K-Ar Study of cretaceous magmatism and metamorphism in the pyrenees: Age and length of rotation of the Iiberian Peninsula

Montigny, R.; Azambre, Bernard; Rossy, Michel; Thuizat, R.

doi:10.1016/0040-1951(86)90255-6

Cited by 149 publications

(140 citation statements)

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“…The North Pyrenean realm is affected by moderate but welldistributed magmatic activity during the Mesozoic, responsible for the emplacement of two main groups of rocks: (i) tholeitic dolerites of Triassic age, generally referred to as "ophites" (Montigny et al, 1982;Azambre et al, 1987), and (ii) a wide variety of small intrusive and effusive Cretaceous alkaline magmatic rocks (Montigny et al, 1986;Azambre et al, 1992;Rossy et al, 1992). The age of the Cretaceous magmatism is often constrained by stratigraphic correlations with the sedimentary formations in which volcanic or intrusive rocks are observed (Fig.…”

Section: Magmatismmentioning

confidence: 99%

“…These rocks, generally referred to as ophites, were emplaced during the Triassic (Montigny et al, 1982). The ophites of the NPZ are strongly affected by a post-magmatic transformation responsible for their recrystallization and the neoformation of Al-rich amphibole, clinopyroxene, plagioclase and scapolite under amphibolite facies conditions (Azambre et al, 1987(Azambre et al, , 1971Golberg and Leyreloup, 1990).…”

Section: Magmatic Rock Samplesmentioning

confidence: 99%

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High-temperature metamorphism during extreme thinning of the continental crust: a reappraisal of the North Pyrenean passive paleomargin

et al. 2015

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Abstract. An increasing number of field examples in mountain belts show that the formation of passive margins during extreme continent thinning may occur under conditions of high to very high thermal gradient beneath a thin cover of syn-rift sediments. Orogenic belts resulting from the tectonic inversion of distal margins and regions of exhumed continental mantle may exhibit high-temperature, low-pressure (HT-LP) metamorphism and coeval syn-extensional, ductile deformation. Recent studies have shown that the northern flank of the Pyrenean belt, especially the North Pyrenean Zone, is one of the best examples of such inverted hot, passive margin. In this study, we provide a map of HT-LP metamorphism based on a data set of more than 100 peak-temperature estimates obtained using Raman spectroscopy of the carbonaceous material (RSCM). This data set is completed by previous PT (pressure and temperature) estimates based on mineral assemblages, and new 40 Ar-39 Ar (amphibole, micas) and U-Pb (titanite) ages from metamorphic and magmatic rocks of the North Pyrenean Zone. The implications on the geological evolution of the Cretaceous Pyrenean paleomargins are discussed. Ages range mainly from 110 to 90 Ma, and no westward or eastward propagation of the metamorphism and magmatism can be clearly identified. In contrast, the new data reveal a progressive propagation of the thermal anomaly from the base to the surface of the continental crust. Focusing on the key localities of the Mauléon basin, Arguenos-Moncaup, Lherz, Boucheville and the Bas-Agly, we analyze the thermal conditions prevailing during the Cretaceous crustal thinning. The results are synthetized into a series of three regional thematic maps and into two detailed maps of the Arguenos-Moncaup and Lherz areas. The results indicate a first-order control of the thermal gradient by the intensity of crustal thinning. The highest grades of metamorphism are intimately associated with the areas where subcontinental mantle rocks have been unroofed or exhumed.

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Section: Magmatismmentioning

confidence: 99%

Section: Magmatic Rock Samplesmentioning

confidence: 99%

High-temperature metamorphism during extreme thinning of the continental crust: a reappraisal of the North Pyrenean passive paleomargin

et al. 2015

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“…Most massifs are spatially associated with crustal granulites (Azambre and Ravier, 1978;Vielzeuf and Kornprobst, 1984) and are embedded within carbonate rocks of Jurassic to Aptian age affected by a low pressure-high temperature metamorphism (the 'North Pyrenean Metamorphic Zone') (Montigny et al, 1986;Golberg and Leyreloup, 1990). Exhumation of mantle rocks is generally ascribed to transcurrent movement of the Iberian plate relative to Europe in the mid-Cretaceous, which resulted in crustal thinning associated with successive opening and closing of elongated, asymmetrical pull-apart basins (Choukroune and Mattauer, 1978;Debroas, 1987).…”

Section: Geological Backgroundmentioning

confidence: 99%

“…considered to represent trans-lithospheric melt conduits for Cretaceous alkaline magmatism in Pyrenees (Conquéré, 1971;Montigny et al, 1986;Bodinier et al, 1987;Vétil et al, 1988). Narrow metasomatized dyke wall rocks and hornblendites veins record limited melt infiltration in host peridotites (Bodinier et al, 1990;Bodinier et al, 2004).…”

Section: Geological Backgroundmentioning

confidence: 99%

The Lherz spinel lherzolite: Refertilized rather than pristine mantle

Roux

Bodinier

Tommasi

et al. 2007

Earth and Planetary Science Letters

336

196

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Differentiation of the Earth's mantle and formation of continental and oceanic crust occur principally through partial melting and extraction of basaltic melt. Among the mantle rocks occurring at the Earth's surface, as tectonically-emplaced massifs, abyssal peridotites or xenoliths, the harzburgites (b 5% clinopyroxene) are widely considered as refractory mantle residues left after extraction of a basaltic component. In contrast, the most fertile lherzolites (15% clinopyroxene) are generally regarded as pristine mantle, only weakly affected by partial melting. In this paper we present new convergent structural and geochemical data from the Lherz massif, the type-locality of lherzolite, indicating that the lherzolites from Lherz do not represent pristine mantle. Detailed structural mapping clearly shows that the lherzolites are secondary rocks formed at the expense of the harzburgites. Variations of major, minor and trace elements through the harzburgite-lherzolite contacts indicate that the lherzolites were formed through a refertilization process involving interaction of refractory, lithospheric mantle with upwelling asthenospheric partial melts. Combined with previously published indications of refertilization in orogenic peridotites, our new observations in Lherz suggest that most lherzolite massifs represent secondary (refertilized) rather than pristine mantle. Together with geochemical data on mantle xenoliths, this indicates that melt transport and melt-rock reaction play a key role on the rejuvenation and erosion of the lithospheric mantle.

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“…The age of the Pyrenean province is given as 82 Ma (Rock, 1982b). Since then, new determinations indicate that the ages are 95-110 Ma in the western part and 90 Ma in the eastern part of the chain (Thuizat et al, 1985;Montigny et al, 1986). The Taourirt rocks, with one available determination at 57 Ma, are almost contemporaneous with a number of similar Portuguese and British rocks.…”

Section: Situation Of the Taourirt Eruptive Rocks In A Geodynamical Cmentioning

confidence: 99%

Xenocrysts in Eocene Camptonites from Taourirt, Northern Morocco

Mokhtari

Velde

1988

Mineral. mag.

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A study of xenocrystic material included in 57 Ma igneous rocks that outcrop in the Taourirt area of north-east Morocco has been made. The mineralogy of the host rocks is essentially clinopyroxene, rare olivine, titanomagnetite and either kaersutite or biotite. Feldspars (plagioclase and alkali feldspar) and nepheline are usually altered. Accessories may include haiiyne, perovskite and ferriannite-rich annite. The complex xenocrystic assemblage includes various types of clinopyroxene, amphiboles, micas of differing compositions and various types of spinel. These inclusions did not dissolve in the melt and, as a consequence, the residual (alkali-rich) mineralogical assemblage is not modified. Their abundance is such that they may not significantly affect the major element compositions, but they may strongly influence the levels of certain trace elements such as Cr and Ni.

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K-Ar Study of cretaceous magmatism and metamorphism in the pyrenees: Age and length of rotation of the Iiberian Peninsula

Cited by 149 publications

References 16 publications

High-temperature metamorphism during extreme thinning of the continental crust: a reappraisal of the North Pyrenean passive paleomargin

High-temperature metamorphism during extreme thinning of the continental crust: a reappraisal of the North Pyrenean passive paleomargin

The Lherz spinel lherzolite: Refertilized rather than pristine mantle

Xenocrysts in Eocene Camptonites from Taourirt, Northern Morocco

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