scholarly journals The Numidian sand event in the Burdigalian foreland basin system of the Rif, Morocco, in a source-to-sink perspective

Author(s):  
Anas Abbassi ◽  
Paola Cipollari ◽  
M.G. Fellin ◽  
M.N. Zaghloul ◽  
Marcel Guillong ◽  
...  

During the Tertiary evolution of the Western Mediterranean subduction system, a migrating foreland basin system developed between the Maghrebian orogenic belt and the adjacent African Craton. However, a comprehensive reconstruction of the foreland basin systems of the Rif Chain is still missing. By integrating field observations with quantitative biostratigraphic data from calcareous nannofossil assemblages, sandstone composition, and detrital zircon U-Pb geochronology from selected stratigraphic successions, we reconstruct the foreland basin system that developed in the early Miocene in front of the growing Rif orogen. The successions analyzed are representative of (1) the classical “Numidian Facies” from the Intrarifian Tanger Unit and (2) the Numidian-like deposits (mixed successions) of the “Mérinides Facies” from the “Maghrebian Flysch Basin” and the “Beliounis Facies” from the Predorsalian Unit. Our petrographic analyses and detrital zircon U-Pb ages show that the quartzarenites of the “Numidian Facies” originated from the African Craton, whereas the sublitharenites and feldspathic litharenites from the Mérinides and Beliounis Facies originated from a cratonic area and the exhuming Rif Chain. Our biostratigraphic analyses suggest a simultaneous arrival of the quartz grains in the Numidian, Mérinides, and Beliounis deposits, which indicates that their deposition occurred at ∼1 m.y. (ca. 20−19 Ma, early Burdigalian) and allows us to delineate the early Burdigalian foreland basin system of the Rif Chain. The foreland depozone received the “Numidian Facies,” the foredeep-hosted ∼2000 m of the “Mérinides Facies” and the Beni Ider Flysch, whereas the wedge-top depozone was characterized by deposition of the “Beliounis Facies.” The Numidian Sandstones and the Numidian-like deposits analyzed in Morocco show the same age as similar deposits from Algeria, Tunisia, and Sicily, which suggests a comparable early Burdigalian tectono-sedimentary evolution along the southern branch of the Western Mediterranean subduction-related orogen.

2021 ◽  
Author(s):  
Anas Abbassi ◽  
Paola Cipollari ◽  
Maria Giuditta Fellin ◽  
Mohamed Najib Zaghloul ◽  
Marcel Guillong ◽  
...  

<p>During the Tertiary evolution of the Western Mediterranean subduction system, the orogenic accretion at the Maghrebian margin let the stacking of three main tectonic zones of the Rif fold-and-thrust belt: 1) the Internal Zone; 2) the “Maghrebian Flysch” Nappes; and 3) the  External Zone. In this context, a migrating foreland basin system developed between the Maghrebian orogenic belt and the adjacent African Craton. </p><p>A comprehensive reconstruction of the foreland basin system of the Rif Chain for each phase of its accretional history is still missing. In this work, by integrating field observations with quantitative biostratigraphic data from calcareous nannofossils assemblages, sandstone composition, and detrital zircon U-Pb geochronology from selected stratigraphic successions, we reconstruct the foreland basin system that in the early Miocene developed in front of the growing Rif orogen. The analyzed successions are representative of (1) the “Beliounis Facies”, made of quartz-arenites and litharenites (Numidian-like “mixed succession”), from the Predorsalian Unit; (2) the “Mérinides Facies”, made of a Numidian-like “mixed succession”, from the “Maghrebian Flysch Basin”; and (3) the classical “Numidian Facies”, exclusively made of quartzarenites, from the Intrarifian Tanger Unit.</p><p>The petrographic analyses and the detrital zircon U-Pb ages show the provenance of the quartzarenites of the “Numidian Facies” from the African Craton, whereas the sublitharenites and feldspathic litharenites, of both the “Mérinides Facies” and “Beliounis Facies”, show provenance from a cratonic area and the growing and unroofing Rif Chain, respectively. </p><p>The Alpine signature of the detrital grains sedimented into the foredeep deposits of the early Miocene orogenic system of the Rif Chain is from the feldspathic litharenites of both the Mérinides Facies and the Beni Ider Flysch. Both show Mesozoic and Cenozoic U-Pb zircon populations, with a large population of zircons centered at ca. 32 Ma. The U and Th concentration, the Th/U ratio, and the REE pattern of this population of zircons suggest a possible source area from Oligocene doleritic rock intrusions, similar to the magmatic dyke swarms (diorite) cropping out in the Malaga region ( SE Spain).</p><p>The biostratigraphic analyses pinpoint the same age for the arrival of the quartz grains in the Numidian, Mérinides, and Beliounis deposits, indicating about 1 Myr for their sedimentation (ca. 20-19 Ma, early Burdigalian). Together with field evidence, the biostratigraphic results point to an autochthonous deposition of the Numidian Sandstones on top of the Tanger Unit, allowing to delineate the early Burdigalian foreland basin system of the Rif Chain. The foreland depozone involved the Tanger Unit and received the “Numidian Facies” deposits ; the foredeep depozone hosted about 2000 m of the “Mérinides Facies” and the Beni Ider Flysch, and developed on the so-called “Flysch Basin Domain”; and, finally, the wedge-top depozone, characterized by the “Beliounis Facies”, developed on top of the Predorsalian Unit.</p><p>The Numidian Sandstones and the Numidian-like deposits analyzed in Morocco show the same age of similar deposits from Algeria, Tunisia, and Sicily, suggesting a comparable early Burdigalian tectono-sedimentary evolution along the southern branch of the Western Mediterranean subduction-related orogen.</p>


Author(s):  
Martin Roddaz ◽  
Wilber Hermoza ◽  
Andres Mora ◽  
Patrice Baby ◽  
Mauricio Parra ◽  
...  

Author(s):  
Chance B. Ronemus ◽  
Devon A. Orme ◽  
Saré Campbell ◽  
Sophie R. Black ◽  
John Cook

The Bridger Range of southwest Montana, USA, preserves one of the most temporally extensive sedimentary sections in North America, with strata ranging from Mesoproterozoic to Cretaceous in age. This study presents new detrital zircon geochronologic data from eight samples collected across this mountain range. Multidimensional scaling and non-negative matrix factorization statistical analyses are used to quantitatively unmix potential sediment sources from these and 54 samples compiled from previous studies on regional correlative strata. We interpret these sources based on reference data from preserved strata with detrital zircon signatures likely representative of ancient sediment sources. We link these sources to their sinks along sediment dispersal pathways interpreted using available paleogeographic constraints. Our results show that Mesoproterozoic strata in southwest Montana contain detritus derived from the nearby craton exposed along the southern margin of the fault-bounded Helena Embayment. Middle Cambrian strata were dominated by the recycling of local sources eroded during the development of the Great Unconformity. In Devonian−Pennsylvanian time, provenance in southwest Montana shifted to more distal sources along the northeastern to southeastern margins of Laurentia, but more western basins received detritus from outboard sources along a tectonically complicated margin. By the Late Jurassic, provenance in the developing retroarc foreland basin system was dominated by Cordilleran magmatic arcs and fold-thrust belt sources to the west. Eastward propagation of the fold-thrust belt caused recycling of Paleozoic and Jurassic detritus into the foreland basin to dominate by the Early Cretaceous.


Geosciences ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 23
Author(s):  
Andrea Di Capua ◽  
Federica Barilaro ◽  
Gianluca Groppelli

This work critically reviews the Eocene–Oligocene source-to-sink systems accumulating volcanogenic sequences in the basins around the Alps. Through the years, these volcanogenic sequences have been correlated to the plutonic bodies along the Periadriatic Fault System, the main tectonic lineament running from West to East within the axis of the belt. Starting from the large amounts of data present in literature, for the first time we present an integrated 4D model on the evolution of the sediment pathways that once connected the magmatic sources to the basins. The magmatic systems started to develop during the Eocene in the Alps, supplying detritus to the Adriatic Foredeep. The progradation of volcanogenic sequences in the Northern Alpine Foreland Basin is subsequent and probably was favoured by the migration of the magmatic systems to the North and to the West. At around 30 Ma, the Northern Apennine Foredeep also was fed by large volcanogenic inputs, but the palinspastic reconstruction of the Adriatic Foredeep, together with stratigraphic and petrographic data, allows us to safely exclude the Alps as volcanogenic sources. Beyond the regional case, this review underlines the importance of a solid stratigraphic approach in the reconstruction of the source-to-sink system evolution of any basin.


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