安徽省和睦山闪长岩体地质地球化学特征及其成因
发布时间：2018-09-11 18:22
【摘要】：安徽和睦山闪长岩体位于宁芜中生代火山岩盆地南段,是和睦山铁矿的成矿地质体。本文在系统收集整理前人资料的基础上,通过野外地质调查与室内分析研究,基本查明了和睦山闪长岩体的岩石学、岩石地球化学及年代学特征,分析了岩石成因及成岩动力学过程。和睦山闪长岩体呈岩枝、岩钟状产出,出露面积约1km2。与上覆周冲村组(T2z)灰岩呈侵入接触关系。岩石学研究表明,和睦山闪长岩中的长石主要为钠长石,其次为拉长石,有少量的中长石和正长石;角闪石主要为浅闪石、透闪石及少量镁角闪石,少量角闪石发生蚀变形成阳起石。全岩主量元素表明和睦山闪长岩体具有富钠(4.90~8.25%)、贫钾(0.62~2.59%)、准铝质(A/CNK为0.70~0.87)的特征,里特曼指数σ为3.46~4.59,属于碱钙性系列,分异指数DI为53.28~72.96。富集大离子亲石元素(如K、Rb、Sr、Ba等),亏损高场强元素(如Nb、Ta、Zr,Ti等)。稀土元素总量较低(∑REE为69.65×10-6~150.84×10-6,平均为102.58×10-6),轻稀土相对富集,重稀土相对亏损(LREE/HREE平均为5.84),不明显的Eu负异常。ISr较低,变化为0.70537~0.70633,INd变化为0.51211~0.52131,εNd(t)变化为-5.33~-7.06,锆石U-Pb年龄为134.9±2.1Ma,表明和睦山闪长岩是燕山期早白垩世(K1)的产物。利用全铝角闪石压力计估算岩浆结晶压力为P=72~165MPa,对应的岩浆侵位深度为2.36~5.44km。岩石学、岩石地球化学及成岩年代学特征表明,和睦山闪长岩是由富集地幔部分熔融形成的玄武质岩浆底侵于下地壳部分,在岩浆上侵过程中与地壳物质发生一定程度的同化混染作用,在地壳浅部形成岩浆房,上侵冷却结晶发生结晶分异作用,形成和睦山闪长岩体。其形成受中国东部中生代的地球动力学背景的制约,形成于软流圈上涌和岩石圈伸展减薄环境。
[Abstract]:The Huoshan diorite in Anhui Province is located in the southern section of the Mesozoic volcanic basin of Ningwu, and is the ore-forming geological body of Hushan Iron Mine. On the basis of systematic collection and collation of previous data, the petrology, geochemistry and geochronology of the Heshan diorite are basically found out by field geological investigation and laboratory analysis. The petrogenesis and diagenetic dynamics are analyzed. The Heshan diorite is a branched rock with a campanulate rock with an area of about 1 km ~ 2. It has an intrusive contact relationship with the limestone of the Zhouchong Village formation (T 2z). The petrological studies show that the feldspar is mainly albite, followed by elongite, with a small amount of meso-feldspar and orthoclase, and hornblende is mainly shallow-amphibole, tremolite and a small amount of magnesium hornblende. A small amount of hornblende is corroded and deformed into actinolite. The main elements of the whole rock show that the Heshan diorite has the characteristics of rich sodium (4.90 ~ 8.25%), poor potassium (0.62 ~ 2.59%) and quasi-aluminite (A/CNK = 0.70 ~ 0.87). The Ritman index 蟽 is 3.46 ~ 4.59, which belongs to the alkali calcium series and the differentiation index (DI) is 53.2872.96. It is rich in large ion lithophile elements (such as Ko Rbsrnb Ba etc.) and depleted in high field strength elements (such as Nb,Ta,Zr,Ti etc.). The total amount of rare earth elements is lower (鈭，
本文编号：2237496
[Abstract]:The Huoshan diorite in Anhui Province is located in the southern section of the Mesozoic volcanic basin of Ningwu, and is the ore-forming geological body of Hushan Iron Mine. On the basis of systematic collection and collation of previous data, the petrology, geochemistry and geochronology of the Heshan diorite are basically found out by field geological investigation and laboratory analysis. The petrogenesis and diagenetic dynamics are analyzed. The Heshan diorite is a branched rock with a campanulate rock with an area of about 1 km ~ 2. It has an intrusive contact relationship with the limestone of the Zhouchong Village formation (T 2z). The petrological studies show that the feldspar is mainly albite, followed by elongite, with a small amount of meso-feldspar and orthoclase, and hornblende is mainly shallow-amphibole, tremolite and a small amount of magnesium hornblende. A small amount of hornblende is corroded and deformed into actinolite. The main elements of the whole rock show that the Heshan diorite has the characteristics of rich sodium (4.90 ~ 8.25%), poor potassium (0.62 ~ 2.59%) and quasi-aluminite (A/CNK = 0.70 ~ 0.87). The Ritman index 蟽 is 3.46 ~ 4.59, which belongs to the alkali calcium series and the differentiation index (DI) is 53.2872.96. It is rich in large ion lithophile elements (such as Ko Rbsrnb Ba etc.) and depleted in high field strength elements (such as Nb,Ta,Zr,Ti etc.). The total amount of rare earth elements is lower (鈭，
本文编号：2237496
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