Additional 40Ar-39Ar dating of the basement and the alkaline volcanism of Gorringe Bank (Atlantic Ocean)

Féraud, Gilbert; York, Derek; Mével, Catherine; Cornen, G.; Hall, Chris M.; Auzende, J.M.

doi:10.1016/0012-821x(86)90184-6

Cited by 75 publications

(39 citation statements)

References 13 publications

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“…1). Rb-Sr, U-Pb and 40 Ar/ 39 Ar ages for these rocks range between 67-77 and 31 Ma (Rock, 1976;Féraud et al, 1982Féraud et al, , 1986McIntyre and Berger, 1982;Bernard-Griffiths et al, 1997;Schärer et al, 2000). We will show that such alkaline magmatism is also a major component of the northern Tore-Madeira Rise, where differentiated alkaline rocks have been recognized.…”

Section: Geological Frameworkmentioning

confidence: 91%

“…It is composed of peridotites that are intruded by 138 ± 1 and 136 ± 1 Ma old gabbros, and 67-77 Ma old alkaline lavas on top of the bank (Féraud et al, 1982(Féraud et al, , 1986Cornen, 1982;Cornen et al, 1999;Schä-rer et al, 2000). The alkaline lavas show two magmatic trends (1) highly alkalic, silica-undersaturated rocks, ranging from nephelinites to phonolites and (2) mildly alkaline, silica-saturated volcanics ranging from alkali basalt and basanites to trachytes (Cornen, 1982).…”

Section: The Ormonde Seamountmentioning

confidence: 95%

“…Prior to this study, only a few geochronological or tracer isotope data were available for volcanoes emplaced Wendt et al (1976); Féraud et al (1981Féraud et al ( , 1982Féraud et al ( , 1986; BernardGriffiths et al (1997); Schärer et al (2000); Geldmacher et al ( , 2005. Location of the J anomaly after Olivet (1996). between the Tore seamounts in the north, and Jo-Sister in the south (Fig.…”

Section: Introductionmentioning

confidence: 99%

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Cretaceous seamounts along the continent–ocean transition of the Iberian margin: U–Pb ages and Pb–Sr–Hf isotopes

Merle¹,

Schärer²,

Girardeau³

et al. 2006

Geochimica et Cosmochimica Acta

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Section: Geological Frameworkmentioning

confidence: 91%

Section: The Ormonde Seamountmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

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Cretaceous seamounts along the continent–ocean transition of the Iberian margin: U–Pb ages and Pb–Sr–Hf isotopes

Merle¹,

Schärer²,

Girardeau³

et al. 2006

Geochimica et Cosmochimica Acta

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“…1) is the most important topographic feature of the area. It is an uplifted block of crustal and upper mantle rocks (AUZENDE et al, 1978;AUZENDE et al, 1982;RYAN et al, 1973;FE´RAUD et al, 1986;GIRARDEAU et al, 1998) forming one of the most prominent gravimetric anomalies of the world. The Gorringe Ridge separates the 5000 m deep Tagus Abyssal Plain from the Horseshoe Abyssal Plain reaching a water depth of 25 m at its top.…”

Section: Gorringe Ridgementioning

confidence: 99%

Neogene Through Quaternary Tectonic Reactivation of SW Iberian Passive Margin

Zitellini

Rovere

Terrinha³

et al. 2004

Pure and Applied Geophysics

115

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Southwest Portugal, the Gulf of Cadiz and Morocco are under the potential threat of natural hazards linked to seismicity and tsunami generation. We report the results of two multi-channel seismic (MCS) surveys carried out in 1992 and 1998 along the continental margin and oceanic crust of SW Iberia. This MCS data set shows the evidence of the compressional deformation which involves both the continental and the oceanic crust of the study area. The area of deformation extends from the southern border of the Tagus Abyssal Plain to the Seine Abyssal Plain, encompassing the continental margin of SW Portugal. Most of the structures observed are probably related to a Mid-Miocene phase of Africa-Europe plate convergence. In this paper we discuss the recent advances on the identification of the tectonic structures that are still active and that may generate great earthquakes and tsunamis. The tectonic structures identified are located respectively at the Guadalquivir Bank, along the eastern border of the Horseshoe Abyssal Plain and along the southern continental slope of SW Portugal.

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“…The formula corresponding to p is that of Berger and York (1970), which takes into account the error in the 40 Ar*/ 39 Ar ratio of the monitor but not the error in its age. The criteria we used to define a plateau are those of Feraud et al (1986): (1) (Roddick et al, 1980).…”

Section: Analytical Techniquesmentioning

confidence: 99%

K-Ar and 40Ar/39Ar Ages of Central Kerguelen Plateau Basalts

Whitechurch¹,

Montigny²,

Sevigny³

et al. 1992

Proceedings of the Ocean Drilling Program

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Conventional K-Ar and 40 Ar/ 39 Ar analyses on whole-rock samples are reported for basaltic samples retrieved on the Central and Southern Kerguelen plateaus during Ocean Drilling Program Leg 120. Sites 747, 749, and 750 recovered basalts from the plateau basement, whereas Site 748 drilled a lava flow interbedded with sediments of probable Albian age.The freshest core basalts from the basement yielded dates falling in the 110-100 m.y. interval. Sample 120-749C-15R-3 (26-31 cm) gave conventional K-Ar, total fusion, and plateau ^Ar/^Ar ages that are closely concordant: 111.5 ± 3.2 m.y., 109.9 ± 1.2 m.y., and 109.6 ± 0.7 m.y., respectively. Sample 120-750B-15R-5 (54-60 cm), when taking into account the analytical uncertainties, yields conventional K-Ar and 40 Ar/ 39 Ar plateau ages that can be considered similar: 101.2 ± 7.5 and 118.2 ± 5 m.y., respectively. Inspection of the 39 Ar/ 40 Ar vs. 36 Ar/ 40 Ar diagram does not reveal the occurrence of an initial argon component of radiogenic composition in the two samples. Accordingly, our results suggest that the formation of the basement of the Central Kerguelen Plateau was closed at 110 m.y.. Furthermore, these results are in agreement with a K-Ar age of 114 ± 1 m.y. mentioned in the literature for a basalt dredged in the 77°E Graben.The still scant amount of data indicates that the outpourings of the Central Kerguelen Plateau correspond rather well with widespread continental magmatism in Gondwanaland that is believed to mark the incipient opening of the eastern Indian Ocean. This implies a huge head for the mantle plume at the source of these liquids. Nevertheless, on land and at sea the exact duration of magmatism remains unknown. Therefore, a catastrophic pattern similar to that currently invoked for the Deccan Traps at the end of the Cretaceous, though possible, is not yet required by present geochronologic data.

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Additional 40Ar-39Ar dating of the basement and the alkaline volcanism of Gorringe Bank (Atlantic Ocean)

Cited by 75 publications

References 13 publications

Cretaceous seamounts along the continent–ocean transition of the Iberian margin: U–Pb ages and Pb–Sr–Hf isotopes

Cretaceous seamounts along the continent–ocean transition of the Iberian margin: U–Pb ages and Pb–Sr–Hf isotopes

Neogene Through Quaternary Tectonic Reactivation of SW Iberian Passive Margin

K-Ar and 40Ar/39Ar Ages of Central Kerguelen Plateau Basalts

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