The Experts below are selected from a list of 291 Experts worldwide ranked by ideXlab platform
Mao Jingwen - One of the best experts on this subject based on the ideXlab platform.
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age and geochemistry of granites in gejiu area yunnan province sw china constraints on their petrogenesis and tectonic setting
Lithos, 2010Co-Authors: Cheng Yanbo, Mao JingwenAbstract:Gejiu is one of the largest polymetallic tin ore districts in the world. Located at the westernmost end of the South China tungsten–tin province (or Nanling tungsten–tin province), it is a granite-related (Gejiu granite) magmatic-hydrothermal system. Nine samples from two phases of Gejiu granitic intrusions have been analyzed by SHRIMP and/or LA-ICPMS zircon U–Pb techniques, yielding ages ranging from 77.4 ± 2.5 Ma to 85.0 ± 0.85 Ma. Whole rock Analysis shows that both phases are high-K and alkali-rich granites and their ACNK values fall mainly into a small range of 1.0–1.1. Moreover, Harker diagrams indicate that granites experienced strong fractional crystallization during magmatic evolution. Most granites display relative enrichment in LREE and strong Eu depletion. The whole rock average (eNd(t)) values of the Gejiu granites vary from − 9.3 to − 6.9, whereas a range of − 8.12 < (eHf(t)) < 1.21 is defined by magmatic zircons. Sr–Nd–Hf isotope data indicate that the granites have been mainly derived from crustal melts with minor input of mantle component. Two stage Nd and Hf model ages, together with isotopic characteristics, indicate that the Gejiu granite magmas were possibly derived from partial melting of Mesoproterozoic continental crust, with minor input of mantle-derived melts, followed by extensive fractional crystallization.
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Age and geochemistry of granites in Gejiu area, Yunnan province, SW China: Constraints on their petrogenesis and tectonic setting
Lithos, 2010Co-Authors: Cheng Yanbo, Mao JingwenAbstract:Gejiu is one of the largest polymetallic tin ore districts in the world. Located at the westernmost end of the South China tungsten–tin province (or Nanling tungsten–tin province), it is a granite-related (Gejiu granite) magmatic-hydrothermal system. Nine samples from two phases of Gejiu granitic intrusions have been analyzed by SHRIMP and/or LA-ICPMS zircon U–Pb techniques, yielding ages ranging from 77.4 ± 2.5 Ma to 85.0 ± 0.85 Ma. Whole rock Analysis shows that both phases are high-K and alkali-rich granites and their ACNK values fall mainly into a small range of 1.0–1.1. Moreover, Harker diagrams indicate that granites experienced strong fractional crystallization during magmatic evolution. Most granites display relative enrichment in LREE and strong Eu depletion. The whole rock average (εNd(t)) values of the Gejiu granites vary from − 9.3 to − 6.9, whereas a range of − 8.12 < (εHf(t)) < 1.21 is defined by magmatic zircons. Sr–Nd–Hf isotope data indicate that the granites have been mainly derived from crustal melts with minor input of mantle component. Two stage Nd and Hf model ages, together with isotopic characteristics, indicate that the Gejiu granite magmas were possibly derived from partial melting of Mesoproterozoic continental crust, with minor input of mantle-derived melts, followed by extensive fractional crystallization
Anja Josties - One of the best experts on this subject based on the ideXlab platform.
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Platinum-group element distribution in base-metal sulfides of the UG2 chromitite, Bushveld Complex, South Africa—a reconnaissance study
Mineralium Deposita, 2014Co-Authors: Inga Osbahr, Thomas Oberthur, Reiner Klemd, Anja JostiesAbstract:Two drill cores of the UG2 chromitite from the eastern and western Bushveld Complex were studied by Whole-Rock Analysis, ore microscopy, SEM/Mineral Liberation Analysis (MLA), and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) Analysis. The top and base of the UG2 main seam have the highest bulk-rock Pd and Pt concentrations. Sulfides mostly occur as aggregates of pentlandite, chalcopyrite, and rare pyrrhotite and pyrite or as individual grains associated mostly with chromite grains. In situ LA-ICP-MS analyses reveal that pentlandite carries distinctly elevated platinum-group element (PGE) contents. In contrast, pyrrhotite and chalcopyrite contain very low PGE concentrations. Pentlandite shows average maximum values of 350–1,000 ppm Pd, 200 ppm Rh, 130–175 ppm Ru, 20 ppm Os, and 150 ppm Ir, and is the principal host of Pd and Rh in the studied ores of the UG2. Mass balance calculations were conducted for samples representing the UG2 main seam of the drill core DT46, eastern Bushveld. Pentlandite consistently hosts elevated contents of the Whole-Rock Pd (up to 55 %) and Rh (up to 46 %), and erratic contents of Os (up to 50 %), Ir (2 to 17 %), and Ru (1–39 %). Platinum-group mineral (PGM) investigations support these mass balance results; most of the PGM are Pt-dominant such as braggite/cooperite and Pt-Fe alloys or laurite (carrying elevated concentrations of Os and Ir). Palladium and Rh-bearing PGM are rare. Both PGE concentrations and their distribution in base-metal sulfides (BMS) in the UG2 largely resemble that of the Merensky Reef, as most of the Pd and Rh are incorporated in pentlandite, whereas pyrrhotite, chalcopyrite, and pyrite are almost devoid of PGE.
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platinum group element distribution in base metal sulfides of the ug2 chromitite bushveld complex south africa a reconnaissance study
Mineralium Deposita, 2014Co-Authors: Inga Osbahr, Thomas Oberthur, Reiner Klemd, Anja JostiesAbstract:Two drill cores of the UG2 chromitite from the eastern and western Bushveld Complex were studied by Whole-Rock Analysis, ore microscopy, SEM/Mineral Liberation Analysis (MLA), and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) Analysis. The top and base of the UG2 main seam have the highest bulk-rock Pd and Pt concentrations. Sulfides mostly occur as aggregates of pentlandite, chalcopyrite, and rare pyrrhotite and pyrite or as individual grains associated mostly with chromite grains. In situ LA-ICP-MS analyses reveal that pentlandite carries distinctly elevated platinum-group element (PGE) contents. In contrast, pyrrhotite and chalcopyrite contain very low PGE concentrations. Pentlandite shows average maximum values of 350–1,000 ppm Pd, 200 ppm Rh, 130–175 ppm Ru, 20 ppm Os, and 150 ppm Ir, and is the principal host of Pd and Rh in the studied ores of the UG2. Mass balance calculations were conducted for samples representing the UG2 main seam of the drill core DT46, eastern Bushveld. Pentlandite consistently hosts elevated contents of the Whole-Rock Pd (up to 55 %) and Rh (up to 46 %), and erratic contents of Os (up to 50 %), Ir (2 to 17 %), and Ru (1–39 %). Platinum-group mineral (PGM) investigations support these mass balance results; most of the PGM are Pt-dominant such as braggite/cooperite and Pt-Fe alloys or laurite (carrying elevated concentrations of Os and Ir). Palladium and Rh-bearing PGM are rare. Both PGE concentrations and their distribution in base-metal sulfides (BMS) in the UG2 largely resemble that of the Merensky Reef, as most of the Pd and Rh are incorporated in pentlandite, whereas pyrrhotite, chalcopyrite, and pyrite are almost devoid of PGE.
Cheng Yanbo - One of the best experts on this subject based on the ideXlab platform.
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age and geochemistry of granites in gejiu area yunnan province sw china constraints on their petrogenesis and tectonic setting
Lithos, 2010Co-Authors: Cheng Yanbo, Mao JingwenAbstract:Gejiu is one of the largest polymetallic tin ore districts in the world. Located at the westernmost end of the South China tungsten–tin province (or Nanling tungsten–tin province), it is a granite-related (Gejiu granite) magmatic-hydrothermal system. Nine samples from two phases of Gejiu granitic intrusions have been analyzed by SHRIMP and/or LA-ICPMS zircon U–Pb techniques, yielding ages ranging from 77.4 ± 2.5 Ma to 85.0 ± 0.85 Ma. Whole rock Analysis shows that both phases are high-K and alkali-rich granites and their ACNK values fall mainly into a small range of 1.0–1.1. Moreover, Harker diagrams indicate that granites experienced strong fractional crystallization during magmatic evolution. Most granites display relative enrichment in LREE and strong Eu depletion. The whole rock average (eNd(t)) values of the Gejiu granites vary from − 9.3 to − 6.9, whereas a range of − 8.12 < (eHf(t)) < 1.21 is defined by magmatic zircons. Sr–Nd–Hf isotope data indicate that the granites have been mainly derived from crustal melts with minor input of mantle component. Two stage Nd and Hf model ages, together with isotopic characteristics, indicate that the Gejiu granite magmas were possibly derived from partial melting of Mesoproterozoic continental crust, with minor input of mantle-derived melts, followed by extensive fractional crystallization.
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Age and geochemistry of granites in Gejiu area, Yunnan province, SW China: Constraints on their petrogenesis and tectonic setting
Lithos, 2010Co-Authors: Cheng Yanbo, Mao JingwenAbstract:Gejiu is one of the largest polymetallic tin ore districts in the world. Located at the westernmost end of the South China tungsten–tin province (or Nanling tungsten–tin province), it is a granite-related (Gejiu granite) magmatic-hydrothermal system. Nine samples from two phases of Gejiu granitic intrusions have been analyzed by SHRIMP and/or LA-ICPMS zircon U–Pb techniques, yielding ages ranging from 77.4 ± 2.5 Ma to 85.0 ± 0.85 Ma. Whole rock Analysis shows that both phases are high-K and alkali-rich granites and their ACNK values fall mainly into a small range of 1.0–1.1. Moreover, Harker diagrams indicate that granites experienced strong fractional crystallization during magmatic evolution. Most granites display relative enrichment in LREE and strong Eu depletion. The whole rock average (εNd(t)) values of the Gejiu granites vary from − 9.3 to − 6.9, whereas a range of − 8.12 < (εHf(t)) < 1.21 is defined by magmatic zircons. Sr–Nd–Hf isotope data indicate that the granites have been mainly derived from crustal melts with minor input of mantle component. Two stage Nd and Hf model ages, together with isotopic characteristics, indicate that the Gejiu granite magmas were possibly derived from partial melting of Mesoproterozoic continental crust, with minor input of mantle-derived melts, followed by extensive fractional crystallization
Inga Osbahr - One of the best experts on this subject based on the ideXlab platform.
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Platinum-group element distribution in base-metal sulfides of the UG2 chromitite, Bushveld Complex, South Africa—a reconnaissance study
Mineralium Deposita, 2014Co-Authors: Inga Osbahr, Thomas Oberthur, Reiner Klemd, Anja JostiesAbstract:Two drill cores of the UG2 chromitite from the eastern and western Bushveld Complex were studied by Whole-Rock Analysis, ore microscopy, SEM/Mineral Liberation Analysis (MLA), and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) Analysis. The top and base of the UG2 main seam have the highest bulk-rock Pd and Pt concentrations. Sulfides mostly occur as aggregates of pentlandite, chalcopyrite, and rare pyrrhotite and pyrite or as individual grains associated mostly with chromite grains. In situ LA-ICP-MS analyses reveal that pentlandite carries distinctly elevated platinum-group element (PGE) contents. In contrast, pyrrhotite and chalcopyrite contain very low PGE concentrations. Pentlandite shows average maximum values of 350–1,000 ppm Pd, 200 ppm Rh, 130–175 ppm Ru, 20 ppm Os, and 150 ppm Ir, and is the principal host of Pd and Rh in the studied ores of the UG2. Mass balance calculations were conducted for samples representing the UG2 main seam of the drill core DT46, eastern Bushveld. Pentlandite consistently hosts elevated contents of the Whole-Rock Pd (up to 55 %) and Rh (up to 46 %), and erratic contents of Os (up to 50 %), Ir (2 to 17 %), and Ru (1–39 %). Platinum-group mineral (PGM) investigations support these mass balance results; most of the PGM are Pt-dominant such as braggite/cooperite and Pt-Fe alloys or laurite (carrying elevated concentrations of Os and Ir). Palladium and Rh-bearing PGM are rare. Both PGE concentrations and their distribution in base-metal sulfides (BMS) in the UG2 largely resemble that of the Merensky Reef, as most of the Pd and Rh are incorporated in pentlandite, whereas pyrrhotite, chalcopyrite, and pyrite are almost devoid of PGE.
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platinum group element distribution in base metal sulfides of the ug2 chromitite bushveld complex south africa a reconnaissance study
Mineralium Deposita, 2014Co-Authors: Inga Osbahr, Thomas Oberthur, Reiner Klemd, Anja JostiesAbstract:Two drill cores of the UG2 chromitite from the eastern and western Bushveld Complex were studied by Whole-Rock Analysis, ore microscopy, SEM/Mineral Liberation Analysis (MLA), and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) Analysis. The top and base of the UG2 main seam have the highest bulk-rock Pd and Pt concentrations. Sulfides mostly occur as aggregates of pentlandite, chalcopyrite, and rare pyrrhotite and pyrite or as individual grains associated mostly with chromite grains. In situ LA-ICP-MS analyses reveal that pentlandite carries distinctly elevated platinum-group element (PGE) contents. In contrast, pyrrhotite and chalcopyrite contain very low PGE concentrations. Pentlandite shows average maximum values of 350–1,000 ppm Pd, 200 ppm Rh, 130–175 ppm Ru, 20 ppm Os, and 150 ppm Ir, and is the principal host of Pd and Rh in the studied ores of the UG2. Mass balance calculations were conducted for samples representing the UG2 main seam of the drill core DT46, eastern Bushveld. Pentlandite consistently hosts elevated contents of the Whole-Rock Pd (up to 55 %) and Rh (up to 46 %), and erratic contents of Os (up to 50 %), Ir (2 to 17 %), and Ru (1–39 %). Platinum-group mineral (PGM) investigations support these mass balance results; most of the PGM are Pt-dominant such as braggite/cooperite and Pt-Fe alloys or laurite (carrying elevated concentrations of Os and Ir). Palladium and Rh-bearing PGM are rare. Both PGE concentrations and their distribution in base-metal sulfides (BMS) in the UG2 largely resemble that of the Merensky Reef, as most of the Pd and Rh are incorporated in pentlandite, whereas pyrrhotite, chalcopyrite, and pyrite are almost devoid of PGE.
Francisco J. Luque - One of the best experts on this subject based on the ideXlab platform.
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quantifying aluminium phosphate sulphate minerals as markers of acidic conditions during the permian triassic transition in the iberian ranges e spain
Chemical Geology, 2016Co-Authors: Violeta Borruelabadia, Ana Belen Galanabellan, Raúl De La Horra, José F. Barrenechea, Jacinto Alonsoazcarate, Francisco J. Luque, Jose LopezgomezAbstract:Abstract In this paper, a method based on element mapping of randomly selected areas of thin sections on electron microprobe is proposed to quantify the relative contents of strontium-rich hydrated aluminium phosphate-sulphate (APS) minerals in siliciclastic continental sedimentary rocks. The main problems for these minerals to be quantified are related to their small size, low concentrations, and optical properties. By comparing the element maps obtained for the rocks in the study area of the Iberian Ranges (E Spain) with the results of whole rock Analysis and with factors indicating the presence of life (bioturbation, palaeosols, and macro-plant remains), it has been possible to correlate relatively high levels of APS minerals in the first sedimentary record (Canizar Formation) after the Permian–Triassic boundary, with the lack of living organisms. The APS are related to early diagenetic phases precipitated at low pH conditions and are therefore markers of formation in an acidic environment. Our findings suggest a long period of sustained acidic conditions followed by an environmental change linked with the recovery of life and with lower APS mineral contents. This change is detected at the top of the Canizar Formation, at the end of the Spathian. The method proposed could be used as a tool to address the environmental changes that took place during the Permian–Triassic transition in continental environments.
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Quantifying aluminium phosphate–sulphate minerals as markers of acidic conditions during the Permian–Triassic transition in the Iberian Ranges, E Spain
Chemical Geology, 2016Co-Authors: Violeta Borruel-abadía, Jacinto Alonso-azcárate, Raúl De La Horra, Ana Belén Galán-abellán, José F. Barrenechea, Francisco J. Luque, José López-gómezAbstract:Abstract In this paper, a method based on element mapping of randomly selected areas of thin sections on electron microprobe is proposed to quantify the relative contents of strontium-rich hydrated aluminium phosphate-sulphate (APS) minerals in siliciclastic continental sedimentary rocks. The main problems for these minerals to be quantified are related to their small size, low concentrations, and optical properties. By comparing the element maps obtained for the rocks in the study area of the Iberian Ranges (E Spain) with the results of whole rock Analysis and with factors indicating the presence of life (bioturbation, palaeosols, and macro-plant remains), it has been possible to correlate relatively high levels of APS minerals in the first sedimentary record (Canizar Formation) after the Permian–Triassic boundary, with the lack of living organisms. The APS are related to early diagenetic phases precipitated at low pH conditions and are therefore markers of formation in an acidic environment. Our findings suggest a long period of sustained acidic conditions followed by an environmental change linked with the recovery of life and with lower APS mineral contents. This change is detected at the top of the Canizar Formation, at the end of the Spathian. The method proposed could be used as a tool to address the environmental changes that took place during the Permian–Triassic transition in continental environments.