摘要
豫西崤山老里湾岩体位于华北陆块南缘崤山地区东部,是河南省地矿局地矿一院近年新发现的二长花岗岩体。岩体内部已发现多个矿体,为探寻岩体的形成机制及其与成矿作用的关系,对岩体进行了岩石学、年代学、地球化学及岩体内部矿化特征研究,揭示其形成机制及成矿作用。全岩Rb-Sr定年结果显示,老里湾岩体的侵位时间是149±11Ma。岩体的地球化学特征总体表现为高硅、高铝、富碱、低镁的钾玄质、准铝质-过铝质花岗岩;轻稀土元素富集,重稀土元素亏损,轻、重稀土元素强烈分异;δ Eu=0.62~0.66,具有中等的负Eu异常,富集Rb、Th、U、K等大离子亲石元素,Nb、Ta、P、Ti等高场强元素亏损;岩体具有中等含量Sr,低Yb、Y,揭示源区除石榴子石外还有斜长石残留;岩体形成于加厚地壳向正常地壳减薄的环境。岩体内部矿化特征具有斑岩型矿床的特征,成矿时代属晚侏罗世,老里湾岩体成矿是豫西地区晚侏罗世成矿事件在崤山东部地区的地质响应。老里湾岩体与成矿作用关系密切,找矿前景较好,岩体周边地区应被视为崤山东部重点找矿靶区之一。
Laoliwan granite lies in Xiaoshan area on the southern margin of North China Block. It is a granite body discovered recently by Henan Provincial Bureau of Geology and Mineral Resources. This granite mainly consists of adamellite. In this granite body several ore deposits have been found. In order to investigate its formation mechanism and metallogenic role, the authors carried out a study in such aspects as petrology, chronology, geochemistry and mineralization. The formation time of Laoliwan granite is 149±11Ma, as shown by Rb-Sr dating. It is highly K calc-alkaline and metaluminous-peraluminous, enriched in silica(SiO_2=65.81%~68.52%), aluminum(Al_2O_3=14.52%~14.75%), alkali(K_2O+Na_2O=6.52%~7.49%) and depleted in MgO(0.21%~0.73%); LREE is relatively enriched while HREE is depleted(ΣLREE/ΣHREE=15.69~16.38), with medium negative Eu anomalies(δ Eu=0.63~0.66). In addition, it is rich in large ion lithophile elements, such as K, U, and Th, poor in high field elements, such as Nb, Ta, P and Ti, and contains medium Sr(265×10^(-6)~415×10^(-6), averagely 315×10^(-6)), low Y(14.7×10^(-6)~18.8×10^(-6), averagely 16.7×10^(-6)) and Yb(1.14×10^(-6)~1.37×10^(-6),averagely 1.26×10^(-6)), suggesting it was formed during the transition from thickened crust to normal crust,with garnet and plagioclase relics. The inner mineralization is similar to feature of porphyry deposits and its mentallogenic age is Late Jurassic. Its metallogenic role is a geological response to the Late Jurassic mineralization event in Yuxi area. So the Laoliwan granite has a close relationship with mentallization. The ore-searching prospect is good, and the area around Laoliwan granite should be considered to be one of the prospecting targets in the east Xiaoshan region.
出处
《地质通报》
CAS
CSCD
北大核心
2017年第7期1242-1250,共9页
Geological Bulletin of China
基金
河南省地质勘查基金(周转金)招标项目<河南省崤山地区1:5万区域矿产调查(2012)>(编号:豫国土资发[2009]93号)
