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1、学生毕业设计（论文）外文译文学生姓名： 学号：专业名称：地质学译文标题（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S. 曼德拉，P. 德勒克斯，H. 杰斯马，T. 布伦金索普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、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。弗雷分析常常被用来确定矿床的空间关系。通过现有矿床位置数据（地质图，分析和开采报告）提取有效数据进
3、行分析。在现有的研究条件下，243个矿床实验数据中已有60个得到了野外验证，经度误差约50米以内，纬度误差约100米以内。这误差是可以接受的，尽管你不能确切知道精确的坐标位置（主矿井或者坑道入口，第一坑道等）。这种分析方法常常被用在绿岩带上各种矿床矿脉中。我们已经多次利用这种方法理论对金矿分类如下：断层/剪切带控制（112个矿床），石英脉（170个矿床），层控/接触矿脉（22个矿床），管状、浸染状矿脉（20个矿床）以及一些共生硫化物矿床。对矿床分类，那些因素：硫化物、矿床地质特征和区域线型模式等有可能被忽视，但在弗雷分析中，这些因素应被重点考虑。这些结果，通过解译并与遥感图片分析的构造和线理相
4、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。待添加的隐藏文字内容3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
5、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
6、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。参考文献（略）Distribution Patterns of Gold Deposits in the Archaean Manica-Mutare-Odzi Greenstone BeltS. Mondlane, P. Dirks, H. Jelsmaand T. BlenkinsopThe Manica -
7、 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 t
8、he 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) mai
9、nly 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 directl
10、y 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 d
11、eposits 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
12、, 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 vein (170 deposits), stratabound/contact reefs (22 deposits), and sto
13、ck work/disseminated (20deposits) and finally for the deposits grouped according to sulphide paragenesis. When grouping the deposits by sulphides, deposit type and region (Manica, Mutare or Odzi) linear patterns that might be subdued when applying the Fry analysis to all deposit types at the same ti
14、me can be revealed. The results interpreted visually and compared to structural and lineament analysis from satellite images suggest that gold mineralization in the MMO greenstone belt clusters repeatedly in corridors of about 5 km wide and generally oriented ENE-WSW, NW-SE or N-S. These corridors a
15、re not evident on the geological -structural maps of the area, suggesting an underlying control by deepseated structures without surface expression. Interpretation of the translation maps shows that the ENE-WSW direction is related to the structural trend of the MMO greenstone belt. The NW-SE and N-
16、S directions are persistent at deposit type level of analysis, except for the contact reef and stratabound deposits, which only show the NE-SW direction. The NE-SW direction, in the all deposit type analysis, is masked by the structural trend of the belt. The stockwork and disseminated deposits, sho
17、w NW-SE as the main direction in the translation maps. The shear zones and fault-hosted deposits are generally aligned NE-SW and NW-SE directions, probably forming conjugate sets. In addition an E-W direction is evident in the Odzi section of the belt while a N-S direction is evident in the Manica a
18、nd Mutare sections of the belt. The quartz vein hosted deposits are more diffuse and show different orientations,for example in the Manica area NW-SE, N-S, NE-SW directions are more dominant while the N-S and NW-SE are important in the Mutare area. The Odzi section is dominated by NE-SW directions f
19、or quartz vein deposits. The NW-SE and N-S directions controlling gold distribution have also been identified in other greenstone belts in the Zimbabwe Craton, e.g., the Mashava area (Blenkinsop, 1991). The above results are also found when the gold deposits are subdivided according to sulphide para
20、genesis, e.g. arsenopyrite and bismutinite-crocoite show a dominant NE-SW alignment.The prominent directions (NW-SE, N-S and NE-SW) have been interpreted as the surface expression of deep-seated crustal structures that channelled the mineralization fluids and control the distribution of gold deposit
21、s in the Zimbabwe Craton and in the MMO belt in particular. The question of whether the different directions postulated by translation maps of different sulphides reflect different mineralization events or different phases of structural reactivation and remobilization of pre-existing concentrations
22、of gold and sulphides has not yet been fully covered.References：Blenkinsop, T.G. (1991) Controls on Archaean gold mineralization in the Mashava area, Zimbabwe.Forster, H., Koeneman, EH. and Knittel, U. (1996) Regional frameworkfor gold deposits of the Manica-Mutare-Odzi greenstone belt,Zimbabwe - Mozambique. Trans. Ins. Min. Metall., v. 105,pp. 60 - 73.（正文页面不够可加页，并在正文后附外文原文，统一用A4纸张打印或手工誊写）
