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Alasdair Skelton - One of the best experts on this subject based on the ideXlab platform.
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fluid rock reactions in the 1 3 ga siderite Carbonatite of the gronnedal ika alkaline complex southwest greenland
Contributions to Mineralogy and Petrology, 2018Co-Authors: E Ranta, Gabrielle Stockmann, Thomas Wagner, Tobias Fusswinkel, Erik Sturkell, Elin Tollefsen, Alasdair SkeltonAbstract:Petrogenetic studies of Carbonatites are challenging, because Carbonatite mineral assemblages and mineral chemistry typically reflect both variable pressure–temperature conditions during crystallization and fluid–rock interaction caused by magmatic–hydrothermal fluids. However, this complexity results in recognizable alteration textures and trace-element signatures in the mineral archive that can be used to reconstruct the magmatic evolution and fluid–rock interaction history of Carbonatites. We present new LA–ICP–MS trace-element data for magnetite, calcite, siderite, and ankerite–dolomite–kutnohorite from the iron-rich Carbonatites of the 1.3 Ga Gronnedal–Ika alkaline complex, Southwest Greenland. We use these data, in combination with detailed cathodoluminescence imaging, to identify magmatic and secondary geochemical fingerprints preserved in these minerals. The chemical and textural gradients show that a 55 m-thick basaltic dike that crosscuts the Carbonatite intrusion has acted as the pathway for hydrothermal fluids enriched in F and CO2, which have caused mobilization of the LREEs, Nb, Ta, Ba, Sr, Mn, and P. These fluids reacted with and altered the composition of the surrounding Carbonatites up to a distance of 40 m from the dike contact and caused formation of magnetite through oxidation of siderite. Our results can be used for discrimination between primary magmatic minerals and later alteration-related assemblages in Carbonatites in general, which can lead to a better understanding of how these rare rocks are formed. Our data provide evidence that siderite-bearing ferroCarbonatites can form during late stages of calciocarbonatitic magma evolution.
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Fluid–rock reactions in the 1.3 Ga siderite Carbonatite of the Grønnedal–Íka alkaline complex, Southwest Greenland
Contributions to Mineralogy and Petrology, 2018Co-Authors: E Ranta, Gabrielle Stockmann, Thomas Wagner, Tobias Fusswinkel, Erik Sturkell, Elin Tollefsen, Alasdair SkeltonAbstract:Petrogenetic studies of Carbonatites are challenging, because Carbonatite mineral assemblages and mineral chemistry typically reflect both variable pressure–temperature conditions during crystallization and fluid–rock interaction caused by magmatic–hydrothermal fluids. However, this complexity results in recognizable alteration textures and trace-element signatures in the mineral archive that can be used to reconstruct the magmatic evolution and fluid–rock interaction history of Carbonatites. We present new LA–ICP–MS trace-element data for magnetite, calcite, siderite, and ankerite–dolomite–kutnohorite from the iron-rich Carbonatites of the 1.3 Ga Grønnedal–Íka alkaline complex, Southwest Greenland. We use these data, in combination with detailed cathodoluminescence imaging, to identify magmatic and secondary geochemical fingerprints preserved in these minerals. The chemical and textural gradients show that a 55 m-thick basaltic dike that crosscuts the Carbonatite intrusion has acted as the pathway for hydrothermal fluids enriched in F and CO_2, which have caused mobilization of the LREEs, Nb, Ta, Ba, Sr, Mn, and P. These fluids reacted with and altered the composition of the surrounding Carbonatites up to a distance of 40 m from the dike contact and caused formation of magnetite through oxidation of siderite. Our results can be used for discrimination between primary magmatic minerals and later alteration-related assemblages in Carbonatites in general, which can lead to a better understanding of how these rare rocks are formed. Our data provide evidence that siderite-bearing ferroCarbonatites can form during late stages of calciocarbonatitic magma evolution.
E Ranta - One of the best experts on this subject based on the ideXlab platform.
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fluid rock reactions in the 1 3 ga siderite Carbonatite of the gronnedal ika alkaline complex southwest greenland
Contributions to Mineralogy and Petrology, 2018Co-Authors: E Ranta, Gabrielle Stockmann, Thomas Wagner, Tobias Fusswinkel, Erik Sturkell, Elin Tollefsen, Alasdair SkeltonAbstract:Petrogenetic studies of Carbonatites are challenging, because Carbonatite mineral assemblages and mineral chemistry typically reflect both variable pressure–temperature conditions during crystallization and fluid–rock interaction caused by magmatic–hydrothermal fluids. However, this complexity results in recognizable alteration textures and trace-element signatures in the mineral archive that can be used to reconstruct the magmatic evolution and fluid–rock interaction history of Carbonatites. We present new LA–ICP–MS trace-element data for magnetite, calcite, siderite, and ankerite–dolomite–kutnohorite from the iron-rich Carbonatites of the 1.3 Ga Gronnedal–Ika alkaline complex, Southwest Greenland. We use these data, in combination with detailed cathodoluminescence imaging, to identify magmatic and secondary geochemical fingerprints preserved in these minerals. The chemical and textural gradients show that a 55 m-thick basaltic dike that crosscuts the Carbonatite intrusion has acted as the pathway for hydrothermal fluids enriched in F and CO2, which have caused mobilization of the LREEs, Nb, Ta, Ba, Sr, Mn, and P. These fluids reacted with and altered the composition of the surrounding Carbonatites up to a distance of 40 m from the dike contact and caused formation of magnetite through oxidation of siderite. Our results can be used for discrimination between primary magmatic minerals and later alteration-related assemblages in Carbonatites in general, which can lead to a better understanding of how these rare rocks are formed. Our data provide evidence that siderite-bearing ferroCarbonatites can form during late stages of calciocarbonatitic magma evolution.
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Fluid–rock reactions in the 1.3 Ga siderite Carbonatite of the Grønnedal–Íka alkaline complex, Southwest Greenland
Contributions to Mineralogy and Petrology, 2018Co-Authors: E Ranta, Gabrielle Stockmann, Thomas Wagner, Tobias Fusswinkel, Erik Sturkell, Elin Tollefsen, Alasdair SkeltonAbstract:Petrogenetic studies of Carbonatites are challenging, because Carbonatite mineral assemblages and mineral chemistry typically reflect both variable pressure–temperature conditions during crystallization and fluid–rock interaction caused by magmatic–hydrothermal fluids. However, this complexity results in recognizable alteration textures and trace-element signatures in the mineral archive that can be used to reconstruct the magmatic evolution and fluid–rock interaction history of Carbonatites. We present new LA–ICP–MS trace-element data for magnetite, calcite, siderite, and ankerite–dolomite–kutnohorite from the iron-rich Carbonatites of the 1.3 Ga Grønnedal–Íka alkaline complex, Southwest Greenland. We use these data, in combination with detailed cathodoluminescence imaging, to identify magmatic and secondary geochemical fingerprints preserved in these minerals. The chemical and textural gradients show that a 55 m-thick basaltic dike that crosscuts the Carbonatite intrusion has acted as the pathway for hydrothermal fluids enriched in F and CO_2, which have caused mobilization of the LREEs, Nb, Ta, Ba, Sr, Mn, and P. These fluids reacted with and altered the composition of the surrounding Carbonatites up to a distance of 40 m from the dike contact and caused formation of magnetite through oxidation of siderite. Our results can be used for discrimination between primary magmatic minerals and later alteration-related assemblages in Carbonatites in general, which can lead to a better understanding of how these rare rocks are formed. Our data provide evidence that siderite-bearing ferroCarbonatites can form during late stages of calciocarbonatitic magma evolution.
Claudia Principe - One of the best experts on this subject based on the ideXlab platform.
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Erratum to ``Eruption style and petrology of a new carbonatitic suite from the Mt. Vulture (Southern Italy): The Monticchio Lakes Formation'' [Journal of Volcanology and Geothermal Research 78 (1997) 251 265]
Journal of Volcanology and Geothermal Research, 1999Co-Authors: Francesco Stoppa, Claudia PrincipeAbstract:Abstract The Monticchio Lakes Formation (MLF) is a newly identified Carbonatite-melilitite tuff sequence which is exposed in the southwestern sector of the Vulture volcano. It is the youngest example (ca. 0.13 m.y.) of this type of volcanism in Italy, although other Carbonatites of smaller volume, but with similar characteristics, have been discovered recently. This volcanic event occurred in isolation after a 0.35 m.y. period of inactivity at Vulture. The eruption produced two maar-type vents and formed tuff aprons mainly composed of dune beds of lapilli. Depositional features suggest that a dry surge mechanism, possibly triggered by CO2 expansion, was dominant during tuff emplacement. The MLF event involved a mixture of Carbonatite and melilitite liquids which were physically separated before the eruption. Abundant mantle xenoliths are direct evidence of the deep-seated origin of the parental magma and its high velocity of propagation towards the surface. Often, these nodules form the core of lapilli composed of concentric shells of melilitite and/or porphyritic Carbonatite. Coarse-ash beds alternate with lapilli beds and consist of abundant lumps and spherulae of very fine-grained calcite immersed in a welded, highly compacted Carbonatite matrix. Porphyritic Carbonatite shells of the lapilli and fine-grained spherulae of calcite in the tuff matrix suggest incipient crystallisation of a Carbonatite liquid in subvolcanic conditions and eruption of Carbonatite-spray droplets. Dark coloured juvenile fragments mainly consist of melilite, phlogopite, calcite, apatite, perovskite, and hauyne crystals in a Carbonatite or melilitite matrix. The rocks have an extremely primitive, ultramafic composition with very high Mg# (> 85) and Cr and Ni content (1500 ppm). The calcite contains high SrO, BaO and REE of up to 1.5 wt.%. Similar compositions are typical of primary, magmatic carbonates which are found in both intrusive and extrusive Carbonatites. The high modal Sr-Ba-REE-rich calcite, the typical mineralogy, and the high amount of Sr-group elements identify the carbonate component as a Carbonatite. The very high Mg#, mantle debris and C, O, He isotope ratios in the range of mantle values indicate a near-primary character for the Carbonatite which is distinctive of a restricted group of extrusive Carbonatites only found in continental rift areas.
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Eruption style and petrology of a new carbonatitic suite from the Mt. Vulture Southern Italy/: The Monticchio Lakes Formation
Journal of Volcanology and Geothermal Research, 1997Co-Authors: Francesco Stoppa, Claudia PrincipeAbstract:Abstract The Monticchio Lakes Formation MLF is a newly identified Carbonatite-melilitite tuff sequence which is exposed in the southwestern sector of the Vulture volcano. It is the youngest example ca. 0.13 m.y. of this type of volcanism in Italy, although other Carbonatites of smaller volume, but with similar characteristics, have been discovered recently. This volcanic event occurred in isolation after a 0.35 m.y. period of inactivity at Vulture. The eruption produced two maar-type vents and formed tuff aprons mainly composed of dune beds of lapilli. Depositional features suggest that a dry surge mechanism, possibly triggered by CO 2 expansion, was dominant during tuff emplacement. The MLF event involved a mixture of Carbonatite and melilitite liquids which were physically separated before the eruption. Abundant mantle xenoliths are direct evidence of the deep-seated origin of the parental magma and its high velocity of propagation towards the surface. Often, these nodules form the core of lapilli composed of concentric shells of melilitite andror porphyritic Carbonatite. Coarse-ash beds alternate with lapilli beds and consist of abundant lumps and spherulae of very fine-grained calcite immersed in a welded, highly compacted Carbonatite matrix. Porphyritic Carbonatite shells of the lapilli and fine-grained spherulae of calcite in the tuff matrix suggest incipient crystallisation of a Carbonatite liquid in subvolcanic conditions and eruption of Carbonatite-spray droplets. Dark coloured juvenile fragments mainly consist of melilite, phlogopite, calcite, apatite, perovskite, and hauyne crystals in a Carbonatite or melilitite matrix. The rocks have an extremely primitive, ultramafic composition with very high Mga) 85. and Cr and Ni content 1500 ppm-. The calcite contains high SrO, BaO and REE of up to 1.5 wt.%. Similar compositions are typical of primary, magmatic carbonates which are found in both intrusive and extrusive Carbonatites. The high modal Sr-Ba-REE-rich calcite, the typical mineralogy, and the high amount of Sr-group elements identify the carbonate component as a Carbonatite. The very high Mga, mantle debris and C, O, He isotope ratios in the range of mantle values indicate a near-primary character for the Carbonatite which is distinctive of a restricted group of extrusive Carbonatites only found in continental rift areas.
Dewashish Upadhyay - One of the best experts on this subject based on the ideXlab platform.
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Highly siderophile element geochemistry and Re–Os isotopic systematics of Carbonatites: Insights from Tamil Nadu, India
Earth and Planetary Science Letters, 2019Co-Authors: Lukáš Ackerman, Ladislav Polák, Tomáš Magna, Vladislav Rapprich, Jana Ďurišová, Dewashish UpadhyayAbstract:Abstract Carbonatite metasomatism has been widely implicated for worldwide mafic mantle suites but so far, no combined data have been available for highly siderophile element systematics (HSE – Os, Ir, Ru, Pt, Pd, Re) and Re–Os isotopic compositions in Carbonatites themselves. We present the first systematic survey of the HSE and Re–Os isotopic compositions in a suite of well-characterized Neoproterozoic Carbonatites, silicoCarbonatites and associated silicate rocks (pyroxenites, monzogabbros, syenites) from south India in order to place constraints on the HSE systematics in Carbonatite magmas, anchoring possible mantle sources of Carbonatites and relationship to the ambient crustal lithologies as well as preliminary constraints on Carbonatite metasomatism in Earth's mantle. The most plausible explanation for generally low HSE contents in calcioCarbonatites from Tamil Nadu (∑HSE
I. A. Izbrodin - One of the best experts on this subject based on the ideXlab platform.
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Trace-element composition of minerals and rocks in the Belaya Zima Carbonatite complex (Russia): Implications for the mechanisms of magma evolution and Carbonatite formation
Lithos, 2017Co-Authors: A. G. Doroshkevich, Ilya V. Veksler, Reiner Klemd, Elena A. Khromova, I. A. IzbrodinAbstract:Abstract The nature of petrogenetic links between Carbonatites and associated silicate rocks is a matter of discussion for several decades and still remains controversial among igneous petrologists. The Belaya Zima plutonic complex in southern Siberia is a typical intrusion, in which Carbonatites are spatially and temporally associated with the ijolite series rocks and nepheline syenites. In this study we use whole-rock compositions and trace element characteristics of the major and accessory minerals for reconstructing the magmatic evolution of the complex and clarifying the origin of Carbonatites. We conclude that the observed gradual increase of Zr, Nb and REE concentrations in the magma is consistent with the process of extensive fractional crystallization and gradual transition from silicate rocks to Carbonatites, and inconsistent with the formation of Carbonatites by liquid immiscibility. Magma differentiation by fractional crystallization continued during the Carbonatite formation. The textural and analytical evidence indicates that the early calcitic Carbonatites evolved to dolomitic and ankeritic Carbonatites. In addition, maximum Nb and Zr concentrations occur in the calcitic Carbonatite, whereas the REE content increases in the dolomitic and ankeritic facies.