.The Xiaguanfang intrusions comprise granodioritic porphyry and quartz diorite porphyrite and are typical metaluminous high-K calc-alkaline to shoshonite series.The magma emplacement age of the rock mass obtained from zircon LA-ICP-MS U-Pb dataing is 139 ～144 Ma.The result of Lu-Hf isotope analysis suggests that the magma source of the Xiaguanfang intrusions may be a mixture of crustal melting magma and mantle remelting magma,and they have a high degree of mixed homogenization.The rock mass is significantly enriched with mineralization element Cu.It is similar to skarn deposits at home and abroad in diagenetic ore-forming tectonic environment,mineralization geological characteristics,wall rock alteration type,and rock mineral combination,indicating that the intrusion has the metallogenic potential of forming a skarn type copper deposit.The Xiaguanfang intrusions was formed at the late Jurassic to early Cretaceous.The stress state of the orogenic belt was changed from extrusion to extension,causing strong crust-mantle interaction and granitic magmatism,and ore-bearing rock mass and skarn type mineralization are subsequently formed.
引文
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吴发富,王宗起,闫臻,陈雷,夏长玲,郭延辉,彭远民.2014.秦岭山阳-柞水地区燕山期中酸性侵入岩地球化学特征、锆石U-Pb年龄及Lu-Hf同位素组成[J].岩石学报,30(2):451-471.
王瑞廷,王向阳,任涛,李剑斌,孟德明,代军治,王涛,张三敏.2015.山阳-柞水矿集区斑岩-矽卡岩型多金属矿床找矿方法组合研究[J].岩石学报,31(1):245-260.
王晓霞,王涛,齐秋菊,李舢.2011.秦岭晚中生代花岗岩时空分布、成因演变及其构造意义[J].岩石学报,27(6):1573-1593.
张本仁,陈德兴,李泽九.1989.陕西柞水山阳成矿带区域地球化学[M].武汉:中国地质大学出版社,1-221.
张国伟,张本仁,袁学诚.2001.秦岭造山带与大陆动力学[M].北京:科学出版社,1-729.
张宏飞,骆庭川,李泽九,张本仁.1994.东秦岭花岗岩类元素丰度及其地质意义[J].矿物岩石,14(4):1-8.
朱赖民,张国伟,郭波,李犇.2008.东秦岭金堆城大型斑岩钼矿床LA-ICP-MS锆石U-Pb定年及成矿动力学背景[J].地质学报,82(2):204-220.
Mao JW,Pirajno F,Xiang JF,Gao JJ,Ye HS,Li YF and Guo BJ.2011.Mesozoic molybdenum deposits in the east Qinling-Dabie orogenic belt:Characteristics and tectonic settings[J].Ore Geology Reviews,43(1):264-293.
Meinert LD,Dipple GM and Nicolescu S.2005.World skarn deposits[J].Economic Geology,100:299-336.
Xie GQ,Mao JW,Wang RT,Ren T,Li JB and Da JZ.2015.Origin of Late Mesozoic granitoids in the newly discovered Zha-Shan porphyry Cu district,South Qinling,central China,and implications for regional metallogeny[J].Journal of Asian Earth Sciences,103:184-197.
Zhu LM,Zhang GW,Guo B,Li B,Gong HJ and Wang F.2010.Geochemistry of the Jinduicheng Mo-bearing porphyry and deposit,and its implications for the geodynamic setting in East Qinling,P.R.China[J].Chemie der Erde,70:159-174.
陈雷,王宗起,闫臻,吴发富,任涛,郭延辉.2014.秦岭山阳-柞水矿集区150~140Ma斑岩-矽卡岩型Cu-Mo-Fe(Au)矿床成矿作用研究[J].岩石学报,30(2):415-436.
陈衍景,李超,张静,李超,李震,王海华.2000.秦岭钼矿带斑岩体锶氧同位素特征与岩石成因机制和类型[J].中国科学(D辑),30(增刊):64-72.
高山,Rudnick RL,Carlson RW,Mcdonough WF,刘勇胜.2003.华北克拉通岩石圈地幔置换作用和壳幔生长耦合的Re-Os同位素证据[J].地学前缘,10(3):61-67.
姜航,朱赖民,赵东宏,李宗会,杨忠堂,王虎,彭璇,罗根根.2015.南秦岭池沟铜(钼)矿床与华北地块南缘金堆城钼矿床成矿斑岩体对比研究[J].矿产勘查,6(4):334-346.
刘凯,李剑斌,任涛,王向阳,张西社,王超.2013.陕西池沟斑岩型铜矿地质特征与找矿前景分析[J].矿产勘查,2013,4(1):26-32.
李诺,陈衍景,张辉,赵太平,邓小华,王运,倪智勇.2007.东秦岭斑岩钼矿带的地质特征和成矿构造背景[J].地学前缘,14(5):186-198.
毛景文,张作衡,余金杰,王义天,牛宝贵.2003.华北及邻区中生代大规模成矿的地球动力学背景:从金属矿床年龄精测得到启示[J].中国科学(D辑),33(4):289-299.
任纪舜,陈廷愚,牛宝贵.1992.中国东部及邻区大陆岩石圈的构造演化与成矿[M].北京:科学出版社,1-230.
吴发富,王宗起,闫臻,陈雷,夏长玲,郭延辉,彭远民.2014.秦岭山阳-柞水地区燕山期中酸性侵入岩地球化学特征、锆石U-Pb年龄及Lu-Hf同位素组成[J].岩石学报,30(2):451-471.
王瑞廷,王向阳,任涛,李剑斌,孟德明,代军治,王涛,张三敏.2015.山阳-柞水矿集区斑岩-矽卡岩型多金属矿床找矿方法组合研究[J].岩石学报,31(1):245-260.
王晓霞,王涛,齐秋菊,李舢.2011.秦岭晚中生代花岗岩时空分布、成因演变及其构造意义[J].岩石学报,27(6):1573-1593.
张本仁,陈德兴,李泽九.1989.陕西柞水山阳成矿带区域地球化学[M].武汉:中国地质大学出版社,1-221.
张国伟,张本仁,袁学诚.2001.秦岭造山带与大陆动力学[M].北京:科学出版社,1-729.
张宏飞,骆庭川,李泽九,张本仁.1994.东秦岭花岗岩类元素丰度及其地质意义[J].矿物岩石,14(4):1-8.
朱赖民,张国伟,郭波,李犇.2008.东秦岭金堆城大型斑岩钼矿床LA-ICP-MS锆石U-Pb定年及成矿动力学背景[J].地质学报,82(2):204-220.