Revised radiolarian ages for the sedimentary cover of the Balagne ophiolite (Corsica, France). Implications for the palaeoenvironmental evolution of the Balano-Ligurian margin

Danelian, Taniel; Wever, Patrick De; Durand-Delga, Michel

doi:10.2113/gssgfbull.179.3.289

Cited by 22 publications

(7 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The broad similarity between dynamic surface uplift, recorded by a depositional hiatus in carbonates and karstification of Ladinian Briançonnais‐domain dolostones [ Lemoine et al , ; Decarlis and Lualdi , ; Mohn et al , ] and middle to lower crustal reheating during rifting suggests that both might be the result of high‐magnitude extension and depth‐dependent thinning along the hyperextended upper plate Corsican margin. In the footwall of the BPSZ, fine‐scale zircon overgrowths of early to middle Jurassic age (200–180 Ma) observed in the lower crust postdate the thermally driven subaerial exposure of the Ladinian dolostones and predate the stratigraphic record of crustal separation by 10–15 Ma, suggesting metamorphic overgrowth during incipient cooling from postpeak conditions [ Chiari et al , ; Bill et al , ; Cordey and Bailly , ; Danelian et al , ; Ewing et al , ]. Drowning and infill of the Briançonnais dolostones with Jurassic sediments is coeval with cooling ages from the BPU, suggesting rapid thermal relaxation partly related to crustal separation and onset of seafloor spreading.…”

Section: Discussionmentioning

confidence: 99%

Tracing the thermal evolution of the Corsican lower crust during Tethyan rifting

et al. 2016

View full text Add to dashboard Cite

Continental rifting requires thinning the continental lithosphere from ~120 km to <20 km by a series of processes which each impart a characteristic thermal signature to the extending lithosphere. Here high‐resolution thermochronology is used to trace the synrift thermal evolution within a lower crustal section of an upper plate hyperextended margin sampled in Corsica. Novel zircon, rutile, and apatite 206Pb/238U depth profiling coupled with garnet trace element diffusion modeling provide compelling evidence for rift‐related crustal reheating. A Jurassic thermal pulse is recorded in the footwall of the Belli Piani Shear Zone (BPSZ), where 200–180 Ma zircon 206Pb/238U overgrowth ages on Permian core populations and the preservation of stranded diffusion profiles in resorbed garnets implies the dominant footwall fabric formed as a result of high‐temperature (T ~ 800°C) ductile thinning of the lower crust. Conductive reheating of middle crustal rocks in the immediate BPSZ hanging wall, demonstrated by Jurassic apatite 206Pb/238U ages, was likely achieved by synkinematic juxtaposition against the hot footwall and wholesale conductive steepening of geothermal gradients. Subsequent rapid cooling from 180 to 160 Ma, coeval with extensional unroofing of the footwall, underscores the importance of extreme ductile thinning during crustal hyperextension. The results of this study suggest that early lithospheric‐scale depth‐dependent thinning follows an early phase of diffuse rifting and tectonic subsidence and triggers crustal reheating during early hyperextension. Continued extension results in rapid exhumation and cooling of the lower crust, extreme crustal attenuation, and mantle exhumation followed by relaxation to a steady state thermal field coeval with the start of seafloor spreading.

show abstract

Section: Discussionmentioning

confidence: 99%

Tracing the thermal evolution of the Corsican lower crust during Tethyan rifting

et al. 2016

View full text Add to dashboard Cite

show abstract

“…Detachment faulting led to the exhumation of subcontinental mantle and to the emplacement and exhumation of gabbros on the seafloor [ Lagabrielle and Lemoine , ]. The age of breakup is constrained by the crystallization ages of gabbros and trondhjemites (158–169 Ma) [ Ohnenstetter et al ., ; Rossi et al ., ; Li et al ., ], by the biostratigraphic ages of overlying radiolarites (upper Bathonian‐lower Callovian) [ Chiari et al ., ; Danelian et al ., ], and by rapid cooling recorded by fission track data during breakup [ Malusà et al ., ]. In the distal European margin, karst features in Triassic‐Lower Jurassic carbonates are filled by Middle Jurassic sediments, attesting to a change from initial subsidence and block tilting to uplift during a later stage of the rifting [ Lemoine et al ., ].…”

Section: Evolution Of the Adria‐europe Plate Boundarymentioning

confidence: 99%

Contrasting styles of (U)HP rock exhumation along the Cenozoic Adria‐Europe plate boundary (Western Alps, Calabria, Corsica)

Malusà

Faccenna

Baldwin

et al. 2015

Geochem Geophys Geosyst

120

145

View full text Add to dashboard Cite

Since the first discovery of ultrahigh pressure (UHP) rocks 30 years ago in the Western Alps, the mechanisms for exhumation of (U)HP terranes worldwide are still debated. In the western Mediterranean, the presently accepted model of synconvergent exhumation (e.g., the channel-flow model) is in conflict with parts of the geologic record. We synthesize regional geologic data and present alternative exhumation mechanisms that consider the role of divergence within subduction zones. These mechanisms, i.e., (i) the motion of the upper plate away from the trench and (ii) the rollback of the lower plate, are discussed in detail with particular reference to the Cenozoic Adria-Europe plate boundary, and along three different transects (Western Alps, Calabria-Sardinia, and Corsica-Northern Apennines). In the Western Alps, (U)HP rocks were exhumed from the greatest depth at the rear of the accretionary wedge during motion of the upper plate away from the trench. Exhumation was extremely fast, and associated with very low geothermal gradients. In Calabria, HP rocks were exhumed from shallower depths and at lower rates during rollback of the Adriatic plate, with repeated exhumation pulses progressively younging toward the foreland. Both mechanisms were active to create boundary divergence along the Corsica-Northern Apennines transect, where European southeastward subduction was progressively replaced along strike by Adriatic northwestward subduction. The tectonic scenario depicted for the Western Alps trench during Eocene exhumation of (U)HP rocks correlates well with present-day eastern Papua New Guinea, which is presented as a modern analog of the Paleogene Adria-Europe plate boundary.

show abstract

“…The presence of Praekurnubia crusei , amongst other species, is indicative of a late Bathonian–Callovian age, according to these authors. The following red radiolarites have been dated by several authors as ranging from Bathonian/Callovian to Kimmeridgian in age (De Wever & Danelian, ; Danelian et al ., ). Near the top of the red radiolarites, oolitic platform turbidites make more and more common interbeds (Fig.…”

Section: Geological and Palaeogeographic Settingmentioning

confidence: 99%

Mesozoic radiolarites – accumulation as a function of sea surface fertility on Tethyan margins and in ocean basins

Baumgartner

2013

Sedimentology

View full text Add to dashboard Cite

Radiolarites, commonly comprising chert‐shale couplets, feature prominently in the Mesozoic stratigraphy of the Neotethyan realm. The origin and significance of these deposits, especially with regard to understanding palaeoproductivity in that region, remains controversial. This study examines transport processes and accumulation rates of radiolarians/radiolarites, as well as the chronology of radiolarite sedimentation based on revised data from the Southern Alps and new data from the Balagne Nappes, Alpine Corsica. Results suggest that the spatio‐temporal distribution of carbonate and silica on Tethyan margins was governed by extensive lateral transport of radiolarian tests from topographic highs to basins. Palaeoclimatic, rather than palaeotectonic, changes seem to have triggered changes in surface fertility which, in turn, brought about major facies changes observed in Tethyan marginal basins: Regional platform demise – possibly due to eutrophication and onset of radiolarite deposition in the Early Bajocian – can be correlated with a positive shift in the carbon isotope curve, whereas platform recovery and the end of radiolarite accumulation correlates with a gradual decline in δ13C‐values. The existence of a vigorous trans‐Pangaean, equatorial current system that could have produced regional upwelling is questioned because of evidence for Middle Jurassic to Early Cretaceous oligotrophic conditions in the Proto‐Caribbean and the Central Atlantic. The ‘Caribbean River Plume Model’ is proposed as a possible alternative to upwelling in the Jurassic Western Tethys. Dissolved nutrients may have been dispersed in low salinity lids that originated from river plumes of rivers from tropical Africa and warm‐temperate Eurasia. Vast areas of the pre‐Late Cretaceous world ocean must have accumulated radiolarites at low rates (<4 g cm−2 10−3years) represented by the condensed, long‐lived (>50 Myr) radiolarite sections observed in many Circumpacific terranes. Radiolarian chert and claystone could be the normal pelagic sediment during Ordovician to Early Cretaceous time in far‐offshore, open oceanic settings, where dilution by terrigenous material and periplatform shallow‐water carbonates was absent.

show abstract

Revised radiolarian ages for the sedimentary cover of the Balagne ophiolite (Corsica, France). Implications for the palaeoenvironmental evolution of the Balano-Ligurian margin

Cited by 22 publications

References 12 publications

Tracing the thermal evolution of the Corsican lower crust during Tethyan rifting

Tracing the thermal evolution of the Corsican lower crust during Tethyan rifting

Contrasting styles of (U)HP rock exhumation along the Cenozoic Adria‐Europe plate boundary (Western Alps, Calabria, Corsica)

Mesozoic radiolarites – accumulation as a function of sea surface fertility on Tethyan margins and in ocean basins

Contact Info

Product

Resources

About