【摘要】：安徽和睦山閃長巖體位于寧蕪中生代火山巖盆地南段,是和睦山鐵礦的成礦地質(zhì)體。本文在系統(tǒng)收集整理前人資料的基礎上,通過野外地質(zhì)調(diào)查與室內(nèi)分析研究,基本查明了和睦山閃長巖體的巖石學、巖石地球化學及年代學特征,分析了巖石成因及成巖動力學過程。和睦山閃長巖體呈巖枝、巖鐘狀產(chǎn)出,出露面積約1km2。與上覆周沖村組(T2z)灰?guī)r呈侵入接觸關系。巖石學研究表明,和睦山閃長巖中的長石主要為鈉長石,其次為拉長石,有少量的中長石和正長石;角閃石主要為淺閃石、透閃石及少量鎂角閃石,少量角閃石發(fā)生蝕變形成陽起石。全巖主量元素表明和睦山閃長巖體具有富鈉(4.90~8.25%)、貧鉀(0.62~2.59%)、準鋁質(zhì)(A/CNK為0.70~0.87)的特征,里特曼指數(shù)σ為3.46~4.59,屬于堿鈣性系列,分異指數(shù)DI為53.28~72.96。富集大離子親石元素(如K、Rb、Sr、Ba等),虧損高場強元素(如Nb、Ta、Zr,Ti等)。稀土元素總量較低(∑REE為69.65×10-6~150.84×10-6,平均為102.58×10-6),輕稀土相對富集,重稀土相對虧損(LREE/HREE平均為5.84),不明顯的Eu負異常。ISr較低,變化為0.70537~0.70633,INd變化為0.51211~0.52131,εNd(t)變化為-5.33~-7.06,鋯石U-Pb年齡為134.9±2.1Ma,表明和睦山閃長巖是燕山期早白堊世(K1)的產(chǎn)物。利用全鋁角閃石壓力計估算巖漿結晶壓力為P=72~165MPa,對應的巖漿侵位深度為2.36~5.44km。巖石學、巖石地球化學及成巖年代學特征表明,和睦山閃長巖是由富集地幔部分熔融形成的玄武質(zhì)巖漿底侵于下地殼部分,在巖漿上侵過程中與地殼物質(zhì)發(fā)生一定程度的同化混染作用,在地殼淺部形成巖漿房,上侵冷卻結晶發(fā)生結晶分異作用,形成和睦山閃長巖體。其形成受中國東部中生代的地球動力學背景的制約,形成于軟流圈上涌和巖石圈伸展減薄環(huán)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，

本文編號：2237496