Phase relations and chemistry of Ti-rich K-richterite-bearing mantle assemblages: An experimental study to 8.0 GPa in a Ti-KNCMASH system
Article Abstract:
Experiments have been undertaken in a peralkaline Ti-KNCMASH system, representing MAR-ID-type bulk compositions, delimiting the stability field of K-richterite in a Ti-rich hydrous mantle assemblage, to study compositional variations of amphibole and coexisting phases as a P and T function. K-richterite was stable from 0.5 to 8.0 GPa, with garnet appearing at 8.0 GPa, as an additional phase. Partial melts produced in the Ti-KNCMASh system were very peralkaline. The results indicate that partial melting of MARID-type assemblages at greater than -4.0 GPa, result in Si-poor and slightly ultrapotassic melts similar to olivine lamproites.
Publication Name: Contributions to Mineralogy and Petrology
Subject: Earth sciences
ISSN: 0010-7999
Year: 1997
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The normal grain growth behaviour of nominally pure calcitic aggregates
Article Abstract:
Normal grain growth at elevated temperatures under isostatic stress conditions is an important process in the control of grain size of rock-forming minerals. The normal grain growth kinetics of pure calcite powders from different sources was investigated, to explore the possible poor state of existing calcite grain growth experimental data. Rates of pore drag exhibited differences for the different materials, indicating that the process is very sensitive to trace solute impurity concentrations.
Publication Name: Contributions to Mineralogy and Petrology
Subject: Earth sciences
ISSN: 0010-7999
Year: 1997
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Constraining a SHRIMP U-Pb age: micro-scale characterization of zircons from Saxonian Rotliegend rhyolites
Article Abstract:
A new study investigates zircons from Saxonian Rotliegend lower volcanic rhyolites to determine how their characterization can constrict the geological significance of U-Pb zircon ages. The Sensitive High Resolution Ion Microprobe method is sued to determine radionuclide content and U-Pb age. It is shown that the zircons have not altered since their time of growth, suggesting that the rhyolite age is 278 Ma and that they were derived from a primary magnetic source.
Publication Name: Contributions to Mineralogy and Petrology
Subject: Earth sciences
ISSN: 0010-7999
Year: 1998
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