magmas in English
Massive sulfide deposits may also form in other settings where water circulates in rocks near cooling magma .
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1. Fractionation of hornblende, biotite and andesine yields granitic magmas.
2. This ambivalence is typical of distensive areas transitional magmas.
3. Chromite forms in deep ultra-mafic magmas and is one of the first minerals to crystallize
4. These volatile-rich magmas precipitated both albite and two generations of K-rich alkali feldspar.
5. Basaltic Crustally-contaminated andesites could be produced by combined assimilation and fractional crystallization of Basaltic magmas
6. Andesite is a fine-grained extrusive igneous rock, forming when volcanic magmas erupt and crystallize outside of the volcano
7. The contrast between gas-rich and gas-poor magmas is much more pronounced at the viscous granitic end of the scale.
8. Basaltic magmas that form the oceanic crust of Earth are generated in the asthenosphere at a depth of about 70 kilometres
9. Hydrothermal fluids released by the cooling granitic magmas then transported those isotopes along the Biotites’ cleavage planes to deposit the Po isotopes in
10. Basaltic magmas contain around 50% silica; they are the most common extrusive rocks and comprise more than 90% of all volcanic rock
11. The main characteristics for the sialic origin of the Aeolean magmas are: excess of Als2O3; the presence of minerals of evidently not magmatic origin (cordierite, garnet, andalusite and sillimanite); inclusions of relicts of metamorphic schists besides granites and granodiorites; the fact, that some of these magmas are characterized by superheating (e. g. the obsidians of Lipari-island).
12. Contamination and assimilation of andesitic and »shoshonitic« rocks by uprising granitic magmas generated, in association with hydrothermal phenomena, composite environments for gold deposits.
13. The hydrothermal fluids released during crystallization of these magmas resulted in considerable element redistribution and recrystallization both in the plutons and the adjacent country rocks.
14. Studies of mafic enclaves and adjoining host rocks indicate that mafic and acidic magmas interacted extensively during the emplacement and crystallization of the granodioritic mass.
15. Some Batholiths that cut sharply across their wallrocks and that are sur rounded by contact-metamorphic aureoles clearly formed from magmas intruded from greater depths.
16. The high water contents of back-arc basin basalt magmas is derived from water carried down the subduction zone and released into the overlying mantle wedge.
17. The parental magma has affinities with arc-type magmas related to subduction (shoshonitic magma series), as is evidenced by high LILE/LREE ratio, and select depletion of HFSE.
18. Batholithic rocks formed from the mixing of basaltic and quartzo- feldspathic end-member magmas, and the removal of variable propor tions of plagioclase and mafic minerals, principally hornblende
19. When postshield hawaiite magmas subsequently entered reservoirs, alkalic-tholeiitic hybridization occurred; the resulting `complex' mixture of hawaiite+tholeiitic hybrids resorbed andesine and clinopyroxene crystals and, upon eruption, entrained xenoliths of gabbro.
20. ‘Magmas Concentrate metals, and magma fluids traveling into the surrounding wall rock plant the seeds for mineral growth.’ ‘These species depend upon a network of blood vessels to Concentrate oxygen in their swim bladder.’
21. The mineral chemistry of several Pliocene alkali basaltic rocks from Burgenland and Styria (Eastern Austria) have been investigated in order to determine the evolution path of the basalt magmas prior to eruption.
22. This fact, along with evidence concerning chemical composition of the rock, suggests that these dikes represent tholeiitic magmas contaminated at depth, mainly by a support of alkalies and volatile constituents and perhaps also barium.
23. Batholithic and silicic-volcanic magmas become in general more silicic and more potassic as the continental crust be comes thicker, so the lower crust may be increasingly involved in melting as its depth increases
24. This suggests that Crustal thickness exerts a first order control on the Sr/Y variability of arc magmas through the stabilization or destabilization of mineral phases that fractionate Sr (plagioclase) and Y (amphibole ± garnet)
25. Unlike their arc-related counterparts, however, the Chinese magmas carry inherited Archaean zircons and have neodymium and strontium isotopic compositions overlapping those of eclogite xenoliths derived from the lower crust of the North China Craton.
26. The accumulation of plagioclase phenocrysts suggests extensive crystal fractionation of the Knee Lake magmas. The gradual transition in affinity of the Knee Lake lavas from tholeiitic to calc-alkaline can be explained by near-surface fractionation under constant fO2 conditions.
27. This assortment of mineral and rock components within alkalic lavas with apparent Mg enrichment is owed to a complex history that began with protracted mixing among primitive and differentiated tholeiitic magmas, probably near the end of shield building.
28. Comparison with petrological data of the volcanic rocks also implies that olivine was in a reaction relationship with an intermediate alkalic magma in both the intruded magmas at shallow depth and in the magma chamber at great depth.
29. Furthermore, Basaltic and gabbroic rocks of the ocean basins represent magmas that have the least likelihood of being contaminated with continental crustal material, and thus should give us the best clues to the composition of and chemical evolution of the underlying mantle …
30. Petrographic Observations on Mixing of Acid and Basic Magmas: Genesis of the Dacitoïdes of the Qom-Aran Area (Central Iran) Among the Upper Eocene pyroclastic materials of the Qom-Aran area (Central Iran) there are rocks (named lava-breccias) with intermediate facies between lavas and pyroclastic rocks.
31. ¶To enhance the ability to distinguish tholeiitic from alkalic magma parentages by mineral compositions, I determined trace-element abundances in plagioclase separated from xenolithic gabbros of Mauna Kea volcano. These gabbros have origins in tholeiitic and alkalic magmas of the Hamakua postshield stage of Mauna Kea volcanism.
32. ‘The Batholith extends into the west Kimberley, and is more than 750 km long and about 60-70 km wide.’ ‘The magmas that formed the Batholith were generated in response to the subduction of the Farallon plate beneath the North American plate.’ ‘The currently accepted name for this part of the craton is the Murehwa Batholith.’
33. Ocean island Basaltic magmas are enriched in H 2 O relative to depleted MORB, giving rise to the possibility that the excess magmatism associated with mantle plumes is caused, at least in part, by the effect of higher H 2 O on mantle melting rather than solely being due to high mantle potential temperature (Schilling et al., 1980; Bonatti, 1990).