Mode of formation of hibonite (CaAl12O19) within the U-Th skarns from the granulites of S-E Madagascar
Article Abstract:
The formation of hibonite (CaAl12O19), found in Madagascar, within U-Th skarns from corundum and spinel occurs during a two-stage metasomatism. Hibonite occurs in close association with anorthite and exhibits an ideal activity of 0.25. Low mobility of Ti seems indicated by the restriction of hibonite to leucocratic segregations enclosed in titanite-containing skarns. In Tanzania and South India, hibonite crystallized during the initial stage of metasomatism due to the presence of Ti and rate earth elements at this stage.
Publication Name: Contributions to Mineralogy and Petrology
Subject: Earth sciences
ISSN: 0010-7999
Year: 1996
User Contributions:
Comment about this article or add new information about this topic:
Modeling of the transport and deposition of tungsten in the scheelite-bearing calc-silicate gneisses of the Montagne Noire, France
Article Abstract:
The role of different physical and chemical parameters on the transport and deposition of tungsten in Montagne Noire is presented. Results show that large amounts of tungsten can be accommodated by aqueous solutions circulating within a micaschist or a calc-silicate gneisses environment at high pressure-temperature conditions. Moreover, the addition of volatiles enhances scheelite crystallization, but scheelite saturation is never reached in the micaschist environment.
Publication Name: Contributions to Mineralogy and Petrology
Subject: Earth sciences
ISSN: 0010-7999
Year: 1992
User Contributions:
Comment about this article or add new information about this topic:
Oxygen and hydrogen isotope geochemistry of gneisses associated with ultrahigh pressure eclogites at Shuanghe in the Dabie Mountains
Article Abstract:
A study was conducted to analyze the oxygen and hydrogen isotope compositions of minerals and whole rosk for biotite gneiss and granitic gneiss. The gneisses were related to ultrahigh pressure eclogites in the Shuanghe district of the Dabie Mountains. Results indicated differences in delta(super 18)O between the two gneisses. Hydrogen isotope disequilibrium among the hydroxyl-bearing minerals was correlated to retrograde exchange of amphibolite-facies metamorphism.
Publication Name: Contributions to Mineralogy and Petrology
Subject: Earth sciences
ISSN: 0010-7999
Year: 1999
User Contributions:
Comment about this article or add new information about this topic:
- Abstracts: Deformation history of tectonic melange and its relationship to the underplating process and relative plate motion: an example from the deeply buried Shimanto Belt, SW Japan
- Abstracts: Tephroite-hausmannite-galaxite from a granulite-facies manganese rocks of the United Arab Emirates. K-Ar ages of the metamorphic sole of the Semail Ophiolite: implications for ophiolite cooling history
- Abstracts: Effects of agriculture, urbanization, and climate on water quality in the northern Great Plains. Direct and interactive effects of allochthonous dissolved organic matter, inorganic nutrients, and ultraviolet radiation on an alpine littoral food web
- Abstracts: Geochemical evolution of Jurassic diorites from the Bristol Lake region, California, USA, and the role of assimilation
- Abstracts: Granulite facies metasomatism: zoned calc-silicate boudins from the Rauer Group, East Antarctica. Carbonate metasomatism in the lithospheric mantle: peridotitic xenoliths from a melilititic district of the Sahara basin