内蒙古呼伦贝尔盟北部砂金矿成矿规律

呼伦贝尔盟北部地区由于新构造运动含金地质体长期风化剥蚀，促使金的活化。河流及其2－3级支流发育，流域广，水流充足，有利于砂金矿的迁移、富集。现代的乐山丘陵、宽阔沟谷有利于砂金的保存。该区已发现数十个砂金矿，多为河谷型，主要含金层为含粘土砂层或砂砾层。砂金富集与河谷地貌关系密切，河床弯曲的凸岸、变异部位、关门咀、迎门山等地貌是砂金富集有利部位。该区金直接来源于加里东和华力西花岗岩。结合金的来源、矿床的分布特征和富集规律，指出了该区今后砂金找矿方向。

METALLOGENIC LAW OF PLACER GOLD DEPOSITS IN NORTH HUNLUNBEIR LEAGUE

Neotectonic movement exposed gold bearing geological bodies in North Hulunbeir League to weathering and degradation, and resulted in gold activation. Rivers and the tributaries developed with wide drainage and sufficient flow providing favorable conditions for gold migration and enrichment. Modern low mountain and mound and wide valleys are favorable for placer gold preservation. Several tens of placer gold deposits have been found in this area and most are of river valley type. Gold occurs mainly in clay sandy gravel of sandy gravel layers. Gold enrichment is closely related with geomorphy of valley. Convex bank and variation parts of river bed, door close mouth, door facing hill are favorable places for placer gold deposition. Gold source is from Caledonian and Hercynian granite. At last, exploring guides for placer gold deposit are pointed out on the base of study of gold source, placer gold distributive features and enrichment law.