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GEOREF RECORD

Magmatic (silicates/saline/sulfur-rich/CO/2) immiscibility and zirconium and rare-earth element enrichment from alkaline magma chamber margins; evidence from Ponza Island, Pontine Archipelago, Italy

Harvey E. Belkin, Benedetto De Vivo, Annamaria Lima and Kalman Torok
Magmatic (silicates/saline/sulfur-rich/CO/2) immiscibility and zirconium and rare-earth element enrichment from alkaline magma chamber margins; evidence from Ponza Island, Pontine Archipelago, Italy
European Journal of Mineralogy (December 1996) 8 (6): 1401-1420

Abstract

EPMA results are given for sanidine, clinopyroxene, amphibole, biotite, titanite, apatite and the Zr-bearing minerals baddeleyite and zirkelite in a feldspathoid-bearing syenite xenolith, entrained in trachyte on Ponza Island on the W coast of Italy, and reveal enrichment in REE, Y, Nb, U, Th as well as Cl and F in appropriate phases. Fluid inclusions in K-feldspar are either silicate-melt or aqueous inclusions, the latter being studied in detail. Daughter crystals observed in three-phase inclusions were tentatively identified as halite, sylvite, glauberite, arcanite, anhydrite and thenardite. Melting of the daughter crystals occurs between 459 and 536 degrees C (54-65 wt.% NaCl eq.) whereas total homogenization is at 640-755 degrees C. The occurrence of silicate-melt inclusions and high-T solute-rich aqueous inclusions suggests that the drusy or miarolitic texture of this xenolith is late-stage magmatic. The Ponza xenolith represents a portion of the peripheral magma chamber wall that has recorded the magmatic/hydrothermal transition and the passage of high solute fluids enriched in chlorides, sulphur and incompatible elements.


ISSN: 0935-1221
Serial Title: European Journal of Mineralogy
Serial Volume: 8
Serial Issue: 6
Title: Magmatic (silicates/saline/sulfur-rich/CO/2) immiscibility and zirconium and rare-earth element enrichment from alkaline magma chamber margins; evidence from Ponza Island, Pontine Archipelago, Italy
Affiliation: U. S. Geological Survey, Reston, VA, United States
Pages: 1401-1420
Published: 199612
Text Language: English
Publisher: Schweizerbart'sche Verlagsbuchhandlung (Naegele u. Obermiller), Stuttgart, Federal Republic of Germany
References: 57
Accession Number: 1997-018114
Categories: Geochemistry of rocks, soils, and sedimentsIgneous and metamorphic petrology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 4 tables, geol. sketch maps
N41°00'00" - N41°00'00", E13°00'00" - E13°00'00"
Secondary Affiliation: Universita di Napoli Federico II, ITA, ItalyEotvos University, HUN, Hungary
Country of Publication: Germany
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United KingdomTwickenhamUKUnited Kingdom
Update Code: 199706
Program Name: USGSOPNon-USGS publications with USGS authors
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