投稿时间：2012-03-29
修订日期：2012-06-15
中文摘要:位于钦—杭成矿带东段北缘的浙江安吉多金属矿区发育侵位序列复杂的坞山关杂岩体及与其有关的蚀变和矿化。为了探讨区内岩浆岩与成矿的关系,在野外调查的基础上,文章对该杂岩体的岩相学、岩石地球化学开展了研究,并籍此对其成因类型、源区特征进行了探讨。坞山关杂岩体由黑云母二长花岗岩、花岗闪长岩和正长花岗岩组成,前者具富碱、高钾特征,属准铝质-钾玄岩系列,花岗闪长岩具高钾特征,属准铝质-高钾钙碱性系列,正长花岗岩具高硅、低钙、贫镁、高FeO*/MgO值、富碱特征,属准铝-弱过铝质钾玄岩系列。该杂岩体的∑REE为(123.5~216.47)×10-6,稀土元素配分型式呈明显的右倾轻稀土元素富集型,Eu呈不同程度的负异常。微量元素蛛网图中,各岩石单元大离子亲石元素(尤其是Rb、Th、K)明显富集,Ba、Sr负异常明显,相对亏损高场强元素Nb、Ti、P。该杂岩体成矿元素ω(Mo)、ω(W)明显高于克拉克值,暗示其具有提供成矿物质的潜力。黑云母二长花岗岩为分异I型花岗岩,花岗闪长岩属I型花岗岩,正长花岗岩具有A型花岗岩的多数特征,但从杂岩体各岩石单元的成岩年龄相差不大、具地球化学亲缘性以及A型花岗岩不具高分异特征来考虑,将其归为高分异I型花岗岩更合理。La/Sm-La图解显示出,该杂岩体为平衡部分熔融作用所形成,其轻稀土元素富集、Ta-Nb、Ti、Eu、Sr、Ba负异常可能是源区为含角闪石族、金红石、斜长石作为难熔相遗留在残留物中所致。
Abstract:In the Anji ore district located in northern Qinzhou-Hangzhou metallogenic belt, there exists the Wushanguan complex body in which the rock units have complicated intrusion sequences and are related to alteration and mineralization. In order to study the relationship between magmatic activity and mineralization, the authors analyzed the major and trace elements concentration and the characteristics of petrogeochemistry and petrogenesis of Wushanguan complex body based on the results of field work and petrographic studies. The major and trace elements concentrations were tested by XRF and ICP-MS. Wushanguan complex body is mainly composed of biotite-monzonitic granite, granodiorite and syenogranite. The biotite-monzonitic granite is characterized by alkali-rich and potassium-high nature, and belongs to quasi-aluminous rock and shoshonite series. The granodiorite is characterized by high potassium and belongs to quasi-aluminous rock and high-K calc-alkaline series. Syenogranite is similar to A-type granite characterized by high SiO2, low CaO, low MgO, high FeO*/MgO ratio, relatively rich alkali and high potassium, and belongs to metaluminous-weakly peraluminous rock and shoshonite series. The total concentrations of the rare earth elements of the complex range from 123.5×10-6 to 216.47×10-6. The rare earth elements distribution patterns of the complex are all of LREE-enriched type 〔(La/Yb)N=7.47~23.93〕 with different negative Eu anomalies (Eu/Eu*=0.38~0.86). In the primitive mantle normalized multi-element variation diagram, large-ion lithophile elements, such as Rb, Th and K, are abundant with obvious negative anomalies of Ba and Sr, and the rocks are all relatively depleted in some high field strength elements such as Nb, Ti and P. Among the ore-forming elements, the element values of Mo and W are higher than their Clarke values obviously, that is to say, the complex has the potential of becoming a mineralization source. According to the characteristics of major elements and trace elements, especially the discrimination diagrams, biotite-monzonitic granite is separately fractionated I-type granites and the granodiorite belongs to I-type granite. Syenogranite has some characteristics of highly fractionated A-type granite, but there are several reasons suggesting that it does not belong to A-type granite: firstly, A-type granites generally do not exhibit evidence of being strongly differentiated; secondly, on the whole, all the complex members have a similar age within the experimental error as well as have an affinity to each other in geochemistry, so that all the rock units should be formed in the same tectonic setting. Considering that biotite-monzonitic granite and granodiorite belong to I-type granite, it is more reasonable to assign moyite to highly fractionated I-type granite. The La/Sm-La diagram shows that the complex body was formed by equilibrium fusion. Light rare earth elements enrichment and Ta-Nb-Ti, Eu, Sr and Ba negative anomalies probably resulted from hornblende group, when rutile and plagioclase stayed in residue in source region.
keywords:geology petrogeochemistry petrography highly fractionated I-type granite Wushanguan complex body western Zhejiang
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中图分类号：P588.1
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基金项目:本文得到科技部公益性行业基金(编号: 201011011)及十二五国家科技计划项目(编号: 2011BAB04B00)的资助
引用文本：
唐燕文,谢玉玲,李应栩,邱立明,刘保顺,李媛,张欣欣,姜妍岑,韩宇达.2012.浙江安吉坞山关杂岩体岩相学和岩石地球化学特征及岩石成因[J].矿床地质,31(4):903~916TANG YanWen,XIE YuLing,LI YingXu,QIU LiMing,LIU BaoShun,LI Yuan,ZHANG XinXin,JIANG YanCen,HAN YuDa.2012.Petrogeochemical and petrographic characteristics and genesis of Wushanguan complex body in Anji ore district, Zhejiang Province[J].Mineral Deposits31(4):903~916
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