Carbonatite melt inclusions in coexisting magnetite, apatite and monticellite in Kerimasi calciocarbonatite, Tanzania: melt evolution and petrogenesis

Guzmics, Tibor; Mitchell, Roger H.; Szabó, Csaba; Berkesi, Márta; Milke, Ralf; Abart, Rainer

doi:10.1007/s00410-010-0525-z

Cited by 107 publications

(67 citation statements)

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“…Knowledge of the composition and evolution of the primary magma(s) responsible for their crystallization is essential in understanding their petrogenesis. The study of primary melt inclusions is a powerful tool to determine such melt compositions (Le Bas and Aspden 1981;Roedder 1987;Veksler and Lentz 2006;Solovova et al 2006;Guzmics et al 2008Guzmics et al , 2011Mitchell 2009;Panina and Stoppa 2009). These melt inclusion studies and those of natural examples (Le Bas 1977;Nielsen 1980;Hay 1983;Kogarko et al 1991;Dawson et al 1994;Mitchell 2005) together with numerous experimental studies (Koster van Groos and Wyllie 1968;Hamilton et al 1979;Kjarsgaard and Peterson 1991;Wyllie 1997, 1998;Brooker and Kjarsgaard 2010) suggest that liquid immiscibility might play a major role in the formation of carbonatites.…”

Section: Introductionmentioning

confidence: 95%

“…These melt inclusion studies and those of natural examples (Le Bas 1977;Nielsen 1980;Hay 1983;Kogarko et al 1991;Dawson et al 1994;Mitchell 2005) together with numerous experimental studies (Koster van Groos and Wyllie 1968;Hamilton et al 1979;Kjarsgaard and Peterson 1991;Wyllie 1997, 1998;Brooker and Kjarsgaard 2010) suggest that liquid immiscibility might play a major role in the formation of carbonatites. Although different evolutionary paths of the parental melt(s) of alkaline silicate and carbonatite rocks have been suggested (Le Bas 1977;Bailey 1993;Dawson et al 1996;Nielsen et al 1997;Lee and Wyllie 1997;Kjarsgaard 1998;Mitchell 2009;Guzmics et al 2011), several questions remain unanswered.…”

Section: Introductionmentioning

confidence: 98%

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Liquid immiscibility between silicate, carbonate and sulfide melts in melt inclusions hosted in co-precipitated minerals from Kerimasi volcano (Tanzania): evolution of carbonated nephelinitic magma

Guzmics

Mitchell

Szabó

et al. 2012

Contrib Mineral Petrol

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The evolution of a carbonated nephelinitic magma can be followed by the study of a statistically significant number of melt inclusions, entrapped in coprecipitated perovskite, nepheline and magnetite in a clinopyroxene-and nepheline-rich rock (afrikandite) from Kerimasi volcano (Tanzania). Temperatures are estimated to be 1,100°C for the early stage of the melt evolution of the magma, which formed the rock. During evolution, the magma became enriched in CaO, depleted in SiO 2 and Al 2 O 3 , resulting in immiscibility at *1,050°C and crustal pressures (0.5-1 GPa) with the formation of three fluidsaturated melts: an alkali-and MgO-bearing, CaO-and FeO-rich silicate melt; an alkali-and F-bearing, CaO-and P 2 O 5 -rich carbonate melt; and a Cu-Fe sulfide melt. The sulfide and the carbonate melt could be physically separated from their silicate parent and form a Cu-Fe-S ore and a carbonatite rock. The separated carbonate melt could initially crystallize calciocarbonatite and ultimately become alkali rich in composition and similar to natrocarbonatite, demonstrating an evolution from nephelinite to natrocarbonatite through Ca-rich carbonatite magma. The distribution of major elements between perovskite-hosted coexisting immiscible silicate and carbonate melts shows strong partitioning of Ca, P and F relative to Fe T , Si, Al, Mn, Ti and Mg in the carbonate melt, suggesting that immiscibility occurred at crustal pressures and plays a significant role in explaining the dominance of calciocarbonatites (sövites) relative to dolomitic or sideritic carbonatites. Our data suggest that Cu-Fe-S compositions are characteristic of immiscible sulfide melts originating from the parental silicate melts of alkaline silicate-carbonatite complexes.

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Section: Introductionmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 98%

Liquid immiscibility between silicate, carbonate and sulfide melts in melt inclusions hosted in co-precipitated minerals from Kerimasi volcano (Tanzania): evolution of carbonated nephelinitic magma

Guzmics

Mitchell

Szabó

et al. 2012

Contrib Mineral Petrol

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“…Averages are from Guzmics et al (2011Guzmics et al ( , 2012 for Keramasi (East African Rift); from Kogarko et al (1991) and Panina (2005) for the Sibirian Guli intrusive and Krestovskiy massiv, respectively, which are about 50 km distant; and from Nielsen et al (1997) for the Gardiner complex (East Greenland).…”

Section: Melt Inclusionsmentioning

confidence: 97%

Carbonatites in oceanic hotspots

Schmidt¹,

Weidendorfer

2018

Geology

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SUPPLEMENTARY MATERIAL METHODSData were compiled from the pre-sorted georoc database ocean island files (http://georoc.mpchmainz.gwdg.de/georoc/). Hot spots such as Aetna or Samoa with geotectonically complex situations and possible direct interference with subduction were avoided; otherwise we used those with sufficiently large data sets. Each file was filtered for analyses with 95-101.5 wt% totals, samples outside this range or listed as altered were excluded. All bulk rock compositions are then normalized to 100 wt% total on a volatile free basis with all Fe as FeO.The histogram of total alkalis for extrusives shows a clear cut-off to <1.4 wt% K 2 O+Na 2 O. Of e.g. 9'000 extrusives of the Hawaiian hotspot only 24 are below this values, these are essentially from three publications (without geographical coherence), suggesting that these rocks were altered or possibly have an analytical problem; this is corroborated by a K 2 O/Na 2 O ranging from 0.01 to 2 for these 24 samples. We have hence excluded all rocks with <1.4 wt% Na 2 O+K 2 O. Similarly, we did not accept trace element concentrations measured by XRF that are below 5-15 ppm (depending on the element).Within each ocean island, rocks were sorted for (i) Those with X Mg >0.77 and/or Ni>650 ppm, this group is mostly olivine cumulative and was excluded from all plots. (ii) Primitive melts were designated when X Mg =0.77-0.65, which corresponds to equilibrium with olivine of Fo 92-88 at 5-15 mol% Fe 3+ (of Fe tot ), and Ni=150-650 ppm, corresponding to roughly 2000-4500 ppm Ni in mantle olivine (note that the K D olivine/melt of Ni strongly depends on temperature, hence this range is chosen rather large). (iii) To enlarge the dataset, rocks with 0.55100 analyses were retained, the dataset sorted for the above criteria contains 124-198 analyses for Pitcairn, Ascension, St. Helena and Tristan da Cunha; 242-331 for GSA Data Repository 2018136

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“…Similar mineral associations have been identified only in two principal rock types: natrocarbonatites 22 , and groundmass, chloride-carbonate and diamond inclusions, and olivine and Cr-spinel hosted inclusions within kimberlites [23][24][25][26][27] . Guzmics et al 12 recently examined the melt inclusions associated with the extrusive (volcanic) calciocarbonatites at Kerimasi volcano (Tanzania), and their results indicate that the carbonatite melt fraction contained between 10 and 20 wt% Na 2 O and K 2 O. Kerimasi is located several kilometres from Oldoinyo Lengai and therefore the alkali-rich nature of its carbonatites is not surprising.…”

Section: Articlementioning

confidence: 99%

“…However, the latter does not represent parental liquid compositions as they are considered to reflect crystal accumulation 11,12 , and may undergo postcrystallization deuteric alteration by late-stage magmatic fluids 13 . In contrast, melt inclusions are: a combination (mechanical mixture) of co-trapped crystals and melt-with the latter typically recrystallizing into daughter crystals; trapped and isolated early in the crystallization history of the magma 14 ; protected by the host mineral from possible low-temperature alteration; and largely excluded from any subsequent reactions or processes within the magma chamber (for example, mixing, degassing, contamination and so on).…”

mentioning

confidence: 99%

Evidence for the alkaline nature of parental carbonatite melts at Oka complex in Canada

2013

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The Earth's sole active carbonatite volcano, Oldoinyo Lengai (Tanzania), is presently erupting unique natrocarbonatite lavas that are characterized by Na-and K-bearing magmatic carbonates of nyerereite [Na 2 Ca(CO 3 ) 2 ] and gregoryite [(Na 2 ,K 2 ,Ca)CO 3 ]. Contrarily, the vast majority of older, plutonic carbonatite occurrences worldwide are dominated by Ca-(calcite) or Mg-(dolomite)-rich magmatic carbonates. Consequently, this leads to the conundrum as to the composition of primary, mantle-derived carbonatite liquids. Here we report a detailed chemical investigation of melt inclusions associated with intrusive (plutonic) calcite-rich carbonatites from the B120 Ma carbonatite complex of Oka (Canada). Melt inclusions are hosted by magnetite (Fe 3 O 4 ), which crystallizes through a significant period of carbonatite melt solidification. Our results indicate mineral assemblages within the melt inclusions that are consistent with those documented in natrocarbonatite lavas. We propose therefore that derivation of alkali-enriched parental carbonatite melts has been more prevalent than that preserved in the geological record.

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Carbonatite melt inclusions in coexisting magnetite, apatite and monticellite in Kerimasi calciocarbonatite, Tanzania: melt evolution and petrogenesis

Cited by 107 publications

References 47 publications

Liquid immiscibility between silicate, carbonate and sulfide melts in melt inclusions hosted in co-precipitated minerals from Kerimasi volcano (Tanzania): evolution of carbonated nephelinitic magma

Liquid immiscibility between silicate, carbonate and sulfide melts in melt inclusions hosted in co-precipitated minerals from Kerimasi volcano (Tanzania): evolution of carbonated nephelinitic magma

Carbonatites in oceanic hotspots

Evidence for the alkaline nature of parental carbonatite melts at Oka complex in Canada

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