莫桑比克马尼卡砂金矿床地质特征

Geological properties in Manica Gold Placer in Mozambique

马尼卡砂金矿区位于莫桑比克马尼卡省马尼卡矿田东侧古河道中。地处世界著名的马尼卡金矿成矿带区,属非洲新元古代基巴拉构造旋回(距今约1100Ma)巨型造山带中部弧形突出部位之东侧。依据砂金矿床的成矿地质特征、重砂矿物组合,认为该矿床属近源型砂金矿,其中砂金的物质来源于该古河道北、西、南侧3个方向山坡上的花岗岩-绿岩地体。砂金聚集于古河道河漫滩砂层、砂砾层和泥砂质填隙物内,特别富集于底部基岩之上的砾石层之中。矿体形状严格受河床底部基岩地貌控制。

Manica Gold Placer was located in the old stream in the east side of the Manica mine field, Manica Province, the Republic of Mozambique. It was situated in the world famous Maniea gold metallogenie belt and belonged to the arc-shaped projecting part in the east side of the central giant orogenic belt of African Neoproterozoic Kibaran Cycle （ about 11 million years ago）. On the basis of metal- logenic geological characteristics of gold placer deposit and heavy placer mineral association, this deposit is believed to be a proximal placer gold deposit, and the placer gold materials were derived from the granite-greenstone terrane on the mountain slopes in the north, west and south of the old stream. Placer gold was gathered in the sand bed, sandy gravel stratum and gravel of this old stream＇s flood plain, particularly concentrated in the gravel stratum on the underlying bedrock. The shape of ore body was strictly controlled by bed- rock landforms of the riverbed at the bottom of the bedrock.