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Resource Geology
资源地质学会
Resource Geology

资源地质学会

1344-1698

Resource Geology/Journal Resource GeologySCIISTP
正式出版
收录年代

    Iron isotopes as an ore-fluid tracer: Case study of Qingchengzi Pb-Zn-Au(-Ag) orefield in Liaoning, NE China

    Li, DedongWang, YuwangWang, JingbinLai, Chunkit...
    13页
    查看更多>>摘要：The Qingchengzi Pb-Zn-Au (-Ag) orefield (eastern Liaoning province, NE China) is located in the northeastern margin of the North China Craton. The unconventional Fe isotopes of pyrites were analyzed to unravel the ore-material source and migration pathway of the ore fluids. Pyrite samples of ores and wallrocks from various deposits in the orefield were collected and the solutions were analyzed by MC-ICP-MS. The results show that most pyrite samples contain heavier Fe isotopes than the international pyrite standard IRMM-014. Within a particular deposit, Fe isotopes become lighter with depth. For example, the pyrite delta Fe-56 values drop from 0.216 similar to 0.408 parts per thousand (150-m level) to -0.284 to -0.132 parts per thousand (210-m level) at the Zhenzigou deposit. Gold deposits in the orefield also have similar features: At Baiyun (Huangdianzi), the pyrite delta Fe-56 values (0.394 similar to 0.627 parts per thousand) of the silicic-/potassic-altered rock-type ore (130-m level) are significantly higher than that (0.359 parts per thousand) of the quartz vein-type ore (440-m level). The lamprophyre delta Fe-56 values from different deposits are largely similar (0.040 similar to 0.024 parts per thousand), whereas those in the wallrocks vary considerably (0.144 similar to 1.238 parts per thousand). Compiling the pyrite delta Fe-56 values from many important sedimentary/metamorphic rock units in the region and magmatic-hydrothermal deposits around the world, we concluded that the Qingchengzi Pb-Zn-Au(-Ag) deposits belong to intrusion-related magmatic-hydrothermal type. The spatial fluid isotope variation pattern, and the fact that early-formed sulfides have lighter isotopes than later ones, suggest that the Qingchengzi ore fluids may have originated from Zhenzigou-Diannan (hydrothermal center) and outflown to Xiaotongjiapuzi, Gujiapuzi-Baiyun and Erdao-Xiquegou areas. The spatial fluid isotope variation pattern also suggests another possible hydrothermal center at Baiyun-Gujiapuzi. The ability to identify hydrothermal center(s) and delineate fluid migration pathways suggests that pyrite Fe isotopes can serve as a tool for precious and base metals prospecting.
      原文链接:
    • NSTL
    • Wiley

    The Hera orebody: A complex distal (Au-Zn-Pb-Ag-Cu) skarn in the Cobar Basin of central New South Wales, Australia

    Matchan, ErinHuang, HuiqingFitzherbert, Joel A.McKinnon, Adam R....
    24页
    查看更多>>摘要：The Hera Au-Pb-Zn-Ag deposit in the southeastern Cobar Basin of central New South Wales preserves calc-silicate veins and remnant sandstone/carbonate-hosted skarn within a reduced anchizonal Siluro-Devonian turbidite sequence. The skarn orebody distribution is controlled by a long-lived, basin margin fault system, that has intersected a sedimentary horizon dominated by siliciclastic turbidite, with lesser gritstone and thick sandstone intervals, and rare carbonate-bearing stratigraphy. Foliation (S1) envelopes the orebody and is crosscut by a series of late-stage east-west and north-south trending faults. Skarn at Hera displays mineralogical zonation along strike, from southern spessartine-grossular-biotite-actinolite-rich associations, to central diopside-rich-zoisite-actinolite/tremolite-grossular-bearing associations, through to the northern most tremolite-anorthite-rich (garnet-absent) association in remnant carbonate-bearing lithologies and sandstone horizons; the northern lodes also display zonation down dip to garnet present associations. High-T, prograde skarn assemblages rich in pyroxene and garnet are pervasively replaced by actinolite/tremolite-biotite-rich retrograde skarn which coincides with the main pulse of sulfide mineralization. The dominant sulfides are high-Fe-Mn sphalerite-galena-non-magnetic high-Fe pyrrhotite-chalcopyrite; pyrite, arsenopyrite; scheelite (low Mo) is locally abundant. The distribution of metals in part mimics the changing gangue mineralogy, with Au concentrated in the southern and lower northern lode systems and broadly inverse concentrations for Ag-Pb-Zn. Stable isotope data (O-H-S) from skarn amphiboles and associated sulfides are consistent with magmatic (or metamorphic) water and sulfur input during the retrograde skarn phase, while hydrosilicates and sulfides from the wall rocks display comparatively elevated delta D and mixed delta S-34 consistent with progressive mixing or dilution of original magmatic (or metamorphic) waters within the Hera deposit by unexchanged waters typical of low latitude (tropical) meteoritic waters. High precision titanite (U-Pb) and biotite (Ar-Ar) geochronology reveals a manifold orebody commencing with high-T skarn and retrograde Pb-Zn-rich skarn formation at >= 403 Ma, Au-low-Fe sphalerite mineralization at 403.4 +/- 1.1 Ma, foliation development remobilization or new mineralization at 390 +/- 0.2 Ma followed by thrusting, orebody dismemberment at 384.8 +/- 1.1 Ma and remobilization or new mineralization at 381.0 +/- 2.2 Ma. The polymetallic nature of the Hera orebody is a result of multiple mineralization events during extension and compression and involving both magmatic and likely formational metal sources.
      原文链接:
    • NSTL
    • Wiley

    Geology, mineralogy, and sulfur isotopes of the Mowana copper deposit, Matsitama Schist Belt, NE Botswana

    Kooganne, AmogelangImai, AkiraAgangi, AndreaTakahashi, Ryohei...
    19页
    查看更多>>摘要：The Mowana hydrothermal Cu deposit is located within the Matsitama-Motloutse Complex in the southwestern part of the Zimbabwe Craton in the northeastern part of Botswana. This study aims to document the characteristics of the mineralization based on geology, quartz textures, ore mineralogy, chlorite geothermometry, and sulfur isotope analyses. The deposit is hosted by the NNE-striking and nearly vertically dipping (70-80 degrees) Bushman Lineament, within the graphitic schist lenses in the carbonaceous and argillaceous metasedimentary rocks of the Neoarchean to Paleoproterozoic Matsitama Sedimentary Group. The hydrothermal alteration of the host rocks is characterized by silicification, chloritization, epidotization, sericitization, hematite, and calcite alteration. Based on the alteration mineral assemblage, the main mineralization stage is attributed to near neutral pH fluids at temperatures between similar to 200 and similar to 340 degrees C. The base metal mineralization of the Mowana deposit was evolved in at least two vein types. The first mineralization type, represented by the quartz+calcite +/- K-feldspar veins and breccias is characterized by the precipitation of principal chalcopyrite with pyrite, minor bornite, and trace amounts of galena. The Type 2 veins represented by the quartz+calcite +/- fluorite veins, host appreciable amounts of galena. The supergene mineralization widely distributed in the shallow levels of the deposit is manifested by the significant presence of chalcocite, bornite, covellite, anglesite, malachite, and hematite. The temperature obtained from the chlorite geothermometry in the Type 1 veins indicate that the mineralization associated with chlorite alteration formed at a temperature ranging from 340 to 400 degrees C. The ore mineral assemblage: pyrite, bornite, and chalcopyrite, paired with the chlorite geothermometry data indicate that the Type 1 veins formed at an intemediate to high sulfidation state. Sulfur isotopic ratios determined on the sulfides indicate the magmatic S and/or leaching of the host metasedimentary rocks and closed system reduction of seawater sulfate as the sources of S.
      原文链接:
    • NSTL
    • Wiley

    The parental magma composition, crustal contamination process, and metallogenesis of the Shitoukengde Ni-Cu sulfide deposit in the Eastern Kunlun Orogenic Belt, NW China

    Zhang, DexinTan, ShuchengSun, FengyueWang, Chao...
    24页
    查看更多>>摘要：Shitoukengde is an important magmatic Ni-Cu sulfide deposit in the Eastern Kunlun Orogenic Belt (EKOB). It comprises several mafic-ultramafic complexes and contains different kinds of mafic-ultramafic rocks. Lherzolite and olivine websterite are the most significant Ni-Cu-hosted rocks. The No. I complex hosts six Ni-Cu ore bodies, and the depth of the intrusion has great exploration potential. Therefore, geochronology, geochemistry, and mineral chemistry of the Shitoukengde deposit were studied to constrain its mineralization time, parental magma composition, and crustal contamination process. Zircon U-Pb dating of olivine websterite shows the magmatic origin (Th/U = 0.40-1.05) and an age of 418.1 +/- 8.7 Ma (MSWD = 0.01), which is coeval with the Xiarihamu, Akechukesai, and other Cu-Ni deposits in the EKOB. Geochemically, the mafic-ultramafic rocks are characterized by low SiO2, TiO2, and Na2O + K2O and high MgO (9.49-36.02%), with Mg-# values of 80-87. They are relatively enriched in LREE and LILEs (e.g., K, Rb, and Th), with weakly positive Eu anomalies (delta Eu = 0.83-2.26), but depleted in HFSEs (e. g., Ta, Nb, Zr, and Ti). Based on the electron microprobe analyses, all of the olivines are chrysolite (Fo = 81-86), and the pyroxenes are dominated by clinoenstatite (En = 80-84) and augite (En = 49-55) in the mafic-ultramafic rocks. Therefore, the composition of parental magma is estimated to be picritic basaltic magma with SiO2 and MgO concentrations of 54.47 and 13.95%, respectively. The zircon epsilon(Hf)(t) values of olivine websterite vary from -0.8 to 4.6, with a T-DM1 of 0.84-1.06 Ga, indicating that the parental magma was derived from relatively high degree partial melting (about 13.4%) of a depleted mantle source and experienced significant crustal contamination (about 12-16%). We propose that crustal assimilation, rather than fractional crystallization, played a key role in triggering the sulfide saturation of the Shitoukengde deposit, and the metallogenesis of "deep liquation-pulsing injection" is the key mechanism underlying its formation. The parental magma, before intruding, underwent liquation and partial crystallization at depth, partitioning into barren, ore-bearing, and ore-rich magma and ore pulp, and was then injected multiple times, resulting in the formation of the Shitoukengde Ni-Cu deposit.
      原文链接:
    • NSTL
    • Wiley

    Interpretation of ground magnetic data in Suyoc, Mankayan Mineral District, Philippines

    Arellano, Creszyl Joy J.Armada, Leo T.Dimalanta, Carla B.Queano, Karlo L....
    14页
    查看更多>>摘要：Ground magnetic surveys conducted in Suyoc, Mankayan, Benguet led to the delineation of features related to epithermal and porphyry copper targets in the area. High reduced to equator (RTE) anomalies are observed in areas with epithermal mineralization. The high RTE anomalies are attributed to hydrothermally altered rock with quartz veins. The previously recognized porphyry copper prospect in Palasaan (Mohong Hill) is characterized by low RTE anomaly surrounded by a high RTE anomaly. One explanation for this signature is the possible presence of a magnetic core and the destruction or absence of magnetite in the alteration haloes at the periphery of a porphyry prospect. Areas such as Mangga and Liten exhibit the same magnetic signatures. This distinct magnetic pattern coupled with observed alteration and mineralization signatures led to the interpretation of prospective blind porphyry deposits in these localities. Results of the study reveal the applicability of ground magnetic data in characterizing and extracting a potential area of mineralized zones at a regional scale.
      原文链接:
    • NSTL
    • Wiley

    Spectral and chemical studies of iron and manganese oxyhydroxides in laterite developed on ultramafic rocks

    Tupaz, Carmela Alen J.Watanabe, YasushiSanematsu, KenzoEchigo, Takuya...
    15页
    查看更多>>摘要：Iron (Fe) oxyhydroxides (goethite and hematite) and manganese (Mn)-oxyhydroxides (lithiophorite, asbolane, lithiophorite-asbolane intermediate) are typically fine-grained and poorly crystalline in nature, and as such are difficult to identify by conventional X-ray powder diffraction. This study employs Raman spectroscopy and electron probe microanalysis (EPMA) to characterize Fe- and Mn-oxyhydroxides found in the Berong Ni-Co laterite deposit at Palawan Island, Philippines. Accurate identification of these minerals is important because these phases contain high Ni and Co contents. Goethite and hematite occur in a wide range of textures, which are related to their compositional variations with respect to Ni, Al, Mn, Cr, and Si. The change in the intensity of the Raman peaks can be linked to the variable concentrations of Ni, Al, Mn, Cr, and Si in goethite. These chemical variations affect the textural transformation of goethite from amorphous to cryptocrystalline. Lithiophorite, asbolane and their intermediates were properly distinguished using Raman spectroscopy. EPMA data shows that these Mn minerals contain appreciable concentrations of Ni, Co, Al, and Fe. The band shift from lithiophorite to asbolane end terms in the 486-593 cm(-1) domain indicates the substitution of Al in lithiophorite by Ni, Co, and Fe.
      原文链接:
    • NSTL
    • Wiley

    Igneous rocks related to porphyry Cu-Au mineralization at the Dizon mine, Philippines

    Midea, William P.Hattori, KeikoValera, Gabriel Theophilus V.
    17页
    查看更多>>摘要：The Dizon Au-rich porphyry Cu deposit, 0.67 Mt Cu and 174 t Au, is hosted by diorite and andesite porphyry intrusions, dated at similar to 2.5 Ma. Amphibole and Fe-Ti oxides in relatively unaltered rocks were used to evaluate the magma conditions of intrusions. Parental magma for diorite porphyry was similar to 950 degrees C at a depth of similar to 15 km, whereas the parental magmas for the andesite porphyry had lower temperatures, 760-820 degrees C at a depth of similar to 5 km. The deposit formed at the locus of multiple intrusions, with evidence for injections of hot mafic magmas, including destabilization texture of plagioclase phenocrysts. Parental magmas at Dizon were oxidized, above FMQ + 2.0, and water-rich, >5 wt%, comparable to conditions of many large porphyry deposits elsewhere in the world. The occurrence of thick opacitic bands of amphibole in the diorite porphyry at Dizon reflects the release of aqueous fluids from the magma; such magmatic fluids were likely responsible for magmatic hydrothermal mineralization of the Dizon porphyry deposit. Subduction of the Scarborough Seamount caused a compressive regime in the overlying plate, which likely contributed to favourable tectonic conditions for mineralization.
      原文链接:
    • NSTL
    • Wiley

    Hydrothermal alteration and Cu-Co mineralization at the peripheral zone (Target H) of the Kitumba iron-oxide copper-gold system, Mumbwa District, Zambia

    Simusokwe, MukukaWatanabe, YasushiEchigo, Takuya
    27页
    查看更多>>摘要：Target H is a new Cu prospect discovered in the Mumbwa district of central Zambia. Copper mineralization in the Mumbwa district is linked to the hydrothermal system associated with the granite-quartz syenite intrusions of the Hook batholith. The extent of the hydrothermal system has not been documented, but various Cu prospects, including Target H, have been discovered at the margins of the granite-quartz syenite bodies. The objective of this study is to investigate the geological characteristics of the Target H prospect using petrographic, geochemical, and sulfur isotope data in order to understand the features of mineralization at the margin of the hydrothermal system. The Cu- and Co-rich orebodies are hosted in siltstone and breccia correlated to the Kundelungu Group of the Neoproterozoic Katanga Supergroup rocks. The siltstone consists of alternating beds of sandstone and mudstone that are composed of diagenetic quartz, albite, dolomite, calcite, and muscovite. Breccia occurs parallel to the bedding planes and in the folded and fractured siltstone units. Lithostratigraphy is characterized by three domains: breccia, transition, and host rock, which are defined depending on the proportion of siltstone and breccia. The diagenetic minerals have been modified by hydrothermal alteration, resulting in alteration products controlled by the primary mineralogy of the host rocks: K-feldspar and muscovite replace albite and muscovite in siltstone, while siderite and hematite replace dolomite and calcite in breccia. Hydrothermal calcite is observed in the veinlets with or without siderite and hematite. Copper mineralization is associated with hydrothermal alteration and occurs as chalcopyrite, bornite, and chalcocite in breccia and stockwork veins. Diagrams correlating geochemistry to lithology show that the bulk of Cu mineralization is hosted in the breccia. An anomalous concentration of Co occurs with Cu in breccia, but the two metals do not show similar enrichment and depletion behaviors. The Cu-rich orebody forms in hematite-dominated breccia domain, whereas Co-rich orebody forms in siderite-dominated breccia units in the transition domain. In addition to Cu and Co, geochemical data show significant enrichment of Fe, P, Ba, Mo, Pb, W, U, V, and light rare earth elements in the breccia. Sulfur isotopic values of sulfide minerals show lighter delta S-34 values between 5 and 9 parts per thousand in the breccia and heavy delta S-34 signatures of approximately 17-28 parts per thousand in the siltstone. The delta S-34 values measured from sulfides in the breccia were comparable to the values obtained from the Kitumba deposit, which is located at the center of the hydrothermal system. We propose a magmatic-hydrothermal origin for the Cu- and Co-rich orebodies in the breccia at Target H. Breccia was the conduit for iron-oxide-rich metal-bearing fluids that originated from the Kitumba deposit. Cooling and reaction of the fluids with dolomite-rich siltstone triggered a redox reaction that deposited Cu sulfide minerals and an anomalous concentration of Co.
      原文链接:
    • NSTL
    • Wiley

    Zircon Hf-isotope constraints on the formation of metallic mineral deposits in Thailand

    Veeravinantanakul, ApivutTakahashi, RyoheiAgangi, AndreaOhba, Tsukasa...
    34页
    查看更多>>摘要：The effects of the Sibumasu-Indochina Terranes collision created several kinds of mineral deposits in Thailand, which include porphyry-skarn copper-gold, epithermal gold and antimony, orogenic gold-antimony-tungsten and tintungsten mineralization among others. The deposits show a distinct spatial zonal distribution and occur in specific tectonic terranes. Combining regional geological data and ore deposit distribution data with Hf-isotopic data of zircons in igneous rocks can be used to investigate the relationship between crustal construction processes and metallogeny. In this study, we investigated the Sukhothai Fold Belt, which is composed of quartz monzodiorite, granodiorite, syenogranite, and monzogranite of I- and S-type affinities. All granitoids were analyzed for zircon U-Pb geochronology and Lu-Hf isotopic analysis. The granitoids of the Sukhothai Fold Belt yielded U-Pb zircon ages ranging from similar to 243 to 202 Ma, which mark the timing of subduction to the syncollisional stage between the Sibumasu-Indochina terranes at similar to 243- 237 Ma and the timing of post-collision between the Sibumasu-Indochina terranes during 230-202 Ma. In addition, an age of similar to 43 Ma in the south of the Sukhothai Fold Belt may indicate intrusion during the sinistral movement of the Klaeng and Mae Ping fault zones resulted from the Indian-Eurasian plate collision. The Doi Tung quartz monzodiorite provided an age of similar to 350 Ma as a timing of formation of the Sukhothai Fold Belt. The negative and positive initial eHf values (similar to 8.0 to +9.2) with two-stage depleted mantle model ages (TDMC of 2.2-0.6 Ga) of zircons from the Sukhothai Fold Belt granitoids indicate that the sources of their magma derived from partial melting of old continental crust and young oceanic crust, which probably mixed with a mantle-derived magma. A zircon Hf-isotope compilation including the data obtained in this study and previously reported values was used to prepare a map that allows a comparison between magmatic source and mineral deposit distribution in Thailand. The spatial distribution of Hf isotopic data reveals a distinct zonation, with initial epsilon Hf values decreasing from the east to the west, that is, from the western margin of the Indochina Terrane or the Loei Fold Belt to the Sukhothai Fold Belt, the Inthanon Zone and the Sibumasu Terrane. The magmatic source for the granitoids in the Loei Fold Belt is dominated by mantle-derived components, as shown by positive average initial eHf values (+1.0 to +12.7), and contributed to porphyry-related skarn copper-gold and iron and epithermal gold mineralization. In contrast, magmas in the Sibumasu Terrane and the Inthanon Zone originated from melting of old crustal materials, as indicated by mostly negative average initial eHf values (similar to 15.1 to +0.8), and are responsible for S-type granite-related tin-tungsten mineralization. The average initial eHf values (similar to 5.0 to +11.0) from the intrusions in the Sukhothai Fold Belt suggest mixed sources, including evolved and juvenile magmatic materials, which generated the orogenic gold deposits and other vein-type antimony, tungsten, fluorite, and base metal deposits. These results imply a close spatial correlation between the source of magmatism in each tectonic terrane of Thailand and different metal ore deposits. These isotope maps can be used as a powerful tool in the exploration for various commodities at the regional scale.
      原文链接:
    • NSTL
    • Wiley

    State-of-the-art geophysics for metal exploration

    Arai, Eiichi
    22页
    查看更多>>摘要：The new discovery of the economical metal deposit is getting more difficult year by year because the unexplored areas tend to be more remote areas than ever, and the metal prospective zones are deepening in the recent decades. Therefore, the advent of the state-of-the-art or advanced geophysics technology to peer the deeper parts of the ground with higher accuracy and spatial resolution has been aspired in metal exploration industry. The author reports and introduces the drone-based magnetic survey, the three-dimensional time-domain IP inversion algorithm using Cole-Cole parameter, the time domain electromagnetic method using superconducting quantum interference device (SQUID), and passive seismic survey as the state-of-the-art or advanced geophysics technology for metal exploration. In the early stage of metal exploration, airborne magnetic survey has been used in a wide variety of exploration programs for large areas to map basement structures and to delineate other magnetic structures. The drone-based magnetic survey is recently getting prevailing in the metal exploration because it can be conducted at much lower cost with simpler clearance for its flight by the governmental authority, and with higher spatial resolution than the conventional fixed-wing or heliborne magnetic survey. In the target identification stage, induced polarization (IP) method has been recognized as one of the extremely powerful tools in the discovery of many new metal deposits. The historical various studies on complex resistivity measurements for metal sulphides, graphite, magnetite and pyrrhotite have revealed that there are significant differences in the spectral responses among metal sulphides, graphite, magnetite and pyrrhotite which is capable of being parametrized using the empirical Cole-Cole parameter model. JOGMEC developed the three-dimensional time-domain IP inversion code using Cole-Cole parameter model so as to interpret the difference of IP sources using Cole-Cole parameters, and has applied this code to its exploration activities. Transient electromagnetic method (TEM) also has a well-established place in metal exploration. Since recent exploration targets are generally concealed by thick conductive overburdens such as weathered layers and black shale, these geological covers preclude induction currents generated by the TEM transmitter loop on the surface from diffusing into the exploration targets plentifully beneath the conductive covers. B-field measurement using SQUID magnetic sensor is one of the technologies which enable TEM to investigate deeper than dB/dt measurement by the conventional induction coil system, because B-field decays slower than dB/dt and time decay of B-field reaches the system noise floor at later time than dB/dt if dynamic ranges of the both systems are almost identical. JOGMEC had developed the TEM system using a high-temperature superconductor (HTS) SQUID, and has been using it in its metal exploration. The other current trend of mining geophysics is application of seismic method to metal exploration. In the target identification stage, deep geochemistry using aircore drilling is much utilized over the areas covered by transported cover. In order to design the aircore drilling survey, passive seismic survey has been utilized to evaluate thickness of transported cover in order to make plans of specification (length) of the aircore drilling survey, which is also a new trend in mining geophysics.
      原文链接:
    • NSTL
    • Wiley