Crystallization and age of zircon from Corsican ophiolitic albitites: consequences for oceanic expansion in Jurassic times

Ohnenstetter, M.; Ohnenstetter, Daniel; Vidal, Ph.; Cornichet, J.; Hermitte, Daniel; Macé, J.

doi:10.1016/0012-821x(81)90056-x

Cited by 64 publications

(34 citation statements)

References 25 publications

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“…Empty ellipses are excluded from the average age calculation (syn-rift) melt intrusion in lithospheric mantle peridotite. U-Pb zircon ages on zircon-bearing Fe-Ti gabbros from the Piemont-Ligurian ocean show ages ranging between 166 and 156 Ma (Costa and Caby 2001;Ohnenstetter et al 1981;Rubatto et al 1998;Rubatto and Hermann 2003;Schaltegger et al 2002) consistent with the new age determinations from Lanzo gabbros. Similar ages were obtained for Internal Liguride gabbros with Sm-Nd mineral isochrons at 164 ± 14 Ma, (Rampone et al 1998).…”

Section: Age Interpretation and Zircon Chemistrysupporting

confidence: 58%

Trace element chemistry and U–Pb dating of zircons from oceanic gabbros and their relationship with whole rock composition (Lanzo, Italian Alps)

Kaczmarek

Müntener

Rubatto

2007

Contrib Mineral Petrol

143

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The U-Pb ages and the trace element content of zircon U-Pb along with major and trace element whole rock data on gabbroic dikes from the Lanzo lherzolitic massif, N-Italy, have been determined to constrain crustal accretion in ocean-continent transition zones. Three Fe-Ti gabbros were dated from the central and the southern part of the massif providing middle Jurassic ages of 161 ± 2, 158 ± 2 and 163 ± 1 Ma, which argue for magmatic activity over few millions of years. Zircon crystals are characterized by high but variable Th/U ratios, rare earth element patterns enriched in heavy rare earths, pronounced positive Ce and negative Eu-anomalies consistent with crystallization after substantial plagioclase fractionation. The zircon trace element composition coupled with whole rock chemistry was used to reconstruct the crystallization history of the gabbros. A number of gabbros crystallized in situ, and zircon precipitated from trapped, intercumulus liquid, while other gabbros represent residual liquids that were extracted from a cumulus pile and crystallized along syn-magmatic shear zones. We propose a model in which the emplacement mechanism of gabbroic rocks in oceancontinent transition zones evolves from in situ crystallization to stratified crystallization with efficient extraction of residual liquid along syn-magmatic shear zones. Such an evolution of the crystallization history is probably related to the thermal evolution of the underlying mantle lithosphere.

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Section: Age Interpretation and Zircon Chemistrysupporting

confidence: 58%

Trace element chemistry and U–Pb dating of zircons from oceanic gabbros and their relationship with whole rock composition (Lanzo, Italian Alps)

Kaczmarek

Müntener

Rubatto

2007

Contrib Mineral Petrol

143

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“…With the notable exception of Permian gabbros (see above), modem radiometric ages for gabbros in Alpine ophiolites from the Ligurian basin range between 185 and 158Ma, very close to the age of the first sediment (radiolarite) deposited on the mafic basement, generally of Callovian-Oxfordian age (e.g. Ohnenstetter et al 1981;Bill et al 1997;Rubatto 1998;Rubatto et al 1998). However, Pinet et aL Caby (1995); Costa & Caby (1997), from their studies of the Queyras and MontGenbvre ophiolites, concluded that intrusion and intra-oceanic deformation of gabbros clearly predate extrusion of the overlying pillow basalts.…”

Section: Time Gap Between Gabbro Crystallization and Superficial Basamentioning

confidence: 90%

Non-volcanic rifted margins, continental break-up and the onset of sea-floor spreading: some outstanding questions

Boillot

Froitzheim

2001

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During the last 20 years, regional studies on the West Iberia margin and on the former margins of the Tethys have considerably advanced the understanding of processes related to continental break-up and the onset of sea-floor spreading. However, some questions remain outstanding. To tentatively answer these, a coherent interpretation of available data is proposed, based on the detachment fault concept applied to the continental as well as the oceanic lithosphere, and on the hypothesis of a multi-staged rifting process. The interpretation addresses the nature of the lower crust beneath non-volcanic passive margins, the origin of ophicalcites, the probable time gap between syn-or post-rift crystallization of gabbros and extrusion of basalts on the sea floor, and the significance of dipping reflectors within oceanic lithosphere adjacent to non-volcanic passive margins. The interpretation also considers the symmetry v. asymmetry of continental rifting and break-up, the location of the ocean-continent boundary, and the possible association of magnetic quiet zones with ultramafic sea floor (serpentinized peridotite) bordering non-volcanic passive margins.

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“…No fragments of continental crust rocks have been detected. U/Pb dating on zircons from plagiogranites indicated an age of 161 ± 3 Ma (Ohnenstetter et al 1981). The metabreccias and metarenites are in turn, covered by metacherts followed by the Erbajolo Formation.…”

Section: Schistes Lustré S Complex In the Inzecca Areamentioning

confidence: 99%

“…The main features of these units include a reduced ophiolite sequence, characterized by a mantle basement covered by a volcano-sedimentary sequence without evidences of associated continental crustal rocks (Ohnenstetter et al 1981). As proposed for the Internal Ligurian units, the ophiolite sequences of these units are regarded as representative of the innermost preserved area of the Liguria-Piemonte basin (e.g., Amaudric du Chaffaut et al 1972).…”

Section: Schistes Lustré S Complex In the Inzecca Areamentioning

confidence: 99%

The architecture of an incipient oceanic basin: a tentative reconstruction of the Jurassic Liguria-Piemonte basin along the Northern Apennines–Alpine Corsica transect

Marroni

Pandolfi

2007

Int J Earth Sci (Geol Rundsch)

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In this paper, a scenario for the early evolution of the Jurassic oceanic Liguria-Piemonte basin is sketched. For this purpose, four selected examples of ophiolite sequences from the Northern Apennines and Corsica are described and analyzed. In the External Ligurian units (Northern Apennines), the ocean-continent transition of the Adria plate was characterized by a basement made up of subcontinental mantle and lower continental crust, covered by extensional allochthons of upper crust. Both, the basement rocks and the extensional allochthons are cut by basaltic dikes and covered by basalts and pelagic deposits. The conjugate ocean-continent transition of the Corsica margin, represented by the Balagne nappe (Corsica), was composed of mantle peridotites and gabbros covered by basaltic flows and minor breccias, that in addition include continent-derived clasts. By contrast, the innermost (i.e., closest to the ocean) preserved area observed in the Internal Ligurian (Northern Apennines) and Inzecca (Corsica) units consists of former morphological highs of mantle peridotites and gabbros, bordered by small basins where the basement is covered by a volcano-sedimentary complex, characterized by ophiolitic breccias and cherts interlayered with basaltic flows. The overall picture resulting from our reconstructions suggests an asymmetric architecture for the Liguria-Piemonte basin with a central area bounded by two different transition zones toward the continental margins. This architecture can be interpreted as the result of a rifting process whose development includes a final stage characterized by passive, asymmetric extension of the lithosphere along an east-dipping detachment fault system.

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Crystallization and age of zircon from Corsican ophiolitic albitites: consequences for oceanic expansion in Jurassic times

Cited by 64 publications

References 25 publications

Trace element chemistry and U–Pb dating of zircons from oceanic gabbros and their relationship with whole rock composition (Lanzo, Italian Alps)

Trace element chemistry and U–Pb dating of zircons from oceanic gabbros and their relationship with whole rock composition (Lanzo, Italian Alps)

Non-volcanic rifted margins, continental break-up and the onset of sea-floor spreading: some outstanding questions

The architecture of an incipient oceanic basin: a tentative reconstruction of the Jurassic Liguria-Piemonte basin along the Northern Apennines–Alpine Corsica transect

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