Lead-zinc Deposits Research Articles

Metallogenic Model and Prospecting Progress of the Qiandongshan–Dongtangzi Large Pb-Zn Deposit, Fengtai Orefield, West Qinling Orogeny

The Qiandongshan–Dongtangzi large Pb-Zn deposit is located in the Fengxian–Taibai (abbr. Fengtai) polymetallic orefield. The ore bodies primarily occur within and around the contact surface between the limestone of the Gudaoling Formation and the phyllite of the Xinghongpu Formation, which are clearly controlled by anticline and specific lithohorizon. Magmatic rocks are well developed in the mining area, consisting mainly of granitoid plutons and mafic–felsic dikes. Previous metallogenic geochronology studies have yielded a narrow range of ages between 226 and 211 Ma, overlapped by the extensive magmatism during the Late Triassic period in this region. The ω(Co)/ω(Ni) ratio of pyrite in lead–zinc ore ranges from 4.44 to 15.57 (avg. 8.56), implying that its genesis is probably related to volcanic and magmatic-hydrothermal fluids. The δD and δ18O values (ranging from −94.2‰ to −82‰, and 18.89‰ to 20.72‰, respectively,) of the ore-bearing quartz indicate that the fluids were perhaps derived from a magmatic source. The δ34S values of ore-related sulfides display a relatively narrow range of 4.29‰ to 9.63‰ and less than 10‰, resembling those of magmatic-hydrothermal origin Pb-Zn deposits. The Pb isotopic composition of the sulfides from the Qiandongshan–Dongtangzi Pb-Zn deposit (with 206Pb/204Pb ratios of 18.06 to 18.14, the 207Pb/204Pb ratios of 15.61 to 15.71, and 208Pb/204Pb ratios of 38.15 to 38.50) is similar to that of the Late Triassic Xiba granite pluton, suggesting that they share the same Pb source. The contents of W, Mo, As, Sb, Hg, Bi, Cd, and other elements associated with magmatic-hydrothermal fluids are high in lead–zinc ores, and the contents of Sn, W, Co, and Ni are also enriched in sphalerite. The contents of trace elements and rare earth elements in the ore are similar to those in the Xiba granite pluton, and they maybe propose a magmatic-hydrothermal origin as well. As a result of this information, the Qiandongshan–Dongtangzi large Pb-Zn deposit may be classified as a magmatic hydrothermal stratabound type, with the Si/Ca contact area being the ore-forming structural plane. Thus, a mineralization model has been proposed based on a comparative analysis of the geological and geochemical properties of the lead–zinc deposit in the Fengtai orefield. It is considered that the secondary anticlines developed on both wings of the Qiandongshan–Dongtangzi composite anticline are the favorable sites for Pb-Zn deposition. Accordingly, the Si/Ca plane and secondary anticline are the major ore-controlling factors and prospecting targets. The verification project was first set up on the north wing of the composite anticline, and thick lead–zinc ore bodies were found in all verification boreholes, accumulating successful experience for deep exploration of lead–zinc deposits in this region.

Application of Spectral Analysis and Image Processing Methods to Discriminate Hydrothermal Alteration Minerals Around the Tutakdağı (Şebinkarahisar-Giresun) Lead–Zinc Deposits, Northeastern Turkey

Application of Spectral Analysis and Image Processing Methods to Discriminate Hydrothermal Alteration Minerals Around the Tutakdağı (Şebinkarahisar-Giresun) Lead–Zinc Deposits, Northeastern Turkey

One-dimensional convolutional neural network for mapping mineral prospectivity: A case study in Changba ore concentration area, Gansu Province

Predictive modeling of mineral prospects is a critical but challenging procedure for delineating undiscovered prospective targets in mineral exploration. In the present study, the one-dimensional convolutional neural network (1D CNN) was utilized for mineral prospectivity mapping (MPM). Local singularity analysis and deposit buffer analysis were used to determine the unfavorable metallogenic regions, and random points were taken as negative samples. Synthetic minority over-sampling technique (SMOTE) was used to generate the training data to enhance the generalization ability of the model. The effects of different hyperparameters on classification performance in 1D CNN were studied and the optimal combination of hyperparameters was determined. The average classification accuracy of this model was 96.2%, and the standard deviation was 2.14%, indicating that the model constructed by this hyperparameter set was robust. On this basis, the geochemical data of 19 elements were used as the input characteristic variable, and the prospecting prospect of lead–zinc deposits in Changba ore concentration area was predicted based on 1D CNN. The results showed that the prospectivity map of lead–zinc deposits generated by the 1D CNN model can effectively link the multivariate geochemical data with the known positions of lead–zinc deposits and greatly increase the precision of the potential exploration areas for lead–zinc deposits.

Genesis of the Giant Huoshaoyun Non-Sulfide Zinc–Lead Deposit in Karakoram, Xinjiang: Constraints from Mineralogy and Trace Element Geochemistry

The Huoshaoyun zinc–lead deposit, a giant non-sulfide deposit in Xinjiang, is one of the most significant discoveries of zinc–lead deposit in China and globally in recent years. The deposit is dominated by zinc–lead non-sulfides, with minor occurrences of sulfides such as sphalerite, galena, and pyrite. The non-sulfide minerals include smithsonite, cerussite, anglesite, and Fe-oxide. This study focuses on the mineralogical characteristics of sulfide and non-sulfide ores, as well as the trace element characteristics of sphalerite, smithsonite, and Fe-oxide. Mineralogical analysis reveals that smithsonite is derived from the oxidation of primary sulfide minerals and can be classified into three types that are generated during different stages of supergene oxidation. The three types of smithsonite are formed through replacing the sphalerite and host limestone, as well as directly precipitating in the fissures and vugs. Trace element analysis of sphalerite indicates that it is rich in Cd, Tl, and Ge, but poor in Fe and Mn. The ore-forming temperature, calculated using the GGIMFis geothermometer, is mostly within the range of 100~150 °C. Moreover, the trace element characteristics, ore-forming temperature, and S and Pb isotope compositions of the sulfide ores of the Huoshaoyun deposit are similar to those of the Jinding and Duocaima MVT lead–zinc deposits, which are also located in the Eastern Tethyan zinc–lead belt. This suggests that the sulfide orebody in the Huoshaoyun Zn-Pb deposit could also be the MVT deposit. Study of the trace element of the non-sulfide minerals shows that the Mn and Cd are relatively enriched in smithsonite, while Ga, Ge, and Pb are enriched in Fe-oxide. This can be attributed to distinct geochemical properties of the trace elements in the non-sulfide minerals of the Huoshaoyun deposit and is consistent with those of the other oxidized MVT deposits, thus indicating the supergene oxidation process of this deposit.

Problems of the genesis of ore deposits of the Ozerninsky polymetallic ore cluster (western Transbaikalian region, Russia)

The Ozerninsky ore cluster is a unique geological megastructure in terms of the concentration of rich and diverse mineralization. More than 20 deposits of lead, zinc, iron, copper, barite, and gold are concentrated here, including the Ozernoye polymetallic deposit, the largest in Russia in terms of the zinc reserve. Our studies have shown that many morphological features of the ores of this deposit, which most researchers assign to the hydrothermal-sedimentary type, are ambiguous; some signs of a metasomatic origin of the sulfide mineralization are observed. Along with lead-zinc deposits, complex gold-polymetallic, iron-oxide (hematite-magnetite), and copper-barite deposits are known within the Ozerninsky ore cluster, the origin of which remains debatable. Due to the wide distribution of exogenous gold deposits, there exists a need to assess the gold content of various types of the endogenous ore mineralization as potential sources of the precious metals. Despite the rather long period of studies of the Ozerninsky ore cluster (more than half a century), many questions related to ratios of the different mineralization types, the age, genesis of the ores, and geodynamic settings of formation of the deposits are still the subject of discussion. Solution of these issues requires more detailed geochronological and lithological-stratigraphic investigations conducted in combination with studying the mineral composition of the ores, their isotope-geochemical characteristics, and the physico-chemical formation conditions.

Active ages of metallogenic structures in the Liangyan lead–zinc deposit, northwestern Guizhou: Constraints from geometric, kinematic, and sphalerite Rb-Sr dating analyses

More than ten lead–zinc deposits formed under the control of the Yadu-Mangdong fault (YMF) are known to have undergone multi-stage activity. However, ore control processes in such fault zones are poorly understood, such as in the Liangyan deposit in northwestern Guizhou. The internal geometrical structure, mineralization, alteration, tectonic stress, and kinematics of the YMF were investigated in three sections (1605, 1655, and 1720) of the Liangyan deposit. The ore-forming age (214.8 ± 4.3 Ma) was obtained by rubidium-strontium dating of sphalerite. The YMF is defined by double-fault cores and superimposed faults that indicate at least three stages of deformation since the mineralization period. The first stage is characterized by the ore-bearing dolomitization ancient fault core formed in the Indosinian period. The principal compressive stress direction was northwest to southeast (NW-SE). The second stage of Yanshanian was the tectonic breccia fault stage (new fault core). The principal compressive stress was northeast to southwest (NE-SW). The third stage was dominated by superposed faults that destroyed the new fault core in the Himalayan period. The principal compressive stress direction was east to west (E-W). In summary, we established a model of evolution for the YMF since the metallogenic period. In conclusion, based on the above research, we consider that the YMF turning point of the Liangyan deposit is prone to orebodies. Additionally, the prospecting target should be concentrated in the footwall (NW-trending) and hanging wall (NE-trending) of the Liangyan deposit YMF model.

Genesis of the carbonate-hosted zinc–lead deposits in the southwestern Yangtze Craton, SW China: Insights from the Maoping deposit

The southwestern Yangtze Craton represents one of the world's largest zinc–lead provinces and contains over 26 million tons of zinc–lead resources. It comprises more than four hundred carbonate-hosted zinc–lead deposits with various sizes; however, genesis of the deposits has long been debated and still remains controversial, due to a lack of comprehensive understanding on the geology and metallogeny. Located in the north of the area, the giant Maoping zinc–lead deposit (Zn + Pb: 3 Mt @ 10–30 wt%) provides an ideal objective to illustrate this issue. In this paper, we conduct detailed field geological investigation at Maoping and present new in situ LA–ICP–MS data of sulfur and lead isotopes and trace elements from 25 sulfide samples. The δ34S values of the sulfides vary from −22.8 ‰ to +22.5 ‰, and the ratios of 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb of the sulfides vary in ranges of 18.247–18.767, 15.712–15.768, and 38.548–39.435, respectively. Combined with previous studies, we interpret that reduced sulfur is likely sourced from marine sulfates in the carbonate of the Upper Devonian Zaige Formation, and ore metals are mainly derived from the Neoproterozoic basement and the Zaige Formation carbonate. Titanium, Cr, Mn, Co, Ni, Cu, Zn, Ge, As, Se, Ag, Cd, Sb, and Pb are enriched in pyrite within the Maoping deposit, and low abundances of Co and Ni (0.01 × 10−6–21.09 × 10−6) and low Co/Ni ratios (0.04–4.95) in pyrite constrain its low-temperature hydrothermal origin. New geological and geochemical data demonstrate that geology, mineralization, and geochemistry of the Maoping deposit coincide with those of the Mississippi-Valley type (MVT) deposits worldwide. Together with previous studies, we suggest that genesis of the carbonate-hosted zinc–lead deposits in the southwestern Yangtze Craton resemble the MVT deposits.

Thermometric and chemical studies of fluid inclusions in sphalerite from Rhodope lead-zinc deposits: Shumachevski Dol – Gyudyurska (Madan District) and Kenan Dere (Laki District), Bulgaria

The objects of this study are fluid inclusions in sphalerite crystals or selected parts of them from two Central Rhodopean deposits: Shumachevski Dol – Gyudyurska (Madan District) and Kenan Dere (Laki District). A set of data for temperature of homogenization and total salinity are presented. The locations of coupled data in coordinates Th vs total salinity reveal that the Kenan Dere sphalerite has been deposited from solutions of higher temperature (280–374 °C) and lower salinity (2–5 wt.% NaCl-eqv.). Conversely, the Shumachevski Dol and Gyudyurska sphalerites show lower Th = 200–230 °C and somewhat higher salinity (S = 6–12 wt.% NaCl-eqv.). Furthermore, it is likely that both late Kenan Dere and Gyudyurska sphalerites were deposited at 30–50 °C lower temperatures than the earlier ones. Additionally, Decrepitation Inductively-Coupled-Plasma Atomic-Emission-Spectrometry was applied to determine the cations in the inclusion solute. The vacuum decrepitation was also used for liberating the volatiles (H2O, CO2) and analysing them by mass spectrometry. On that account, more detailed preliminary studies of the process of decrepitation were performed. However, the Zn-concentration in sphalerite-hosted fluid inclusions cannot be evaluated and the results from syngenetic quartz offer the only possibility for obtaining information about ore-element content. On the basis of a compilation of both present and previously published data, it can be concluded that the hydrothermal fluid under the Central Rhodope Dome was constituted in situ as a closed system at a depth of ~1 km, under nearly lithostatic pressure (~200 bars), T ≥ 350 °C, and NaCl-dominated salt content ~10%. Under these conditions, a solution with a pH of ~4.0–4.5 contains ore elements (Fe, Zn, Pb) as soluble chlorido-complexes; for Zn, the total concentration may reach 1 wt.%. Sulphide-S compound under these conditions is H2S. The sphalerite deposition follows a reverse path of the chemical reactions. The elevation of the hydrothermal fluid along the extensional dislocations results in boiling (i.e., separation of CO2) and cooling. The temperature decrease destabilizes the chlorido-complexes and leads to an increase in the Zn2+ activity. On the other hand, CO2 loss enhances pH, and thus dissociates H2S, yielding HS- and S2- ions, needed for sphalerite deposition.

Genesis and Prospect Evaluation of Sinongduo Skarn Type Lead-zinc Deposit in Tibet

Tibet Sinongduo lead-zinc mine is one of the largest lead-zinc mines in Tibet Autonomous Region, located in Gongjue County, Changdu City, Tibet Autonomous Region. The deposit mainly produces lead, zinc and other metal elements, which is one of the important metal resources in Tibet. This paper mainly introduces the geological characteristics, ore body characteristics, ore types and wall rock alteration of the Sinongduo lead-zinc deposit in Tibet, further analyzes the genesis of the deposit in the region, sorts out the prospecting indicators in the region, and makes a prospect prediction. It is found that there is a prospect of expanding the scale of the deposit in the deep, southern and northern abnormal areas of the No.1 ore belt in the mining area.

Structural and geochemical constraints on the genesis of the Kuangshanchang carbonate-hosted zinc–lead deposit, Huize district, southwestern Yangtze Craton

Structural and geochemical constraints on the genesis of the Kuangshanchang carbonate-hosted zinc–lead deposit, Huize district, southwestern Yangtze Craton

Enrichment Characteristics, Source Apportionment, and Risk Assessment of Heavy Metals in the Industrial and Mining Area of Northern Guangdong Province

In order to understand the heavy metal pollution of the industrial and mining area in northern Guangdong Province, topsoil samples (0-20 cm) from 209 sites in study area were collected, and the concentrations of As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn were analyzed. The source and distribution characteristics of Cd, Cr, Hg, Ni, Pb, As, Cu, and Zn in soil samples were analyzed using the geographic information system (GIS) and principal component analysis (PCA), and the geo-accumulation index and potential ecological hazard index were used to evaluate their pollution status and ecological risk. The results showed that:① Except Ni, all seven heavy metal elements exceeded the national soil background value but were below the pollution risk screening value. The soil environment as a whole was relatively clean. ② The spatial distribution of heavy metals in soil differed. The contents of As and Pb showed northwest-southeast zonal distribution. The contents of Cd, Cu, Hg, and Zn generally decreased from the middle to the surrounding, which was consistent with the industrial and mining enterprise locations. However, the spatial distribution of Cr and Ni had no direct relationship with the location of pollution sources such as industrial enterprises. ③ The eight heavy metals could be identified as three principal components (PCs). PC1 (Cd, Cu, Pb, and Zn) was mainly affected by human activities such as lead-zinc deposit dressing, traffic emissions, and agricultural production. However, PC2 (Cr and Ni) was a natural source, mainly affected by soil parent material. In addition, PC3 (As and Hg) was mainly affected by industrial activities such as non-ferrous metal smelting and thermal power generation. ④ According to the geo-accumulation index method, the risk degree of the eight heavy metals was:Cd>As>Zn>Hg>Pb>Cu>Cr=Ni. The contents of Cr and Ni in soil were at a no-risk level; the contents of As, Cu, Hg, Pb, and Zn were at a low-risk level; and the content of Cd was at a high-risk level. Most potential ecological hazards for single elements in the study area were at a mild risk level. In contrast, a small proportion of the surface soils in areas of intense industrial activity were subject to substantial levels of heavy metal stress and require further attention.

Pore Variation Characteristics of Altered Wall Rocks in the Huize Lead–Zinc Deposit, Yunnan, China and Their Geological Significance

The porosity and permeability of the rock surrounding lead–zinc deposits are key factors for controlling the migration and precipitation of ore-forming hydrothermal fluid. In this paper, the Huize super-large lead–zinc deposit was taken as the case study, and variations in the porosity and permeability of the wall rocks and their relationship with the orebody were analyzed by using CT scanning technology. The experimental results showed that the average pore radius of dolomite with a decreasing distance to the orebody ranged from 1.60 to 1.65 μm, increasing to 1.77~2.05 μm. The CT porosity increased from 2.76%–2.81% to 3.35%–3.99%. The average pore throat length decreased from 29.57–39.95 μm to 13.57–16.83 μm. In the research, it was found that the hydrothermal fluids rich in chemical elements changed the properties of the surrounding rocks. Temperature rise will lead to dolomitization of limestone and recrystallization of dolomite. This process led to an increase in the porosity of the wall rocks. During the formation of the orebody, the metal minerals in the hydrothermal fluid entered the pores of the rock. As a result, the pore radius and pore volume of the wall rocks were reduced, along with the pore throat radius and pore throat length. Therefore, the wall rock pores near the orebody were isolated from each other, and the permeability of the surrounding rock decreased. The variation characteristics for the porosity and permeability of the dolomite at various distances from the mine can be used to discover orebodies.

Discrimination of Pb-Zn deposit types using sphalerite geochemistry: New insights from machine learning algorithm

Due to the combined influences such as ore-forming temperature, fluid and metal sources, sphalerite tends to incorporate diverse contents of trace elements during the formation of different types of Lead-zinc (Pb-Zn) deposits. Therefore, trace elements in sphalerite have long been utilized to distinguish Pb-Zn deposit types. However, previous discriminant diagrams usually contain two or three dimensions, which are limited to revealing the complicated interrelations between trace elements of sphalerite and the types of Pb-Zn deposits. In this study, we aim to prove that the sphalerite trace elements can be used to classify the Pb-Zn deposit types and extract key factors from sphalerite trace elements that can discriminate Pb-Zn deposit types using machine learning algorithms. A dataset of nearly 3600 sphalerite spot analyses from 95 Pb-Zn deposits worldwide determined by LA-ICP-MS was compiled from peer-reviewed publications, containing 12 elements (Mn, Fe, Co, Cu, Ga, Ge, Ag, Cd, In, Sn, Sb, and Pb) from 5 types, including Sedimentary Exhalative (SEDEX), Mississippi Valley Type (MVT), Volcanic Massive Sulfide (VMS), skarn, and epithermal deposits. Random Forests (RF) is applied to the data processing and the results show that trace elements of sphalerite can successfully discriminate different types of Pb-Zn deposits except for VMS deposits, most of which are falsely distinguished as skarn and epithermal types. To further discriminate VMS deposits, future studies could focus on enlarging the capacity of VMS deposits in datasets and applying other geological factors along with sphalerite trace elements when constructing the classification model. RF’s feature importance and permutation feature importance were adopted to evaluate the element significance for classification. Besides, a visualized tool, t-distributed stochastic neighbor embedding (t-SNE), was used to verify the results of both classification and evaluation. The results presented here show that Mn, Co, and Ge display significant impacts on classification of Pb-Zn deposits and In, Ga, Sn, Cd, and Fe also have relatively important effects compared to the rest elements, confirming that Pb-Zn deposits discrimination is mainly controlled by multi-elements in sphalerite. Our study hence shows that machine learning algorithm can provide new insights into conventional geochemical analyses, inspiring future research on constructing classification models of mineral deposits using mineral geochemistry data.

Geological features and genesis of the Dyusembay Central (Sayakhat) ore deposit

The article considers the geological features and ore composition of the Dyusembay Central (Sayakhat) leadzinc deposit in the Karsakpai metallogenic complex in the Central Kazakhstan. Historically, the complex was considered industrially significant in terms of iron ores, rather than of lead, zinc, and copper. It is shown that the ore deposit is composed of tuffaceous, silty-sandstone, carbonaceous-terrigenous (ore-hosting), terrigenous, and volcanogenic rocks assigned to the lower subformation of the Zhilandysai Formation of the Upper Proterozoic. The subvolcanic rocks identified and outlined in the area of the ore deposit belong to vent volcanic facies and are represented by felsic automagmatic breccias. All the rock complexes developed within the deposit have undergone multiple alterations: the regional, postvolcanic, contact, and hydrothermal (near-ore) ones. Commercial ores are represented by veinlet-disseminated sulfide mineralization in carbonaceous mudstones and silty sandstones, regionally and metasomatically altered to varying degrees. The ore bodies are composed of heterogeneous mineral assemblages corresponding to various stages and phases of the ore formation. The composition and structural and textural features of the ores reflect the long and complicated history of their formation. It is concluded that this ore deposit belongs to a new formational type of veinlet-disseminated stratified lead-zinc deposits localized in black shale sequences, with a significant role of volcanic activity and regional metamorphism, and is a remobilized SEDEX-type ore deposit.

Structural controls on the Bonsucesso Zinc-Lead Deposit, Vazante Group, Brazil

Structural controls on the Bonsucesso Zinc-Lead Deposit, Vazante Group, Brazil

ПОРІВНЯЛЬНА ХАРАКТЕРИСТИКА ГЕОЛОГІЧНОЇ БУДОВИ І СВИНЦЕВО-ЦИНКОВОЇ МІНЕРАЛІЗАЦІЇ УСПЕНСЬКОГО (ЦЕНТРАЛЬНИЙ КАЗАХСТАН) І БЕРЕГІВСЬКОГО (ЗАКАРПАТТЯ) РУДНИХ РАЙОНІВ

The purpose of the article is to conduct a comparative description of the Uspensky in Central Kazakhstan and Beregivsky in Transcarpathian ore regions in order to clarify the factors and criteria for lead-zinc mineralization, patterns of location, formation and localization of polymetallic deposits. The study used general geological methods of research, in particular, methods of geological survey, prospecting and exploration of deposits, a comparative analysis of areas with different geological structures, etc. As a result, it was found that the main factors of polymetallic mineralization are structural, lithological-stratigraphic, magmatic and metasomatic, manifested at different levels of organization of ore matter, at different times, in different geological and structural conditions. The scientific novelty lies in the fact that the conducted studies allow us to recommend the findings regarding the factors and criteria of polymetallic mineralization as scientific and methodological foundations for forecasting and prospecting for leadzinc deposits in other regions of the world, including Ukraine. The practical significance lies in the fact that the new data obtained on the Atasu type of deposits in Kazakhstan allow us to successfully solve many issues of the genesis of such polymetallic deposits, show their relationship and patterns of formation in connection with submarine volcanic activity. These data, in their significance, undoubtedly go far beyond the limits of the Uspensky belt and Central Kazakhstan and are close to other materials of polymetallic deposits of the world.

Zinc on the edge—isotopic and geophysical evidence that cratonic edges control world-class shale-hosted zinc-lead deposits

The North Australian Zinc Belt is the largest zinc-lead province in the world, containing three of the ten largest known individual deposits (HYC, Hilton-George Fisher, and Mount Isa). The Northern Cordillera in North America is the second largest zinc-lead province, containing a further two of the world’s top ten deposits (Red Dog and Howards Pass). Despite this world-class endowment, exploration in both mineral provinces during the past 2 decades has not been particularly successful, yielding only two significant discoveries (Teena, Australia, and Boundary, Canada). One of the most important aspects of exploration is to choose mineral provinces and districts within geological belts that have the greatest potential for discovery. Here, we present results from these two zinc belts that highlight previously unused datasets for area selection and targeting. Lead isotope mapping using analyses of mineralized material has identified gradients in μ (238U/204Pb) that coincide closely with many major deposits. Locations of these deposits also coincide with a gradient in the depth of the lithosphere-asthenosphere boundary determined from calibrated surface wave tomography models converted to temperature. Furthermore, gradients in upward-continued gravity anomalies and a step in Moho depth correspond to a pre-existing major crustal boundary in both zinc belts. A spatial association of deposits with a linear mid- to lower-crustal resistivity anomaly from magnetotelluric data is also observed in the North Australian Zinc Belt. The change from thicker to thinner lithosphere is interpreted to localize prospective basins for zinc-lead mineralization and to control the gradient in lead isotope and geophysical data. These data, when combined with data indicative of paleoenvironment and changes in plate motion at the time of mineralization, provide new exploration criteria that can be used to identify prospective mineralized basins and define the most favorable parts of these basins.

Audio Magnetotellurics Study of the Geoelectric Structure across the Zhugongtang Giant Lead–Zinc Deposit, NW Guizhou Province, China

Non-invasive geophysical exploration methods a play key role in the exploration of ore deposits. In the present study, the audio-frequency magnetotelluric (AMT) method was applied to metallic mineral exploration. The metallic mineral deposit targeted was the recently discovered super large lead–zinc deposit of the Zhugongtang mining area of Hezhang County in the northwestern Guizhou province in China. The main objectives of this study were to estimate the geoelectric strike and generate geoelectric models that estimate both the depth and distribution of resistivity structures across the deposit. To achieve the objectives, we deployed sixty-one (61) AMT survey sites with an interstation separation of 20 m on a 1280 m survey track perpendicular to the geological strike across the Zhugongtang deposit. We operated in fifty-three (53) frequencies in the range 1–10,400 Hz to record the resistivity distribution of subsurface to a depth of more than 1200 m. The results from the AMT data computations estimated the geoelectric strike that varies between NE285° and NE315°. This range of strikes suggested that structures across the deposit are oriented in the NW–SE direction. Obtained two-dimensional (2D) models elucidated a remarkably low resistivity body (<15 Ωm) at an elevation of less than 1600 m above sea level (>0.50 km depth), thus extending to great depth and were interpreted as lead–zinc mineralization. Furthermore, low resistivity (<63 Ωm) features were imaged both in superficial and deeper depths and interpreted as shale, sandstone, claystone, and silty mudstone units. Dolomite and limestone lithologies were found widely distributed with high resistivity (>1000 Ωm). Bioclastic limestone and dolomite limestone were inferred and characterized by moderate-high resistivity (>250 Ωm) and were not widely distributed. A unit of basalts was found with moderate resistivity (>63 Ωm). In addition, it was also found that regions with high number of faults tend to have low resistivity values compared to regions with a low fault number. In summary, this case study presents the results of applying an AMT approach to explore the conductivity characteristics of structures across the Zhugongtang deposit. The findings may contribute to the literature about this deposit.

Relationship between bitumen and zinc–lead mineralization in the Nanmushu zinc–lead deposit, northern margin of Sichuan Basin, China

Relationship between bitumen and zinc–lead mineralization in the Nanmushu zinc–lead deposit, northern margin of Sichuan Basin, China

The roles of hydrocarbons on the mineralization of Carlin-type gold deposits, Nanpanjiang Basin, South China

The spatial association of hydrocarbons with metalliferous ore deposits, like MVT lead–zinc deposits, sandstone uranium deposits and various type gold deposits (epithermal Au-Ag (-Hg) deposits, orogenic gold deposits and Carlin-type gold deposits) is found worldwide. However, the genetic relationship between hydrocarbon evolution and mineralization is still under controversy. Integrating isotope dates related to timing of petroleum evolution and gold mineralization from published data, as well as high-resolution transmission electron microscopy (TEM) analysis of pyrobitumen, electron probe microanalysis (EPMA) on both pyrobitumen and pyrite, the In-situ S isotope analyses of the gold-bearing pyrite in this study, we consider different type hydrocarbons (liquid oil and gas) played different roles on the mineralization of Carlin type gold deposits. As the residue of liquid oil cracking, the widespread high maturity pyrobitumen within the reservoir indicate both oil and gas has ever accumulated in the Nanpanjiang Basin. The high gold abundance (EPMA: ∼120 ppm; TEM: ∼1500 ppm) within the pyrobitumen in agreement with the metal solubility experiment suggest liquid oils could have acted as gold carrier before metal precipitation. The late Triassic timing overlapping between gas generation and gold mineralization and the δ34S features with gold bearing pyrite ∼ 10 ‰ lighter than the coeval seawater sulfate indicate gas dominated TSR process may play an important role on the supply of gold bisulfide complex (Au(HS)2−) in the ore-forming fluid and directly involved the precipitation of the Carlin-type gold deposit.