胶东丛家花岗闪长岩体与玲珑金矿闪长岩脉的矿物特征研究  

STUDY OF MINERALS IN CONGJIA GRANODIORITIC PLUTON AND DIORITIC VEINS OF LINGLONG ORE FIELD,EASTERN SHANDONG

作　　者：杜静国 申俊峰[1] 刘畅[1] 刘海明[1] 

机构地区：[1]中国地质大学地球科学与资源学院,北京100083

出　　处：《矿物岩石》2014年第2期40-47,共8页Mineralogy and Petrology

基　　金：国家自然科学基金重点项目(90914002);中国地质大调查项目(1212011220926;20089937)

摘　　要：胶东西北部中生代白垩纪岩浆活动剧烈,在许多中生代岩浆岩中常见有大量的闪长质包体和中基性岩脉。因此特选取胶东西北部的丛家花岗闪长岩(130Ma)及其岩体中的闪长质包体,和玲珑矿区的闪长岩脉(121Ma^96Ma)进行角闪石、黑云母和副矿物磷灰石、榍石的成因分析。发现角闪石均属钙质角闪石系列的浅闪石,镁指数M*在0.5~0.7之间,而黑云母均为镁质黑云母,镁指率大于0.45。结合这两种矿物的TiO2-Al2O3、MgO-FeO/(FeO+MgO)成分特点,认为其寄主岩石应源于壳幔混合作用,并且副矿物磷灰石、榍石也具壳幔特征。值得强调的是,角闪石、黑云母Mg含量较高,所以可能形成于壳幔作用较深源区。通过角闪石-黑云母矿物对温度图谱和黑云母全铝压力计进行成岩温压和深度计算,结果显示:花岗闪长岩、闪长质包体、闪长岩脉的形成温压和深度分别为:625℃~650℃,86MPa,3.24km;700℃,95MPa^118MPa,3.66km^4.17km;700℃~750℃,96MPa^111MPa,3.59km^4.45km;可以看出花岗闪长岩、闪长质包体、闪长岩脉均具壳幔混合特征,并且成岩物理条件相近,加上成岩年龄接近,所以三者可能是同一时期经过相同地质作用形成的产物。Mineralogical analysis is carried out on dioritic xenoliths and their hosts in Congjia pluton as well as dioritic veins in Linglong ore field, Shandong Province. Amphiboles are characterized by high Mg （0. 5〈M＊ 〈0.7） and belong to endenite of calc-alkaine series;and biotites are characterized by high Mg （M^# 〉0.45） and belong to magnesia biotite,indicating that the dioritic xenoliths in Congjia pluton and dioritic veins may originate from crust-mantle mixing zones. Otherwise, some accessory minerals （apatites,sphenes） also have a crust-mantle mixing characteristics. Confined by amphibolesbiotites geothermometry, biotite geobarometer, the temperatures, pressures and depths of Congjia pluton （130 Ma）,dioritic xenoliths and dioritic veins （121 Mat 96 Ma） are 625 ℃-650 ℃,86 MPa,3.24 km;700 ℃ ,95 MPa-118 MPa,3.66 km-4. 17 km-700 ℃ - 750 ℃, 96 MPa - 111 MPa, 3.59 km - 4.45 km ; respectively. These temperatures, pressures and depths indicate that Congjia pluton, dioritic xenoliths and dioritic veins may be products of the same period and have a close relationship with the thinning of lithosphere in Mesozoic.

关 键 词：角闪石 黑云母 压力计 壳幔特征 

分 类 号：P62[天文地球—地质矿产勘探]