XLFRAC: a program for the interactive testing of magmatic differentiation models

Stormer, John C.; Nicholls, J.

doi:10.1016/0098-3004(78)90083-3

Cited by 401 publications

(136 citation statements)

References 5 publications

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“…Rudnick and Fountain, 1995) is added to an undepleted mantle region (e.g., 25AMlh);(b) a silica-rich, low Ca/ (Mg, Fe) component (e.g., 701 Ssand, pelagic sediment;Planck and Langmuir, 1998) is added to a fertile mantle region (e.g.,36Mlh). Insert (c) shows the variations of meaningful trace element ratios (normalized to the primordial mantle; McDonough and Sun, 1995;see to s p the mineral phases (a i,j = constant), but changing their proportions by using a least-squared based mass balance calculation (e.g., Stormer and Nicholls, 1978). This provides an estimate of the weight fraction of the solid phases j of given compositions in the metasomatized assemblage (P j *) that are necessary to obtain the starting bulk composition in order to get: In Table 5, the major element compositions of the primary assemblages, metasomatic liquids and calculated products are compared to the observed metasomatized assemblages.…”

Section: Discussionmentioning

confidence: 99%

Ultramafic xenoliths from the Veneto Volcanic Province (Italy): Petrological and geochemical evidence for multiple metasomatism of the SE Alps mantle lithosphere

et al. 2006

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Petrologic and geochemical characteristics of whole rocks and minerals may be explained by metasomatism of the local mantle lithosphere induced by both alkaline magmas upwelling to the surface (OIB-like mantle diapirism) and interaction with slab-derived material. In comparison with the geochemistry of xenoliths carried by alkaline magmas in typical withinplate tectonic environments, the Veneto xenoliths record a major heterogeneity of the local lithosphere. This appears to be related to a geodynamic scenario that was previously dominated by active continental collision, in which plume-like magmatism subsequently manifested itself.

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Section: Discussionmentioning

confidence: 99%

Ultramafic xenoliths from the Veneto Volcanic Province (Italy): Petrological and geochemical evidence for multiple metasomatism of the SE Alps mantle lithosphere

et al. 2006

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“…Mass balance calculations for major elements were done with the program GENESIS developed by Leo Fernandes, based on a modification of XLFRAC (Stormer and Nicholls 1978). According to this, fractionation of about 70-90 wt.% of an assemblage with alkali feldspar (36 wt.%) + diopside (23 wt.%) + mica (23 wt.%) + andesine (15 wt.%) + apatite (3 wt.%) could have generated granitic compositions similar to those of the Piquiri granites considering an initial composition equivalent to the fine-grained syenites.…”

Section: Petrogenesis Of Syenitic and Granitic Rocksmentioning

confidence: 99%

Geochemistry and petrogenesis of post-collisional ultrapotassic syenites and granites from southernmost Brazil: the Piquiri Syenite Massif

Nardi

Plá-Cid

Bitencourt

et al. 2008

An. Acad. Bras. Ciênc.

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The Piquiri Syenite Massif, southernmost Brazil, is part of the post-collisional magmatism related to the Neoproterozoic Brasiliano-Pan-African Orogenic Cycle. The massif is about 12 km in diameter and is composed of syenites, granites, monzonitic rocks and lamprophyres. Diopside-phlogopite, diopside-biotite-augite-calcic-amphibole, are the main ferro-magnesian paragenesis in the syenitic rocks. Syenitic and granitic rocks are co-magmatic and related to an ultrapotassic, silica-saturated magmatism. Their trace element patterns indicate a probable mantle source modified by previous, subduction-related metasomatism. The ultrapotassic granites of this massif were produced by fractional crystallization of syenitic magmas, and may be considered as a particular group of hypersolvus and subsolvus A-type granites. Based upon textural, structural and geochemical data most of the syenitic rocks, particularly the fine-grained types, are considered as crystallized liquids, in spite of the abundance of cumulatic layers, schlieren, and compositional banding. Most of the studied samples are metaluminous, with K 2 O/Na 2 O ratios higher than 2. The ultrapotassic syenitic and lamprophyric rocks in the Piquiri massif are interpreted to have been produced from enriched mantle sources, OIB-type, like most of the post-collisional shoshonitic, sodic alkaline and high-K tholeiitic magmatism in southernmost Brazil. The source of the ultrapotassic and lamprophyric magmas is probably the same veined mantle, with abundant phlogopite + apatite + amphibole that reflects a previous subduction-related metasomatism.

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“…Genetic relationships among the Fernandina lavas were investigated by thermodynamic numerical experiments at various temperatures and pressures using the MELTS software [Ghiorso and Sack, 1995], supported for low-pressure fractionation processes by least squares mixing calculations [Stormer and Nicholls, 1978]. The paucity of suitable representative parental melt candidates was a frustrating shortcoming; sample Ga is coarse-grained and shows evidence for significant plagioclase accumulation in its large Eu and Sr anomalies (Figure 7), and the high m1203 and plagioclase phenocryst contents indicate that sample M also likely underwent plagioclase accumulation.…”

Section: Melt Modelingmentioning

confidence: 99%

Fernandina Volcano's evolved, well‐mixed basalts: Mineralogical and petrological constraints on the nature of the Galapagos plume

Allan¹,

Simkin²

2000

J. Geophys. Res.

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MgO. Cr-spinel and glass melt inclusions in plagioclase, together with zoned olivine, give evidence for a range of parental melts in the recent shallow magmatic system, with Mg # as high as 0.62. Extensive, shallow magma mixing is required to explain these variations in mineral and inclusion chemistry, indicating more thermal variation within the shallow magmatic system than is implied by the relatively monotonous whole rock compositions. Apparently, Fernandina's shallow magma chamber has physically blocked passage of more primitive magmas to the surface and homogenized the erupted lavas by extensive mixing. Small variations in lava isotopic and compatible element composition, combined with the need to resupply melt to maintain thermal balance, indicate that replenishment of the magma chamber is semicontinuous, with resupply occurring of the order of a decade or less. Plagioclase-dominated, evolved Fernandina lavas are in sharp contrast to more primitive, olivine-dominated Hawaiian lavas; the total lack of primitive melts in the shallow Fernandina magmatic system implies that substantial fractionation and heat loss occurred during melt transportation from the mantle source to the edifice magma chamber, despite the fact that these melts were transported through relatively warm, young, and thin lithosphere adjacent to the Cocos-Nazca ridge. The diffuse nature of Galapagos volcanism, with 20th century eruptions from eight distinct volcanoes over a 2 20,000 km area, further supports this interpretation and suggests that the Galapagos plume is relatively diffuse, weak, and significantly less thermally intense than the vigorous Hawaiian plume. It may in fact be waning.

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XLFRAC: a program for the interactive testing of magmatic differentiation models

Cited by 401 publications

References 5 publications

Ultramafic xenoliths from the Veneto Volcanic Province (Italy): Petrological and geochemical evidence for multiple metasomatism of the SE Alps mantle lithosphere

Ultramafic xenoliths from the Veneto Volcanic Province (Italy): Petrological and geochemical evidence for multiple metasomatism of the SE Alps mantle lithosphere

Geochemistry and petrogenesis of post-collisional ultrapotassic syenites and granites from southernmost Brazil: the Piquiri Syenite Massif

Fernandina Volcano's evolved, well‐mixed basalts: Mineralogical and petrological constraints on the nature of the Galapagos plume

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