Crustal structure of the eastern Mediterranean inferred from Rayleigh wave dispersion

Cloetingh, Sierd; Nolet, Guust; Wortel, Rinus

doi:10.1016/0012-821x(80)90215-0

Cited by 20 publications

(9 citation statements)

References 16 publications

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“…Obviously if these basins are floored by Mesozoic or younger oceanic crust the hypothesis should be abandoned. Crustal thicknesses of 19 km for the Ionian Sea (Hinz 1974) and 27 km for the Levant Sea (Lort et al 1974), derived from seismic refraction data, are inconsistent with more recent surface wave data which give 35-40 km minimum crustal thicknesses for these two basins (Calcagnile et al 1982;Cloetingh et al 1980). Similar crustal thicknesses (30-40 kin) are apparent from surface waves crossing the Adriatic Sea (Nolet et al 1978;Calcagnile & Panza 1979.…”

Section: Crustal Structurementioning

confidence: 91%

Palaeomagnetism and continental collision in the Alpine Belt and the formation of late-tectonic extensional basins

Channell

1986

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Summary New palaeomagnetic data are consistent with the hypothesis that Adria moved as a promontory of the African Plate during the Mesozoic. This hypothesis is supported by regional facies analysis and by geophysical data from the eastern Mediterranean basins which indicate a continental lithosphere. However, the new data cast doubt upon the concept of a rigid, autochthonous African promontory remaining coherent during Alpine deformation. It is apparent that small-scale relative rotations have occurred during the Tertiary in areas which were previously considered authochtonous. Late-tectonic extensional basins, such as the Tyrrhenian Sea, are superimposed on the continent-continent collision suture and their growth is contemporaneous with thrusting in surrounding arcs. The very rapid evolution of the collision suture into a region of extension is due to a rapid lithospheric thinning process, such as catastrophic delamination of part of the mantle lithosphere. Such delamination would be most likely to occur very soon after a collision involving fast lithospheric thickening.

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Section: Crustal Structurementioning

confidence: 91%

Palaeomagnetism and continental collision in the Alpine Belt and the formation of late-tectonic extensional basins

Channell

1986

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“…Recent volcanism associated with subduction from these trenches is found in the Hellenic volcanic arc, with major volcanic centres on Thera and Mylos (Figs 1 and 2). Most of the present-day Levantine Basin is probably underlain by thin continental crust belonging to the margin of the African Plate (Cloetingh, Nolet & Wortel, 1980). Subduction of oceanic crust at the Hellenic trench system must have occurred until fairly recently, as volcanism along the volcanic arc is still going on today.…”

Section: Geological Settingmentioning

confidence: 99%

Metamorphic evolution of the Attic Cycladic Metamorphic Belt on Naxos (Cyclades, Greece) utilizing ⁴⁰Ar/³⁹Ar age spectrum measurements

Wijbrans

McDougall

1988

Journal Metamorphic Geology

196

153

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U'Ar/"Ar age spectrum analysis of phengite separates from Naxos, part of the Attic Cycladic Metamorphic Belt in Greece, indicates that cooling following high-pressure, low-to medium-temperature metamorphism, M I , occurred about 50 Ma ago. Phengite has *"AT* gradients that suggest that part of the scatter observed in conventional K-Ar ages was caused by diffusion of radiogenic argon from the minerals during a younger metamorphism, M2. In central Naxos, this metamorphism ( M 2 ) has overprinted the original mineral assemblages completely, and is associated with development of a thermal dome. Excellent "'Ar/'yAr plateaus at 15.0 2 0.1 Ma, 11.8 -C 0.1 Ma, and 11.4 2 0.1 Ma, obtained on hornblende, muscovite and biotite, respectively, from the migmatite zone, indicate that relatively rapid cooling followed the M2 event, and that no significant thermal overprinting occurred subsequent to Mz. Toward lower M I metamorphic grade, Q'Ar/"9Ar plateau ages of hornblendes increase to 19.8 2 0.1 Ma; concomitantly the proportion of excess '"Ar in the spectra increases as well. We propose that the peak of M 2 metamorphism occurred beween 15.0 and 19.8 Ma ago. K-Ar ages of biotites from a granodiorite on the west coast are indistinguishable from those found in the metamorphic complex, and hornblende K-Ar ages from the same samples are in the range 12.1-13.6 Ma. As the latter ages are somewhat younger than most ages obtained from the metamorphic complex, intrusion of the granodiorite most likely followed the peak of the M 2 metamorphism.The metamorphic evolution of Naxos is consistent with rapid crustal thickening during the Cretaceous or early Tertiary, causing conditions at which supracrustal rocks experienced pressures in the range 900-1500 MPa. Transition to normal crustal thicknesses ended the 'Current address: Z. W.O. Laboratorium voor Isotopen Geologie, De Boelelaan 1085, 1081 HV Amsterdam, The Netherlands.M , metamorphism about 50 Ma ago. The M 2 metamorphism and granodiorite intrusion occurred during a period of heat input into the crust, possibly related to the migration of the Hellenic volcanic arc in a southerly direction through the area.

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“…Only oceanic lithosphere is likely to be subducted to depths greater than a few tens of kilometres (Molnar & Gray, 1979). The crust in the Ionian Sea is about 17-20 km thick (Boccaletti, Nicolich & Tortorici 1984;Cloetingh, Nolet & Wortel 1980) and is thus not typically oceanic, although Finetti (1981Finetti ( , 1982 believes that some of the NE Ionian abyssal plan is 'old oceanic crust'. This study suggests that the subducted slab is the remnant of a sizeable area of oceanic lithosphere that lay between Africa and Eurasia less than IOMa.…”

Section: T H E F O R M a T I O N O F T H E T Y R R H E N I A N S E Amentioning

confidence: 99%

The deep seismicity of the Tyrrhenian Sea

Anderson¹,

Jackson²

1987

Geophysical Journal International

192

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l'he study reappraises the deep seismicity of the Tyrrhenian Sea. Careful examination of the quality of reported hypocentres shows that the earthquakes define a zone dipping NW, about 200 km along strike, 50 km thick, and reaching a depth of about 500 km. The zone is slightly concave to the NW at a depth of 300 km, but, contrary to many previous reports, is not tightly concave, nor are there significant spatial gaps in the seismicity, which is effectively continuous with depth. Seismicity is, however, concentrated in the depth interval 250-300 km, where the dip of the seismic zone changes from 70" (above 250 km) to a more gentle dip of 45" at greater depths. Seven fault-plane solutions are available for the largest earthquakes in this depth interval, all of them consistent with a P-axis down the dip of the seismic zone, and all of them requiring movement on faults out of the plane of the subducting slab.Two deep earthquakes near Naples lie well outside the main zone of activity; for one of which a fault-plane solution is available that has aP-axis not aligned with the dip of the seismic zone. The tightly concave slabgeometry favoured by other reports is supported mainly by the location of these events near Naples, which we think may represent deformation in a separate, probably shallower dipping, piece of subducted lithosphere.The lack of shallow seismicity, and particularly of thrust faulting earthquakes, at the surface projection of the Benioff zone suggests that active subduction has ceased. Estimates of the convergence rate responsible for subduction in the last 10 Myr far exceed the present convergence rate of Africa and Eurasia, suggesting that the subduction was related instead to the stretching and thinning of the crust in the Tyrrhenian Sea.

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Crustal structure of the eastern Mediterranean inferred from Rayleigh wave dispersion

Cited by 20 publications

References 16 publications

Palaeomagnetism and continental collision in the Alpine Belt and the formation of late-tectonic extensional basins

Palaeomagnetism and continental collision in the Alpine Belt and the formation of late-tectonic extensional basins

Metamorphic evolution of the Attic Cycladic Metamorphic Belt on Naxos (Cyclades, Greece) utilizing ⁴⁰Ar/³⁹Ar age spectrum measurements

The deep seismicity of the Tyrrhenian Sea

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Crustal structure of the eastern Mediterranean inferred from Rayleigh wave dispersion

Cited by 20 publications

References 16 publications

Palaeomagnetism and continental collision in the Alpine Belt and the formation of late-tectonic extensional basins

Palaeomagnetism and continental collision in the Alpine Belt and the formation of late-tectonic extensional basins

Metamorphic evolution of the Attic Cycladic Metamorphic Belt on Naxos (Cyclades, Greece) utilizing 40Ar/39Ar age spectrum measurements

The deep seismicity of the Tyrrhenian Sea

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Metamorphic evolution of the Attic Cycladic Metamorphic Belt on Naxos (Cyclades, Greece) utilizing ⁴⁰Ar/³⁹Ar age spectrum measurements