Silicate–carbonate liquid immiscibility and crystallization of carbonate and K-rich basaltic magma: insights from melt and fluid inclusions

2012 ◽  
Vol 76 (2) ◽  
pp. 411-439 ◽  
Author(s):  
I. P. Solovova ◽  
A. V. Girnis
Keyword(s):  
Fluid Inclusions ◽  
Melt Inclusions ◽  
Basaltic Magma ◽  
Liquid Immiscibility ◽  
Igneous Complex ◽  
Silicate Minerals ◽  
Incompatible Elements ◽  
Melt And Fluid Inclusions ◽  
Silicate Carbonate ◽  
Carbonate Melt

AbstractThis paper reports an investigation of the crystallization products of K-rich silicate and carbonate melts trapped as melt inclusions in clinopyroxene phenocrysts from the Dunkeldyk alkaline igneous complex in the Tajik Republic. Heating experiments on the melt inclusions suggest that the carbonate melt was formed by liquid immiscibility at 1180°C and ∼0.5 GPa. The carbonate-rich inclusions are dominated by Sr-bearing calcite, and rich in incompatible elements. Most of the silicate minerals are SiO2-poor and rich in K, Ba and Ti. Leucite, kalsilite and aegirine are the earliest magmatic minerals. High Ba and Ti contents in the melt resulted in the crystallization of Ba-rich K-feldspar, titanite, perovskite and Ti-bearing garnet, and the rare Ba-Ti silicates fresnoite and delindeite. The last minerals to crystallize from volatile-rich melts and fluids were aegirine, götzenite, K-Ba- and Ca-Sr-bearing zeolites, fluorite and strontium-rich baryte. Interaction of the early minerals with residual melts and fluids produced Ba-rich phlogopite and Sr-rich apatite.

Tin and associated metal and metalloid geochemistry by femtosecond LA-ICP-QMS microanalysis of pegmatite–leucogranite melt and fluid inclusions: new evidence for melt–melt–fluid immiscibility

2012 ◽  
Vol 76 (1) ◽  
pp. 91-113 ◽  
Author(s):  
A. Y. Borisova ◽  
R. Thomas ◽  
S. Salvi ◽  
F. Candaudap ◽  
A. Lanzanova ◽  
...  
Keyword(s):  
Fluid Inclusions ◽  
Inductively Coupled Plasma ◽  
Melt Inclusions ◽  
Saturation Index ◽  
Femtosecond Laser Ablation ◽  
Type A ◽  
Inductively Coupled ◽  
Melt And Fluid Inclusions ◽  
Layer Effect ◽  
Primary Melt

AbstractGranitic pegmatites are exceptional igneous rocks and the possible role of an immiscibility process in their origin is strongly debated. To investigate metal and metalloid behaviour in hydrous peraluminous systems (aluminium saturation index, ASI >1), we analysed 15 quartz-hosted primary melt and fluid inclusions from pegmatites in the Ehrenfriedersdorf Complex (Erzgebirge, Germany) and 26 primary melt inclusions from leucogranites of the Ehrenfriedersdorf district (Germany), Kymi (Finland) and Erongo (Namibia) by femtosecond laser ablation inductively coupled plasma quadrupole mass spectrometry. The results presented here for 32 elements provide evidence for metal and metalloid fractionation between two types of immiscible melts (A and B) and NaCl – HCl-rich brine in the pegmatite system. No evidence for the boundary layer effect was observed in the 40 – 500 μm size melt inclusions that were investigated. The data on the Ehrenfriedersdorf pegmatites allow quantification of the metal and metalloid partitioning between natural NaCl-rich brine and the two types of melt (e.g. KAsbrine/type-A,B melts = 0.01 – 1.7; KSbbrine/type-A,B melts = 10 – 285; KZnbrine/type-A,B melts ≥ 50; KPbbrine/type-A melt ≥ 50; KAgbrine/type-A melt = 46). These data are in accord with existing natural and experimental data on equilibrium fluid – melt partitioning as well as spectroscopic data on the metal and metalloid complexation in hydrous aluminosilicate melts and NaCl – HCl-rich fluids.

Silicate-carbonate-salt liquid immiscibility and origin of the sodalite-haüyne rocks: study of melt inclusions in olivine foidite from Vulture volcano, S. Italy

2009 ◽  
Vol 1 (4) ◽  
Author(s):  
Liya Panina ◽  
Francesco Stoppa
Keyword(s):  
Magma Chamber ◽  
Melt Inclusions ◽  
Liquid Immiscibility ◽  
Pyroclastic Flows ◽  
Silicate Inclusions ◽  
Low Degree ◽  
Primary Inclusion ◽  
Probable Presence ◽  
Silicate Carbonate ◽  
Carbonate Salt

AbstractMelt inclusions in clinopyroxenes of olivine foidite bombs from Serra di Constantinopoli pyroclastic flows of the Vulture volcano (Southern Italy) were studied in detail. The rocks contain abundant zoned phenocrysts and xenocrysts of clinopyroxene, scarce grains of olivine, leucite, haüyne, glass with microlites of plagioclase and K-feldspar. The composition of clinopyroxene in xenocrysts (Cpx I), cores (Cpx II), and in rims (Cpx III) of phenocrysts differs in the content of Mg, Fe, Ti, and Al. All clinopyroxenes contain two types of primary inclusion-pure silicate and of silicate-carbonate-salt composition. This fact suggests that the phenomena of silicate-carbonate immiscibility took place prior to crystallization of clinopyroxene. Homogenization of pure silicate inclusions proceeded at 1 225 – 1 190°C. The composition of conserved melts corresponded to that of olivine foidite in Cpx I, to tephrite-phonolite in Cpx II, and phonolite-nepheline trachyte in Cpx III. The amount of water in them was no more than 0.9 wt.%. Silicate-carbonate inclusions decrepitated on heating. Salt globules contained salts of alkali-sulphate, alkali-carbonate, and Ca-carbonate composition somewhat enriched in Ba and Sr. This composition is typical of carbonatite melts when decomposed into immiscible fractions. The formation of sodalite-haüyne rocks from Vulture is related to the presence of carbonate-salt melts in magma chamber. The melts conserved in clinopyroxenes were enriched in incompatible elements, especially in Cpx III. High ratios of La, Nb, and Ta in melts on crystallization of Cpx I and Cpx II suggest the influence of a carbonatite melt as carbonatites have extremely high La/Nb and Nb/Ta and this is confirmed by the appearance of carbonatite melts in magma chamber. Some anomalies in the concentrations and relatives values of Eu and especially Ga seems typical of Italian carbonatite related melts. The mantle source for initial melts was, most likely, rather uniform, undepleted and was characterized by a low degree of melting and probable presence of garnet in restite.

Features of Mineral Crystallization at Different Stages of the Magmatism Evolution of the Gorely Volcano (Kamchatka): Data on Melt and Fluid Inclusions

2021 ◽  
Vol 62 (1) ◽  
pp. 83-108
Author(s):  
V.A. Simonov ◽  
N.L. Dobretsov ◽  
A.V. Kotlyarov ◽  
N.S. Karmanov ◽  
A.A. Borovikov
Keyword(s):  
Computational Modeling ◽  
Fluid Inclusions ◽  
Melt Inclusions ◽  
Depth Interval ◽  
Published Data ◽  
Two Phase ◽  
Subsequent Formation ◽  
Melt And Fluid Inclusions ◽  
Homogenization Temperatures ◽  
Magmatism Evolution

Abstract ––Studies of melt and fluid inclusions and minerals as well as computational modeling (based on the data on the composition of melt inclusions, clinopyroxenes, and amphiboles) gave an insight into the physicochemical parameters of magmatic systems during the evolution of the precaldera Pra-Gorely Volcano and during the subsequent formation of rock complexes of the Young Gorely Volcano. The estimated temperatures of crystallization of olivine, clinopyroxene, and plagioclase phenocrysts (1115–1260 °С) and amphibole (740–890 °С) are in agreement with the earlier published data on the magmatism of the Gorely Volcano. Computational modeling based on the compositions and homogenization temperatures of melt inclusions showed that the established depth interval of mineral crystallization (21.0–1.5 km) with pressures of 7.0–0.5 kbar can be divided into two ranges, 21–15 km and 9.0–1.5 km. Both the Pra-Gorely and Young Gorely volcanoes have magma chambers in these depth ranges. The Pra-Gorely Volcano is characterized by higher temperatures of mineral crystallization (1240–1190 °С) as compared with the Young Gorely Volcano (1190–1125 °С). The presence of primary fluid inclusions with low-density CO2 and of syngenetic primary melt inclusions in plagioclase of the Pra-Gorely Volcano indicates that the mineral crystallized from a heterophase melt. At the same time, the cores of plagioclase phenocrysts formed from a homogeneous melt. A drastic drop in pressure led to the phase separation of magma throughout the magma column (upper and lower chambers) and to the growth of zones saturated with CO2 fluid inclusions in the plagioclase crystals formed from a two-phase melt. The subsequent closure of the system and the disappearance of CO2 phase resulted in the growth of plagioclase from a homogeneous melt.

scholarly journals Parental magma composition of the Main Zone of the Bushveld Complex: Evidence from in-situ LA-ICP-MS trace element analysis of silicate minerals in the cumulate rocks

2020 ◽  
Author(s):  
Shenghong Yang ◽  
Wolfgang D. Maier ◽  
Belinda Godel ◽  
Sarah-Jane Barnes ◽  
Eero Hanski ◽  
...  
Keyword(s):  
Trace Elements ◽  
Trace Element ◽  
Bushveld Complex ◽  
Trace Element Analysis ◽  
Parental Magma ◽  
Main Zone ◽  
Element Analysis ◽  
Silicate Minerals ◽  
Incompatible Elements

<p>In-situ trace element analysis of cumulus minerals may provide a clue to the parental magma from which the minerals crystallized. However, this is hampered by effects of the trapped liquid shift (TLS). In the Main Zone (MZ) of the Bushveld Complex, the Ti content in plagioclase grains shows a clear increase from core to rim, whereas most other elements (e.g., rare earth elements (REEs), Zr, Hf, Pb) do not. This is different from the prominent intra-grain variation of all trace elements in silicate minerals in mafic dikes and smaller intrusion, which have a faster cooling rate. We suggest that crystal fractionation of trapped liquid occurred in the MZ of Bushveld and the TLS may have modified the original composition of the cumulus minerals for most trace elements except Ti during slow cooling. Quantitative model calculations suggest that the influence of the TLS depends on the bulk partition coefficient of the element. The effect on highly incompatible elements is clearly more prominent ­­than on moderately incompatible and compatible elements because of different concentration gradients between cores and rims of cumulate minerals. This is supported by the following observations in the MZ of Bushveld: 1) positive correlation between Cr, Ni and Mg# of clinopyroxene and orthopyroxene, 2) negative correlation between moderately incompatible elements (e.g., Mn and Sc in clinopyroxene and orthopyroxene, Sr, Ba, Eu in plagioclase), but 3) poor correlation between highly incompatible elements and Mg# of clinopyroxene and orthopyroxene or An# of plagioclase. Modeling suggests that the extent of the TLS for a trace element is also dependent on the initial fraction of the primary trapped liquid, with strong TLS occurring if the primary trapped liquid fraction is high. This is supported by the positive correlation between highly incompatible trace element abundances in cumulus minerals and whole-rock Zr contents.</p><p>We have calculated the composition of the parental magma of the MZ of the Bushveld Complex. The compatible and moderately incompatible element contents of the calculated parental liquid are generally similar to those of the B3 marginal rocks, but different from the B1 and B2 marginal rocks. For the highly incompatible elements, we suggest that the use of the sample with the lowest whole-rock Zr content and the least degree of TLS is the best approach to obtain the parental magma composition. Based on calculation, we propose that a B3 type liquid is the most likely parental magma to the MZ of the Bushveld Complex.</p>

Applications to Silicate, Carbonate, and Borate Minerals and Related Species

1992 ◽  
Author(s):  
John A. Tossell ◽  
David J. Vaughan
Keyword(s):  
Related Species ◽  
The Other ◽  
Quantum Mechanical ◽  
Quantum Mechanical Calculations ◽  
Solid Solution Series ◽  
Silicate Minerals ◽  
Borate Minerals ◽  
Cluster Unit ◽  
Silicate Carbonate

The most abundant materials making up the crust of the earth (i.e., the “rock-forming minerals”) can be regarded as dominated by oxyanion units; notably, the units that can be formally represented by SiO44- and AlO45- clusters of the silicate minerals, and the CO32- unit of the carbonates. less common, but geochemically interesting, oxyanion units include, for example, BO33-, BeO46- , and PO43-. in this chapter, applications of quantum-mechanical calculations and experimental techniques to such materials are considered. first, the silicates are discussed, commencing with the large amount of work undertaken on the olivines, before considering such work as has so far been done on the other silicate minerals and related materials. second, the most important of the nonsilicate rock-forming mineral groups, the carbonates, are discussed. finally, although of less petrological importance but interesting geochemically and in terms of contrast with the othergroups, the borates and related species are considered. in each case, geometric aspects of structure and the problems of calculating structural properties are considered before going on to consider electronic structures and the factors controlling stabilities and a wider range of physical properties. in all of these materials, there is considerable interest in the, bonding in the oxyanion unit and how this is affected by, and controls, the interaction with counterions or the polymeric units. the building up of the minerals by such interactions exerts the dominant control over their crystal chemistries and properties and thus forms a central theme of this chapter. the silicate minerals are, of course, characterized by the presence of the tetrahedral siO4 cluster unit and the crystal chemistry and classification of silicates dominated by the structures built up by the linking together (polymerization) of these units. in the “simplest” of the silicates, the island silicates such as the olivine minerals (dominated by the forsterite (Mg2 SiO4)-fayalite (Fe2SiO4) solid solution series), the sio4 units are isolated by counterions such as Mg2+, Fe2+, Ca2+.

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