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1.
《Journal of Geochemical Exploration》1997,58(1):1-14
Biogeochemistry has not been widely used as an exploration technique for Au in Western Australia because (1) sampling of soils and other surficial materials have been reasonably effective in finding new mineral deposits, and (2) it has been difficult to identify a consistent and regionally typical vegetation sample type. The potential of the technique has been tested at three sites in the goldfields of southern Western Australia. Vegetation and soil were analysed for Au from the Bounty (Mt Hope), Panglo and Zuleika Au deposits in the southern Yilgarn Craton. Gold concentrations in vegetation were generally lower at Panglo and Zuleika compared with Bounty, and probably reflect the depth to mineralization which is considerably greater at Panglo (40 m) and Zuleika (20 m) than at Bounty, where it is close to the surface. At Bounty, Au concentrations in dried vegetation varied from < 0.5 ppb in background areas to a maximum of 11 ppb (the highest for any area) over mineralization. In general, the association between Au concentrations in vegetation and mineralization is only weak although, at Zuleika, Maireana (bluebush) seemed a slightly better sample medium than soil for predicting the location of underlying mineralization.As the emphasis in exploration changes to more difficult terrains, the suitability of biogeochemistry needs to be re-examined. These preliminary results from Western Australia suggest that biogeochemistry may have some role to play in the search for deeply buried mineral deposits. 相似文献
2.
Geochemical anomaly separation and identification using the number–size (N–S) model at Bardaskan area, NE Iran is studied in this paper. Lithogeochemical data were used in this study which was conducted for the exploration for Au and Cu mineralization and enrichments in Bardaskan area. There are two major mineralization phases concluded epithermal gold and a disseminated systems. N–S log–log plots for Cu, Au, Sb, and As illustrated multifractal natures. Several anomalies at local scale were identified for Au (32 ppb), Cu (28 ppm), As (11 ppm), and Sb (0.8 ppm) and the obtained results suggest existence of local Au and Cu anomalies whose magnitudes generally are above 158 and 354 ppm, respectively. The most important mineralization events are responsible for presence of Au and Cu at grades above 1,778 and 8,912 ppm. The study reveals threshold values for Au and Cu are a consequence of the occurrence of anomalous accumulations of phyllic and silicification alteration zones and metamorphic rocks especially in tuffaceous sandstones and sericite schist types. The obtained results were correlated with fault distribution patterns, revealing a positive direct correlation between mineralization in anomalous areas and the faults present in the mineralized system. 相似文献
3.
At Norseman Au mineralization is hosted by parallel easterly dipping quartz reefs in a westerly dipping sequence of Archaean basaltic flows and As is strongly correlated with this mineralization. Near-surface exploration is hampered by an extensive cover of deeply weathered soils and a veneer of silty calcareous material, probably of aeolian origin, which, because of its low Fe content of < 5%, has a very low (< 10 ppm) and often indiscernible As signature over mineralization. At a test traverse over the southern end of the Mararoa quartz reef, drill sampling to 10 m depth in highly weathered in situ material beneath the calcareous veneer produced As anomalies which are strongly correlated with the extrapolation to surface of a shear zone hosting Au mineralization which is probably blind. The As anomalies can be extended into the surface horizon by manipulating the data to compensate for the low Fe content of the calcareous layer.The Au values in the drill samples were very low and poorly correlated with the extrapolation to surface of the Mararoa shear. However, the absence of a Au halo (at a 10 ppb detection limit) may be due to the shear being barren near surface, or may be due to the samples being taken from the strongly leached zones of a laterite profile. In the area of the test traverse at the southern Mararoa area, the upper horizons of the original laterite profile have been eroded away and the remaining horizons covered by a veneer of calcareous material. There is a better correlation of the Au values of the shallow drill samples with the projection to surface of a porphyry, which hosts minor low-grade Au mineralization.The results for Au dispersion around the Mararoa shear contrast with dispersion at the nearby Hinemoa Mine where gold mineralization crops out. Channel sampling in costeans showed that an Au anomaly (threshold 40 ppb) extends 50 to 150 m into oxidized wall rocks. This well defined halo may be due to the secondary dispersion of Au from the quartz reef into the ferruginous zone of the laterite profile.Gold in the leaves and twigs of Melaleuca pauperiflora F. Muell. from the traverse at the southern end of the Mararoa shear was determined by neutron activation analysis and found to be broadly correlated with the projected Au mineralization. However, the lack of correlation with the soil Au values to 10 m may be due to the plants taking up most of their water from below the depth of sampling. 相似文献
4.
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
5.
The Dest-Or epigenetic Au deposit occurs in a breccia zone within gabbro, basalt and andesite of the Archean Upper Deguisier Formation. It is located approximately 30 km NE of Noranda. Quebec and 2.5 km N of the Porcupine-Destor Fault, an important vertical shear zone that extends east-west for more than 100 km. The known orebody contains 2.44 Mt of ore at 4.29 g/t Au.Host rocks of the Upper Deguisier Formation typically contain 3.6 ppb Au, 0.8 ppm Sb and 4.5 ppm As. The Au values are comparable to those of tholeiitic mafic rocks elsewhere in the world. but Sb and As values are a little higher.Gold values on approximately 30% of the area of the Dest-Or and Bassignac properties define a log-normal distribution with a median at 9.4 ppb Au (P16 at 3.1 and P84 at 27). These are referred to as ore zone halos: they envelop orebody halos which in turn envelop orebodies.An orebody halo can best be defined by close sampling in the immediate vicinity of a known orebody. Around the Dest-Or orebody, this halo is approximately 100 m wide (60 m on the hanging wall and 40 m on the footwall), and it has a median value at 37 ppb Au (P16 at 17 and P84 at 74).Gold enrichment in the orebody is 1900 times background value. There are also lesser but significant Sb and As enrichments (20 /sX each). High W values occur in the ore ( > 30 ppm W), but background values were too low ( <5 ppm) to be established with confidence.Gold analyses in the 0.2–100 ppb range can be gainfully used in the search for blind gold ore deposits: As, Sb and W can also be used, but anomalies are less extensive and enrichment is also less pronounced. 相似文献
6.
Gold abundance in granitic rocks of different geological periods in southern China has been estimated. A review of the quantitative data available indicates that unaltered granitic rocks have a rather restricted range in gold content, rarely exceeding 4 ppb and generally ranging from 1.4 to 3.3 ppb. The mean gold content tends to decrease from basic to acidic granitoids. This tendency suggests that gold isnot concentrated in the residual silicate meltduring the formation of granitic rocks. It is necessary to establish the background values of gold for various rock types although it seems that gold abundance data for the granitic rocks of southern China can necessarily provide any geochemical clues or guides to areas favorable or unfavorable for gold mineralization. 相似文献
7.
Geochemical anomaly separation using the concentration–number (C–N) method at the Haftcheshmeh porphyry system in NW Iran is the aim of this study. We used lithogeochemical data sets to explore Cu, Mo, Au and Re mineralization in gabbroic, dioritic and monzonitic units at the Haftcheshmeh Cu–Mo porphyry system. The obtained results were interpreted using a rather extensive set of information available for each mineralized area, consisting of detailed geological mapping, structural interpretation and alteration data. Threshold values of elemental anomalies for the mineralized zone were computed and compared with the statistical methods based on the data obtained from chemical analyses of samples for the lithological units. Several anomalies at local scale were identified for Cu (40 ppm), Mo (12 ppm), Au (79 ppb), and Re (0.02 ppm), and the results suggest the existence of local Cu anomalies whose magnitude generally is above 500 ppm. The log–log plots show the existence of three stages of Cu and Mo enrichment, and two enrichment stages for Au and Re. The third and most important mineralization event is responsible for presence of Cu at grades above 159 ppm. The identified anomalies in Haftcheshmeh porphyry system, and distribution of the rock types, are mainly gabbrodiorite–monzodiorite, granodiorite and monzodiorite–diorite that have special correlation with Cu–Mo and gabbroic and monzonitic rocks, especially the gabbrodiorite–monzodiorite type, which is of considerable importance. The study shows that these elemental anomalous parts have been concentrated dominantly by potassic and phyllic, argillic and propylitic alterations within the gabbroic, monzonitic and dioritic rocks especially in the gabrodioritic type in certain parts of the area. The results, which were compared with fault distribution patterns, revealed a positive correlation between mineralization in anomalous areas and the faults present in the mineralized system. 相似文献
8.
This research paper aims to delineate and recognize different gold mineralization stages based on surface lithogeochemical data using factor analysis and Spectrum-Area (S-A) modeling, as well as geological data in Arabshah sedimentary rock hosted epithermal gold deposit, NW Iran. Based on the factor analysis, Au and Mn were allocated to factor 2 (F2) and then classified by the S-A fractal modeling. In addition, Au and F2 values were transformed to spectrum data, which were categorized by the S-A log-log plots. Accordingly, the main mineralization phase contains Au and F2 (Au-Mn) values greater than 800 ppb and 0.3, respectively, and is associated with the occurrence of minerals such as pyrite, arsenian pyrite, realgar, orpiment and oxidized sulfides. The first phase of gold mineralization, where Au typically ranges between 80 and 350 ppb, is associated with base metal sulfides, arsenian pyrites and F2 values between 0.1 and 0.2. The second gold mineralization phase consists of Au values from 350 to 800 ppb and F2 values between 0.2 and 0.3. Combination of the S-A modeling, factor analysis and geological data outlined three gold mineralization stages in Arabshah gold deposit. The main mineralization stage showed a strong positive correlation with the NE-SW and NW-SE trending structures, the altered intrusive rocks such as microdiorite and granodiorite, and the altered subvolcanic dacitic domes. 相似文献
9.
Gold concentrations have been determined by neutron activation in sixteen samples of komatiites and related rocks from Barberton, South Africa. All the rocks give Au values in the ranges 1–1.5 ppb with no evidence for anomalously high values in such old primitive igneous types. As the rocks are extensively hydrated, it is possible that Au has been leached from the rocks during later hydration processes. 相似文献
10.
H. Rolf Schmitt Eion M. Cameron Gwendy E.M. Hall Judy Vaive 《Journal of Geochemical Exploration》1993,48(3)
To be an effective indicator of mineralization in lake sediment surveys within the Canadian Shield, it is desirable that an element migrate in solution or adsorbed on suspensates. Given the low relief and disorganized drainage patterns of this region, dispersal in clastic form in drainage systems is limited and gives rise to erratic distributions. The purpose of this study was to discover whether Au shows significant hydromorphic mobility, which would justify the increasing use that is being made of this element in lake sediments as an indicator for gold mineralization.Waters and lake sediments were collected from Napier Lake, Ontario; PAP Lake, Saskatchewan; and Foster Lake, Manitoba, all of which contain Au-quartz vein mineralization and lie within the glaciated boreal forest zone of the Canadian Shield. In all three areas, profundal lake sediments down-drainage of mineralization contain Au concentrations higher than regional mean concentrations. Significant dissolution and transport of Au was found under oxidizing conditions associated with waters with pH that varied from acid to alkaline. Waters from drill holes penetrating mineralization contain up to 401 ng L−1 Au (note; 1 ng L−1 is equivalent to 1 part per trillion, 10−12). Surface waters overlying or near mineralization collected from bogs, seeps, ponds and streams contain up to 13 ng L−1. The content of Au in lake waters is lower, with a maximum of 1.1 ng L−1. There is also a detectable quantity of Au present in suspensates. Two samples of particulates (> 1 μm) filtered from lake water have Au equivalent to 0.17 ng L−1 and 0.039 ng L−1. While the contents of Au present in solution or as suspensates in lake and stream water are relatively small, they are sufficient, if precipitated, to generate anomalies in lake sediments. Thus for Reservoir Lake, in the Foster Lake area, water from the principal stream entering the lake carries 0.3 ng L−1 Au. This provides an annual flux which far exceeds that required to generate the 7.3 ppb Au contained in profundal sediments of this lake; a content that is anomalous relative to the regional median content of < 1 ppb Au for lake sediments.Hydrogeochemical prospecting involving analysis for Au is one method for tracing the source of anomalous Au in lake sediments. Collection of 1 L samples without field treatment, followed by extraction of Au into MIBK, then analysis by graphite-furnace atomic absorption spectrophotometry, permits detection levels for Au of 0.5 ng L−1. This is below the contents of Au found in some waters from mineralized areas. A detection limit of 0.3 ng L−1 was obtained using larger water samples. 相似文献
11.
A biogeochemical orientation survey was carried out in the vicinity of an epithermal Au deposit in the Moisan Au–Ag mineralized area, Haenam district in Korea. The Au–Ag bearing quartz veins of the mine occur as narrow open-space fillings within Cretaceous silicic pyroclastics. The vein minerals consist mainly of quartz, sericite, pyrite, chalcopyrite, and galena, with some electrum and argentite. The main objectives of this study were to study the geochemical characteristics of rocks, soils and plants in this area, to investigate the spatial relationship between Au and associated elements in rock–soil–plant system, and to evaluate the applicability of biogeochemical prospecting for Au vein occurrences in Korea. Samples of rocks and soils, and leaves of three plant species (Japanese red pine — P. densiflora, oriental white oak — Q. aliena, Japanese mallotus — M. japonicus) were collected from the target mineralized area and control barren locations, and analyzed for trace elements by instrumental neutron activation analysis. Sampling lines were composed of one slope line which is almost parallel to the mineralized quartz-veins, and four transect lines spaced 100 m apart across the veins at 20 m sampling intervals. From the multi-element data of rock samples (n = 9), high values of Au (maximum 2030 ppb) are spatially related to Au–quartz veins. Soil samples (n = 61) collected from five sampling lines show higher values of Au (24–825 ppb) whereas soil samples from the control locations have lower values of Au (below 25 ppb). Many plant species collected from the vicinity of the veins have high Au contents compared with those at the control locations, but the ranges of Au values are variable among plant species. In a total of 128 samples of plant leaves, Q. aliena yielded Au values of 0.4 to 6.9 ppb, and M. japonicus 0.9 to 4.1 ppb. Gold contents in P. densiflora ranged from 0.1 to 5.6 ppb. Plant leaves from control areas show less than 1.6 ppb Au. The biological absorption coefficient (BAC) of Au in plants decreases in the order of Q. aliena > M. japonicus > P. densiflora. Based on the results of the study, Q. aliena appeared to be the best sampling media for biogeochemical prospecting of Au in the study area. 相似文献
12.
An orientation survey was conducted over the Quartz Mountain, Oregon, hot-spring type disseminated gold deposit to address three questions critical to successful exploration of the area: What is the relationship between bedrock geology and the trace-element content of trees and soils; do these relationships change seasonally; are these relationships similar in the two tree species which discontinuously blanket the area?Twig, needle and wood samples were collected four times during the year from both ponderosa pine (Pinus ponderosa) and white fir (Abies concolor). Soils were collected once. All samples were analyzed for Au and As and the wood samples were analyzed also for Sb.Arsenic was the best pathfinder element, having little analytical, spatial, or seasonal variation in the twig and needle samples. Anomalous levels were 150 μg/g (ppm) As in pine and 30 μg/g in fir. Gold showed analytical variation of 20–30%, sample duplicate variation up to 90%, spatial changes, and seasonal variation ranging from winter-summer background [10–20 ng/g (ppb) Au] to anomalies of 300–400 ng/g (ppb) Au in pine and 100 μg/g (ppb) Au in fir in the spring and fall. Antimony could not be completely evaluated as a pathfinder element because it was only determined in wood samples.Needles and twigs from both species proved to be viable sample media for exploration of the area. Wood was not a suitable medium because of low, erratic values, perhaps due in part to analytical technique. Needles had 2 to 20 times higher As concentrations than did twigs. Twigs had a slightly higher Au content [25 ng/g (ppb)] than did needles. The pine samples were higher in both elements than were the fir samples. The data, normalized by species, could be treated as one homogeneous data base.The soil Au and As data outlined the mineralization clearly with a central Au anomaly [100 ng/g (ppb) and greater] surrounded by As anomalies [100 μg/g (ppm) and greater] over a distance of 594 m. Neither spring nor fall tree Au anomalies were coincident with the soil Au anomaly. Consistent throughout the year, tree As anomalies coincided with the soil As anomalies, but covered a smaller area. Both the Au and As anomalies in trees appeared to be related to bedrock contact zones rather than to the soil the trees were growing in. 相似文献
13.
The geology of the Republic of Djibouti, in the SE Afar Triangle, is characterized by intense tectonic and bimodal volcanic activity that began as early as 25–30 Ma. Each magmatic event was accompanied by hydrothermal activity. Mineralization generally occurs as gold–silver bearing chalcedony veins and is associated with felsic volcanism. Eighty samples from mineralized hydrothermal chalcedony, quartz ± carbonate veins and breccias were studied from ten sites representing four major volcanic events that range in age from early Miocene to the present. The most recent veins are controlled by fractures at the edges of grabens established during the last 4 Myr. Gold in excess of 200 ppb is present in 30% of the samples, with values up to 16 ppm. Mineralogical compositions allowed us to identify different types of mineralization corresponding to different depths in the hydrothermal system: (1) surface and subsurface mineralization characterized by carbonate chimneys, gypsum, silica cap and quartz ± carbonate veins that are depleted in metals and Au; (2) shallow banded chalcedony ± adularia veins related to boiling that contain up to 16 ppm Au, occurring as native gold and electrum with pyrite, and tetradymite; (3) quartz veins with sulfides, and (4) epidote alteration in the deepest hydrothermal zones. Samples in which pyrite is enriched in As tend to have a high Au content. The association with bimodal volcanism, the occurrence of adularia and the native Au and electrum in banded chalcedony veins are typical of epithermal systems and confirm that this type of mineralization can occur in a young intracontinental rift system. 相似文献
14.
热泉热液系统金的成矿地球化学研究 总被引：2，自引：0，他引：2
通过腾冲热海、硝塘和藏中羊八井、羊应乡等高温热田内金矿化体地质、地球化学、水化学、微生物和有机质的调查及生物功能实验研究,阐述了热泉热液的金矿化作用和成矿效应。金矿化发生在沸腾面以上非平衡条件和溶解金不饱和且不稳定的水热流体中,金主要富集在非晶质到结晶质的硫化物相中。沸泉、汽泉和热泉流体在升流带和地表泉塘中有不同的成矿效应和特征矿化体,反映了多种成矿作用。证实微生物尤其是嗜热硫酸盐还原菌是热液流体氧化还原作用和金硫化物析沉的内在的动力学因素。 相似文献
15.
Gold deposits at El Sid are confined to hydrothermal quartz veins which contain pyrite, arsenopyrite, sphalerite and galena. These veins occur at the contact between granite and serpentinite and extend into the serpentinite through a thick zone of graphite schist. Gold occurs in the mineralized zone either as free gold in quartz gangue or dissolved in the sulfide minerals. Ore-microscopic study revealed that Au-bearing sulfides were deposited in two successive stages with early pyrite and arsenopyrite followed by sphalerite and galena. Gold was deposited during both stages, largely intergrown with sphalerite and filling microfractures in pyrite and arsenopyrite.Spectrochemical analyses of separated pyrite, arsenopyrite, sphalerite and galena showed that these sulfides have similar average Au contents. Pyrite is relatively depleted in Ag and Te. This suggests that native gold was deposited in the early stage of mineralization. Arsenopyrite and galena show relatively high concentrations of Te. They are also respectively rich in Au and Ag. Tellurides are, thus, expected to be deposited together with arsenopyrite and galena. 相似文献
16.
Control of Melt Structures on Cu-Au Mineralization in Basic-Ultrabasic Complexes of Northern China 总被引：1，自引：0，他引：1
YUAN Wanming Institute of High Energy Physics Chinese Academy of Sciences Beijing MO Xuanxue China University of Geoscienses Beijing 《《地质学报》英文版》2000,74(4):786-794
Based on systematic analyses of 72 samples of different basic-ultrabasic rocks, the present paper discusses the relationship between melt structure and Cu and Au mineralization. It is found that if the NBO/T, NBO, M2+, FeO and MgO values are relatively high and the T, M3+, Fe2O3 and CaO values are low the basic-ultrabasic melt will be favourable to Cu (Ni) mineralization, but if the former are low and the latter are high it is favourable to Au metallization. Cu ions occupy dominantly octahedra in basic-ultrabasic melt and the higher the NBO/T, NBO and M2+ values, the more the octahedra in the melt. Au element mainly takes the form of Au+ ions in basic-ultrabasic melt and the Au+ ions constitute tetrahedral sites together with Fe3+ ions. Therefore, low M2+ and high Fe3+, i.e. high oxygen fu-gacity, can promote the enrichment of Au+ ions and Au mineralization. Components NT (other than Au+), Al2O3 and SiO2 in basic-ultrabasic melt have no effect on metallogenetic species. As mentioned above, in relevant d 相似文献
17.
西藏甲马铜多金属矿床金的叠加成矿 总被引：2，自引：0，他引：2
甲马铜多金属矿床各类矿石中金含量普遍较高。层次主矿体中金主要以细小的自然金形式包裹于斑铜矿和黝铜矿中。矿区多底沟组大理岩（层状主矿体顶板）中的构造破碎带内有独立金矿（化）体产出。喜山期中酸性，酸性岩脉也有不同程度的金矿化。不同产状金矿化持征，矿石ω（Au)/ω（Ag)比值等综合分析后认为：甲马矿区存在两期金矿化，即燕山期海底喷流积成矿作用中的伴生金矿化和与喜山期岩浆作用密切相关的热液型金矿化。 相似文献
18.
19.
W.E. Stone J.H. Crocket M.E. Fleet M.S. Larson 《Journal of Geochemical Exploration》1996,56(3):237-263
PGE-rich disseminated zones with discrete platinum-group minerals (Pd, Pt and Rh mineral phases) have been discovered in three thick (80–130 m), differentiated (peridotite-gabbro) mafic-ultramafic flows of the Archean Abitibi greenstone belt, Ontario. Three mineralization zones (whole-rock ∑PGE + Au = up to 1000 ppb) occur along four stratigraphic cross sections through a 2 km strike-length of the Boston Creek Flow ferropicritic basalt. Their occurrence most strikingly correlates with lenticular-podiform concentrations of disseminated chalcopyrite (1 %) and clinopyroxene + interstitial magnetite-ilmenite intergrowths (15–20% oxide), high concentrations of related metals (3000 ppm Cu, 3000 ppm S, 1200 ppb Ag, and 1000 ppm V), strong PGE depletion in adjacent rocks and along strike, and lithological and textural complexity in the margins of the central gabbro-diorite layer. The mineralization zone (whole-rock Ir + Pt + Pd + Au = 110 ppb) within Theo's Flow tholeiitic basalt is somewhat similar in occurrence, style, and composition to those within the Boston Creek Flow. In contrast, the mineralization zone (whole-rock Ir + Pt + Pd + Au = 340 ppb) in Fred's Flow komatiitic basalt most strikingly correlates with vesicle-filling intergrowths of pyrrhotite + pentlandite ± chalcopyrite (2 modal %) and high whole-rock concentrations of Ni (2500 ppm), Cu (700 ppm), and S (1.1%) in the upper chilled margin of the flow.Although apparently uneconomic, these flow-hosted PGE mineralization zones are of interest in exploration, because they are more similar in stratigraphie setting, style, and composition to PGE-rich disseminated Fe-Cu sulfide mineralization zones within thick differentiated intrusions than to mineralization zones in other Archean volcanic rocks. The characteristics of the mineralization zones and their host rocks, especially high degrees of PGE enrichment, vertical and horizontal patterns of PGE depletion, and accumulation of clinopyroxene + magnetite-ilmenite intergrowths, indicate a critical genetic role for variations in the regime of melt flowage. The mineralization zones in the Boston Creek and Theo's Flows are interpreted to have formed by simultaneous in situ formation of PGE-rich Fe-Cu sulfide and Fe-Ti oxide from flowing silicate liquid in the margins of internal lava channels. The mineralization zone in Fred's Flow is interpreted to have formed by ponding and coalescence of PGE-enriched sulfurous vapor bubbles in the upper chilled margin during olivine accumulation on the base of a dynamic lava channel. The relative abundance of PGE mineralization zones and high degree of PGE enrichment in the Boston Creek Flow suggest that the most favorable exploration targets are rocks crystallized from late-stage, highly fractionated derivative liquids in large differentiated terropicritic units. 相似文献
20.
《Journal of Geochemical Exploration》2004,84(1):3-20
The Chinkuashih is a group of dacite-related hydrothermal enargite-gold deposits of the Quaternary age, which produced 94 tons of gold and 119,101 tons of copper from 1895 to 1987. It has remaining reserves of 656 tons of gold with an average grade range of 1.5–3.5 g/ton of Au for all orebodies discovered.Mercury content in different media such as stream sediments, heavy minerals in stream sediments, soils, rocks/ores, and pyrite samples was analyzed by a gold–film mercury detector to evaluate whether mercury is a good pathfinder for these types of deposits at Chinkuashih. The gold film technique is more rapid and cheaper than the traditional fire assay or fire assay/ICP-MS gold and trace element analyses.Mercury in stream sediments and soils indicated the border zone of gold mineralization 12 km away from the center of mineralization at Chinkuashih. Mercury in heavy minerals of the stream sediments distinguished the intermediate zone with gold veins and gold/gold–copper breccia pipes from the core or inner zone with the gold–copper zone. It has been found that contours of 1000 or 500 ppb Hg of soil samples can delineate the outcropping gold orebodies. The gold ores generally contain 1000 ppb or more Hg. 相似文献