Magma type and tectonic setting discrimination using immobile elements

Floyd, P. A.; Winchester, J. A.

doi:10.1016/0012-821x(75)90031-x

Cited by 669 publications

(260 citation statements)

References 54 publications

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“…This can only be done using immobile elements, elements that are little affected by alteration processes, which are also good petrogenetic indicators. Several studies of this problem (Cann, 1970;Pearce and Cann, 1973;Wood et al, 1976;Floyd and Winchester, 1975) suggest that the elements least affected by alteration are those with high formal ionic changes, such as Ti, Zr, Nb, Ta, Hf, and P. These elements seem to form very stable and very insoluble complex oxy-anions. Formally trivalent elements, such as the rare earths and yttrium, are not as immobile.…”

Section: Leg 49 Implications For Mantle Heterogeneitymentioning

confidence: 99%

Mantle Heterogeneity in the North Atlantic: Evidence from Leg 49 Geochemistry

Cann¹,

Tarney²,

Varet³

et al. 1979

Initial Reports of the Deep Sea Drilling Project

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Section: Leg 49 Implications For Mantle Heterogeneitymentioning

confidence: 99%

Mantle Heterogeneity in the North Atlantic: Evidence from Leg 49 Geochemistry

Cann¹,

Tarney²,

Varet³

et al. 1979

Initial Reports of the Deep Sea Drilling Project

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“…Group 2 is characterized by comparison with the previous group with relatively high contents of TiO 2 (3.40-3.62%), Y (29.2-42.6 ppm), P O (0.52 0.7%) and Nb 2 5 (17-22.6 ppm). The reports 1<Y/Nb<2 (1.71-1.91) show the transitional affinity of the group (Floyd and Winchester, 1975). The REE (Evensen et al, 1978) are relatively enriched in LREE ((La/Sm) = 2.34-2.60) and slightly N depleted in HREE ((La/Yb) = 7.56-8.38 and (Gd/Yb) = N N 1.98-2.14) (Fig.…”

Section: Introductionmentioning

confidence: 90%

Geochemical and Geodynamic Implications of Mafic Dykes of the Iguerda Inlier (Central Anti-Atlas, Morocco)

Hassan¹,

Aouli²,

Amaouain³

2010

Online J. of Earth Sciences

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Abstract:In the inlier of Iguerda (Anti-Atlas, Morocco), the Neoproterozoic basic rocks consist dominantly of dolerite dykes intruded the Palaeoproterozoic basement and overlain by the late Neoproterozoic series. Major and immobile trace elements (HFS and REE elements) allow to identify 2 groups of mafic rocks: the 1st is tholeiitic, the 2nd shows a transitional affinity with chondrite normalized REE patterns more fractionated. Their geochemical signatures display similarities with those of intraplate series found in young continental rift structures (they are enriched in incompatible elements, excepted Y and Yb, relative to N-MORB but they are depleted in Nb). This preorogenic magmatism can be related to begining of rifting in the northern border of the West-African craton which allows the emplacement of bassins of Pan-African belt of Anti-Atlas. This rifting may be related to the opening of an oceanic domain in Siroua and Bou-Azzer areas.

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“…The TAS proxy diagram Nb/Y vs. Zr/ Ti ( Fig. 9a; Pearce 1996, after Floyd andWinchester 1975) shows that the studied samples correspond to subalkali basalts/basaltic andesites except for the olivine-bearing sample VP46, which falls into the alkali basalt field. Similar signatures can be deduced from the ternary plot relating the cation percentages of Al 2 O 3 , FeO + Fe 2 O 3 + TiO 2 , and MgO (Fig 9b; Jensen 1976), where four of the studied samples correspond mostly to high-Mg tholeiitic basalts.…”

Section: Whole-rock Geochemistrymentioning

confidence: 97%

Metamorphic reactions and textural changes in coronitic metagabbros from the Teplá Crystalline and Mariánské Lázně complexes, Bohemian Massif

Jašarová¹,

Ráček²,

Jeřábek³

et al. 2016

J. Geosci.

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Coronitic metagabbros occur as small isolated bodies along the contact between the Mariánské Lázně and the Teplá Crystalline complexes in the northwestern part of the Teplá-Barrandian Unit in the Bohemian Massif. Metagabbros show variable metamorphic and textural characteristics with respect to their magmatic mineral assemblage and degree of metamorphism. The aim of this study has been to characterize the mineralogical, chemical, and microstructural changes related to metamorphism in selected samples. Magmatic mineral assemblages in the metagabbros represented by plagioclase, orthopyroxene, clinopyroxene, amphibole, biotite, ilmenite and occasionally involving olivine, spinel or quartz are generally well preserved. Metamorphism is mainly reflected by the formation of single or multiple coronas at the contact of plagioclase with the other primary minerals. The coronas typically consist of amphibole, garnet and orthopyroxene. The progressive breakdown of magmatic plagioclase is reflected by the formation of a mixture of An 40 and An 90 plagioclase associated with spinel, corundum and locally also kyanite. The calculated P-T conditions show an increase in metamorphic grade towards the structural footwall, i.e. from the east-southeast (~600 ± 50 °C; 10 ± 1.5 kbar) to the west-northwest (~700 ± 50 °C; 13.5 ± 1.5 kbar), which corresponds to the previously reported Variscan metamorphic field gradient in this area. Since there is no gap in P-T conditions between metagabbros included in MLC and TCC and showing similar age and geochemical signature, it is concluded that both complexes were brought together before the gabbro intrusion at ~500 Ma. In addition, the maximum pressure of ~14 kbar estimated for the metamorphism of the gabbro occurring in the eclogite-bearing Mariánské Lázně Complex suggests that the eclogite-facies metamorphism might have been pre-Variscan. The chemistry of the studied metagabbros corresponds to subalkaline basalts with traceelement signatures characteristic of E-MORB, which is consistent with an interpretation that the intrusion of these rocks was related to an intracontinental rifting of the Teplá-Barrandian Unit during Late Cambrian and was not connected to any subduction processes.

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Magma type and tectonic setting discrimination using immobile elements

Cited by 669 publications

References 54 publications

Mantle Heterogeneity in the North Atlantic: Evidence from Leg 49 Geochemistry

Mantle Heterogeneity in the North Atlantic: Evidence from Leg 49 Geochemistry

Geochemical and Geodynamic Implications of Mafic Dykes of the Iguerda Inlier (Central Anti-Atlas, Morocco)

Metamorphic reactions and textural changes in coronitic metagabbros from the Teplá Crystalline and Mariánské Lázně complexes, Bohemian Massif

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