Ore Belt Research Articles

关于中国西部龙首山、祁连山成矿区（带）进一步找矿问题的思考

Many mines in China have been confronting with crisis of reserved resources since the 21st century. The mines, which situated in the Longshoushan-Qilianshan ore belt in Gansu province can not run away from such a fate. From the idea of metallogenic systems, We analyzed regional metallogenic tectonic settings of the Longshoushan-Qilianshan ore belt, and considered that there are two continental margins of Southwestern North-China paleo-continent and Northern Qitam-Mid-Qilianshan plate. We think it very necessary to carry out a new circle of mineral exploration under the guidance of nontraditional-mineral-resources-theory. In the Longshoushan-Qilianshan ore belt, we should not only strengthen the exploration of traditional minerals but also pa more attention to new type of mineral resources. At the same time environment protection should also be emphasized. Minerals exploration is based on talents who have advanced theory, abundant exploration experiences and large amount of capitals.

Isotope geochemistry of the Tieluping silver-lead deposit, Henan, China: A case study of orogenic silver-dominated deposits and related tectonic setting

The Tieluping silver deposit, which is sited along NE-trending faults within the high-grade metamorphic basement of the Xiong’er Terrane in the Qinling orogenic belt, is part of an important, recently discovered Mesozoic orogenic-type Ag-Pb belt. Ore formation includes three stages: an early barren quartz-pyrite stage (E), an intermediate polymetallic sulfide ore stage (M), and a late barren carbonate stage (L). Carbon, sulfur and lead isotope systematics indicate that the E-stage fluids are deeply sourced; the L-stage fluids are shallow-sourced meteoric water; whereas the M-stage fluids are a mix of deep-sourced and shallow-sourced fluids. Sulfur and lead isotope data show that the ore-forming fluids must have originated from a source with elevated radiogenic lead and low δ34S values, that differs significantly from exposed geologic units in the Xiong’er Terrane, the lower crust and the mantle. This supports the view that the carbonate-shale-chert sequences of the Guandaokou and Luanchuan Groups south of the Machaoying fault might be the favorable sources, although little is known about their isotopic compositions. A tectonic model that combines collisional orogeny, metallogeny and hydrothermal fluid flow is proposed to explain the formation of the Tieluping silver deposit. During the Mesozoic collision between the North China Craton and South China Block (Early-Mid Triassic Indosinian Orogeny), crustal slabs containing the carbonate-shale-chert sequences of the Guandaokou and Luanchuan Groups, locally rich in organic matter (carbonaceous shale), were thrust northwards beneath the Xiong’er Terrane along the Machaoying fault. Metamorphic devolatilisation of this underthrust slab probably provided the ore-forming fluids to develop the Ag-Pb ore belt, which includes the Tieluping silver deposit. Fluids and magmas were emplaced during extensional stages related to the Jurassic-Cretaceous Yanshanian Orogeny.

Impact of geological origin on trace element composition of edible mushrooms

This study aims to examine elements detected in edible mushrooms grown in two geochemically different regions in Finland. One study area lies in the main sulphide ore belt of Finland and is characterised by high metal concentrations in the soil. The reference area with low concentrations of the elements is located in the granitoid complex area of central Finland. Two common mycorrhizal species of mushrooms were analysed— Boletus edulis (cep) and Lactarius trivialis (trivial milk-cup). The concentrations of 33 elements were measured by inductively coupled plasma-mass spectrometry (ICP-MS) after nitric acid dissolution. Soil samples from the habitat were analysed for total and bioavailable fractions. Both mushroom species growing in the main sulphide ore belt were enriched in Ba, Cu, Ni, Zn, and Ag as compared to those growing in the reference area. Thus, the influence of natural geochemistry on the trace element concentrations of the studied mushrooms seems to be evident. This finding leads to the conclusion that inclusion of geographically linked information in food composition databases would enhance their value and allow better utilisation in applied studies.

Melt components derived from a subducted slab in late orogenic ore-bearing porphyries in the Gangdese copper belt, southern Tibetan plateau

A porphyry-type Cu (Mo, Au) polymetallic ore belt extends in an E–W direction for >400 km along the Gangdese magma arc in the southern Tibetan plateau. Extensive field investigations and systematic geochemical study, combined with S and Pb isotopic tracing, indicate that Cu polymetallic mineralization of the copper belt is genetically related to late orogenic granitic porphyries formed in a late Himalayan crustal extension stage (18–14 Ma). Geochemistry of the porphyries shows the essential characteristics of adakite and suggests a dominant role of subduction-related components in their genesis. The genesis of these ore-bearing porphyries is mainly related to melt components derived from subducted slabs and has little relationship with fluids released from them. Pb isotopes show a clear linear array in the plumbotectonics model and are manifested by a progressive variation from orogenic Pb in the east segment of the copper belt to mantle Pb in the west segment, forming a mixing line of Indian Oceanic MORB and Indian Oceanic sediments. This suggests that the porphyry magma dominantly originated from partial melting of subducted oceanic crust and was mixed with a minor melts of sediments and mantle wedge components.

Hydrothermal Mineralization on the Mesoproterozoic Passive Continental Margins of China: A Case Study of the Langshan‐Zha'ertaishan Belt, Inner Mongolia, China

Abstract Most ore‐forming characteristics of the Langshan‐Zha'ertaishan hydrothermal exhalation belt, which consists of the Dongshengmiao, Huogeqi, Tanyaokou and Jiashengpan large‐superlarge Zn‐Pb‐Cu‐Fe sulfide deposits, are most similar to those of Mesoproterozoic SEDEX‐type provinces of the world. The characteristics include: (1) All deposits of this type in the belt occur in third‐order fault‐basins in the Langshan‐Zha'ertaishan aulacogen along the northern margin of the North China Platform; (2) these deposits with all their orebodies hosted in the Mesoproterozoic impure dolomite‐marble and carbonaceous phyllite (or schists) have an apparent stratabound nature; ores display laminated and banded structures, showing clear depositional features; (3) there is some evidence of syn‐sedimentary faulting, which to a certain extent accounts for the temporal and spatial distribution and the size of the orebodies in all deposits and the formation of intrabed conglomerates and breccias; (4) they show lateral and vertical zonation of sulfides; (5) The Cu/(Pb+Zn+Cu) ratio of the large and thick Pb+Zn+Cu orebodies gradually decreases from bottom to top; and (6) barite is interbedded with pyrites and sometimes with sphalerite. However, some characteristics such as the Co/Ni radio of the pyrites, the volcanism, for example, of the Langshan‐Zha'ertaishan metallogenic belt, are different from those of the typical SEDEX deposits of the world. The meta‐basic volcanic rock in Huogeqi, the sodic bimodal volcanic rocks in the Dongshengmiao and potassic bimodal‐volcanic rocks with blastoporphyritic and blasto‐glomeroporphyritic texture as well as blasto‐amygdaloidal structure in the Tanyaokou deposits have been discovered in the only ore‐bearing second formation of the Langshan Group in the past 10 years. The metallogeny of some deposits hosted in the Langshan Group is closely related to syn‐sedimentary volcanism based on the following facts: most of the lead isotopes in sphalerite, galena, pyrite, pyrrhotite and chalcopyrite plot on both sides of the line for the mantle or between the lines for the mantle and lower crust in the lead isotope composition diagram; cobalt content of some pyrites samples is much higher than the nickel content (Co/Ni=11.91‐12.19). Some volcanic blocks and debris have been picked out from some pyritic and pyrrhotitic ores. All Zn‐Pb‐Cu‐Fe sulfide orebodies in these deposits occur in the strata overlying metamorphic volcanic rocks in the only ore‐bearing second formation. In the Jiashengpan deposit that lacks syn‐sedimentary volcanic rocks in the host succession only Pb and Zn ores occur without Cu ore, but in the Dongshengmiao, Tanyaokou and Huogeqi deposits with syn‐sedimentary volcanic rocks in the host succession Cu ores occur. This indicates a relatively higher ore‐forming temperature. The process of syn‐sedimentary volcanic eruption directly supplied some ore‐forming elements, and resulted in secular geothermal anomaly favorable for the circulation of a submarine convective hydrothermal system, which accounts for the precipitation of deep mineralizing fluids exhaling into anoxidic basins along the syn‐sedimentary fault system in the Langshan‐Zha'ertai rift. The Dongshengmiao, Tanyaokou, and Huogeqi deposits hosted in the Langshan Group appear to be a transitional type of mineral deposit between SEDEX and VMS‐types but with a bias towards SEDEX, while the Jiashengpan deposit hosted in the Zha'ertai Group is of a characteristic SEDEX type. This evidence, together with other new discoveries of Mesoproterozoic volcanic rocks and the features of lithogeny and metallogeny of the Bayun Obo deposit in the neighborhood emphasize the diversity, complexity and uniqueness of the Mesoproterozoic Langshan‐Zha'ertai‐Bayun Obo ore belt.

Himalayan magmatism and porphyry copper-molybdenum mineralization in the Yulong ore belt, East Tibet

¶The NW–SE-trending Yulong porphyry Cu–Mo ore belt, situated in the Sanjiang0 area of eastern Tibet, is approximately 400 km long and 35 to 70 km wide. Complex tectonic and magmatic processes during the Himalayan epoch have given rise to favorable conditions for porphyry-type Cu–Mo mineralization.

Heavy metal contamination of soils in a mining area in South Africa and its impact on some biotic systems

In soils, animals and plants from selected sites in the Rustenburg mining area, a part of the South African ore belt, the heavy metal burden was examined. These sites belong to different soil types and are characterized by different land-use (agriculture, grassland). The heavy metal contamination of the soil samples is relatively high and is dominated by chromium and nickel, metals, which are extracted in the mine near the sampling sites. These high heavy metal concentrations had no clear inhibitory influence on micro-organisms or the enzyme activity of soils. It appears that the high clay content of the soils may counteract the influence of heavy metals. On the other hand, tolerant microbial populations may have been established. In addition, the investigated culture plants there was no correlation between the heavy metal content of the soils and the concentrations in roots and shoots. The dangerous, potential contamination of organs in humans seems to be modest, with the exception of tobacco leaves. The heavy metal content of tissues in the examined animals reflect the environmental habitat in situ with no obvious influence on the health of the animals.

One potential superlarge Pb-Zn ore occurrence with himalayan thermal brine genesis—Wuqia Region, Xinjiang, China

The paper focuses on geological and geochemical evidence of thermal brine genesis of Pb-Zn deposits in Wuqia district, Xinjiang. The results suggest that the known Pb-Zn deposits, such as Wulagen, are thermal brine genesis, which is supported by the features of tectonic setting, magma and regional metamorphism, and the characteristics of trace element distribution in strata and redistribution in the ore-forming process, the REE patterns and their main parameters of main type ores, the composition features and the source indicators of Pb, S isotopes. Ore-forming conditions of superlarge Pb-Zn deposits studies show that there exists tectonic and sources setting of Jinding-type superlarge Pb-Zn deposits in this area. Five Pb-Zn ore belts and central uplift belts discovered lately have not only confirmed that the genesis of Wulagen Pb-Zn deposits is thermal genesis, but also further proved that there exists tectonic and source setting of Jinding-type superlarge Pb-Zn deposit in the study area. Mineral deposit model was described and prospecting potentiality of superlarge Pb-Zn deposit and their significance were discussed.

Exploration geophysics at the Pyhäsalmi mine and grade control work of the Outokumpu Group

The power of geophysics is often realized while surveying barren exploration holes. Integrated interpretation of borehole electromagnetic (EM) and lithogeochemical data led to the discovery of a new volcanogenic massive sulfide (VMS) ore deposit at 500 m depth in the Pyhäsalmi area, which belongs to the Main Sulfide ore belt in Finland. In the deep exploration program, wide‐band multifrequency EM ground surveys were successfully used to detect both new ore lenses and geological structures. Mise‐a‐la‐masse (MAM) borehole and ground surveys as well as borehole EM surveys were effectively used to correlate intersections between drill holes and to locate new orebodies. The latest modeling of MAM data resulted in an exploration target at 700 m depth. The use of geophysics for exploration has been extended to mine production at Outokumpu. Geophysical logging detects ore‐waste boundaries, reduces expensive core drilling, and obtains physical property information quickly on ore intersections. Depending on ore type, geophysical borehole logging can also be applied to classify mineralization, interpret lithology, and sometimes to transform physical responses to metal grades in ore. At the Pyhäsalmi zinc‐copper‐sulfur mine, density logging in percussion boreholes is used to locate mineable ore boundaries and to classify drillhole intersections as massive or semimassive sulfide ore types. Pyrrhotite‐bearing zones are separated from other sulfides by inductive conductivity logs. The use of geophysical logging for grade estimation and control has been most effective in the nickel mines at Enonkoski, Finland, and Namew Lake, Canada (using conductivity logs), and in the Kemi chromium mine, Finland (using gamma‐gamma density logs).

Helium, Argon, and Xenon Isotopic Compositions of Ore‐forming Fluids in Jinding‐Baiyangping Polymetallic Deposits, Yunnan, Southwest China

Abstract The Jinding superlarge lead and zinc deposit has attracted the attention of geologists of the world and its metallogenesis has long been in dispute. This paper takes the Jinding deposit and the Baiyangping Cu‐Ag‐Co deposit which was recently found at about 30 km north of Jinding as one ore belt, and, based on researches on the helium, argon, and xenon isotopic compositions of primary inclusions in ore‐forming solutions of the main stage, the authors have found that the 3He/4He ratio of the ore‐forming fluid is 2.7×10−6 (varying from 0.19 to 1.97 Ra), the 4He/40Ar ratio (0.24–3.12) is close to the mantle characteristic ratio, and the xenon isotopic composition and evolution show characters of the mantle xenon. The above results reveal the characteristics of mantle source and crust‐mantle fluid mixing (mantle helium reaching 32%) and the metallogenic contributions of the deep processes in the Jinding‐Baiyangping ore belt.

THE MANGANESE FORMATION OF THE NEOPROTEROZOIC PENGANGA GROUP, INDIA—REVISION OF AN ENIGMA—A DISCUSSION

Sir : Gutzmer and Beukes (1998) have revised the sedimentary-diagenetic mode of origin suggested earlier for the todorokite-rich (with birnessite, manganite, braunite, and bixbyite) manganese deposits of the Penganga Group, India (Roy, 1981; Roy et al., 1990; Bandopadhyay, 1996), concluding that these Mn oxide deposits were entirely derived by supergene alteration of a Mn carbonate protolith which they discovered in one deep quarry section (near Nipani) below the Mn oxide ore horizon. I congratulate the authors for this discovery of the Mn carbonate horizon that eluded us in spite of thorough search (Roy et al., 1990) during the 1980s, that perhaps was limited by the depth-extension, at that time, of the section by mining operations. Credit must also go to these authors for the very detailed characterization of these Mn carbonates including stable isotope and REE geochemistry. I have, however, strong misgivings on several conclusions drawn in this paper. In a 40-km-long belt of Mn oxide deposits, this study was confined to only two spots (p. 1091) near Nipani (Mn carbonate rock) and Jamdapur (supergene ore) and yet a generalization is made that the entire Mn oxide ore horizon was formed by supergene alteration of a Mn carbonate protore rejecting our conclusion (Roy et al., 1990), based on studies over the entire ore belt, that the Mn oxide ores are sedimentary-diagenetic in character. Our studies showed that the …

On Geophysical Background of Superlarge Deposits in the Chinese Continent

Abstract Based on the study of tens of geophysical profiles (seismic, geothermal flow and magnetotelluric sounding profiles) and 3‐D shear wave velocity structures of the Chinese continent and its neighbouring regions, this paper describes the 3‐D crustal and upper mantle structures and discusses briefly the deep geophysical background of superlarge ore deposits in the Chinese continent. Superlarge deposits are usually very few in number, but they are distributed still in certain forms such as “point”, “zone” and “area”. Most of the large‐, medium‐ and small‐sized deposits occur near the margins of different tectonic units; while the superlarge endogenic polymetallic deposits occur mostly in thinned mantle lithosphere, uplifts of the asthenosphere (vertical low‐velocity zones) and the transformation zones of lateral inhomogeneity (weak zones) in the upper mantle. The superlarge endogenic polymetallic deposits are almost unevenly distributed in three major ore zones in China, corresponding to the boundaries of inhomogeneous regions in the asthenosphere.The authors argue that the lithospheric structure is to some extent in agreement with the geotectonic units, suggesting that the crust structure is influenced and restricted by the lithosphere, and that the crust and upper mantle both exhibit low‐velocity nature. Therefore, vertical low‐velocity zones of seismic waves are considered to be a favourable environment for endogenic polymetallic ore belts.

REE characteristics of microfine disseminated gold ores in Danzhai, Guizhou

Described in this paper are the fundamental characteristics of mineralization of gold ores in the Sandu-Danzhai Hg-Sb-As-Au ore belt of Guizhou Province. Through systematic sampling of the industrial orebody and alteration zone, the total amount of the rare-earth elements, that of the light rare-earth elements, Eu depletion and other parameters are clarified. There have been distinguished two types of REE distribution patterns: the “clay type” and the “quartz type”. High-grade orebodies are closely related with silicification, illitization and pyritization. The seven-component diagram of the REEs of even numbers in the periodic table (Balasov, 1966) is capable of distinguishing ore-bearing from ore-barren deposits.

The influence on EM-anomalies of the position of the generator in a Turam loop

The Bainaimiao Cu–Mo–Au deposit, located at the northern margin of the North China Craton (NCC) in central Inner Mongolia, is a large Cu-dominant deposit. Orebodies are hosted in strongly deformed and metamorphosed granodiorite porphyry intrusions or in EW-trending shear zones in greenschist and sericite felsic schist of the Bainaimiao Group. Mineralization can be divided into early, middle and late stages, characterized by quartz–pyrite, polymetallic quartz–sulfides and carbonate–quartz, respectively. Hydrothermal activity led to pervasive silicification, K-feldspar, biotite and chlorite–epidote–carbonate alteration.Eight samples from Cu–Mo-bearing quartz veins and massive sulfide ores in greenschist were collected from the VIII orebody in the North ore belt and molybdenite separates were selected for Re–Os analyses. The concentrations of Re and 187Os range from 216.6 to 1051 ppm and 2302 to 4913 ppb, respectively. All samples give Re–Os model ages between 441.2 and 445.9 Ma and yielded an isochron age of 445.0 ± 3.4 Ma (MSWD = 0.26), with an initial 187Os of − 4 ± 17 ppb. A granodiorite porphyry sample for SHRIMP U–Pb dating was collected from the underground of the XIII orebody of the North ore belt. Spots from 14 zircon grains have 206Pb/238U values between 426.2 and 462.9 Ma and form a tight cluster on Concordia yielding a weighted mean 206Pb/238U age of 445 ± 6 Ma. This is considered to be the best estimate of crystallization age of the granodiorite porphyry. The Re–Os isochron age of the molybdenite is consistent with the SHRIMP U–Pb age of the granodiorite porphyry, which indicates that the deposit is a porphyry system of Paleozoic age.According to geodynamic setting and geological history of the northern margin of the NCC, the deposit was probably related to magmatic activity of the Middle Paleozoic Ondor Sum subduction–accretion complex-Bainaimiao arc. During the Devonian, the Bainaimiao arc was accreted to the northern margin of the NCC. Collision between the Bainaimiao arc and NCC led to regional metamorphism of the ore-hosting terrane and ore metals were remobilized in this process. Gold mineralization was probably overprinted onto the earlier Cu–Mo mineralization.

Geochemical exploration for concealed nickel-copper deposits

During the period 1985 to 1991, a systematic study was done on the geochemical characteristics of the Karatüngk nickelcopper deposit in the Xinjiang-Uygur Autonomous Region in northwestern China. Surface rock and drill core sampling and CHIM surveying were carried out. Geochemically anomalous distribution patterns of Cu, Ni, Co, Cr, Ag, Mo, Ba, B, and As were outlined. A preliminary study showed that Cu, Ni and Co are diagnostic indicators for outcropping Ni-Cu-bearing intrusives, but are much less useful for concealed Ni-Cu-bearing bodies. Distinct anomalous associations of Ba, As, Mo, B, Ag, and Cr have been found over concealed intrusive bodies containing Cu-Ni deposits. Geochemical criteria for evaluating the nickel potential in basic-ultrabasic intrusive bodies in the Ertix ore belt were identified and a series of new anomalies discovered. Since completion of the study, two nickeliferous basic intrusives have been intersected by drilling.

Isotope Geochemistry of the Xinchang – Yongjia Silver (Lead – Zinc) Ore Belt in Eastern Zhejiang Province

Abstract In the Xinchang‐Yongjia silver (lead‐zinc) ore belt, there mainly occur the large to medium‐sized Haoshi, Bamao, Dalingkou and Wubu silver deposits or silver‐bearing lead‐zinc deposits. On the basis of researches on these typical deposits, the mechanism of leaching‐drawing mineralization of Mesozoic geothermal water and the related model are put forward in this paper in the light of the time interval between rock and formation ages as well as hydrogen, oxygen, sulphur and lead isotope geochemical characteristics. The major metallogenic process occurred in volcanic rock layers. The ore‐forming fluids are geothermal water coming from meteoric water and circulating at shallow layers. This geothermal water leached and absorbed ore‐forming materials from its country rocks during its flowing (such metallogenic elements as silver, lead‐zinc and sulphur mainly came from consolidated volcanic rocks), leading to the formation of meso‐epithermal silver deposits.

Atmospheric sulfur deposition and streamwater quality in Finland

The correlation between sulfate concentrations in Finnish headwater streams and atmospheric sulfate deposition has been studied by using data from the streamwater chemistry in August–September 1990 and computed S deposition from the anthropogenic emissions. The sulfate concentrations and acidity in water are interpolated and smoothed into a deposition model grid. These data are compared with geological and pedogeochemical (glacial till) background information. The areas where the streamwater SO4 concentrations are mainly controlled by either anthropogenic S deposition or sulfur in till is estimated by applying the fuzzy Gustafsson-Kessel algorithm, which provides a soft clustering suitable for overlapping control factors. Residual areas can be well explained by the SO4-rich Littorina clay deposits. The higher overall background SO4 concentrations in streams in south Finland compared with central and northern Finland are an indisputable consequence of the heavier S deposition load in the south. However, anthropogenic sulfur deposition has a clear correlation with the sulfates in streamwaters only in northeastern Lapland impacted by the large industrial emissions in the Kola Peninsula. The secondary sulfide and sulfate minerals of marine Littorina sediments are dominating sources in the broad coastal belts, as are the primary sulfide minerals locally in the Pori-Vammala area, at the eastern end of the main sulfide ore belt between Lake Ladoga and the Gulf of Bothnia, in the Outokumpu area, and in the Perapohja and central Lapland schist belts. Consequently, in addition to the anthropogenic deposition, there are natural sources of sulfur which cause acidity of streamwaters.

Mineralogical and Genetic Features of Volcanic Gold-Silver Deposits of the Pacific Ore Belt: ABSTRACT

Mineralogical and Genetic Features of Volcanic Gold-Silver Deposits of the Pacific Ore Belt: ABSTRACT

Age and formation conditions of alteration associated with a collapse structure, Temple Mountain uranium district, Utah

Research Article| July 01, 1988 Age and formation conditions of alteration associated with a collapse structure, Temple Mountain uranium district, Utah STAN J. MORRISON; STAN J. MORRISON 1Department of Geology and Geophysics, University of Utah Salt Lake City, Utah 84112 Search for other works by this author on: GSW Google Scholar W. T. PARRY W. T. PARRY 1Department of Geology and Geophysics, University of Utah Salt Lake City, Utah 84112 Search for other works by this author on: GSW Google Scholar Author and Article Information STAN J. MORRISON 1Department of Geology and Geophysics, University of Utah Salt Lake City, Utah 84112 W. T. PARRY 1Department of Geology and Geophysics, University of Utah Salt Lake City, Utah 84112 Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (1988) 100 (7): 1069–1077. https://doi.org/10.1130/0016-7606(1988)100<1069:AAFCOA>2.3.CO;2 Article history First Online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation STAN J. MORRISON, W. T. PARRY; Age and formation conditions of alteration associated with a collapse structure, Temple Mountain uranium district, Utah. GSA Bulletin 1988;; 100 (7): 1069–1077. doi: https://doi.org/10.1130/0016-7606(1988)100<1069:AAFCOA>2.3.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract Temple Mountain, Utah, is an erosional remnant capped by resistant dolomtic alteration of the Triassic Wingate and Chinle Formations. Carbonate, Fe-oxide, phyllosilicate, sulfate, and other mineral alterations are related to a collapse structure. Elemental zoning (Cr, Cu, Co, Ni, As) of the ore district is unlike that found in other uranium districts hosted by the Chinle Formation. A major uranium ore belt in the Chinle Formation partially encircles the collapse structure ∼500 m away.Two theories on the genesis of the Temple Mountain district have been proposed. Both suggest a relationship between alteration, ore mineralization, and formation of the collapse structures but differ substantially as to the intrinsic parameters of the alteration/ore mineralizing fluids. One theory suggests hydrothermal solutions up to 350 °C, whereas the other proposes cool solutions rich in CO2. Fluid-inclusion data collected from alteration dolomite and sphalerite and geochemical modeling of a CO2-rich system support aspects of the latter theory. Median homogenization temperatures for fluid inclusions in dolomite, calcite, quartz, and sphalerite are 67, 59, 74, and 73 °C, respectively. Fluid salinity measured in inclusions in sphalerite is 7.8 to 9.7 eq. wt % NaCl. Alunite, spatially associated with uranium mineralization and the collapse structure alteration, has been dated at ∼13 Ma by K-Ar methods. Acid solutions containing carbon and sulfur derived from natural gas dissolved carbonate, caused collapse, and transported and fixed uranium as oxidation states varied. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

On nonlinearities in the Fennoscandian land uplift within the main sulphide ore belt

The general features of the Fennoscandian land uplift are well known. Owing to the stability of the old shield, the relative local vertical displacements are of a marginal magnitude, and the mechanism of the phenomenon is under investigation. The relevellings carried out in the last decade have, however, brought discontinuities to light that seem to correlate with the fracture systems and fault lines. The most marked vertical displacements have been observed in the Main Sulphide Ore Belt (MSOB), where the fracture density is comparatively high. The present paper gives the preliminary results of certain series of observations connected with the MSOB. The vertical displacements observed can be interpreted as block movements on a small scale.