The Westernmost Tethys Blog Geology mapping, basin analysis and 3D modeling


Oligocene-Lower Miocene sandstones of Western Tethys

Filed under: paleogeography,PID2020-114381GB-I00,Tethys — Tags: , , , , — messinianalicante @ 7:26 AM

 The changing nature of detrital signatures in clastic wedges of the Circum-Mediterranean orogenic systems reflect the provenance relations from different source rocks of evolving geo-puzzle terranes, including ophiolite bearing, uplifted continental crust (both shallow to deep crust terranes), volcanic and sedimentary source rocks. We selected here sandstone suites directly occurring over the Mesomediterranean Micropaleoplate during the final stages of closure of the western-southern Tethyan realm. They are unconformably over the internal domains of the Circum-Mediterranean thrust belts, and include Oligocene-to-lower Miocene siliciclastic formations of the Betic Cordillera (As, Bosque, Río Pliego, El Niño, Ciudad Granada, Fuente-Espejos, Alozaina and Viñuela fms), Rif Chain (Fnideq and Sidi Abdeslam fms), and Calabrian terranes (Paludi, Pignolo and Stilo Capo d’Orlando fms). All these sandstone suites range from quartzolitic to quartzofeldspathic detrital modes reflecting close relations with their Paleozoic metasedimentary and plutonic source rocks and their related Mesozoic sedimentary covers.

QmFL diagrams with synthesis of detrital modes of the studied sectors: A, Espuña sector; B, Almería sector; C, Málaga sector; D, Ghomaride of the Tetuan sector; E, Sila sector; and F, Serre-Aspromonte-Peloritani sector. Qm (monocrystalline quartz), F (feldspars), Lt (total lithic fragments L + Qp), L (aphanitic lithic fragments), Qp (polycrystalline quartz).

Marked differences have been recognized from western (Betic-Rif) to eastern (Calabria) portions in terms of detritic suites. Detrital suites of the Betic-Rif portions reflect a transition between a craton, transitional and recycled orogenic provenance type. Contrarily, detrital suites of the Calabria portions reflect their transition from transitional continental to basement uplift orogenic provenance reflecting deposition in wedge-top basins during final subduction of the Magrebian-Lucanian-Ionian Basin below the Mesomediterranean and the opening of the Mediterranean basin as a backarc.

Cites as: Critelli, S., Martín-Martín, M., 2022. Provenance, paleogeographic and paleotectonic interpretations of Oligocene-Lower Miocene sandstones of the western-central Mediterranean region: A review. J. Asian Earth Sci. X 8, 100124. doi: 10.1016/j.jaesx.2022.100124


Provenance and paleogeographic implications for the Cenozoic sedimentary cover of the Ghomaride Complex (Internal Rif Belt), Morocco

 The Cenozoic sedimentary cover from the Ghomaride Complex (Internal Rif Belt) has been studied in the Tetuan area (N Morocco) where a suite of sedimentary successions from shallow-marine to deep-marine environments crops out. For that purpose stratigraphic relations and petrological and geochemical signatures have been analyzed. Sandstone suites of the overall succession are heterogeneous and testify a multi-source area, in response of accretionary processes of the Ghomaride-Malaguide units and the exhumation of the lower units of the Internal Rif Zone (e.g. Sebtide-Alpujarride Complex). Pre-orogenic and Syn-orogenic (according to the eoalpine phase) deposits have been identified consisting in two depositional sequences: lower Paleocene and Cuisian-Bartonian, and upper Oligocene-upper Aquitanian and lower Burdigalian, respectively. Pre-orogenic deposits are mainly intra-arenite and hybrid arenites made of a minor amount of siliciclastic detritus but with abundance of intrabasinal carbonate grains. The syn-orogenic sandstone suites are quartzolithic, having abundance of low-grade metamorphic and sedimentary lithic fragments. Sedimentary lithic fragments are derived from the Mesozoic successions of the Ghomaride-Malaguide Complex while metamorphic detritus is related to an unknow Internal Rif Zone basement that was exhumed starting from the late Oligocene and mainly early Miocene. Modal analyses of sandstone suites for the extrabasinal grains mainly indicate lower rank metamorphic and sedimentary source terranes of a recycled orogen. Major and trace elements coupled to the mineralogical composition of the mudrock samples indicate a provenance from felsic source area(s) with a minor but not negligible contribution from mafic rocks mainly in the syn-orogenic suites.

Geochemical analyses (Al–Ti–Zr ternary plot) indicate minor reworking and recycling processes before the final deposition through prolonged processes of sedimentary transportation. The trends evident in both CIA and CIA’ diagrams indicate source areas characterized by moderate weathering in non-steady-state conditions with a weak change of weathering condition from the pre-orogenic to the syn-orogenic cycle. Deposition during the Paleocene and Eocene, took place in the southern continental margin of the Ghomaride-Malaguide domain as a carbonate ramp. Contrarily, sedimentation in the late Oligocene-late Aquitanian took place in wedge-top basins within the Ghomaride- Malaguide domain. These changes occurred during the Burdigalian, when back arc basins were developed in the Internal Betic-Rif Zone. The Cenozoic reconstructed record was contemporaneous of the structuring of the Circum-Mediterranean chains and the Ghomaride-Malaguide Complex played a key role in the geodynamic evolution of the Rif Cordillera, representing a key tectonic element of the western Mesomediterranean domains. 

Cite as: Perri, F., Martín-Martín, M., Maaté, A., Hlila, R., Maaté, S., Criniti, S., Capobianco, W., Critelli, S., 2022. Provenance and paleogeographic implications for the Cenozoic sedimentary cover of the Ghomaride Complex (Internal Rif Belt), Morocco. Mar. Pet. Geol. 143, 105811. doi: 10.1016/j.marpetgeo.2022.105811

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