scholarly journals Forecasting criteria for sulphide PGE-copper-nickel deposits of the Noril’sk province (In English)

LITOSFERA ◽  
2021 ◽  
Vol 21 (5) ◽  
pp. 660-682
Author(s):  
K. N. Malitch
Keyword(s):  
Geochemical Data ◽  
Low Grade ◽  
Geochemical Analysis ◽  
Restricted Range ◽  
Research Subject ◽  
Economic Potential ◽  
Sulphide Deposit ◽  
Promising Target ◽  
Nickel Deposits ◽  
World Class

Research subject. World-class sulphide platinum-group-element (PGE)-Cu-Ni deposits occur within the Noril’sk-Talnakh region of northern Siberia, Russia. The signifcance of these deposits presents opportunities to determine the most effective approaches for the search of similar deposits using commercial PGE-Cu-Ni deposit examples. Materials and methods. Petrological and geochemical analysis of the ultramafc-mafc intrusions of the Noril’sk province ranks them into three types in terms of sulphide mineralization style and economic signifcance: 1) economic intrusions containing unique and large sulphide PGE-Cu-Ni deposits (Oktyabr’sk, Talnakh and Noril’sk-1); 2) subeconomic intrusions that contain small- to medium-sized Cu-Ni sulphide deposits, and medium-sized to large PGE deposits (Chernogorsk, Zub-Marksheider, Vologochan, etc.); 3) uneconomic intrusions that contain low-grade disseminated Cu-Ni ores with ≈0.2 wt % of Cu and Ni, and low Cr and PGE (Nizhny Talnakh, Zelyonaya Griva, etc.). Results and conclusions. Principal sources used in exploration for rich sulphide PGE-Cu-Ni ores include structural, magmatic, stratigraphic-lithological, geochemical, mineralogical, metamorphic and some others. Based on an analysis of isotope-geochemical data, new indicators for locating sulphide PGE-Cu-Ni mineralization are suggested. A restricted range of S-isotope values, and a negative trend for coupled S-Cu isotope compositions can be employed as useful guides to assess the economic potential of a PGE-Cu-Ni sulphide deposit. It is proposed that the Chernogorsk ultramafc-mafc intrusion of the Noril’sk province is the most promising target in a search for rich PGE-Cu-Ni ores. It is suggested that the previously known mineralogical-geochemical and novel isotope-geochemical characteristics of sulphide and silicate minerals are important indicators in assessing the potential ore content of ultramafc-mafc intrusions of the Noril’sk province.

scholarly journals A step towards unraveling the paleogeographic attribution of pre-Mesozoic basement complexes in the Western Alps based on U–Pb geochronology of Permian magmatism

2020 ◽  
Vol 113 (1) ◽  
Author(s):  
Michel Ballèvre ◽  
Audrey Camonin ◽  
Paola Manzotti ◽  
Marc Poujol
Keyword(s):  
Early Stage ◽  
Western Alps ◽  
Geochemical Data ◽  
Alkaline Magmatism ◽  
Low Grade ◽  
Calc Alkaline ◽  
Alpine Orogeny ◽  
History Of ◽  
External Part ◽  
The One

Abstract The Briançonnais Domain (Western Alps) represented the thinned continental margin facing the Piemonte-Liguria Ocean, later shortened during the Alpine orogeny. In the external part of the External Briançonnais Domain (Zone Houillère), the Palaeozoic basement displays microdioritic intrusions into Carboniferous sediments and andesitic volcanics resting on top of the Carboniferous sediments. These magmatic rocks are analysed at two well-known localities (Guil volcanics and Combarine sill). Geochemical data show that the two occurrences belong to the same calc-alkaline association. LA-ICP-MS U–Pb ages have been obtained for the Guil volcanics (zircon: 291.3 ± 2.0 Ma and apatite: 287.5 ± 2.6 Ma), and the Combarine sill (zircon: 295.9 ± 2.6 Ma and apatite: 288.0 ± 4.5 Ma). These ages show that the calc-alkaline magmatism is of Early Permian age. During Alpine orogeny, a low-grade metamorphism, best recorded by lawsonite-bearing veins in the Guil andesites, took place at about 0.4 GPa, 350 °C in the External Briançonnais and Alpine metamorphism was not able to reset the U–Pb system in apatite. The Late Palaeozoic history of the Zone Houillère is identical to the one recorded in the Pinerolo Unit, located further East in the Dora-Maira Massif, and having experienced a garnet-blueschist metamorphism during the Alpine orogeny. The comparison of these two units allows for a better understanding of the link between the Palaeozoic basements, mostly subducted during the Alpine convergence, and their Mesozoic covers, generally detached at an early stage of the convergence history.

scholarly journals Geoquímica do gabro coronítico de Amparo, RJ

2002 ◽  
Vol 25 ◽  
pp. 44-67
Author(s):  
Isabel Pereira Ludka ◽  
Cristina Maria Wiedemann
Keyword(s):  
Major Elements ◽  
Geochemical Data ◽  
Mobile Belt ◽  
Olivine Gabbro ◽  
Geochemical Analysis ◽  
Minor And Trace Elements ◽  
Tholeiitic Magma ◽  
Basic Rocks ◽  
The Town ◽  
Janeiro State

The aim of this paper is to present geochemical data and some petrological aspects of the Amparo gabbroic (hyperite) body, located approximately 30 km east of the town, Nova Friburgo, Rio de Janeiro State. Ten samples of these basic rocks were analysed for major, minor and trace elements, and three of these for REE. The data obtained reflect the limited mineralogical range. The contents of the major elements indicate a sub-alkalic tholeiitic magma, as shown by modal analysis, which classified these rocks as an olivine gabbro. Geochemical analysis of the minor, trace and rare-earth elements shows abnormal incompatible enrichment, such as the high LREE, Ba and Sr contents. Similar results for other basic and ultrabasic intrusions are common in this portion of the Ribeira Mobile Belt.

Identifying pathfinder elements for gold in bulk-rock geochemical data from the Cripple Creek Au–Te deposit: a statistical approach

2020 ◽  
Vol 21 (1) ◽  
pp. geochem2020-048
Author(s):  
Irene M. Kadel-Harder ◽  
Paul G. Spry ◽  
Audrey L. McCombs ◽  
Haozhe Zhang
Keyword(s):  
Gold Mineralization ◽  
Correlation Coefficients ◽  
Principal Component ◽  
Hierarchical Cluster ◽  
Geochemical Data ◽  
Northwestern Part ◽  
Low Grade ◽  
Gold Telluride ◽  
Cripple Creek ◽  
Host Rocks

The Cripple Creek alkaline igneous rock-related, low-sulfidation epithermal gold telluride deposit, Colorado, is hosted in the 10 km wide Oligocene alkaline volcanic Cripple Creek diatreme in Proterozoic rocks. Gold occurs as native gold, Au-tellurides, and in the structure of arsenian pyrite, in potassically altered high-grade veins, and as disseminations in the host rocks.Correlation coefficients, principal component analysis, hierarchical cluster analysis and random forests were used to analyse major and trace element compositions of 995 rock samples primarily from low-grade gold mineralization in drill core from three currently operating pits (Wild Horse Extension, Globe Hill and Schist Island) in the northwestern part of the Cripple Creek diatreme. These methods suggest that Ag, As, Bi, Te and W are the best pathfinders to gold mineralization in low-grade disseminated ore. Although Mo correlates with gold in other studies and is spatially related to gold veins, molybdenite post-dated the formation of gold and is likely related to a late-stage porphyry overprint. These elements, in conjunction with mineralogical studies, indicate that tellurides, fluorite, quartz, carbonates, roscoelite, tennantite-tetrahedrite, pyrite, sphalerite, muscovite, monazite, bastnäsite and hübnerite serve as exploration guides to ore.

Characteristics of Grain Size Distribution on Beaches Sediment of Sumba Island, Nusa Tenggara Timur Based on Grainsize and Geochemical Data

2019 ◽  
Vol 20 (3) ◽  
pp. 153
Author(s):  
Septriono Hari Nugroho ◽  
Purna Sulastya Putra
Keyword(s):  
Grain Size ◽  
Trend Analysis ◽  
High Tide ◽  
Grain Size Analysis ◽  
Geochemical Data ◽  
Geochemical Analysis ◽  
Beach Sediment ◽  
Geochemical Elements ◽  
Coastal Deposits ◽  
Grain Size Trend Analysis

Study of beaches sediment characteristics were conducted on three beaches on Sumba Island, East Nusa Tenggara.The research is a part of Widya Nusantara Expedition which conducted by using Research Vessel of Baruna Jaya VIII. The aim of this study is to determine the characteristics of coastal deposits through the observation of grain size by using the grain size trend analysis approach (Grain Size Trend Analysis, commonly abbreviated as GSTA) and geochemical analysis. A total of 36 samples were taken on each coast representing high tide, transition and low tide along the coast. A grain size analysis was performed using a Malvern Mastersizer 2000 that was processed with Gradistat 4.0 software. Geochemical analysis was carried out using X-ray fluorescence spectrometry (XRF). The distribution of beach sediments is dominated by moderate sand - coarse sand and differences on content of geochemical elements (Ca, Sr, Fe, K, and Ti). The coastal conditions that are connected to the Indian Ocean (B1) have different characteristics from the beach that connected to the Sumba strait (B5 and B7). GSTA analysis showed sediment of Laboya Beach finer than sediment on Waikelo and Melolo Beach. Geochemical elements on Laboya Beach indicates different values than others. It indicates there are differences in the provenance and composition of sediment on the all three beaches. The supply of coastal deposits on these three beaches is influenced by the mechanism of precipitation of the walls and the processes of waves and rivers.Keywords: distribution, sediment, grainsize, geochemical, XRF, beach sediment.

Blueschist facies conditions in Tethyan passive margin metabasaltic rocks of the easternmost Lower Alpujarride Units (Internal Betic Zone, Spain)

2021 ◽  
Author(s):  
Eva Santamaría-Pérez ◽  
Idael Francisco Blanco-Quintero ◽  
Agustín Martín-Algarra ◽  
David Benavente ◽  
Juan Carlos Cañaveras ◽  
...  
Keyword(s):  
Thermal Gradient ◽  
Early Stage ◽  
Passive Margin ◽  
Geochemical Data ◽  
Geodynamic Setting ◽  
Low Grade ◽  
Alkaline Basalt ◽  
Metamorphic Overprint ◽  
Sedimentary Sequences ◽  
Basalt Composition

<p>Jurassic shallow-intrusive basic bodies within the Permian-Triassic Tethyan passive margin sedimentary sequences of the Lower Alpujarride units (Internal Betic Zone, Spain) locally show Alpine low-grade metamorphism in the greenschist and blueschist facies. A small sill-like mafic body near Redován town (Callosa Range) partially preserves igneous ophitic/subophitic texture and relics of augite, ferrohornblende-ferroedenite, kaersutite and K-feldspar (orthoclase). The metamorphic overprint corresponds to high-pressure and low-temperature mineral assemblages that comprise magnesioriebeckite, actinolite, albite, stilpnomelane, phengite and chlorite, with rutile, apatite and titanite as accessory minerals. Major and trace element geochemical data reveal igneous protoliths derived from magmas of alkaline basalt composition enriched in incompatible elements and E-MORB geochemical affinity. The intrusion emplacement occurred at shallow crustal levels in an extensional geodynamic setting (within-plate basalts) related to the breakoff of Pangea. Pressure-Temperature (P-T) conditions estimated by means of pseudosection calculations and the intersection of phengite (Si) and chlorite (Mg#) isopleths indicate a cold thermal gradient with calculated peak metamorphic conditions of ca. 8 kbar at 310 ºC. These conditions are consistent with metamorphism during burial down to ca. 24 km depth and a thermal gradient of ca. 13 ºC/km. Although the easternmost Lower Alpujarride units have been traditionally described as reaching only lower-greenschist to greenschist metamorphic peak conditions, the textures, mineral compositions and P-T conditions of the studied metagabbroic body reveal blueschist facies conditions that attest for a regional early stage (Eocene) of subduction of the lower Alpujarride units. This event predates the late Oligocene - early Miocene subduction-related metamorphism of the Intermediate and Upper Alpujarride units.</p>

Geochemical and mineralogical characteristics of beach sediments along the coast between Alanya and Silifke (southern Turkey)

Clay Minerals ◽  
2015 ◽  
Vol 50 (2) ◽  
pp. 233-248 ◽  
Author(s):  
M.G. Yalcin ◽  
M. Setti ◽  
F. Karakaya ◽  
E. Sacchi ◽  
N. Ilbeyli
Keyword(s):  
Grain Size ◽  
Trace Metals ◽  
Trace Metal ◽  
Water Content ◽  
Source Rocks ◽  
Geochemical Data ◽  
Metamorphic Rocks ◽  
Low Grade ◽  
Mineral Phases ◽  
Beach Sands

AbstractThe aim of this work was to determine the distribution of trace metals in the coastal sediments from the area between Silifke and Alanya (Turkey) and to investigate the sources of these elements, based on their mineralogical, petrographical and geochemical characteristics. Forty three samples were analysed for the determination of their water content, grain-size distribution, petrographical features and their chemical and mineralogical compositions. The samples had low water content, in agreement with the large sand grain size.The mineralogical composition reflects the complex geological setting of the area. The most abundant mineral phases are represented by calcite and dolomite, followed by quartz and mica. Chlorite, feldspar and other carbonates are present in lesser amounts, while kaolinite was detected in one sample only. All samples contain hematite, chromite, magnetite and goethite and one sample contained pyrite. Samples with high concentrations of trace metals, contained fragments of metamorphic rocks with pyroxene, amphibole, quartz and feldspar, whereas carbonates and opaque minerals were subordinate. Compared to literature data, the average concentrations of several elements and trace metals were great enough to be considered as possibly toxic, exceeding the Turkish higher acceptable limits. Geochemical data were treated statistically using Principal Component Analysis (PCA) to obtain evidence of their distribution and to identify any correlations.Based on the distribution of mineral phases, the area investigated was divided into different provinces, each characterized by the abundance of one, or more, tracer minerals. In the westernmost areas, between Alanya and Demirtas, the sediments indicate a provenance from dolomites or marbles. In the area between Demirtas and Gazipasa the provenance was from quartzites, clastic and metamorphic rocks and in the sector between Guney and Anamur, the sediments were derived mostly from low-grade metamorphic rocks, in particular metaschists and metabasites. The sediments in the area between Anamur and Ovacik, display variable source rocks and those between Ovacik and Silifke, were derived from limestones and, subordinately, clastic rocks.The trace-metal concentrations in beach sands appear to be related to the abundance of silicate minerals derived from weathering of the metamorphic-rock outcrops in the inland mountainous regions. In contrast, the trace-metal contents of the limestone- and dolomite-bearing beach sands were small.

scholarly journals Geochemical analysis for evaluating the paleoweathering, paleoclimate, and depositional environments of the siliciclastic Miocene-Pliocene sequence at Al-Rehaili area, Northern Jeddah, Saudi Arabia

2021 ◽  
Vol 14 (4) ◽  
Author(s):  
Faisal Alqahtani ◽  
Mohammed Khalil
Keyword(s):  
Chemical Weathering ◽  
Major And Trace Elements ◽  
Climatic Conditions ◽  
Depositional Environments ◽  
Geochemical Data ◽  
Geochemical Analysis ◽  
Climatic Control ◽  
Trace Elements Analysis ◽  
Area North ◽  
Semi Arid

AbstractGeochemical data and their various approaches are useful to evaluate the climatic control on the depositional environments. This study aims to evaluate the paleoweathering and plaeoclimate condition that have controls on the depositional environments of the Miocene to Pliocene siliciclastic sequence at Al-Rehaili area, north of Jeddah. To achieve this aim, selected sandstone samples were geochemically (major and trace elements analysis) and petrographically examined. The results of these analyses reveal that the examined sandstones were deposited in non-marine (fluvial/alluvial-lacustrine) environments and suffered from weak to intermediate chemical weathering and intense physical induration under semi-arid to semi-humid climatic conditions.

scholarly journals Supplemental Material: Nonclimatic and extrabasinal processes controlled pedogenesis in paleosols of the Paleocene Nacimiento Formation, New Mexico, USA

2021 ◽  
Author(s):  
Kevin M. Hobbs
Keyword(s):  
New Mexico ◽  
Statistical Analysis ◽  
Analysis Data ◽  
Geochemical Data ◽  
Geochemical Analysis ◽  
X Ray ◽  
Data Tables

Geochemical data tables, X-Ray diffractograms from paleosol B horizon materials, and results of statistical analysis of pedotype and geochemical analysis data.

Early Cambrian back-arc volcanism in the western Taurides, Turkey: implications for rifting along the northern Gondwanan margin

2005 ◽  
Vol 142 (5) ◽  
pp. 617-631 ◽  
Author(s):  
S. GÜRSU ◽  
M. C. GÖNCÜOGLU
Keyword(s):  
Oceanic Lithosphere ◽  
Tholeiitic Basalt ◽  
Central Anatolia ◽  
Geochemical Data ◽  
Low Grade ◽  
Early Cambrian ◽  
Spinel Lherzolite ◽  
Mafic Rocks ◽  
Clastic Rocks ◽  
Back Arc

The Lower Cambrian (Tommotian) Gögebakan Formation in western Central Anatolia is made up of slightly metamorphosed continental to shallow marine clastic rocks with pillowed and massive spilitic lavas and dolerite dykes. Spilitic lavas, commonly amygdaloidal, are albite- and pyroxene-phyric with the metamorphic mineral paragenesis albite+calcite+sericite±epidote±tremolite±chlorite. Dolerite dykes mainly include plagioclase and pyroxene as primary minerals and tremolite±epidote±chlorite as low-grade secondary minerals. Geochemical data show that the spilitic lavas and dolerite dykes are sub-alkaline, of oceanic tholeiitic basalt character and display a tholeiitic fractional trend, characterized by an increase in FeO/MgO and Zr and TiO2 in variation diagrams. They are characterized by relatively high Zr/Y (2–4.5), relatively high Th/Yb (0.15–1.0) and La/Nb (0.5–2.5). Both show marked negative Nb and Ti anomalies relative to Th and La (Ce), implying a subduction-related chemistry. Chondrite-normalized REE patterns display slight enrichment of light REE (spilitic lavas (La/Yb)N = 0.79–1.56; dolerite dykes (La/Yb)N = 0.89–3.50) fairly comparable with MORB. The geochemical similarity of the spilitic lavas and dolerite dykes suggests a co-genetic origin. La/Nb ratios of both types are slightly higher than average MORB values and were possibly formed in the early stages of back-arc basin development. Petrogenetic modelling suggests the mafic rocks of the formation were formed by 9% batch melting of spinel lherzolite in shallower depths (c. 60 km). Taken together the data suggest that the Early Cambrian mafic rocks of the Taurus units were developed in a back-arc basin along the northern edge of Gondwana above the southward-subducting oceanic lithosphere and may represent initial rifting that resulted in separation of the peri-Gondwanan terranes.

Geochemical and Sr-Nd isotopic characteristics of the lamprophyre in the Tethyan Himalaya, South Tibet

2020 ◽  
Author(s):  
Zhi-Chao Liu ◽  
Jian-Gang Wang ◽  
Xiao-Chi Liu
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Lithospheric Mantle ◽  
Indian Plate ◽  
Late Triassic ◽  
Geochemical Data ◽  
Low Grade ◽  
Northern Margin ◽  
Two Samples ◽  
Tethyan Himalaya

<p>A lamprophyre dyke has been found in Ramba area within the Tethyan Himalaya. It intruded into the Late Triassic low-grade metasedimentary rocks (Langjiexue Group) and show typical porphyritic textures, with phlogopite as the dominant phenocrysts. In this study, we performed phlogopite 40Ar/39Ar dating and whole-rock major and trace element as well as Sr and Nd isotope geochemical analyses on the lamprophyre. The <sup>40</sup>Ar/<sup>39</sup>Ar plateau ages (13.1 ± 0.2 Ma and 13.5 ± 0.2 Ma) of the phlogopites from two samples are both in excellent agreement with the inverse isochron ages of 13.1 ±0.3 Ma and 13.6 ± 0.3 Ma, recording the times at which the lamprophyre dyke has cooled below ~300 °C. The lamprophyre has low contents of SiO<sub>2</sub> (51.43–55.15 wt%) and Al<sub>2</sub>O<sub>3</sub> (11.10–11.85 wt%), high Fe<sub>2</sub>O<sub>3T</sub> (8.57–9.27 wt%) and MgO (9.14–9.49 wt %) contents with Mg<sup>#</sup> of 66–69, higher content of K<sub>2</sub>O (3.26–5.57 wt%) relative to Na<sub>2</sub>O (0.50–1.39 wt%) with K<sub>2</sub>O/Na<sub>2</sub>O of 2.3–11.1. Furthermore, the lamprophyre has high abundances of large ion lithophile elements (e.g., Rb, Ba, Sr), shows depletions in high field strength elements (e.g., Nb, Ta, Ti), and displays enrichment in light rare-earth elements over heavy rare earth elements with (La/Yb)<sub>N</sub> of 42.3~47.0. Besides, the lamprophyre is characterized by high initial <sup>87</sup>Sr/<sup>86</sup>Sr ratios of 0.7196~0.7204 and negative ε<sub>Nd</sub>(t) values of -10.7~-10.8. Geochemical data suggest that the Ramba lamprophyre was likely generated by partial melting of a metasomatized, phlogopite-bearing harzburgite lithospheric mantle source, followed by crystal fractionation and varying degree of crustal assimilation. The studied lamprophyre provides a window into the composition of the subcontinental lithospheric mantle (SCLM) in the northern margin of the Indian plate. We suggest that the northern Indian plate might be involved in the Andean-type orogeny from the subduction of the Proto-Tethys Ocean during Cambrian to Early Ordovician.</p>

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