莫桑比克马尼卡砂金矿床地质特征          下载免费PDF全文

龚德奎  徐强 《江苏地质》2013,37(2):248-251

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。  相似文献   

辽东地区水系样品中铬尖晶石特征     

周丽霞 《国土资源》1992,(2)

铬尖晶石以在风化过程中稳定性高,分布广等特征作为寻找金刚石的重要指示矿物已在找矿中取得了较满意的结果。根据普查找矿中的水系重砂样品所获取的大量铬尖晶石的分布特征、晶体形态、化学成分,以及辽宁已知金伯利岩中铬尖晶石的物理化学特征,将水系重砂中铬尖晶石与金伯利岩中铬尖晶石进行对比。研究表明,辽东北部、中部地区的铬尖晶石基本上不是来自有价值的金伯利岩,而南部地区的铬尖晶石许多是来自有价值的金伯利岩。  相似文献   

Fine and ultrafine gold in placers of northeastern Russia     

I. S. Litvinenko 《Russian Journal of Pacific Geology》2008,2(2):175-186

The main features of the migration and accumulation of fine and ultrafine gold during the evolution of placer-forming processes in northeastern Russia are discussed. The results of loose sediment sampling (over 2000 samples) with a screw separator and strake facilities have been taken into consideration. The approximate grades and potential resources of gold were estimated for various genetic types of placers. The most favorable conditions for the mobilization and accumulation of fine and ultrafine gold in the placers of northeastern Russia prevailed during the Paleogene to Miocene stage of the evolution of orogenic morphostructures, when the residual (illuvial and alluvial) placers were formed. During the Pliocene to Quaternary stage, the tectonic activation caused the reworking of placers by slope and fluvial processes and resulted in the formation of new hillside and alluvial placers. At this stage, the dispersal of fine gold fractions prevailed over accumulation. Under conditions of the periglacial lithogenesis of the Pliocene to Quaternary tectonic activation, the formation of new placers with fine and ultrafine gold derived from primary sources was suppressed due to the low rate of metal release in the process of physical weathering. In terms of the economic importance of placers with fine and ultrafine gold, residual, eluvial, or hillside placers, as well as alluvial stratal placers located in low-order (and partly medium-order) stream valleys, are the most attractive in northeastern Russia. The primary sources of such placers comprise gold-bearing porphry copper, gold-sulfide-quartz, and other hydrothermal deposits with similar placer-forming capability, as well as gold-quartz stockworks. The grade of fine and ultrafine gold in such placers may be as high as a few g/m³. The placers located in the constratal alluvium of graben-type valleys and the bar and floodplain placers in the areas with stockwork-like orebodies containing fine (<0.25 mm) gold are regarded as prospective objects.  相似文献   

Some geological-morphological features of the formation of gold-bearing placers in the Amur region     

L. V. Eirish 《Russian Journal of Pacific Geology》2008,2(5):454-463

The intensity of placer formation is controlled by many factors, mainly by the erosion level of orebearing structures. Their deep erosion and long-term denudation resulted in the formation of numerous, often large placers with fine gold, which lost their relation with bedrocks and were derived mainly by rewashing of loose deposits from the depressions adjacent to the ore-bearing orogens. These placers are developed in many gold-bearing areas: Dambuki, Sutara, Erik, and others. Rich placers with coarse gold of high fineness were formed via erosion of gold mineralization that was previously metamorphosed by post-ore granitoids (Niman and Kerbi regions, Central Sikhote Alin).  相似文献   

砂金粒度特性研究     

任天秀 《矿物岩石》1991,(4)

本文介绍砂金粒度分析采用筛析-镜测的联合粒度分析方法,并提出砂金粒度的分级意见。  相似文献   

Magnetics in geoexploration     

William J. Hinze  Ralph R. B. Von Frese 《Journal of Earth System Science》1990,99(4):515-547

The magnetic method is the oldest and one of the most widely used geophysical techniques for exploring the earth’s subsurface. It is a relatively easy and inexpensive tool to employ, being applicable to a wide variety of subsurface exploration problems involving horizontal magnetic property variations occurring from near the base of the crust to within the uppermost meter of soil. Successful applications of the magnetic method require an in-depth understanding of its basic principles and careful field work, data reduction, and interpretation. Commonly, interpretations are limited to qualitative approaches which simply map the spatial location of anomalous subsurface conditions, but under favourable circumstances the technological status of the method will permit more quantitative interpretations involving specification of the nature of the anomalous sources. No other geophysical method provides critical input to such a wide variety of problems. However, seldom does the magnetic method provide the complete answer to an investigation problem. As a result, it is generally used in concert with other geophysical and geological data to limit its interpretational ambiguities.  相似文献   

嫩江上游第四纪砂金矿控矿条件和富集规律的初步研究   总被引：2，自引：1，他引：2  

王瑞山 《海洋地质与第四纪地质》1996,16(4):87-94

在论述了嫩江上游区域地质背景后，总结了该区砂金矿形成的控矿条件和富集规律。提出了决定砂金矿形成的主要因素是丰富的砂金物质来源，有利的外营力作用，适宜的新构造运动和良好的沉积环境，而且要经历搬运－沉积、再搬运－再沉积的复杂过程，才能达到工业要求的富集程度。  相似文献   

沉积型钛铁矿品位计算方法     

彭程 《地质论评》2023,69(4):1605-1608

沉积型钛铁矿品位计算中时常出现简化计算公式,忽视钛铁矿中TiO2实际含量和钛物相分布中钛铁矿占比等因素,导致钛铁矿品位计算数据偏差,影响钛铁矿储量计算和项目经济测算。为了减少钛铁矿品位计算的错误,本文以莫桑比克和马拉维钛铁矿项目勘查资料数据为基础,论述钛铁矿物中TiO2实测含量及钛物相分析中钛铁矿占比的意义,正确运用钛铁矿品位计算公式,使沉积型钛铁矿品位计算更接近实际,为提升钛铁矿砂矿资源储量和项目经济性测算的准确性提供重要支撑。  相似文献   

科特迪瓦共和国热雷波砂金矿地质特征     

康云骥 《南方国土资源》1999,12(4):27-30

文章简要介绍了科特迪瓦共和国热雷波砂金矿区地质特征和成矿地质条件 ,并把砂金的类型分为 3种 :铁质壳型、残积粘土型、河沼冲积型。  相似文献   

贵州凯里龙井街发现火山岩屑重砂异常     

秦守荣  罗晋辉  易国贵 《贵州地质》2001,18(1):68-69

贵州凯里龙井街火山岩屑重砂异常位于区域性施洞口深大断裂近旁，异常物质为黑曜岩屑及火山玻璃，它的存在，显示了施洞口断裂带附近，挽近地质时期曾有酸性火山喷发活动，为贵州基础地质研究提供了新的重要信息。  相似文献