Phase equilibria involving humite minerals in impure dolomitic limestones

Rice, Jack M.

doi:10.1007/bf01166761

Cited by 23 publications

(51 citation statements)

References 11 publications

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“…Fluorine-bearing Ti-Cl occurs also in ultramafic rocks that underwent garnet-lherzolite metamorphism in the Central Alps (800° C, 25kb, Evans and Trommsdorff 1983). These observations confirm that the presence of fluorine has a strong effect in increasing the stability of titanian OH-clinohumite (Rice 1980). Engi and Lindsley (1980) investigated experimentally the upper thermal stability limit of a natural, F-free Ti-Cl from the Malenco serpentinites, and modelled quantitatively the effects of the OHF _ i substitution.…”

Section: Discussionmentioning

confidence: 53%

“…Titanian varieties of the humite group minerals are quite common in metamorphic carbonate rocks and have been found at numerous localities (Rankama 1938;Sahama 1953;Muthuswami 1958;Bradshaw and Leake 1964;Moore and Kerrick 1976;Rice 1980;Bucher-Nurminen 1982;Ehlers and Hoinkes 1987). In marbles from the eastern Bergell contact aureole (Switzerland/Italy) humite minerals were first mentioned by Cornelius (1915).…”

Section: Introductionmentioning

confidence: 99%

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Titanian clinohumite and geikielite in marbles from the Bergell contact aureole

Gieré¹

1987

Contr. Mineral. and Petrol.

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Abstract. The assemblage titanian clinohumite + forsterite + spinet + calcite is widespread in marbles from the eastern Bergell contact aureole (Switzerland/Italy). The Bergell titanian clinohumites vary considerably in composition (Ti0 2 : 0.19 to 2.05 wt%, F: 2.2 to 3.4 wt%). Electron microprobe analyses show that the titanian clinohumites contam less than detectable amounts of Co, Cu, Ni, Zn, Al, Cr and CI. No trace of ferric iron could be detected by Moessbauer spectroscopy. Moreover, the Moessbauer spectra indicate that Fe 2 + occurs only in one of the five octahedral positions in the crystal structure of the studied titanian clinohumite. Under the conditions of the contact metamorphism (600 650° C, 3 kb total pressure) the compositional variation along the exchange vector TiO 2 M 1 (OH,F) 2 takes place at constant x 0 , 1 which is fixed by the pore fluid. Titanian clinohumite sometimes contains geikielite inclusions which strongly fractionate Fe and Mn relative to titanian clinohumite. The geikielites from the Bergell marbles are poor in Cr 2 0 3 , Fe 2 0 3 and MnO, and thus different from those found in carbonatites, kimberlites and serpentinized ultramafic rocks.

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Section: Discussionmentioning

confidence: 53%

Section: Introductionmentioning

confidence: 99%

Titanian clinohumite and geikielite in marbles from the Bergell contact aureole

Gieré¹

1987

Contr. Mineral. and Petrol.

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“… Calculated position of equilibrium (13) at 1–5 kbar total pressure; for error bars refer to Rice (1980a); the dashed line is the 4 kbar position, in grey is the position of equilibria observed in this study (modified after Rice, 1980a). …”

Section: P–t–x Co 2 Estimatesmentioning

confidence: 94%

“…We used diagrams developed by Rice (1980a, b) to evaluate the T–X CO2 conditions of clinohumite‐ and chondrodite‐bearing marbles during amphibolite facies retrogression at 2 kbar and 1 kbar, respectively. According to Rice (1980a, b) and calculations by Buick et al . (1997 ), higher pressures shift equilibrium boundaries to higher temperatures, decreasing the size of the clinohumite+calcite (Fig.…”

Section: P–t–x Co 2 Estimatesmentioning

confidence: 99%

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Humite‐ and scapolite‐bearing assemblages in marbles and calcsilicates of Dronning Maud Land, Antarctica: new data for Gondwana reconstructions

Piazolo

Markl

1999

Journal Metamorphic Geology

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This study investigates marbles and calcsilicates in Central Dronning Maud Land (CDML), East Antarctica. The paleogeographic positioning of CDML as part of Gondwana is still unclear; however, rock types, mineral assemblages, textures and P-T conditions observed in this study are remarkably similar to the Kerala Khondalite Belt in India. The CDML marbles and calcsilicates experienced a Pan-African granulite facies metamorphism at c. 570 Ma and an amphibolite facies retrogression at c. 520 Ma. The highest grade assemblage in marbles is forsterite+spinel+calcite+dolomite, in calcsilicates the assemblages are diopside+spinel, diopside+garnet, scapolite+wollastonite+clinopyroxene±quartz, scapolite±anorthite±calcite+clinopyroxene+wollastonite. These assemblages constrain the peak metamorphic conditions to 830±20°C, 6.8±0.5 kbar and X CO 2 >0.46. During retrogression, highly fluoric humite-group minerals (humite, clinohumite, chondrodite) replaced forsterite, and garnet rims formed at the expense of scapolite during reactions with wollastonite, calcite or clinopyroxene but without involvement of anorthite. Metamorphic conditions were about 650°C, 4.5±0.7 kbar, 0.2

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Fluid Exchange between Reacting Bodies of Rock

Greenwood

1987

Chemical Transport in Metasomatic Processes

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Phase equilibria involving humite minerals in impure dolomitic limestones

Cited by 23 publications

References 11 publications

Titanian clinohumite and geikielite in marbles from the Bergell contact aureole

Titanian clinohumite and geikielite in marbles from the Bergell contact aureole

Humite‐ and scapolite‐bearing assemblages in marbles and calcsilicates of Dronning Maud Land, Antarctica: new data for Gondwana reconstructions

Fluid Exchange between Reacting Bodies of Rock

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