Explosion pipes in carbonatite complexes

Kapustin, Yu. L.

doi:10.1080/00206818309466819

Cited by 5 publications

(9 citation statements)

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“…A similar depth of emplacement is likely for late-stage carbonatite explosion breccias at Vuorijärvi, Salmagorsk, Osnaya Varaka, Afrikanda and several other alkaline magmatic centres ( Fig. 9; Kapustin, 1983). • In the intermediate group, emplacement depth at Kovdor is constrained by fluid inclusions in early apatites that record a fluid pressure of 1.1 to 1.5 kbar corresponding to 3.5-5 km depth (Sokolov, 1981) and by the homogenisation temperature of fluid inclusions in quartz and apatite from late-stage ankeritic and dolomitic, quartz-bearing carbonatite at 4 ± 0.7 km (Epshteyn & Kaban'kov, 1984).…”

Section: Figure 8 Schematic Model Of Denudation Patterns Since 460 Mmentioning

confidence: 92%

“…Examples include: 1. Late dykes associated with PCPs (Kapustin, 1983), 2. Late dykes in the major alkaline magmatic centres (Sindern et al, 2004;Men'shikov et al, 2006), 3.…”

Section: Figure 9 Schematic Model Of Denudation Patterns Since 360 Mmentioning

confidence: 99%

“…• Presence of explosion breccias, indicating venting of dykes within 1 km of the surface as feeder channels for surface volcanic fields. Examples include Kandalaksha Bay (Beard et al, 1998), Turiy Mys (Downes et al, 2005), Khibiny (Ivanyuk et al, 2012), Kontozero (MacBride, 2005) and numerous PCPs (Kapustin, 1983), including Kovdor ( Fig. 9; Mikhailova et al, in press).…”

Section: Figure 9 Schematic Model Of Denudation Patterns Since 360 Mmentioning

confidence: 99%

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Phanerozoic denudation across the Kola Peninsula, Northwest Russia: implications for long-term stability of Precambrian shield margins

Hall¹

2015

NJG

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Contrasting views exist on the stability of the Earth's shield regions over the last 1 Ga that have major implications for reconstructing erosion patterns on shields and the supply of sediment to intra-cratonic and marginal basins. This paper explores Phanerozoic denudation rates and patterns on the northern part of the Fennoscandian Shield in the Kola Peninsula, Northwest Russia. This shield region was intruded by magmatic rocks of the Kola Alkaline Province (KAP) in the Devonian and Early Carboniferous. The KAP comprises a varied suite of alkali-ultramafic plutonic and hypabyssal intrusions, diatremes and dykes that was emplaced at various depths in the crust and allows assessment of depths and rates of erosion during and since the KAP magmatic episode. Further evidence of long-term denudation is provided by Mesoproterozoic and Neoproterozoic cover rocks found around the margins of the Kola Peninsula and in the White Sea. The burial and exhumation history is compared to available Apatite Fission Track (AFT) data for the Kola Peninsula and adjacent areas. Post-Devonian denudation rates on the shield rocks of the Kola Peninsula have varied in space and time. Around the periphery of the Kola Peninsula, low long-term denudation of shield rocks is indicated by the survival of Riphean cover rocks and Late Devonian lavas, kimberlite crater facies and near-surface emplacement of dykes. In contrast, in the main belts of KAP intrusions, 4-6 km of rock was removed in response to doming between 460 and 360 Ma. Deep denudation is indicated by the emplacement depths of alkaline intrusions and Phoscorite-Carbonatite pipes (PCPs). Erosion on the Kola Peninsula since 360 Ma has been far more limited. Extensive, shallow, late-stage magmatism associated with PCPs, dykes and the large alkaline intrusions in the KAP indicates that erosion depths nowhere exceeded 2 km. PostDevonian denudation has removed <1 km of rock from the margins of the Kola Peninsula and from the backslope of the Saariselkä-Karelia scarp in northern Finland. AFT data point to an important phase of erosion in the early Mesozoic but depths of unroofing of 3-5 km based on AFT cooling ages for this later phase are in conflict with the evidence of lesser erosion provided by the late-stage KAP intrusions and also require unrealistic depths of former Devonian to Triassic cover rocks. Mean denudation rates were greatest (up to 40 m/Myr) during the KAP magmatic phase. Post-Devonian rates across the Kola Peninsula and adjacent shield areas were much lower (<3-6 m/Myr) and are compatible with low long-term denudation rates for other cratons. Further resolution of long-term denudation patterns and rates on the Kola Peninsula requires the application of low-temperature thermochronometry, detailed examination of the regional geomorphology and firmer dating of ancient weathering episodes.

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Section: Figure 8 Schematic Model Of Denudation Patterns Since 460 Mmentioning

confidence: 92%

“…Examples include: 1. Late dykes associated with PCPs (Kapustin, 1983), 2. Late dykes in the major alkaline magmatic centres (Sindern et al, 2004;Men'shikov et al, 2006), 3.…”

Section: Figure 9 Schematic Model Of Denudation Patterns Since 360 Mmentioning

confidence: 99%

Section: Figure 9 Schematic Model Of Denudation Patterns Since 360 Mmentioning

confidence: 99%

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Phanerozoic denudation across the Kola Peninsula, Northwest Russia: implications for long-term stability of Precambrian shield margins

Hall¹

2015

NJG

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“…The first sub-complex forms a smoothly zoned body where forsterite-rich phoscorite is concentrated near the pipe wall, with the axial zone is made of calcite-rich phoscorite and phoscorite-related calcite carbonatite. Importantly, almost every variety of phoscorite and carbonatite has an eruptive analogue (Kapustin 1983;Ivanyuk et al 2002;Krasnova et al 2004) to cement fragments of all earlier rocks within 1-to 120-m-wide funnel-like bodies.…”

Section: Phoscorite-carbonatite Complexmentioning

confidence: 99%

“…Since then, the deposit has been the subject of continuous study (see overview in Ivanyuk et al 2002). Kukharenko et al (1965), Kapustin (1980), RimskayaKorsakova and , Ivanyuk et al (2002), and many others investigated the petrography, mineralogy, and geochemistry of the Kovdor iron deposit that has become a reference for carbonatite-phoscorite complexes worldwide (Wall and Zaitsev 2004). A photographic overview of the modern Kovdor baddeleyite-apatite-magnetite open pit is shown in Fig.…”

Section: Introductionmentioning

confidence: 99%

3D mineralogical mapping of the Kovdor phoscorite–carbonatite complex (Russia)

Mikhailova

Kalashnikov

Sokharev³

et al. 2015

Miner Deposita

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The Kovdor baddeleyite-apatite-magnetite deposit in the Kovdor phoscorite-carbonatite pipe is situated in the western part of the zoned alkali-ultrabasic Kovdor intrusion (NW part of the Fennoscandinavian shield; Murmansk Region, Russia). We describe major intrusive and metasomatic rocks of the pipe and its surroundings using a new classification of phoscorite-carbonatite series rocks, consistent with the IUGS recommendation. The gradual zonation of the pipe corresponds to the sequence of mineral crystallization (forsterite-hydroxylapatite-magnetite-calcite). Crystal morphology, grain size, characteristic inclusions, and composition of the rock-forming and accessory minerals display the same spatial zonation pattern, as do the three minerals of economic interest, i.e. magnetite, hydroxylapatite, and baddeleyite. The content of Sr, rare earth elements (REEs), and Ba in hydroxylapatite tends to increase gradually at the expense of Si, Fe, and Mg from early apatite-forsterite phoscorite (margins of the pipe) through carbonate-free, magnetite-rich phoscorite to carbonate-rich phoscorite and phoscorite-related carbonatite (inner part). Magnetite displays a trend of increasing V and Ca and decreasing Ti, Mn, Si, Cr, Sc, and Zn from the margins to the central part of the pipe; its grain size initially increases from the wall rocks to the inner part and then decreases towards the central part; characteristic inclusions in magnetite are geikielite within the marginal zone of the phoscoritecarbonatite pipe, spinel within the intermediate zone, and ilmenite within the inner zone. The zoning pattern seems to have formed due to both cooling and rapid degassing (pressure drop) of a fluid-rich magmatic column and subsequent pneumatolytic and hydrothermal processes.

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The origin and composition of carbonatite-derived carbonate-bearing fluorapatite deposits

et al. 2020

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Carbonate-bearing fluorapatite rocks occur at over 30 globally distributed carbonatite complexes and represent a substantial potential supply of phosphorus for the fertiliser industry. However, the process(es) involved in forming carbonate-bearing fluorapatite at some carbonatites remain equivocal, with both hydrothermal and weathering mechanisms inferred. In this contribution, we compare the paragenesis and trace element contents of carbonate-bearing fluorapatite rocks from the Kovdor, Sokli, Bukusu, Catalão I and Glenover carbonatites in order to further understand their origin, as well as to comment upon the concentration of elements that may be deleterious to fertiliser production. The paragenesis of apatite from each deposit is broadly equivalent, comprising residual magmatic grains overgrown by several different stages of carbonate-bearing fluorapatite. The first forms epitactic overgrowths on residual magmatic grains, followed by the formation of massive apatite which, in turn, is cross-cut by late euhedral and colloform apatite generations. Compositionally, the paragenetic sequence corresponds to a substantial decrease in the concentration of rare earth elements (REE), Sr, Na and Th, with an increase in U and Cd. The carbonate-bearing fluorapatite exhibits a negative Ce anomaly, attributed to oxic conditions in a surficial environment and, in combination with the textural and compositional commonality, supports a weathering origin for these rocks. Carbonate-bearing fluorapatite has Th contents which are several orders of magnitude lower than magmatic apatite grains, potentially making such apatite a more environmentally attractive feedstock for the fertiliser industry. Uranium and cadmium contents are higher in carbonate-bearing fluorapatite than magmatic carbonatite apatite, but are much lower than most marine phosphorites.

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Explosion pipes in carbonatite complexes

Cited by 5 publications

References 1 publication

Phanerozoic denudation across the Kola Peninsula, Northwest Russia: implications for long-term stability of Precambrian shield margins

Phanerozoic denudation across the Kola Peninsula, Northwest Russia: implications for long-term stability of Precambrian shield margins

3D mineralogical mapping of the Kovdor phoscorite–carbonatite complex (Russia)

The origin and composition of carbonatite-derived carbonate-bearing fluorapatite deposits

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