Catalogo Articoli (Spogli Riviste)

OPAC HELP

Titolo:
MELT INCLUSIONS IN HIGH-AN PLAGIOCLASE FROM THE GORDA RIDGE - AN EXAMPLE OF THE LOCAL DIVERSITY OF MORB PARENT MAGMAS
Autore:
NIELSEN RL; CRUM J; BOURGEOIS R; HASCALL K; FORSYTHE LM; FISK MR; CHRISTIE DM;
Indirizzi:
OREGON STATE UNIV,DEPT GEOSCI,WILKINSON 104 CORVALLIS OR 97331 OREGON STATE UNIV,COLL OCEAN & ATMOSPHER SCI CORVALLIS OR 97331
Titolo Testata:
Contributions to Mineralogy and Petrology
fascicolo: 1-2, volume: 122, anno: 1995,
pagine: 34 - 50
SICI:
0010-7999(1995)122:1-2<34:MIIHPF>2.0.ZU;2-S
Fonte:
ISI
Lingua:
ENG
Soggetto:
MID-ATLANTIC RIDGE; LAMONT SEAMOUNT CHAIN; EAST PACIFIC RISE; UPPER MANTLE; BASALTS; EVOLUTION; OLIVINE; LAVAS; GEOCHEMISTRY; PETROGENESIS;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Science Citation Index Expanded
Citazioni:
61
Recensione:
Indirizzi per estratti:
Citazione:
R.L. Nielsen et al., "MELT INCLUSIONS IN HIGH-AN PLAGIOCLASE FROM THE GORDA RIDGE - AN EXAMPLE OF THE LOCAL DIVERSITY OF MORB PARENT MAGMAS", Contributions to Mineralogy and Petrology, 122(1-2), 1995, pp. 34-50

Abstract

The use of ocean floor basalt chemistry as a tool to investigate mantle composition and processes requires that we work with basalts that have been modified little since leaving the mantle. One source of such basalts is melt inclusions trapped in primitive crystals. However, obtaining information from these melt inclusions is complicated by the fact that melt inclusions in natural basalts are essentially always altered by post-entrapment crystallization. This requires that we develop techniques for reconstructing the original trapped liquid compositions. We conducted a series of experiments to reverse the effects of post-entrapment crystallization by re-heating the host crystals to their crystallization temperature. For these experiments we used plagioclase crystals separated from a single Gorda Ridge lava. The crystallization temperature for these crystals was determined by a set of incremental re-heating experiments to be similar to 1240-1260 degrees C. The inclusions are primitive, high Ca-Al basaltic melts, saturated with plagioclase, olivine and Al-rich chromite at low pressure. The inclusion analyses can be linked to the host lava composition by low pressure fractionation. The major element composition of the re-homogenized melt inclusions within each crystal is relatively constant. However, the incompatible element analyses have extremely wide ranges. The range of La/Smand Ti/Zr from inclusions analyzed from a single sample from the Gorda Ridge exceeds the range reported for lavas sampled from the entire ridge. The pyroxene compositions predicted to be in equilibrium with the melt inclusion trace element signature cover much of the range represented by pyroxenes from abyssal peridotites. The volumetric proportions of the magmas entering the base of the crust can be evaluated usingfrequency distribution of melt inclusion compositions. This distribution suggests that the array of magmas was skewed towards the more depleted compositions, with little evidence for an enriched component in this system. This pattern is more consistent with a dynamic flow model of the mantle or of a passive flow model where the melts produced in the peripheral areas of the melting regime were not focused to the ridge.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 30/03/20 alle ore 19:47:40