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Titolo:
The effects of variable bulk composition on the melting systematics of fertile peridotitic assemblages
Autore:
Pickering-Witter, J; Johnston, AD;
Indirizzi:
Univ Oregon, Dept Geol Sci, Eugene, OR 97403 USA Univ Oregon Eugene OR USA 97403 egon, Dept Geol Sci, Eugene, OR 97403 USA
Titolo Testata:
CONTRIBUTIONS TO MINERALOGY AND PETROLOGY
fascicolo: 2, volume: 140, anno: 2000,
pagine: 190 - 211
SICI:
0010-7999(200012)140:2<190:TEOVBC>2.0.ZU;2-1
Fonte:
ISI
Lingua:
ENG
Soggetto:
MIDOCEAN RIDGE BASALTS; UPPER-MANTLE; THERMODYNAMIC MODELS; PRIMARY MAGMAS; ABYSSAL PERIDOTITES; HIGH-PRESSURES; OCEAN RIDGES; GENERATION; MINERALS; DIAMOND;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
81
Recensione:
Indirizzi per estratti:
Indirizzo: Pickering-Witter, J Univ Calif Davis, Dept Geol, 1 Shields Ave, Davis, CA 95616 USA Univ Calif Davis 1 Shields Ave Davis CA USA 95616 USA
Citazione:
J. Pickering-Witter e A.D. Johnston, "The effects of variable bulk composition on the melting systematics of fertile peridotitic assemblages", CONTR MIN P, 140(2), 2000, pp. 190-211

Abstract

Experiments were conducted at 1 GPa on four starting materials to investigate the effects of variable mineral proportions on the melting systematics of compositionally fertile peridotitic assemblages. Starting materials wereconstructed by recombining Kilbourne Hole xenolith mineral separates by weight into four mixtures with mineral proportions olivine (01): orthopyroxene (Opx): clinopyroxene (Cpx): spinel (Sp) of 0.50:0.07:0.40:0.03 (FER-B), 0.50:0.46:0.01:0.03 (FERC), 0.50:0.30:0.10:0.10 (FER-D), and 0.50:0.235:0.235: 0.03 (FER-E). Experiments were performed on a 1.27cm (0.5 in.) piston-cylinder apparatus over the temperature interval 1270-1390 degreesC, using a variation of the diamond aggregate melt extraction technique employing vitreous carbon spheres in place of diamonds as the melt extraction layer. The solidus temperatures are similar for all the starting materials, with an average value of 1250 degreesC. In FER-D and -E, the near-solidus melting reaction for a Iherzolite assemblage was determined to be of the form Cpx + Opx + Sp -> melt + Ol. A subsequent reaction of the form Opx + Sp ->,melt + Ol was determined for FER-D after the exhaustion of Cpx. Over the entire temperature interval investigated for FER-B and -C, reactions were determined to be of the form Cpx + Sp -> melt + Ol and Opx + Sp -> melt + Ol, respectively. Melt percent (F) vs temperature (T) curves are concave up for all starting materials, demonstrating that isobaric melt productivity increases with progressive batch melting. At any given melt fraction, (dF/dT)(p) increases with increasing amount of Cpx in the starting material, indicating thatthe modal proportion of Cpx is one of the primary controls on isobaric melt productivity of upwelling peridotite. The concave up melt productivity functions for peridotitic assemblages determined in this study suggest that assuming linear or concave down melt productivity functions for modeling mantle melting may not be appropriate.

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Documento generato il 15/07/20 alle ore 07:32:29