毕业论文外文译文

毕业论文外文译文

学生姓名: 学号: 专业名称: 译文标题(中英文):太古代马尼卡-穆塔雷-奥济绿岩带金矿分布模式(Distribution Patterns of

Gold Deposits in the Archaean Manica-Mutare - Odzi Greenstone Belt) 译文出处:Gondwana Research, V. 4, No. 4,2001 指导教师审阅签名:

太古代马尼卡——穆塔雷——奥济绿岩带金矿分布模式

晚太古代的马尼卡——穆塔雷——奥济 (MMO)绿岩带呈线型分布在西部莫桑比克和东部津巴布韦上，大约2.74亿年前被津巴布韦的彭哈隆加花岗闪长岩侵入。北东东向延伸的绿岩带由超镁铁变质火山岩组成，并且沿着中心地带的粗碎屑变质沉积物和岩石分布。岩石单元发生强烈变形褶皱，同时形成区域性剥理线理构造。褶皱向东西方向缓慢倾伏，总体方向与原始矿物的线理构造相平行。

MMO绿岩带附近已经开采了128顿金矿(福斯特, 1996) ，矿床成因主要为韧性剪切带、断层和石英脉控制。矿化主要沿控矿岩浆的通道展部。弗雷分析帮助我们确定了控矿的隐伏构造方向，这些方面不太直接明显容易观察。这可以通过提高线性趋势中X-Y数据点。

这些结果，通过解译并与遥感图片分析的构造和线理相比较，可以看出在绿岩带上金矿沿着5千米宽的狭长地带成群分布，主要方向是北东东——南西西，北西——南东和南北向分布。这种长条状构造分布在区域地质图件上面并不是很明显，暗示了受地下深部构造所控制而在地表没明显的出露。

解译图象上分析可知这种北东东——南西西方向与绿岩带构造方向密切相关。同时，北西——南东向和南北向在矿床特征分析上大致是连续的，除开接触矿脉和层控矿床只是显示出北东——南西向生长。在所有矿床分析中北东——南西向被这绿岩带构造方向所掩盖了。在地质解译图中细脉浸染状矿床主要呈北西——南东分

布。韧性剪切带金矿和受断裂控制的矿床主要是呈北东——南西和北西——南东向展部，大致共轭分布。此外在奥济绿岩带附近有一明显的东西构造方向，这与马尼卡和穆塔雷绿岩带附近的南北向对比明显。相比较而言，石英脉型金矿要更分散一点，显示出不同的分布方向。比如说在马尼卡区域北西——南东向、北东——南西向和南北向更多一点，而在穆塔雷地区北西——南东向和南北向却更加重要。在奥济区域内主要的矿床分布方向是石英脉型矿床呈北东——南西向分布。这北西——南东向和南北向控制金矿床的分布在津巴布韦克拉通的其他绿岩带上也已经被验证了，比如说在马沙瓦地区(布伦金索普, 1991)。以上这种分布规律当金矿床再按硫化物矿物共生次序细分亚类时也同样适用，比如说毒砂和辉铋矿——赤铅矿主要呈北东——南西向展部。

在津巴布韦克拉通和绿岩带上主要的矿床分布方向(北西——南东向，南北向和北东——南西向)可以解释为深部地壳断裂引导成矿流体分布，并最终控制金矿床在地面上的分布方向。在解译图象上这种假定因为硫化物分布不同所引起不同方向的矿床分布是否反映了不同时期的成矿事件，或者说明已经存在的金和硫化物集合体受构造再生过程和再活化作用而形成的不同相带，这个问题还有待进一步探讨和研究。

1

Distribution Patterns of Gold Deposits

in the Archaean Manica-Mutare-Odzi Greenstone Belt

S. Mondlane, P. Dirks, H. Jelsmaand T. Blenkinsop

The Manica - Mutare - Odzi (MMO) greenstone belt in West Mozambique and East Zimbabwe is a late Archaean linear structure that was intruded by the Penhalonga granodiorite at ca. 2.74 Ga. The ENE-trending belt

comprises ultramafic metavolcanic rocks along the margins and coarse clastic metasedimentary rocks in the central zone. Rock units are intensely folded and a regional penetrative foliation has developed. Fold axes generally plunge shallowly either to the east or to the west and parallel the regional mineral lineation.

The MMO greenstone belt has produced ca. 84 tonnes of Au (Forster et al., 1996) mainly from shear zone hosted, fault hosted and quartz vein hosted deposits. Mineralization follows corridors, which seem to control the localisation of the deposits.Fry analysis helps to define the underlying structural directions controlling the

distribution of gold deposits, which may not be directly obvious otherwise. This is done by enhancing linear trends

in an X - Y data points. Fry analysis was used to determine the spatial relationships of gold deposits. The input data were extracted from existing records (geological maps, bulletins and mine reports) of mine positions. Sixty out-of 243 deposits were field checked during the present study and were found to be within a maximum offset range of ca. 100 meters in Latitude and ca. 50 meters in Longitude. This offset is deemed acceptable, as it is not

known exactly at what point the previous location was taken (main shaft or adit entrance, first adit, etc.).

The Fry analysis is applied to sectors of the belt (Manica, Mutare and Odzi) for all deposit types. The method has been repeated for gold deposits grouped by type (fault/shear zonehosted (112 deposits), quartz