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

Merle, Renaud; Schärer, Urs; Girardeau, J.; Cornen, G.

doi:10.1016/j.gca.2006.07.004

Cited by 41 publications

(43 citation statements)

References 86 publications

(123 reference statements)

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“…It is clear that significant along margin variations in mantle exhumation occurred along the Iberian margin. Unfortunately, the gap in seismic coverage and the later emplacement of the Tore Seamount (between 80 and 104 Ma; Merle et al 2006) between the IAP and the TAP preclude investigation of the along strike transition from a wide zone of exhumed mantle to no exhumation. As argued in Tucholke & Sibuet (2007), this variation may largely be due to the influence of plume magmatism at the southern end of the margin where the higher temperatures were more conducive to seafloor spreading than mantle exhumation.…”

Section: Discussionmentioning

confidence: 99%

Structure and rifting evolution of the northern Newfoundland Basin from Erable multichannel seismic reflection profiles across the southeastern margin of Flemish Cap

Welford

Smith

Hall

et al. 2010

Geophysical Journal International

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S U M M A R YWe present the results from processing and interpreting five lines from the 1992 Erable multichannel seismic reflection experiment extending from the southeastern margin of Flemish Cap into the northern Newfoundland Basin. These profiles reveal significant along strike variations in the rifting styles experienced by Flemish Cap. In the southwest, a 100-km-wide transition zone is identified between thinned continental crust and thin oceanic crust. Similar to the conjugate Galicia Bank and Iberian margins, this transition zone contains a section of deep basement adjacent to a series of shallower ridges and is interpreted as exhumed serpentinized mantle. Along strike towards the northeast, this transition zone pinches out completely within 100 km and is replaced by thin oceanic crust directly adjacent to thinned continental crust. By interpreting nearby seismic profiles and profiles on the conjugate margins using the same classification criteria, we construct regional maps of the distribution of crustal domains on both sides of the North Atlantic. These maps reveal significant variations in rifting style on the conjugate margins and along strike of each margin and also highlight the role of ancient transfer zones in compartmentalizing these rifting variations into four distinct regions. We propose that the limited localization of shallow topographically high serpentinized peridotite ridges on the Newfoundland-Iberia and Flemish Cap-Galicia Bank conjugate margins, was directly related to an increase in the rate of extension following the separation of Flemish Cap and Galicia Bank which exhumed deeper, less serpentinized mantle.

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Section: Discussionmentioning

confidence: 99%

Structure and rifting evolution of the northern Newfoundland Basin from Erable multichannel seismic reflection profiles across the southeastern margin of Flemish Cap

Welford

Smith

Hall

et al. 2010

Geophysical Journal International

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“…Results of 40 Ar/ 39 Ar and U/Pb age determinations, as well as paleontological constraints, recently revealed that this *1,000-km-long submarine ridge was initially formed in the Late Cretaceous (Geldmacher et al 2006a;Merle et al 2006). Based on plate tectonic reconstructions and gravity data, the Madeira-Tore Rise could have formed as an aseismic ridge (e.g., Peirce and Barton 1991) possibly by interaction of the westward-migrating Mid-Atlantic spreading center with the early Canary hotspot (Geldmacher et al 2006a).…”

Section: Geological Overview and Summary Of Previous Workmentioning

confidence: 97%

“…Hoernle and Schmincke 1993b;Geldmacher et al , 2001) to largescale regional upwellings and mega plumes (e.g. Hoernle et al 1995;Merle et al 2006Merle et al , 2009 Ar age dating, the regional volcanic pattern can be interpreted to reflect two parallel but independent hotspot tracks, Madeira and Canary (Morgan 1972;Duncan 1984;Geldmacher et al 2001Geldmacher et al , 2005. The present location of the Madeira and Canary hotspots are considered to be at the southwestern ends of the tracks, at Madeira and Hierro Islands, respectively (e.g.…”

Section: Geological Overview and Summary Of Previous Workmentioning

confidence: 99%

“…However, both explanations are not entirely satisfying since one location (Dragon Seamount, from which the only dated sample yielded a young 40 Ar/ 39 Ar plateau age of 3.94 ± 0.30 Ma, Geldmacher et al 2006a) lies at the southern end of the Madeira-Tore Rise (far away from any known active fault zone). The alternative model, attributing the origin of the entire Madeira-Tore Rise and the neighboring islands and seamounts of the Madeira domain to a long-lived thermal anomaly (mega plume) with a generally but broad southward-migrating, pulsating magma production below the lithosphere (Merle et al 2006;Merle et al 2009) would allow for an easier integration of this outlier sample from Dragon Seamount. Recent swath bathymetric mapping, however, supports the existence of local extension zones at the northern end of the MadeiraTore Rise (Zitellini et al 2009).…”

Section: Geological Overview and Summary Of Previous Workmentioning

confidence: 99%

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Hafnium isotopic variations in East Atlantic intraplate volcanism

Geldmacher

Hoernle

Hanan

et al. 2010

Contrib Mineral Petrol

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The broad belt of intraplate volcanism in the East Atlantic between 25°and 37°N is proposed to have formed by two adjacent hotspot tracks (the Madeira and Canary tracks) that possess systematically different isotopic signatures reflecting different mantle source compositions. To test this model, Hf isotope ratios from volcanic rocks from all individual islands and all major seamounts are presented in this study. In comparison with published Nd isotope variations (6 eNd units), 176 Hf/ 177

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“…Although the WIM is usually described as a non-volcanic or magma-poor margin, characterized by the absence of typical seaward-dipping reflectors and significant magnetic anomalies and by the occurrence of exhumed mantle portions (e.g., Pinheiro et al, 1996;Whitmarsh et al, 2001;Jagoutz et al, 2007;Reston et al, 2009;Bronner et al, 2011;Minshull et al, 2014), magmatic occurrences are known both offshore and onshore (e.g., Rock, 1982;Scharer et al, 2000;Merle et al, 2006). On the onshore portions of the Mesozoic basins (Algarve, Alentejo and Lusitanian) of the West Iberian Margin, three magmatic cycles were identified, separated by intervals of ≈50 Ma of A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT 5 quiescence and characterized by different geochemical signatures (e.g., Ribeiro et al, 1979;Ferreira and Macedo, 1983;Martins, 1991;Pinheiro et al, 1996;Martins et al 2010).…”

Section: Introductionmentioning

confidence: 99%

40Ar/39Ar ages and petrogenesis of the West Iberian Margin onshore magmatism at the Jurassic–Cretaceous transition: Geodynamic implications and assessment of open-system processes involving saline materials

Mata

Alves

Martins

et al. 2015

Lithos

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The West Iberian Margin (WIM) preserves onshore testimonies of three Mesozoic magmatic cycles. In this paper, we present and discuss 40 Ar/ 39 Ar ages and geochemical data for the second cycle, which occurred at least from 148 Ma to 140 Ma, at the Jurassic-Cretaceous transition, during the late stages of an important extensional event associated with the Iberia-Newfoundland rifting. The related lithospheric stretching induced magma genesis by adiabatic decompression. Primitive rocks are fairly alkaline but evolved to SiO 2 -saturated and oversaturated rocks at "high" pressure. Magmas sampled a source of fairly homogenous composition characterized by Sr and Nd isotopic compositions (Nd i from +1.6 to +4.2), more enriched than the typical N-MORB source. Magmas were generated at the top of the garnet zone. Considering the thickness of the lithosphere and the geochemical constraints, an origin by melting of a metasomatized domain of the lithosphere is favoured. The composition of these onshore magmas is somewhat distinct from the quasi coeval magmas emplaced offshore, which is interpreted as a result of the less important onshore lithospheric stretching, leading to lower degrees of partial melting. This favoured the contribution of lithospheric metasomatized domains to onshore magmas. Rocks intruded two sectors of the Lusitanian Basin separated by the Nazaré Fault and characterized by distinct subsidence rates during the Jurassic. The fact that the rocks to the north of the Nazaré Fault are significantly more evolved indicates the more important development of magma chambers in the north, suggesting distinct thermal profiles for those two sectors. Such magma chambers enabled the "high-pressure" fractionation necessary to drive magma compositions from Ne-normative to SiO 2 -saturated and -over-saturated. The rocks cropping out south of the Nazaré fault are clearly less evolved, and its variability is mostly due to different partial melting events. Some rocks present evidence of post- A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT3 magmatic processes involving neighbouring Jurassic evaporite materials, leading to an increase in the Na 2 O content and 87 Sr/ 86 Sr ratio.

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

Cited by 41 publications

References 86 publications

Structure and rifting evolution of the northern Newfoundland Basin from Erable multichannel seismic reflection profiles across the southeastern margin of Flemish Cap

Structure and rifting evolution of the northern Newfoundland Basin from Erable multichannel seismic reflection profiles across the southeastern margin of Flemish Cap

Hafnium isotopic variations in East Atlantic intraplate volcanism

40Ar/39Ar ages and petrogenesis of the West Iberian Margin onshore magmatism at the Jurassic–Cretaceous transition: Geodynamic implications and assessment of open-system processes involving saline materials

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