摘要
苏北海州群云台组上段变火山岩富含碱性长石(60-70％)和钾长石(35-60％),黑云母为富铁黑云母,部分火山岩含霓辉石、萤石等.其岩石地球化学特征:高硅(SiO_2>6.41％),富碱(Na_2O+K_2O8.54％).高钾(K_2O4.52％),低铝(Al_2O_311.88％).贫钙、镁(CaO0.25％,MgO0.13％);富Nb、Zr、Y、Zn和Ga等元素;富REE、LREE和Eu强烈亏损.上述特征与世界和福建魁歧、浙江青田、江苏苏州、山东崂山等A型(或碱性)花岗岩的特征一致,为A型火山岩.其连云港市东部分布区是寻找与海相A型火山岩有关的Sn、W、Zn、Ph、Ag(Au)等华前型块状硫化物矿床和热液矿床的重要靶区.
The metamorphosed volcanic rock of the upper member of the Haizhou group is rich in alkali-feldspar (60 to 70%) and high potash feldspar (35 to 60%). It contains also fcrri-biotite, acgirinc and fluorite etc. Their geochemical features are Si-high (SiO2 76.41%), alkali-rich (Na2O+K2O-8.54%), K-high (K2O 4.52%), Al-low (A12O311.88%), Ca-low (CaO 0.25%), Mg-low (MgO 0.13%); exhibits high Nb, Zr,Y, Zn, Ga and Ga / Al; the REE content high (142.79 to 351.24 × 10-6), enriched in light REE, heavy negative Eu-anomaly (δEu 0.20 to 0.34). All these features indicate that the volcanic rocks of the upper member of Yuntal formation A-type granites (or alcaline granites) in Suzhou (Jiangsu), Laoshan (Shandong), Qingtian (Zhejiang), Kuiqi (Fujian) as well as abroad; so it belongs to the A-type volcanic rock.
As the A-typc volcanic rock shows high Sn, W, Mo, Bi, Zn, Pb, Ag, As etc., their distributive conccntcration are nonuniform in the regional metamorphism and alteration. In addition its rich alkali and halogen may cause trace elemenes enriching and ore-forming. So the area is a potcntal targel for south China typical measive surfide mineral deposits and hydrothcmal deposits bound up with masine fanies volcanic rocks .
出处
《火山地质与矿产》
1992年第4期42-54,共13页
Volcanology & Mineral Resources
关键词
海州群
A型
火山岩
含矿性
江苏
Haizhou Group A-type volcanic rock Pay nature Jiangsu
