The Experts below are selected from a list of 6648 Experts worldwide ranked by ideXlab platform

Alessandra Costanzo - One of the best experts on this subject based on the ideXlab platform.

  • fluid inclusion characteristics and molybdenite re os geochronology of the qulong porphyry copper molybdenum deposit tibet
    Mineralium Deposita, 2017
    Co-Authors: David Selby, M Feely, Alessandra Costanzo
    Abstract:

    The Qulong porphyry copper and molybdenum deposit is located at the southwest margin of the Lhasa Terrane and in the eastern region of the Gangdese magmatic belt. It represents China’s largest porphyry copper system, with ∼2200 million tonnes of ore comprising 0.5 % Cu and 0.03 % Mo. The mineralization is associated with Miocene granodiorite, monzogranite and quartz-diorite units, which intruded into Jurassic volcanic units in a post-collisional (Indian-Asian) tectonic setting. Field observations and Core Logging demonstrate the alteration and mineralization at Qulong are akin to typical porphyry copper systems in subduction settings, which comprise similar magmatic-hydrothermal, potassic, propylitic and phyllic alteration assemblages. Molybdenite Re-Os geochronology confirms the relative timeframe defined by field observations and Core Logging and indicates that the bulk copper and molybdenum at Qulong were deposited within 350,000 years: between 16.10 ± 0.06 [0.08] (without and with decay constant uncertainty) and 15.88 ± 0.06 [0.08] Ma. This duration for mineralization is in direct contrast to a long-lived intrusive episode associated with mineralization based on previous zircon U-Pb data. Our fluid inclusion study indicates that the ore-forming fluid was oxidized and contained Na, K, Ca, Fe, Cu, Mo, Cl and S. The magmatic-hydrothermal transition occurred at ∼425 °C under lithostatic pressure, while potassic, propylitic and phyllic alteration occurred at hydrostatic pressure with temperature progressively decreasing from 425 to 280 °C. The fluid inclusion data presented here suggests that there has been ∼2.3 km of erosion at Qulong after its formation, and this erosion may be related to regional uplift of the Lhasa Terrane.

David Selby - One of the best experts on this subject based on the ideXlab platform.

  • fluid inclusion characteristics and molybdenite re os geochronology of the qulong porphyry copper molybdenum deposit tibet
    Mineralium Deposita, 2017
    Co-Authors: David Selby, M Feely, Alessandra Costanzo
    Abstract:

    The Qulong porphyry copper and molybdenum deposit is located at the southwest margin of the Lhasa Terrane and in the eastern region of the Gangdese magmatic belt. It represents China’s largest porphyry copper system, with ∼2200 million tonnes of ore comprising 0.5 % Cu and 0.03 % Mo. The mineralization is associated with Miocene granodiorite, monzogranite and quartz-diorite units, which intruded into Jurassic volcanic units in a post-collisional (Indian-Asian) tectonic setting. Field observations and Core Logging demonstrate the alteration and mineralization at Qulong are akin to typical porphyry copper systems in subduction settings, which comprise similar magmatic-hydrothermal, potassic, propylitic and phyllic alteration assemblages. Molybdenite Re-Os geochronology confirms the relative timeframe defined by field observations and Core Logging and indicates that the bulk copper and molybdenum at Qulong were deposited within 350,000 years: between 16.10 ± 0.06 [0.08] (without and with decay constant uncertainty) and 15.88 ± 0.06 [0.08] Ma. This duration for mineralization is in direct contrast to a long-lived intrusive episode associated with mineralization based on previous zircon U-Pb data. Our fluid inclusion study indicates that the ore-forming fluid was oxidized and contained Na, K, Ca, Fe, Cu, Mo, Cl and S. The magmatic-hydrothermal transition occurred at ∼425 °C under lithostatic pressure, while potassic, propylitic and phyllic alteration occurred at hydrostatic pressure with temperature progressively decreasing from 425 to 280 °C. The fluid inclusion data presented here suggests that there has been ∼2.3 km of erosion at Qulong after its formation, and this erosion may be related to regional uplift of the Lhasa Terrane.

M Feely - One of the best experts on this subject based on the ideXlab platform.

  • fluid inclusion characteristics and molybdenite re os geochronology of the qulong porphyry copper molybdenum deposit tibet
    Mineralium Deposita, 2017
    Co-Authors: David Selby, M Feely, Alessandra Costanzo
    Abstract:

    The Qulong porphyry copper and molybdenum deposit is located at the southwest margin of the Lhasa Terrane and in the eastern region of the Gangdese magmatic belt. It represents China’s largest porphyry copper system, with ∼2200 million tonnes of ore comprising 0.5 % Cu and 0.03 % Mo. The mineralization is associated with Miocene granodiorite, monzogranite and quartz-diorite units, which intruded into Jurassic volcanic units in a post-collisional (Indian-Asian) tectonic setting. Field observations and Core Logging demonstrate the alteration and mineralization at Qulong are akin to typical porphyry copper systems in subduction settings, which comprise similar magmatic-hydrothermal, potassic, propylitic and phyllic alteration assemblages. Molybdenite Re-Os geochronology confirms the relative timeframe defined by field observations and Core Logging and indicates that the bulk copper and molybdenum at Qulong were deposited within 350,000 years: between 16.10 ± 0.06 [0.08] (without and with decay constant uncertainty) and 15.88 ± 0.06 [0.08] Ma. This duration for mineralization is in direct contrast to a long-lived intrusive episode associated with mineralization based on previous zircon U-Pb data. Our fluid inclusion study indicates that the ore-forming fluid was oxidized and contained Na, K, Ca, Fe, Cu, Mo, Cl and S. The magmatic-hydrothermal transition occurred at ∼425 °C under lithostatic pressure, while potassic, propylitic and phyllic alteration occurred at hydrostatic pressure with temperature progressively decreasing from 425 to 280 °C. The fluid inclusion data presented here suggests that there has been ∼2.3 km of erosion at Qulong after its formation, and this erosion may be related to regional uplift of the Lhasa Terrane.

Erwan Gloaguen - One of the best experts on this subject based on the ideXlab platform.

  • using machine learning to estimate a key missing geochemical variable in mining exploration application of the random forest algorithm to multi sensor Core Logging data
    Journal of Geochemical Exploration, 2019
    Co-Authors: Nathalie Schnitzler, Pierresimon Ross, Erwan Gloaguen
    Abstract:

    Abstract Mining exploration increasingly relies on large, multivariate databases storing data ranging from drill Core geochemical analysis to geophysical data or geological descriptions. Utilizing these large datasets to their full potential implies the use of multivariate statistical analysis such as machine learning. The Random Forest algorithm has proved its efficiency in mining applications. In this study we use it to estimate a key geochemical element, sodium, using a multivariate chemo-physical dataset measured on drill Cores in the Matagami mining district of Quebec, Canada. Sodium is important to characterize hydrothermal alteration in volcanogenic massive sulfide settings, since Na depletion can be used to vector towards ore, but this element is not readily measured by portable X-ray fluorescence (pXRF). We first test the algorithm on a database of over 8000 traditional laboratory geochemistry analyses and find a correlation of 0.95 between estimated and measured Na. We then test the algorithm on the multi-sensor Core Logging data, including density, magnetic susceptibility, and 15 geochemical elements by pXRF, but borrowing Na from traditional geochemistry (n = 260). This yields correlations of 0.66 to 0.75 depending on the training and testing sets. Finally the algorithm is applied to the whole multiparameter database (n = 9675) to estimate Na downCore. There is a good general correspondence with the downCore Na patterns seen through traditional geochemistry, and the estimated Na which has much greater spatial resolution. Random Forest appears to be a very good estimation tool when using large amounts of data and variables, as it uses all variables and automatically prioritizes the most useful. This method also allows visualization of the weight of each variable in the estimation. Future studies should compare RF with other methods.

  • lithological discrimination based on statistical analysis of multi sensor drill Core Logging data in the matagami vms district quebec canada
    Ore Geology Reviews, 2017
    Co-Authors: Bastien Fresia, Pierresimon Ross, Erwan Gloaguen, Alexandre Bourke
    Abstract:

    In mineral exploration, traditional Core Logging is largely based on the visual inspection of drilled Cores, a process which is often subjective and non-reproducible. However, a number of physical, chemical and mineralogical properties of rocks can now be measured at high spatial resolution on drill Cores. The resulting large multiparameter databases can help geologists to quantitatively discriminate between lithologies, study hydrothermal alteration, and potentially vector towards mineralization. Multivariate statistical methods are important tools to assist geologists in interpreting such large databases. We present an application of model-based cluster analysis in the Matagami base metal mining district, more specifically to improve lithological discrimination at the zinc-rich Bracemac and McLeod volcanogenic massive sulfide (VMS) deposits. The model-based cluster analysis method is able to efficiently discriminate different geological units encountered, even in cases where two units are visually similar or in the presence of strong hydrothermal alteration.

  • using stochastic crosshole seismic velocity tomography and bayesian simulation to estimate ni grades case study from voisey s bay canada
    Journal of Applied Geophysics, 2012
    Co-Authors: Lorenzo Perozzi, Erwan Gloaguen, Stephane Rondenay, Glenn Mcdowell
    Abstract:

    Modeling of grades is a key step and the major source of error in appraisal stage of mining projects. We used a geostatistical approach to explicitly integrate seismic travel time data, as well as acoustic and Core Logging data into the estimation of nickel grades in the Voisey's Bay deposit. Firstly, the crosshole seismic travel times are inverted using a stochastic tomographic algorithm. This algorithm allows for the inclusion of acoustic log data and seismic covariance into the inverse problem, leading to high-resolution velocity tomographic images of the orebody. Secondly, grade realizations are generated using a Bayesian sequential Gaussian simulation algorithm, which integrates the ore grades measured on the Core logs and the previously inverted tomographic data. The application of the presented method to the Voisey's Bay deposit yields an improved knowledge of the geology setting and generates grade models with realistic spatial variability compared to conventional methods.

Strandvik, Stein Oddvar - One of the best experts on this subject based on the ideXlab platform.

  • Characterization and engineering properties of the NGTS Onsøy soft clay site
    2019
    Co-Authors: Gundersen Aleksander, Hansen Ragnhild, Lunne Tom, Heureux L Jean-sebastien, Strandvik, Stein Oddvar
    Abstract:

    In the 1960s, NGI investigated numerous potential research sites and established the first Onsøy soft clay site in 1968. In 2016, the NGTS project established five research sites, one of which is the NGTS Onsøy soft clay site. The purpose of this paper is to provide a reference for further in-situ and laboratory testing at the site and easy access to high-quality soil investigation data. The paper interprets the soil conditions providing engineering soil properties, comments on data reliability and quality, and correlations between different soil parameters where appropriate. The lightly overconsolidated soft clay site has been characterized based on extensive in-situ and laboratory testing. In-situ methods include electrical resistivity tomography, multichannel analysis of surface waves, total soundings, rotary pressure soundings, cone penetration testing with and without seismic and electrical resistivity measurements, dilatometer with seismic measurements, self-boring pressuremeter, electric piezometers, thermistor string, hydraulic fracture testing and earth pressure cells. Soil samples were obtained using Sherbrook block sampler, Geonor φ 72 mm piston sampler, Geonor φ 54 mm composite piston sampler and hydraulic piston and push samplers with liners. Laboratory tests include multi-sensor Core Logging, index testing, cyclic and monotonic, consolidated and unconsolidated triaxial tests, bender element tests, oedometer tests with constant rate of strain and incremental loading and direct simple shear tests

  • Characterization and engineering properties of the NGTS Onsøy soft clay site
    'American Institute of Mathematical Sciences (AIMS)', 2019
    Co-Authors: Gundersen Aleksander, Hansen Ragnhild, Lunne Tom, Heureux L Jean-sebastien, Strandvik, Stein Oddvar
    Abstract:

    In the 1960s, NGI investigated numerous potential research sites and established the first Onsøy soft clay site in 1968. In 2016, the NGTS project established five research sites, one of which is the NGTS Onsøy soft clay site. The purpose of this paper is to provide a reference for further in-situ and laboratory testing at the site and easy access to high-quality soil investigation data. The paper interprets the soil conditions providing engineering soil properties, comments on data reliability and quality, and correlations between different soil parameters where appropriate. The lightly overconsolidated soft clay site has been characterized based on extensive in-situ and laboratory testing. In-situ methods include electrical resistivity tomography, multichannel analysis of surface waves, total soundings, rotary pressure soundings, cone penetration testing with and without seismic and electrical resistivity measurements, dilatometer with seismic measurements, self-boring pressuremeter, electric piezometers, thermistor string, hydraulic fracture testing and earth pressure cells. Soil samples were obtained using Sherbrook block sampler, Geonor φ 72 mm piston sampler, Geonor φ 54 mm composite piston sampler and hydraulic piston and push samplers with liners. Laboratory tests include multi-sensor Core Logging, index testing, cyclic and monotonic, consolidated and unconsolidated triaxial tests, bender element tests, oedometer tests with constant rate of strain and incremental loading and direct simple shear tests.Characterization and engineering properties of the NGTS Onsøy soft clay sit