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1.
《Chemie der Erde / Geochemistry》2021,81(4):125830
Increasing the prediction rate in the identification of mineralization zones using the stream sediment geochemical data is an essential issue in the regional exploration stage. The various univariate (such as fractal and probability plot (PP) methods) and multivariate methods (such as principal component analysis (PCA)) have been performed for interpreting the geochemical data and detecting the mineralization areas. In this study, a new geochemical criterion named geochemical anomaly intensity index (GAII) was proposed for geochemical anomaly mapping. This approach was developed based on the PCA method and the catchment basin coefficient (CBC). The GAII as a weighted geochemical index is calculated using the mineralization principal component (MPC) scores and CBC. GAII can be mapped and utilized for geochemical anomaly mapping and detecting the mineralization areas. Besides, GAII can identify paragenesis elements better than the current methods. In this research, GAII was successfully used to generate geochemical anomaly maps on shear zone gold mineralization in the southwest of Saqqez, NW Iran. The geochemical data have been divided into three groups based on catchment basins and the host rock type. Then the MPCs and paragenesis elements of Au mineralization have been obtained individually using PCA. Three mineralization paragenesis groups consisting of (Au, Sn), (Au, W), and (Au, As, Sb and Ba) have been recognized for different catchment basins of the southwest of Saqqez district using PCA. GAII was calculated and mapped based on the CBC(Au, Sn), CBC(Au, W), CBC(Au, As, Sb, Ba), and their MPC scores. GAII accurately detected the Au mineralization zones and improved the geochemical anomaly map in this area compared to the PP method, concentration-area fractal model, and U-spatial statistics method. The results demonstrated that GAII was successfully used for (a) identifying the mineralization paragenesis elements, (b) intensifying the geochemical anomaly, and (c) increasing the prediction rate of mineralization zones. The shear zone gold mineralization areas in the southwest of Saqqez district were effectively detected using this new data analysis approach. GAII has provided better results than the current PP method, concentration-area fractal model, and U-spatial statistics method. 相似文献
2.
辽东地区金矿床主要分布在丹东、青城子、营口－盖县、清原等4个金矿化集中区（带）。S，Pb同位素特征显示金矿的成矿物主要来源于下地壳和上地幔。成矿流体中的CO2与金矿成矿关系密切，在成矿过程中流体的盐度较低，且由弱酸性向弱碱性变化，金矿多为中低温矿床。韧性剪切带对金矿化的空间分布显示出多级有序的控制作用，同时对金矿的矿床类型和矿化类型也表现出显著的控制作用，构造应变场和地球化学场的改变，促使成矿元素迁移富集而形成金矿。研究认为，在元古宇分布区，在深部寻找脆韧性变形带中的金矿仍然具有较大远景，同时要注意寻找与BIF建造有关的金矿新类型。 相似文献
3.
H. Alizadeh-Dinabad R. Ghavami-Riabi T. Eslamkish Y. Mirzaeian 《Arabian Journal of Geosciences》2013,6(5):1457-1464
Investigating the secondary geochemical environments, river, and stream sediments are considered as one of the geochemical exploratory methods on a primary scale, which is justifiable regarding the expenses and time of execution. Evaluating the factors related to mineralization of gold shear zones based on stream and river sediment sampling, located in the southwest of Saqqez (Kurdistan), is the main purpose of this research. Using multivariable analyses and investigating the cluster graph of the elements, controlling factors of mineralization have been investigated and effective factors are divided into two groups, one is probably related to the mineralization of gold in the region which contains the elements (Pb, Zn, Mo, Ag, Cu, Bi, etc.), and other is related to typical petrogenetic processes which contains the elements (Co, V, Cr, Ti, Ni, Mn, etc.). Based on factor analysis, seven main factors, which justify about 80% of the changes of the region, were introduced; factors 3, 1, 5, and 6 were related to mineralization and factors 2, 4, and 7 were related to the lithology of the region. For a more precise separation of the processes related to mineralization, various ratios were investigated and reagent ratios (Au/Bi and Au/Mo) were identified. It is found that the ranges of [23–100] for Au/Bi and [8–80] for Au/Mo are related to gold mineralization. Using the modeling of the reagent ratios probability graph and determining the exploratory threshold, significant parameters in gold mineralization were separated from insignificants. 相似文献
4.
Short-wave infrared (SWIR) reflectance spectroscopy was used to characterize hydrothermal minerals and map alteration zones
in the Tuwu Cu–Au deposit, Xinjiang, China. The Palaeozoic hydrothermal system at Tuwu is structurally controlled, developed
in andesitic volcanic rocks and minor porphyries. Hydrothermal alteration is characterized by horizontally zoned development
of quartz, sericite, chlorite, epidote, montmorillonite and kaolin about individual porphyry dykes and breccia zones, as is
shown by changes outward from a core of quartz veining and silicification, through an inner zone of sericite + chlorite to
a marginal zone of chlorite + epidote. The alteration system comprises several such zoning patterns. Silicification and sericitization
are spatially associated with Cu–Au mineralization. Zoning is also shown by compositional variations such that Fe-rich chlorite
and Al-rich sericite occur preferentially toward the core and the most intensely altered parts, whereas Mg-rich chlorite and
relatively Al-poor sericite are present on the margin and the relatively weakly altered parts of the hydrothermal alteration
system. The compositions of chlorite and sericite, therefore, can be potentially used as vectors to Cu–Au mineralization.
Montmorillonite and kaolinite, of probable weathering origin, are located near the surface, forming an argillic blanket overlying
Cu–Au mineralization. Sporadic montmorillonite is also present at depth in the hydrothermal alteration system, formed by descending
groundwater. Presence of a well-developed kaolinite-bearing zone on the surface is an indication of possible underlying Cu–Au
mineralization in this region. Epidote occurs widely in regional volcanic rocks, as well as in variably altered rocks on the
margin of the hydrothermal mineralization system at Tuwu. The widespread occurrence of epidote in volcanic country rocks probably
reflects a regional hydrothermal alteration event prior to the localized, porphyry intrusion-related hydrothermal process
that led to the Cu–Au mineralization at Tuwu. 相似文献
5.
甘肃李坝金矿围岩蚀变与金成矿关系 总被引：1，自引：0，他引：1
西秦岭地区是目前国内造山型和卡林型金矿找矿的热点地区之一,已发现的甘肃李坝造山型金矿为超大型规模。以李坝金矿6号矿带为例,系统地研究了其蚀变矿物组合、近矿围岩蚀变分带及相应的金矿化特征,总结了矿床(带)的蚀变分带模式。该模式具典型的中心式环带结构,可分为3个蚀变带,由中心向外依次为黄铁绢英岩化带、绢云母化带和绿泥石化带。蚀变矿物组合分别为黄铁矿+绢云母+石英±毒砂±白云母±电气石±方解石、绢云母+绿泥石+石英+黄铁矿±黑云母及绿泥石+黑云母±绢云母±黄铁矿;与这3个蚀变带相对应的是金的富集带、矿化带和无矿带。蚀变岩石物质组分迁移分析表明,围岩蚀变及其分带是热水流体/岩石反应时岩石化学组分发生迁移的结果,矿化伴随着蚀变发生,且金矿化与黄铁矿化和浸染状硅化关系最为密切。 相似文献
6.
岭壳铜(银-金)矿床赋存于白垩纪岭壳村组流纹质角砾凝灰熔岩和早白垩世花岗闪长岩中.目前已发现11条铜(银-金)矿(化)体,矿体的产出严格受断裂破碎带控制,与成矿关系密切的围岩蚀变呈现出自东(20线)向西的钾化→绢云母化→强高岭石化、绿泥石化蚀变分带,矿化相应呈现从铜(金)向铜(银)的过渡.根据其对称性的蚀变分带,应加强20线以东的地质找矿;根据成矿元素分形和统计研究发现,Au,Ag矿化具有专属性,即在流纹质凝灰熔岩中寻找Cu,Ag矿,而在花岗闪长岩中以寻找Cu,Au矿为主. 相似文献
7.
内蒙古东部二连浩特-乌兰浩特地区金矿化特征的初步研究 总被引：2，自引：0，他引：2
研究区属含古老地块并经中生代改造的中古生代造山带,存在金、锡等丰度较高的锡林浩特元古宙杂岩、古生代蛇绿岩及板块缝合带、二叠系火山岩、中生代伸展构造背景下的大规模火山-侵入活动及锡多金属成矿作用.本区金矿化类型主要有:韧性剪切带中的石英脉型、蚀变岩型金矿,产于幔源中基性侵入岩中的铜金矿,燕山晚期斑岩型铜金矿,与燕山期次火山岩浆活动有关的脉状铜矿床中的伴生金矿化,微细浸染型金矿化,浅成低温热液型金矿化等.研究区金矿成矿时代可分为242~229Ma、169~161.8Ma、132~159Ma (可能以130~140Ma为主)、127~109.2Ma四个区间.认识到存在印支期成矿、燕山期多阶段成矿等特点对于区内金矿勘查有重要意义.新发现7个矿床(点)的伴生金矿化.毛登、大井等多金属矿床的伴生金矿化具有重要的潜在工业意义. 相似文献
8.
9.
“煌斑岩”与金矿的实际观察与理论评述 总被引：17，自引：1，他引：16
新的分析资料和研究表明,Ｒｏｃｋ等人提出的煌斑岩中温热液金矿成因模式在理论上和实际上都存在明显的问题,根据金和铂族元素,铜等元素的地球化学相关性,可以鉴别出绝大多数金异常高的煌斑岩类岩石受到次生蚀变和金富集作用。一些钾玄岩类岩石与中温热液金矿时空上的密切共生,是由于两者形成的构造环境相同,扩大“煌斑岩”这个术语的运用及其所包含的岩石类型,容易造成岩石学分类的混乱,并给岩石学和经济地质学研究带来困扰 相似文献