Processes and timescales in the evolution of a chemically zoned trachyte: Fogo A, Sao Miguel, Azores
Article Abstract:
A study was conducted to examine the formation of chemically zoned trachytes. The study considered U-series disequilibria analyses combined with chemical and petrographic analyses for determining processes and timescales for Fogo A trachytes. A least squares model offers the possibility of parental origin from alkali basalt composed of augite, plagioclase, magnetite, kaersutite, olivine and apatite. Results show that such trachytes exhibit properties equivalent to a chemically zoned magma chamber.
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:
Chromatographic separation of the platinum-group elements, gold, base metals and sulfur during degassing of a compacting and solidifying igneous crystal pile
Article Abstract:
Model calculations were formulated which explains the presence of platinum-group element (PGE)-enriched sulfide zones in layered intrusions. The presence of sulfide zones can be attributed to the migration of sulfide enrichment resorption fronts that accompany the degassing of interstitial liquids. A chromatographic mechanism was found to be capable of producing high PGE/S ratios. It is also revealed that the creation of ore-element offsets occur during sulfide resorption migration.
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:
Rates of grain boundary diffusion through enstatite and forsterite reaction rims
Article Abstract:
The effects of varying water concentrations on the grain growth rates of enstatite and forsterite rims are studied. Growth rates for enstatite rims were measured at 250-1500 MPa and 900-1100 degrees Centrigrade and forsterite rims determined between MgO and Mg2Si2O6, and MgO and SiO2. Results show that water increases grain boundary diffusion rates by a factor of 5-30 depending on the mineralogy.
Publication Name: Contributions to Mineralogy and Petrology
Subject: Earth sciences
ISSN: 0010-7999
Year: 1997
User Contributions:
Comment about this article or add new information about this topic:
- Abstracts: The need for mass balance and feedback in the geochemical carbon cycle: reply. The need for mass balance and feedback in the geochemical carbon cycle: comment
- Abstracts: Path modeling methods and ecological interactions: a response to Grace and Pugesek. Assembly rules: desert rodent communities are structured at scales from local to continental
- Abstracts: Earthquake focal mechanisms, moment tensors, and the consistency of seismic activity near plate boundaries. Extensional reactivation of the Chocolate Mountains subduction thrust in the Gavilan Hills of Southeastern California
- Abstracts: The paleozoic tectonic evolution of the northern edge of North America: a structural study of northern Ellesmere Island, Canadian Arctic Archipelago
- Abstracts: A dynamic model of extension in the Baltimore Canyon trough region. Oblique-slip deformation in extensional terrains: a case study of the Lakes Tanganyika and Malawi rift zones