Search

Identifying magma fertility is an important task in ore genesis research. In this paper, we use apatite chemistry and Sr-Nd isotopes for such a study. The apatite crystals are from four Cretaceous coeval granodiorite intrusions with different styles of hydrothermal mineralization in the Tongling ore district, South China. The selected intrusions are Hucun, Dongguashan, and Xinwuli, which host both porphyry and skarn Cu deposits, and the Chaoshan, which hosts a skarn Au deposit. The abundances of apatite major and trace elements, such as Mn, V, Ce, S, F, Cl, and Cu, together with the whole-rock compositions, are used to decipher the oxidation states, volatile compositions, and Cu fertility of the parental magmas. The apatite Sr-Nd isotope compositions are used as tracers for the magma sources. The results show that: (1) the parental magma of the Au-mineralized intrusion is less oxidized and has higher S-Cl contents than those of the Cu-mineralized intrusions, and (2) the proportion of mantle-derived melt is much higher in the former than in the latter. The results also reveal that the Cumineralized intrusions have highly variable apatite Cu-Cl-S compositions. Specifically, the Xinwuli intrusion has much higher Cu but lower Cl-S contents in apatite than the other two intrusions, indicating that a Cu-rich magma is not universally required for the formation of hydrothermal Cu deposits. This study demonstrates that apatite is a robust petrogenetic and metallogenic indicator for porphyry and skarn-type Cu-Au ore deposits.

The Jinding deposit in the Lanping basin, southwest China, is the largest sandstone-hosted Zn deposit in the world and the second largest Zn-Pb deposit in China. However, questions related to the metal compositions and origin of the ore fluids remain. In this study, microthermometry and laser ablation-inductively coupled plasmamass spectrometry (LA-ICP-MS) were employed to determine the properties and compositions of individual fluid inclusions trapped in sphalerite and calcite. The results show that the fluid inclusions trapped in sphalerite and calcite have similar homogenization temperatures (79°–173°C with the majority 100°–130°C), salinities (10.3–29.1 wt % NaCl + CaCl2 equiv with the majority 24.5–27.4 wt % NaCl + CaCl2 equiv), and concentrations of alkali and alkali earth elements (e.g., Na, Ca, Mg, K, Sr, Ba, Li, Rb, and Cs). However, the concentrations of ore and associated metals (e.g., Pb, Sb, Ag, and Tl) in the fluid inclusions hosted by sphalerite are significantly higher than those hosted by calcite. Based on these observations, we propose that the sulfides including sphalerite were precipitated from a low-temperature, high-salinity, Ca-rich, metal-rich fluid, while the gangue minerals such as calcite crystallized subsequently from fluids depleted in metals due to prior precipitation of sulfides, and that the high salinities of the fluid inclusions are likely due to a combination of seawater evaporation and subsequent dissolution of evaporitic sequences during fluid percolation. The LA-ICP-MS analyses reveal that the fluid inclusions have K/Na, Rb/Na, and Cs/Na ratios within the range of modern basinal brines, and Li/Na, Ba/Na, and Ca/Na ratios share similar compositions with the ore fluids of basement interacted deposits in the world. The Jinding ore fluids contain ~200 to 650 ppm Pb, based on the data of fluid inclusions trapped in sphalerite. The estimated concentrations of Zn in the ore fluids are also very high at ~200 to 6,500 ppm. Our results reveal that anomalously metal rich fluids played a critical role in the formation of the giant Jinding sediment-hosted Pb-Zn deposit. We concur with the previous suggestion that sulfide precipitation at Jinding occurred when ascending metal-rich brines encountered an H2S-rich, Ca-rich fluid, which was produced by interaction of hydrocarbons with evaporites, in the cap of the Jinding dome.

The Youjiang Basin is characterized by a wide distribution of Au and Sb deposits. These deposits are mainly hosted by sedimentary rocks from Cambrian to Triassic and are structurally controlled by faults and folds. Three types of Sb mineralization can be distinguished based on geologic characteristics, economic metals, and mineral associations. The first type is dominated by Sb mineralization but contains minor or little Au, similar to the large Qinglong deposit. The second type has a spatial association with the gold deposit but formed independent Sb mineralization, reminiscent of the Badu deposit. In the third type, Sb generally formed as an accompanying element in the Carlin-type gold deposit, and stibnite occurred as euhedral crystals filling the open space and faults in the late stage of gold mineralization, analogous to the Yata deposit. Trace element concentrations and sulfur isotopic ratio of stibnite, and oxygen isotope of stibnite bearing quartz were analyzed to infer the ore source(s) for Sb mineralization and genesis. To distinguish the various types of stibnite mineralization between the deposits, Cu, Pb, and As have recognized most diagnostic, with an elevated concentration in Au and Au-Sb deposits and depleted in Sb deposit. The δ34S isotopic composition of stibnite samples from three deposits show a wide variation, ranging from −6.6 ‰ to + 17.45 ‰. Such isotopic values may indicate the sedimentary sulfur source, introduced by fluid–rock interaction. On the other hand, fluid mixing of several end members cannot be excluded. The calculated δ18O isotopic data of Sb-bearing quartz show the initial ore fluid in Au and Au-Sb deposits most likely have a magmatic or metamorphic origin that enriched during fluid–rock interaction, and Sb deposit characterized by initial meteoric water. From these data, we proposed that different lithologies, fluid–rock interaction, fluid pathways, and different ore fluids controlled the compositional evolution of fluids, which might be the main reason for the diversity of Au or Sb mineralization.

This research reviews the geology, petrogenesis, compositional trends and geochronology of the rare-metal pegmatite of southwestern Nigeria. The source of these pegmatites is still presently debated which have been explained as either product of highly fractionated molten material or anatexis of the local crust. However, published works of past authors have been compiled to give a detailed understanding of the formation of the mineral deposits. The basement complex of southwestern Nigeria comprises of Precambrian rocks of amphibolite, the hornblende gneiss and the granite gneisses which were formed as a result of the opening and closing of the ensialic basin with significant, extensive subduction during the Pan-African orogeny. The pegmatites in this region have shown internal zoning and a high degree of evolution from the border zone to the core zone during the crystallization and solidification of the felsic granite to pegmatite melt. The rare-metal pegmatites have distinct chemical compositions and mineralogy, containing quartz, biotite, muscovite, microcline, garnet with localized tourmaline, tantalite and columbite. These pegmatites vary significantly by their bulk-rock and mineral chemistry which indicates a more peraluminous attribute and enrichments of lithophile elements of Rb, Cs, Ta and Ba. Previous K/Ar isotopic ages (502.8±13.0 Ma and 514.5±13.2 Ma) suggest that the pegmatites are related to the post-collisional phase of intensive metasomatism. Adopted from previous studies, a five-stage conceptual model of evolution which is widely accepted have been proposed for the origin of the pegmatites.

This study is aimed at determining the level of environmental degradation as well as the concentration of trace elements in soil and stream sediments in order to evaluate the environmental impact of the mining operation. Twenty-five (25) soils and ten (10) stream sediment samples were collected from the study area. The physicochemical parameters were determined using appropriate instrumentation with the aid of a digital pH meter (Milwaukee meter) to measure the pH and electrical conductivity, total dissolved solids, moisture content and loss on ignition of the soil and stream sediment samples. The pH of the soil sample ranged from (6.10 to 7.19); Electrical conductivity ranged from (21.3 to 279.4 µS/cm), moisture content varied from (0.60% to 7.20%), and the LOI ranged from (2.03% to 18.62%). The results of the analysis showed that the concentrations of the trace elements in the soils and stream sediment samples were slightly higher than the background values. Plots of the trace elements in stream sediment samples show moderate, consistent decrease downstream except at points where there was mine water discharge into the main river. The pollution levels of heavy metals were examined in stream sediment and soil samples using different assessable indices, such as the enrichment factor, which showed significant-moderate enrichment for Cr, Th, Nb, Zn, Pb, Y and Zr and the geo-accumulation index, which showed practically moderate contamination with Cr, Ni and Sr based on regional background reference values. Geo-accumulation index and contamination index for soils and stream sediment revealed uncontaminated to moderate contamination. Likewise, elements with moderate contamination were Cr, Ni and Sr. The Pearson correlation showed that there were significant positive associations among selected metals in soil and stream sediment samples.

This study is conducted to evaluate aggregate characteristics and alkali carbonate reactivity (ACR) potential of carbonate rocks of the Bouhti Pind and Bajar area, Hassan Abdal, Pakistan. Physical and chemical tests were performed to assess aggregate suitability. Mean specific gravity (2.65–2.65), water absorption (0.51–0.68%), Los Angeles abrasion (24.78–26.10%) and sulphate soundness values (2.86–4.25%) of the carbonate rocks of these areas are within specified limits of their respective standards. Petrographic studies of Bajar area reveal the presence of 96.3% calcite, 2% clays, 1% hematite and 0.7% quartz. These rocks do not contain dolomite and show no expansion in rock cylinder test. Therefore, the aggregate is not prone to ACR and can be used in cement concrete. Rocks of Bouhti Pind area have mean 92% calcite, 3.8% dolomite, 2% clays, 1.2% hematite and 1% monocrystalline quartz. The amount of deleterious minerals specifically dolomite and clays are below the maximum allowed limit to initiate ACR. However, one of the rock cylinders shows 0.043% expansion which is below threshold limit of 0.10% to cause ACR as specified in ASTM C-585. Hence, these carbonate rocks qualify physical characterization and ACR tests and can be used in the construction of roads and in cement concrete.

Climate change will impact every aspect of biophysical systems and society. However, unlike other components of the climate system, the impact of climate change on the groundwater system has only recently received attention. This focus is due to the realization that groundwater is a vital freshwater resource crucial to global food and water security, and is essential in sustaining ecosystems and human adaptation to climate variability and change. This paper synthesizes findings on the direct and indirect impacts of climate change on the entire groundwater system and each component. Also, we appraise the use of coupled groundwater-climate and land surface models in groundwater hydrology as a means of improving existing knowledge of climate change-groundwater interaction, finding that most models anticipate decreases in groundwater recharge, storage and levels, particularly in the arid/semi-arid tropics. Reducing uncertainties in future climate projections and improving our understanding of the physical processes underlying models to improve their simulation of real-world conditions remain a priority for climate and Earth scientists. Despite the enormous progress made, there are still few and inadequate local and regional aquifer studies, especially in less developed regions. The paper proposes two key considerations. First, physical basis: the need for a deeper grasp of complex physical processes and feedback mechanism with the use of more sophisticated models. Second, the need to understand the socioeconomic dimensions of climate-groundwater interaction through multidisciplinary synergy, leading to the development of better groundwater-climate change adaptation strategies and modeling.

Apatite is significant phosphate-bearing accessory mineral that is omnipresent in most granitic rocks. In this study, we present geochemical characteristics of magmatic apatites from the Luming and Lower Yangtze granitic belts of NE and eastern China to explore their potential in petrogenesis, mineralization and tectonic evolution of granites. The petrogenetic, metallogenic and tectonic aspects of these granites remain subjects of great debate. This review aims to clarify these issues based on apatite geochemistry. The investigated apatites from both these localities are mainly fluorapatites reflecting the actual attributes of parental melts. Apatites from Luming and Lower Yangtze River Belt (LYRB) exhibit strong negative Eu anomalies suggesting plagioclase crystallization earlier than apatite. The negative correlation of Eu/Eu* (δEu) vs Mn, δEu vs δCe and δEu vs Ga in the apatites signifies that the parental magmas of both granites are produced under moderate reduced conditions. The Sr contents and REEs ratios in apatites serve as significant proxies to trace the differentiation history of Luming and Lower Yangtze granitic plutons. The apatites Sr/Y ratios vs δEu also exhibit that both granites are non-adakitic in nature which is consistent with the host rocks non-adakitic affinities. Halogen data indicates that apatites of Lower Yangtze comprising more chlorine (0.02–1.45 wt.%) and less fluorine (1.51–3.85 wt.%) are linked with slab dehydration whereas apatites from Luming having lower Cl (0–0.04 wt.%) and higher F contents (3.36–5.29 wt.%) suggest association of granites with partial melting of juvenile crust material. Based on the positive correlation of SO3 with Li, (La/Sm)N vs (Yb/Sm)N and obvious variations of (La/Yb)N vs Eu/Eu*, it is inferred that these host rocks are ore-associated. Furthermore, geochemical signatures of apatites from LYRB show low F/Cl ratios, stable La/Sm ratios, high δEu (0.04–0.43, average 0.21) and low δCe values (0.96–1.12, average 1.02) indicating that the magmas of these granites have association with slab dehydration and linked with Cu–Mo–W mineralization, induced from the mutual impacts of Paleo-Pacific plate subduction and intraplate extension. In comparison, fairly high F/Cl ratios, La/Sm ratios, low δEu (0.12–0.23, average 0.16), high δCe values (0.98–1.09, average 1.04) and low Sr/Th ratios of Luming apatites infer that the Mo–W bearing granites are originated in consequence of partial melting of juvenile crustal material. Based on apatite geochemistry, we document first time varieties of ore deposits specifically Mo–W and Cu deposit in LYRB and Mo–W deposit in Luming which are developed under lower oxygen fugacity. The compiled geochemical data and interpretations propose that apatite chemical constituents are worthwhile to pinpoint polymetallic mineralization and fingerprint for ore types. In view of these findings, we confirm that apatite is not only consistent to trace geological facts about parental magma characteristics but also a reliable pointer of geodynamic evolution and ore varieties.

The Qilinchang Pb-Zn deposit ( 5Mt of sulphide ore at mean grades of 2.3–9.2% Pb and 2.7–22.5% Zn) is hosted in Early Carboniferous carbonate rocks and mainly controlled by NE-, NS-, and NW- trending structural belts between the Xiaojiang and Zhaotong-Qujing buried faults. Ore minerals are sphalerite, galena, pyrite, chalcopyrite, and marmatite, whereas gangue minerals are dolomite, calcite, and quartz. Three generations of pyrite are recognized; these include fine-grained anhedral pyrite (Py-I), medium-grained anhedral to subhedral hydrothermal pyrite (Py-II), and coarse-grained subhedral to euhedral hydrothermal pyrite (Py-III), while the sphalerite occurs in two forms as fine-grained intergrown with galena and associated with Py-I and Py-II. Laser-ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) analysis was performed to evaluate trace element compositions of pyrite and sphalerite from different generations of ores. Py-I has relatively higher concentrations of Mg, Mn, Co, Ni, and Tl. Py-II in Cu, As, Se, Mo, and Sb relative to pyrite of other generations. The contents of trace elements in Py-III are variable but significantly enriched in Ti, V, Bi, Ag, and Pb compared to Py-I and Py-II. This variation indicates that these elements occur as micro mineral inclusions of possible Ag-Pb-bearing phases. Sphalerite of stage I has higher concentrations of Mn, Fe, Co, Ni, Cu, Ga, Ge, As, Ag, Cd, In, Sb, Hg, and Pb than stage II. These elements are homogeneously distributed in all samples analyzed. The incorporation of these elements is primarily through simple substitution mechanisms (e.g., 2Zn2+ ↔ Cu+ + In3+) as indicated from binary plots. Principal component analyses (PCA) applied to LA-ICP-MS dataset for pyrite reveal two main clusters; Py-I enriched in Ni, Co and As, Py-II and Py-III high in with V, Mn, Cu, Zn, Se, Mo, Ag, Sb, Au, and Bi. Likewise, the PCA also confirms two clusters of elements for sphalerite; Ge, Cu, As, Sb, Ag, Fe, and Cd corresponding to Sph-I and In, Sn, and Ga corresponding to Sph-II. Py-I has higher Co/Ni ratio ranging from 0.04 to 1.6 compared to Py-II and Py-III having Co/Ni ratios from 0 to 0.706 and 0 0.696, respectively. We report that the pyrites from the Qilinchang deposit have Co/Ni ratios slightly lower than typical Mississippi Valley-Type (MVT) deposits (0.2–7.2) and different from iron oxide copper-gold (IOCG) and porphyry Cu deposits. Considering these geochemical signatures, it can be suggested that the Qilinchang deposit was not related to magmatic activities. We thus propose that the ore-forming fluids responsible for the formation of the deposit were generated from a low-temperature environment, similar to typical MVT deposits.

Abundant Carlin-type gold deposits and vein-type antimony deposits were discovered in the Youjiang basin of SW China, constituting the Youjiang Metallogenic Province (YMP). Although they had been widely studied by geologists, the genesis of these deposits remains debatable, while both intrusion-linked and non-intrusion linked models have been proposed. In this paper, new data of in situ trace elements (LA-ICP MS) and oxygen isotope (SIMS) analysis of hydrothermal quartz from the Yata Carlin-type gold deposit and the Qinglong vein-type antimony deposit in the province were provided to better understand the origin of ore-forming fluids as well as the genetic mechanism of Au and Sb mineralization. Four quartz generations were identified from the Yata (YTi to YTiv) and the Qinglong (QLi to QLiv) deposits. In the Yata deposit, the fluid inclusions in quartz have varied homogenization temperatures from 140–260 ℃ and salinities of 2.4–7.4 wt％ NaCleq, while in the Qinglong deposit, the temperatures and salinities ranged from 140–200 ℃ and 0.2–7.2 wt％ NaCleq., respectively. Both of the temperatures and salinities tend to decrease from early to late generations in the two deposits. δ18O values of initial fluids in the Yata (YTi: 7.70–10.56‰) and the Qinglong (QLi: 4.66–8.75‰) deposits are similar and suggest that they were mainly from magmatic or metamorphic fluids. The covariability of oxygen isotope and Al concentrations indicate that interaction between fluids and wall rocks is a significant factor in determining the compositions of fluids in Au mineralization, and the meteoric water is a key proxy in Sb mineralization, respectively. From these observations, we proposed that the Carlin-type Au deposit and vein-type Sb deposit in YMP were sourced from an analogous ore fluid. Different lithologies of wall rocks and the dilution of meteoric water controlled the compositional evolution of fluids, which might be the main reason for the diversity of Au and Sb mineralization.

The Dian-Qian-Gui area in southwestern China is the second-largest concentration of the Carlin-type gold deposits in the world, and the southwestern Guizhou is the most important gold-producing district of the Dian-Qian-Gui area. Dating of the Carlin-type gold deposits is always a challenge due to the lack of ore-stage minerals which are suitable for conventional radiometric dating. Low-temperature thermochronometers, including fission track and (U-Th)/He, are temperature-sensitive radiometric dating techniques and have been successfully applied to elucidate many aspects of ore deposits, including the timing and duration of mineralization processes. In this study, zircon fission track, zircon (U-Th)/He and apatite fission track dating techniques were applied to the Carlin-type gold deposits in southwestern Guizhou. Samples for zircon and apatite analyses were collected from mineralized or altered sedimentary rocks in Shuiyindong, Taipingdong, Bojitian, Yata and Getang gold deposits. Four groups of thermochronological ages were obtained, i.e., 192–216 Ma, 132–160 Ma, 88 Ma, and 19–40 Ma, which are considered to be the records of four geological thermal events. Of them, most zircon fission track ages and all zircon (U-Th)/He ages concentrate in 132–160 Ma. Thermochronological constraints, combined with field relationships, suggest that the mineralization of the Carlin-type gold deposits in southwestern Guizhou most likely occurred in this period. Partial zircon fission track ages are in 192–216 Ma. They may record the cooling timing of a pre-ore thermal event caused by the Indosinian orogeny, which is supported by the paleogeotemperature restoration. A few zircon grains with high U content yield fission track age of 88 Ma, which may record a post-ore thermal event associated with the intrusion of local mafic dykes. All apatite fission track ages range in 19–40 Ma, which may record a lower temperature but extensive hydrothermal superimposition in the Cenozoic. Additionally, a corresponding relationship between zircon fission track ages and stratigraphic sequences was identified in the Huijiabao anticline, which is considered to reflect the decrease of temperature and duration of ore-forming hydrothermal activity from lower to upper stratigraphic sequences.

This present study is aimed at evaluating the level of environmental degradation and potential ecological risk in soils around an active (tantalum-niobium) mining site of Iludun-Oro, southwestern Nigeria. A total of 18 topsoil samples were randomly collected from different parts of the study area and analysed using the inductively coupled plasma-mass spectrophotometry. The concentrations of Pb, Zn, Fe, Cu, Cr and Ni varied between 0–678, 7–222, 1.64–8.87, 8.8–145, 1.4–81 and 1.6–93.1 ppm, respectively, with an average concentration of 107.72, 48.17, 5.17, 45.28, 14.76 and 21.53 ppm, respectively. The order of abundance of these heavy metals analysed in the soils is as follows: Pb > Zn> Cu> Ni> Cr> Fe. The concentration values of Pb, Fe, Cu, Ba and Sr are higher than the background values indicating that mining activities have an adverse impact on the study area. On accessing the soil quality in the study area, the results of the geo-accumulation, contamination factor (CF) and pollution load indices (PLIs) indicated high concentrations of Pb in the soils. Likewise, most of the Igeo values reported uncontaminated to moderately contaminated for all elements except for Pb. This study has further provided the background information for a vulnerability assessment of the study area as well as for future impact assessment and proper planning of the mining site. These findings have provided useful information for making appropriate environmental management strategies to mitigate the influence of heavy metal pollution generated from an active mining site in Nigeria and other similar areas.