东北地区中生代火山岩成分空间变异及其成矿规律

Spatial Variability of Composition of Mesozoic Volcanic Rocks and Metallogenic Regularity in Northeast China

根据火山岩的时代、成分特征及与其相关的矿床类型、成矿时代等,将东北地区中生代火山岩划分为3个火山岩带:西部与南部火山岩带成岩时代分别集中在150～120Ma和205～112Ma,岩性以富(钾)碱性-亚碱性粗玄岩-粗安岩-粗面岩类为主,成矿时代西部集中在140～130Ma(南段成矿时代局部偏大),南部为200～108Ma,成矿与火山岩中次火山-浅成相(爆破相)花岗质岩类具有成生关系,矿产以银、铅、锌、铜、钼等多金属系列为主;东部火山岩带成岩时代集中在140～110Ma,以高钾钙碱性粗安岩-粗面岩,安山岩-英安岩-流纹岩为主,成矿时代集中在130～110Ma,金矿成矿(伴生多金属)与火山岩中次火山-浅成相(或其中爆破相)闪长质岩类具有成生联系。结合典型金矿床研究与对比,进一步明确了该火山岩区的金矿找矿方向。

According to diagenetic epoch, composition, associated deposit types and metallogenic ages, the Mesozoic volcanic rocks in Northeast China can be divided into three volcanic belts. The diagenetic epoch of the western and southern volcanic belts change from 150 to 120 Ma and from 205 to 112 Ma, respectively. Volcanic rocks in both belt are potassium-rich alkaline-subalkaline trachybasalt-trachyandesite-trachyet, metallogenic epoch of the western belt change from 140 to 130 Ma （froming the southern section of the metallogentic epoch is too large）. Metallogenic epoch of the southern concentrates in 200 to 108 Ma. There is a close relationship between mineralization and subvolcanic-hypabyssal granitic rocks. Mineral resources mainly contain silver, lead, zinc, copper, molybdenum and other polymetallic series. The diagenetic epoch of the eastern volcanic belts varies from 140 to 110 Ma, and the vocanic rocks mainly include potassium alkaline-subalkaline trachyandesite, trachyet, andesite, dacite, rhyolite. The metallogenic epoch changes from 130 to 110 Ma. Gold and polymetallic mineralization have genetic relationship with subvolcanic and hypabyssal dioritic rocks. Based on the comparison of typical gold deposits in NE China, the prospecting direction of gold is also discussed.