International Geological Journal - Official Journal of the Carpathian-Balkan Geological Association

Oligocene-Miocene sandstone suites from the Gibraltar and Calabria-Peloritani Arcs: provenance changes and paleogeographic implications

Pages: 525 - 535


Abstract: Oligocene-Miocene turbiditic flows which formed thick sedimentary successions cropping out in the internal sectors of the Betic-Maghrebian Chain, Tell and Calabria-Peloritani Arc, are commonly related to the dismantling of pre-Alpine crystalline basements. These are now included in different tectonic edifices along the central-western peri-Mediterranean Alpine Chain but originally they could have belonged to the same crustal block, known as the AlKaPeCa Block (Al = Alboran, southern Spain and northern Morocco, Ka = Kabylian, Algeria, and PeCa = Calabria-Peloritani Arc). Detrital modes from Oligocene-Miocene late-orogenic sandstone suites, unconformably overlying the uppermost structural units of the Betic-Rifian Chain and the Rifian “Dorsale Calcaire” Units, show a provenance closely related to source areas mainly formed by Mesozoic carbonate sedimentary covers and, partially, by very slightly metamorphic rocks. In contrast, sandstones of equivalent late-orogenic successions from the Calabria-Peloritani Arc appear to be mainly derived by the erosion of high rank metamorphic and plutonic sources, which can be identified with the Hercynian basement rocks, now forming the highest structural units of the Arc. This bimodality of provenance (carbonate covers with, partially, epimetamorphic sources against a mainly plutonic and/or gneissic supply in the Gibraltar and Calabria-Peloritani Arcs, respectively) occurring between coeval late-orogenic sandstone suites, equivalent for age, geological significance and structural position, can be justified by admitting that the Internal Domains, which played a role as sediment sources, did not belong to the same crustal block or they were already separated as the consequence of an incipient break-out and fragmentation of the AlKaPeCa Block before the Late Oligocene (age of the base of the studied late-orogenic deposits).

Keywords: Oligocene-Miocene, Betic-Rifian Chain, Calabria-Peloritani Arc, paleogeography, provenance, sedimentary petrography, turbidite sandstone suites

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