No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
San Venanzo intrappenninic volcanic complex, Part II: mineral chemistry evolution related to volatiles in kamafugitic magmas.
Abstract
These data strongly suggest that PEG facies and the amygdules, are the consequence of different cooling and crystallization processes in the venanzitic magma. The preliminary texture analysis presented by Campagnola et al. (2013 - this volume) describes how the number of vesicles plus amygdules is consistent throughout the flow, thus suggesting that the volatile composition in the kamafugitic non-fragmentated melt was constant and equally distributed.
ResearchGate has not been able to resolve any citations for this publication.
Vertical, W- and NW-trending, post-tectonic, Proterozoic dykes at Napoleon Bay, southeastern Baffin Island, Northwest Territories, contain mineral assemblages typical of lamproites: 1) phenocrysts of Fe-bearing leucite and sanidine, Ti-rich phlogopite, and high-Mg olivine and diopside, and 2) a groundmass of Ti-rich phlogopite, Fe-bearing sanidine and apatite. Except where preserved in chill zones, leucite has decomposed to a sanidine - kalsilite intergrowth or has been replaced completely by sanidine. Phlogopite grains are enriched in Fe (to annite and ferri-annite) on their margins, relative to cores. Late-stage titanian potassium magnesio-arfvedsonite appears in some dykes and is also progressively enriched in Fe (to titanian potassium arfvedsonite) toward the margins of grains. In a few crystals, aegirine and aegirine-augite (some grains Ti-rich) overgrow diopside. Rare and very late-stage, possibly magmatic development of minerals involves overgrowths of potassium magnesio-arfvedsonite on Fe-rich amphibole, and phlogopite and "ferriphlogopite" on Fe-rich mica. With the exception of aegirine and aegirine-augite, all ferromagnesian silicates are undersaturated in Si + IVA1, with average deficits in the tetrahedral position extending from 15.7% in annite and ferri-annite (grain margins) to 1.5% in magnesio-arfvedsonite (overgrowths). The vacancies in the tetrahedral position can be filled with Fe3+. Rare minerals in the Baffin dykes, that are characteristic of known occurrences of lamproite, are K, Ti-rich sodic-calcic amphiboles, shcherbakovite, Ti-rich chromite, and K-Ti-Fe oxide. However, some (ninor minerals in these dykes have not been described from lamproite [pectolite, lorenzenite, barytolamprophyllite, alcioancylite-(Ce), djerfisherite], and the late Na-Fe overprint seems extreme for lamproite. Evidence suggests differentiation with repeated, post-consolidation magmatic injections. Rocks that are possibly related include a porphyritic volcanic rock containing pseudoleucite (sanidine) - forsterite - diopside - titanian phlogopite, located ca. 20 km west of Napoleon Bay, not found in situ, small diatreme dykes and sills (cemented with K-rich, peraluminous glass), 8 km WSW, and coeval, mineralogically similar lamproite dykes at Sisimiut, southwest Greenland.
The habit of apatite in synthetic and igneous system New minerals data from the kamafugite-carbonatite association: the melilitolite from Pian di Celle
- P J Wyllie
- K G Cox
- G M Biggar
Wyllie P.J., Cox K.G. and Biggar G.M. (1962): The habit of apatite in synthetic and igneous system. – Journal of Petrology, 1: 1-46. Stoppa F., Sharygin V.V. & Cundari A. (1997): New minerals data from the kamafugite-carbonatite association: the melilitolite from Pian di Celle, Italy – Mineralogy and petrology, 61: 27-45.