北岔沟门中生代岩浆侵入作用成矿系统

采用颗粒锆石U Pb同位素年代学研究方法 (TIMS)阐明河北省北部北岔沟门地区极具特色的中生代浅成侵入岩组合的形成时代及其成矿意义。研究表明 ,北岔沟门一带发育了包括闪长玢岩、石英二长斑岩、角闪黑云二长岩和花岗闪长斑岩等在内的具浅成岩浆侵入作用特征的侵入岩共生组合 ,其中石英二长斑岩、角闪黑云二长岩、花岗闪长斑岩的TIMS锆石U Pb同位素年龄分别为 14 7.6± 1.6Ma、14 6 .2± 1.4Ma和 14 6 .2± 3.9Ma,代表了浅成侵入岩的侵位成岩时代 ,该侵入岩石组合与北岔沟门含金银多金属矿床的形成具有密切的时、空及成因联系 ,构成了华北陆块北缘地区中生代典型的浅成岩浆侵入作用成矿系统。

Mesozoic Intrusive Magmatism-Related Metallogenetic System in Beichagoumen Area

TIMS U-Pb ages of the distinctive Mesozoic hypabyssal intrusions in Beichagoumen area of northern Hebei are presented in this paper,together with a discussion on their metallogenetic significance. These Mesozoic hypabyssal intrusions consist of dioritic porphyrite,monzonitic porphyry,amphibole biotite monzonite and granodiorite porphyry,and the last three sorts of intrusive rocks have TIMS U-Pb ages of 147.6±1.6 Ma,146.2±1.4 Ma and 146.2±3.9 Ma,respectively,which represent their formation ages. The formation of Beichagoumen gold-and silver-bearing polymetallic ore deposit is closely related to the development of these hypabyssal intrusions in time,space and genesis,thus making up a typical metallogenetic system of Mesozoic hypabyssal intrusive magmatism along the northern margin of North China platform.