Depth of origin of basalts inferred from Ti/V ratios and a comparison with the K2O-depth relationship for island-arc volcanics

Hodder, A. P. W.

doi:10.1016/0009-2541(85)90031-2

Cited by 9 publications

(3 citation statements)

References 44 publications

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“…The Ti/V ratio appears to be increasing systematically from island arc theoleiitic basalt (IATB), to mid-oceanic ridge basalt (MORB), and to intraplate volcanics. Hodder (1985) stated that the depth of origin of basalts can be inferred from Ti/V ratios. The order of magma depth origin (island arc > MORB > plume) is the reverse of Ti/V ratios of the basalt in Shervais (1982) discrimination.…”

Section: Origin and Petrogenesismentioning

confidence: 99%

Geological Studies on the Abu Fannani Mylonitic Amphibolites and Related Amphibolite Xenoliths in the Juvenile Neoproterozoic Meatiq Dome Area, Central Eastern Desert, Egypt.

2019

Assiut University Journal of Multidisciplinary Scientific Resea

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The Neoproterozoic crustal rocks exposed in the Meatiq dome area, Central Eastern Desert of Egypt, comprise medium -to high -grade mylonites. They form strongly foliated and folded mappable units, including (in the core): Um Baanib granite-gneiss, followed structurally upward by Fiadiya augen schists, Gabal Meatiq phyllonitic mylonites, Abu Zohleiqa augen gneisses, Um Esh El-hamra quartzofeldspathic mylonites, and Abu Fannani mylonitic amphibolites. These appear to have been largely derived from granitic, pelitic to semipelitic, and basaltic to basaltic andesite rocks. The present work is focused only on the Abu Fannani mylonitic amphibolites which occur mainly in the shear zone constituting the frame of the Meatiq Dome. The amphibolite xenoliths hosted by the Um Baanib granite-gneiss are supposed to be originally belonging to the Abu Fannani unit. Field and petrographic characteristics of both amphibolitic types indicate that they were undergone a complex evolution of repeated deformations and metamorphisms. These were genetically connected with three major events, including subduction, obduction and updoming processes. Due to subduction, the original basaltic to basaltic andesites, together with the pelitic to semipelitic sediments formed a strongly folded and highly metamorphosed (M 1 ) orogenic belt. The lower part of this belt was migmatized and intruded by a synkinematic granite (i.e., Um Baanib granite-gneiss). During obduction, thick nappes overrode the highly metamorphosed belt leading to its transformation into high-to mediumgrade mylonites having the amphibolite facies grade metamorphism (M 2 ). Thereafter, updoming processes originally linked with the Najd Fault System took place where brittle-ductile shear zones accompanied with greenschist facies metamorphism (M 3 ) were achieved. Regarding geochemistry of the amphibolites, major elements refer to their derivation from tholeiitic basalt to basaltic andesites. In Harker variation diagrams, immobile and incompatible elements (Zr,Ti,Y, and P) show good linear correlation relative to the mobile elements. Tectonic discrimination diagrams suggest the presence of two tectonic settings for both amphibolites, i.e., within-plate and MORB environments.

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Section: Origin and Petrogenesismentioning

confidence: 99%

Geological Studies on the Abu Fannani Mylonitic Amphibolites and Related Amphibolite Xenoliths in the Juvenile Neoproterozoic Meatiq Dome Area, Central Eastern Desert, Egypt.

2019

Assiut University Journal of Multidisciplinary Scientific Resea

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“…Ti (ppm)/1000 versus V (ppm) pour les diorites ferrifères. Limites de Hodder (1985), basé sur les données de Shervais (1982). 222 Figure 4.8.…”

Section: Xu1unclassified

“…Ti (ppm)/1000 versus V (ppm) pour les diorites ferrifères. Limites de Hodder (1985), basé sur les données de Shervais (1982). (Owens, et Dymek, 1992) Un des arguments en faveur de l'immiscibilité est la présence d'un hiatus compositionnel dans la série d'échantillons.…”

Section: Diorites Ferrifèresunclassified

Pétrographie, géochimie et potentiel économique en Fe-Ti-P du secteur du Lac à Paul, partie nord de la suite anorthositique de Lac-Saint-Jean, province de Grenville, Québec /

Frédette¹

2006

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Ill légers que les compositions magmatiques parentales calculées pour le secteur du lac à Paul. Cependant, il est possible qu'elles soient génétiquement associées aux roches enrichies en Fe-Ti±P du secteur du lac à Paul.Les péridotites nelsonitiques, avec 10 à 25 % d'apatite, représentent le meilleur potentiel en terme de phosphore (4 à 10 % P2O5). Elles possèdent une bonne distribution à travers le secteur d'étude et elles pourraient également représenter un potentiel économique' secondaire en ilménite et magnetite. Les roches à oxydes de Fe-Ti sont les plus enrichies fer et titane. Toutefois, dans le contexte de cette étude, leur potentiel économique semble limité car elles possèdent une distribution plutôt erratique à travers le secteur d'étude. IV ABSTRACTThis master's project is a study of the geochemistry, the petrography and economic potential of iron-, titanium-, and phosphorus-rich rocks (Fe-Ti±P) of the lac à Paul area, located in the northern part and on the margins of the Lac Saint-Jean anorthositic suite (LSJAS). The LSJAS is part of the Grenville province, which is characterized by numerous proterozoic AMCG-type anorthositic suites. This type of Fe-TüP enrichment is caracteristic of these suites.The Fe-Ti±P enrichment of the different types of rocks in the lac à Paul area reflects their variable enrichment in magnetite, ilmenite and apatite. The sampled rocks that show this type of Fe-Ti±P enrichment were divided into six lithologies: 1) Fe-Ti oxides-and apatite-bearing anorthosites, leucogabbros, leuconorites and leucogabbronorites; 2) Fe-Ti oxides-and apatite-bearing troctolites and leucotroctolites ±; 3) nelsonitic peridotites; 4) Fe-Ti oxides rocks; 5) Fe-Ti oxides-bearing pyroxenites, and; 6) Fe-Ti oxides-bearing dunites. Some ferrodiorites, in the form of crosscutting dykes, were also sampled.The minerals analysed by microprobe (olivine, plagioclase, orthopyroxene, clinopyroxene, ilmenite, magnetite, spinel and apatite) all display evolved compositions. The plagioclase is mostly andesine (An2? à Anjo) and the forsterite content of the olivines varies from F046 à F063. Unlike the other lithologie, which are characterized by ilmenite, the ferrodiorites contain hemo-ilmenite.The evolved nature of the different rock types of the lac à Paul area, illustrated by the pétrographie and geochemical studies, indicates that the parental magma of these rocks is also evolved. Moreover, the ubiquitous distribution of apatite indicates that the parental magma had a composition where apatite was on the liquidus. The REE composition of the parental magma was calculated using the REE composition of separated apatites analyzed by INAA. This (calculated) composition is similar to the composition of ferrodioritic rocks often associated with anorthosite massifs. The formation of the anorthositic and troctolitic rocks is possible by crystal fractionation, from a magma of ferrodioritic composition. The origin of the nelsonitic peridotites remains problematic and liquid immiscibility cannot be excluded. The Fe-Ti oxid...

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Evolution of the Silvretta Nappe

Maggetti¹,

Flisch²

1993

Pre-Mesozoic Geology in the Alps

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Depth of origin of basalts inferred from Ti/V ratios and a comparison with the K2O-depth relationship for island-arc volcanics

Cited by 9 publications

References 44 publications

Geological Studies on the Abu Fannani Mylonitic Amphibolites and Related Amphibolite Xenoliths in the Juvenile Neoproterozoic Meatiq Dome Area, Central Eastern Desert, Egypt.

Geological Studies on the Abu Fannani Mylonitic Amphibolites and Related Amphibolite Xenoliths in the Juvenile Neoproterozoic Meatiq Dome Area, Central Eastern Desert, Egypt.

Pétrographie, géochimie et potentiel économique en Fe-Ti-P du secteur du Lac à Paul, partie nord de la suite anorthositique de Lac-Saint-Jean, province de Grenville, Québec /

Evolution of the Silvretta Nappe

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