Flysch Basin Research Articles

Changes in hydraulic and physico-water parameters of surface waters under the influence of anthropogenic activities in the Western Carpathians

To evaluate the quality of watercourses in the Western part of Carpathians from a hydro-chemical perspective, a systematic approach is required. This involves gradually excluding factors that contribute to the washing, mixing, and transportation of contaminants in the watercourse pathway. The model that considers spatial dependencies by autoregression was implemented in this study to determine the correlation between hydrodynamic and physico-chemical characteristics of waters at surface in different groups and forms of catchment use. The surface water at forested areas had the maximum average shear stress of 0.178 N∙m−2. The watercourse at sustained grassland had the maximum average Reynolds number (Re) of 23,654 and the minimum number of 0.426 at arable lands. Spatial autoregression analysis revealed space-time relations in various measurement points. When constructing the space-physical model, it is important to consider the influence of hydraulic characteristic parameters on the generation of physicochemical indicators in the flysch basin. Specifically, it may be beneficial to take into account the turbulent diffusion coefficient. The autoregression analysis demonstrated that for the ions P-PO43− and K+ in surface water on cropland and for total iron and the cation K+ ion grassland (p < 0.05), the turbulent diffusion coefficient proved to be of great importance. The study did not identify any physicochemical dependency for woodland surface waters. The findings can be utilised to create an erosion model that considers the contribution of material supply in a catchment area, specifically from weathered Carpathian flysch or surface runoff, to the alimentation of alluvial deposits.

Sedimentology of the Beni Ider and associated Talaa Lakrah turbidite successions of the Maghrebian Flysch Basin (Northern Rif, Morocco)

Sedimentology of the Beni Ider and associated Talaa Lakrah turbidite successions of the Maghrebian Flysch Basin (Northern Rif, Morocco)

Geological Correlation of the Mubarak (Southern Tien Shan) and Podhale (Inner Carpathians) Flysch Basins

Geological Correlation of the Mubarak (Southern Tien Shan) and Podhale (Inner Carpathians) Flysch Basins

Detrital Tourmalines in the Cretaceous–Eocene Julian and Brkini Flysch Basins (SE Alps, Italy and Slovenia)

In the SE Alps, two Cretaceous–Eocene flysch basins, Julian and Brkini, filled with turbidite sediments, are present. This study novelly reports heavy mineral assemblage counts and detrital tourmaline characterization for 11 samples. It is possible to define three different groups, characterized by the presence of (1) a clinopyroxene–epidote–low-ZTR (zircon+tourmaline+rutile; 5%) sample association, (2) a high-ZTR (>48%)–garnet–apatite association and (3) a low-ZTR (<40%)–Cr-spinel–garnet association. Detrital tourmalines from both the Julian and Brkini flysch basins are rather similar in composition, associated with metapelites and metapsammites coexisting or not coexisting with an Al-saturating phase, ferric-iron-rich quartz–tourmaline rocks and calc–silicate rocks; however, their number is drastically different. In fact, even if the percentage of heavy minerals is very low and similar in both basins (0.17–1.34% in weight), in the Julian basin, the number of tourmaline crystals is much lower than that in Brkini (1–14 vs. 30–100), suggesting an important change in the provenance area. Interestingly, the presence of a high amount of tourmaline derived from ferric-iron-rich quartz–tourmaline rocks and calc–silicate rocks makes these two basins different from all the Cretaceous flysch basins of Bosnia and the Northern Dinaric zone, where these supplies are missing or very limited.

Geological Correlation of the Mubarak (South Tien Shan) and Podhale (Inner Carpathians) Flysch Basins

Geological Correlation of the Mubarak (South Tien Shan) and Podhale (Inner Carpathians) Flysch Basins

First report of the benthic foraminifera from Maastrichtian in the Eastern of Iran (Tutak section)

In this research, benthic foraminifera from the Upper Cretaceous Maastrichtian in the Tutak section (Eastern Iran) was studied for the first time. In the Tutak section, there are outcrops of scattered and lenticular Maastrichtian carbonate sediments between the ophiolitic units. Some of the benthic foraminifera identified in this section are Orbitoides apiculatus, Orbitoides medius, Omphalocyclus cf. macroporus, Orbitoides cf. gruenbachensis, Orbitoides gensacicus, Orbitoides spp., Sirelina orduensis, Canalispina iapygia, Goupillaudina spp., Selimina spinalis, Postomphalocyclus merici. Since there is no comprehensive study of this benthic foraminifera in eastern Iran, the authors suggest the name of the Makhunik unit for these Maastrichtian sediments in the Flysch Basin in the eastern part of Iran.

Heavy minerals as indicators of source material in soils on carbonates

The origin of the soils formed on carbonate rocks remains uncertain, as they are probably of polygenetic origin. Of particular interest are the elevated contents of some trace elements detected in these soils, as they can hardly be attributed to insoluble residues of carbonate rock. The aim of this study was to uncover the relationship between heavy minerals in bedrock and soil and to identify other sources that influence the mineral and chemical composition of soil. We investigated representative samples of soils and dolomite bedrock as well as sandstones and marlstones from the nearby flysch basin as an expected source of the aeolian contribution. XRD and SEM/EDS showed that mineral diversity is higher in soils compared to the dolomites. Heavy minerals found in dolomite insoluble residue include sphalerite, Ti-oxide (probably rutile), zircon, fluorite, pyrite, minerals of REE phosphates and apatite group, interpreted as terrigenous detrital material. The mineral composition of soil heavy fraction is only partly following insoluble residues of bedrock and indicates possible aeolian contribution. Comparison with nearby flysch sandstones and marlstones showed similarities in mineralogical diversity by the presence of chromite and Fe-Cr(Mn) oxides (probably carmichaelite). Other minerals present in soils and flysch layers, such as Ti-oxide (probably rutile), zircon, REE phosphates, and pyrite grains, however, show similarities in mode of occurrence and transport indications. Signs of aeolian transport on the grains detected in soils were further confirmed by SEM/EDS.

Origin of the Songpan–Garzê terrane, Tibetan Plateau: a perspective from the tectonic evolution of the Palaeo-Tethys Ocean

Abstract The Songpan–Garzê terrane is the largest Triassic remnant flysch basin on Earth and formed as the Palaeo-Tethys Ocean closed during the final amalgamation of the Pangaea supercontinent. However, the origin of the Songpan–Garzê terrane is highly controversial. A synthesis of the tectonic evolution of the Palaeo-Tethys Ocean and its branches surrounding the Songpan–Garzê terrane is presented, which clarifies the nature and relationships among the many Palaeo-Tethys sutures. Provenance analyses suggest that branches of the Palaeo-Tethys near the Songpan–Garzê terrane closed before the Early Triassic. In contrast, the main Palaeo-Tethys Ocean (Longmu Co-Shuanghu) did not close until the beginning of the Late Triassic. This study argues against the Songpan–Garzê terrane being a remnant ocean basin, and proposes that it was a back-arc basin of the main Palaeo-Tethys Ocean. It initially underwent extension by the combined effects of the main Palaeo-Tethys Ocean subduction and the Emeishan mantle plume in the Late Permian, and subsequently developed into a back-arc basin in the Triassic, into which huge turbiditie units were deposited derived from all surrounding terranes and orogens. The final closure of the main Palaeo-Tethys Ocean in the beginning of the Late Triassic and subsequent continent–continent collision led to basin inversion in the Late Triassic.

Provenance for the Makran Flysch Basin in Pakistan: Implications for interaction between the Indian, Eurasian, and Arabian plates

Provenance for the Makran Flysch Basin in Pakistan: Implications for interaction between the Indian, Eurasian, and Arabian plates

Type and evolution of the Middle Jurassic–Early Cretaceous basin at the northern margin of the Lhasa Block: constraints of sedimentary characteristics and provenance tracing based on zircon U-Pb ages

To identify its type and evolution features of the Middle Jurassic–Early Cretaceous basin at the northern margin of the Lhasa Block (NMLB) is of great significance for reconstructing its tectonic-paleogeography and assessing the petroliferous basins in the Bangong-Nujiang suture zone (BNSZ) and its adjacent area. This study conducted the sedimentary characteristic analyses and detrital zircon U-Pb dating of the Middle Jurassic–Lower Cretaceous strata exposed in the northern part of Nagqu County (NPNC), Tibet. The Middle–Upper Jurassic Lagongtang Formation was mainly deposited in a steep slope delta and its middle part is characterized by debris flows moving southeastward. The lower part of the Upper Jurassic–Lower Cretaceous Duoni Formation was characterized by molasses formation, and its middle and upper part were primarily deposited on a tidal flat-mixed shelf. The 384 detrital zircons from the debris-flow deposits of the Lagongtang Formation yielded ages of 2800∼210 Ma, except for one yielding an age of 174 Ma. The detrital zircons from the lower part of the Duoni Formation yielded ages of 2744∼152 Ma. Comprehensive research results show that the basin located at the NMLB is a peripheral foreland basin controlled by the BNSZ and had dual source supply, and around 152 Ma, the basin was accompanied by a stronger overthrust event and experienced the conversion from flysch basin to molasses one. Subsequently, a new foreland basin formed marked by the deposition of the Shamuluo Formation in the BNSZ.

ПЕРША ЗНАХІДКА РОДУ ARCTICOCARCINUS SHWEITZER ET AL., 2016 (DECAPODA, BRACHYURA) У ДАНСЬКОМУ ЯРУСІ КРИМУ (УКРАЇНА) ТА ЇЇ ПАЛЕОБІОГЕОГРАФІЧНЕ ЗНАЧЕННЯ

The Paleogene decapod crustaceans of Ukraine are insufficiently studied. This group of arthropods has not attracted much attention of researchers, despite the fact that the remains of decapods are known in the Paleogene sediments of the Dnipro River area, Donetsk Basin, the Crimea and the Ukrainian Carpathians. The article describes the first find of a decapod crustacean of the genus Arcticocarcinus Schweitzer et al, 2016 in Ukraine. The fossil comes from the lower part of the Danian of the Crimea (Ak-kaya Section near the Bila Skelia, Bilogirsk District). The fossil was found in situ in the decapod burrow Thalassinoides Ehrenberg, 1944. Such finds allow us to establish which fossil decapod crustaceans produced burrows Ophiomorpha, Thalassinoides, and Spongeliomorpha. Sediments with crab remains were accumulated in the environment of Skolithos Ichnofacies. This ichnofacies is usually confined to areas of the seabed whose sediments are constantly mixed by waves. There was a cold-water paleobasin on the territory of modern northern Ukraine in the Danian Age. This basin was connected to the Western European paleobasin and the Boreal paleobasin. The southern basin, located in the Carpathians, the Black Sea Depression, and the Crimea, was much warmer and closely connected with the Mediterranean Basin. A representative of the genus Arcticocarcinus was first found outside Sweden. It is very unlikely that the genus Arcticocarcinus Schweitzer et al, 2016 entered modern Sweden from the Crimea or vice versa via the Polish Channel, as the Carpathian flysch basin was obviously a barrier. Apparently, the exchange of fauna took place through the Dnipro-Donetsk Sea and the Pripyat Strait. These basins were part of the so-called "Sea of Arkhangelskyi" (a large sublatitudinal basin that stretched from the spurs of the Caucasus and the Urals to Western Europe). Arcticocarcinus cf. insignis (Segerberg, 1900) expands the paleontological characteristics of the Danian of Crimea and testifies to the free exchange of benthic faunas of North-Western Europe and Crimea.

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

Abstract 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.

Susceptibility to detachment and transportation of soil material as a result of water erosion in a flysch basin in the Beskid Wyspowy (Western Carpathians): Modeling of rainwater flow paths

Susceptibility to detachment and transportation of soil material as a result of water erosion in a flysch basin in the Beskid Wyspowy (Western Carpathians): Modeling of rainwater flow paths

The Numidian Sandstones in northern Morocco: Evidence for early Burdigalian autochthonous deposition on top of the Tanger Unit

The Numidian Sandstones are widespread throughout the western Mediterranean, from Spain and North Africa to southern Italy. They consist of intercalations of thick ultra-mature sandstones within brownish shale deposits. Crucial issues about the Numidian Sandstones are still under debate, such as their pertinence to an undisputed paleogeographic domain and their age. In addition, in the Moroccan Rif, detailed sedimentological studies are still lacking, preventing the understanding of the main features of the sedimentary basin in which the Numidian Sandstones were deposited. This paper aims to reconstruct the Numidian Sandstone depositional environment via a detailed sedimentological study and provides new time constraints through quantitative analyses of calcareous nannofossil assemblages. The Numidian Sandstone sedimentary features suggest a depositional environment located in the transition between a lower muddy slope and a deeper basin plain. Quartz-rich sandy turbidites supplied sediments to this basin during a tectono-sedimentary event lasting ca. 1 Myr in the early Burdigalian. A key section from the Tanger Unit shows the Numidian Sandstones in stratigraphic continuity with the pre-Numidian deposits of the External Tanger Unit (Intrarif sub-domain). This evidence allows us to reject the notion of the Numidian Sandstones as a nappe, detached at their base from the pre-Oligocene deposits of the more internal units of the Flysch Basin. The new biostratigraphic analyses performed on the Numidian Sandstones from northern Morocco mostly correlate with the depositional age of the Numidian Sandstones outcropping in the rest of the Maghrebian Chain. The Numidian sand event, which affected the SW sector of the Mediterranean Basin from the Betics to the southern Apennines, was a unique and extensive event that was possibly triggered by the interplay among the uplift of the Atlas Chain, the sea-level drop at 20.4 Ma, and the establishment of a humid climate in North Africa at the beginning of the Miocene.

Geological correlation between northern Cyprus and southern Anatolia

The island of Cyprus constitutes a fragment of southern Anatolia separated from the mainland by left-oblique transtension in late Cenozoic time. However, a geological framework of offset features of south-central Anatolia, for comparison of Cyprus with a source region within and west of the southeastern Anatolian suture zone, has not yet been developed. In this paper, I enumerate, describe, and compare a full suite of potentially correlative spatial and temporal elements exposed in both regions. Northern Cyprus and south-central Anatolia have identical tectonostratigraphic units. At the base of both belts, crop out ophiolitic mélange – accretionary complex generated during the northward subduction of the Neo-Tethyan Oceanic lithosphere from the Late Cretaceous until the end of middle Eocene. The nappes of the Taurus carbonate platform were thrust above this internally chaotic unit during late Eocene. They began to move as a coherent nappe pile from that time onward. An asymmetrical flysch basin was formed in front of this southward-moving nappe pile during the early Miocene. The nappes were then thrust over the flysch basin fill and caused its tight folding. Cyprus separated from Anatolia in the Pleistocene–Holocene when transtensional oblique faults with dip-slip components caused the development of the Adana and Iskenderun basins and the separation of Cyprus from Anatolia.

Middle Eocene carbonate platforms of the westernmost Tethys

A study of the paleoenvironmental evolution of the middle Eocene platforms recognized in the westernmost Tethys has been carried out in the well-exposed middle Eocene succession from Sierra Espuña-Mula basin (Betic Cordillera, S Spain). Eight microfacies (Mf1 to Mf8) have been recognized, based mainly on fossil assemblages (principally larger benthic foraminifera), and rock texture and fabric. The fossiliferous assemblage can be assigned to the ‘subtropical’ heterozoan association or to the low-latitude ‘foralgal facies’, which are dominated by non-framework building, light-dependent biota such as perforate larger benthic foraminifera, coralline algae, and sometimes green algae and solitary corals. Larger benthic foraminifer assemblages, corresponding from euphotic to oligophotic conditions and the large surface showed, suggest a progressive marine ramp under essentially oligotrophic conditions. Eventually, supply of detrital sediments from the continent and/or upwelling currents increases the nutrients of marine waters. Comparison with other Tethyan sectors allows stating that coral-reef buildups (z-corals) were widespread on shallow platforms of the central and eastern Tethys Ocean, but these were neither of great dimensions nor dominant because of the much more dominant presence of larger benthic foraminifera. Moreover, these coral constructions were completely absents in the westernmost Tethys. The dominance of larger benthic foraminifera and the absence of z-corals in the westernmost Tethys are explained by particular paleogeographic features due to the occurrence of a narrow and deep oceanic branch (i.e., the Maghrebian Flysch Basin) connecting the Tethys with the Atlantic Ocean. The various issues regarding the morphological characters and evolution of larger benthic foraminifera in the study area, such as sizes of tests, specific diversity and/or intraspecific variability, number of appearances and last occurrences during the middle Eocene are analyzed and compared with those appearing in other Tethyan sectors. In addition, the early to late Bartonian boundary is recognized in the study area as critical for the biological change as in other shallow-marine environments along the Tethys margins.

Provenance analysis of Late Triassic turbidites in the eastern Songpan–Ganzi Flysch Complex: Sedimentary record of tectonic evolution of the eastern Paleo-Tethys Ocean

The Xikang Group represents the main stratigraphic sequence of the Songpan–Ganzi complex (SGC), a flysch basin with a wide distribution and monotonous lithology. Strong tectonic deformation and accumulation of folds have led to destruction of the original sedimentary sequence and sedimentary structure of the strata, such that there exists no reasonable sedimentary model that can explain the massive flysch. Herein, we investigated in detail the sedimentary structures, paleocurrent direction, particle sizes, major and trace elements, and magmatic zircon and detrital zircon U–Pb ages of the typical sections of the Xikang Group in the eastern SGC. Our analysis led to the following findings: 1) The U–Pb zircon ages from the Galazi (215.6 ± 1.1 Ma), Sudi (214.5 ± 1.5 Ma and 221.1 ± 1.5 Ma), and Gulu (221.3 ± 1.2 Ma) plutons, which intrude the Xikang Group, and detrital zircon samples from the uppermost part of the Xinduqiao Fm. indicated the youngest mean age (YC1σ[2+]) of 222.4 ± 2.5 Ma. This in turn indicates a pre-221 Ma depositional age for the Xikang Group. 2) The provenance was derived from the North China Block and Qiangtang Terrane, Qinling–Dabie orogenic belt, South China Block, and East Kunlun–Qaidam, and the construction of the flysch in the SGC belongs to the multi-source or line source provided by the peripheral orogenic belt. 3) Trace elements suggested that the Xikang Group may have been deposited in a sedimentary basin associated with a continental island arc. 4) The sedimentary environment in this area belonged to the distal fan of a submarine, and the new sedimentation age and sedimentation rate indicate that the Carnian pluvial event may have been the trigger mechanism. 5) The formation of the flysch deposition in SGC related to the Paleo-Tethys Ocean underwent a scissor-like closure from east to west.

Very low-grade metamorphism of the Dezadeash Formation (Jura-Cretaceous): Constraints on the tectonometamorphic history of the Dezadeash flysch basin and implications regarding the tectonic evolution of the Northern Cordillera of Alaska and Yukon

<abstract> <p>Mesozoic convergence of the Wrangellia composite terrane with the western margin of North America resulted in the collapse of intervening flysch basins. One of these basins, the Jurassic-Cretaceous Gravina-Nuzotin belt, comprises from south to north, the Gravina sequence and Gravina belt in southeastern Alaska, the Dezadeash Formation in Yukon, and the Nutzotin Mountains sequence in eastern Alaska. Previous work shows that the Gravina sequence and Gravina belt were underthrust > 20 km beneath the margin of North America in mid-Cretaceous time, culminating in amphibolite facies metamorphism. This tectonometamorphic scenario was subsequently applied to the entire Gravina-Nutzotin belt, despite any detailed studies pertaining to the tectonometamorphic evolution of the Dezadeash Formation. The present analysis of the Dezadeash Formation reveals that metamorphic mineral assemblages in sandstone and tuff document subgreenschist, high temperature zeolite facies metamorphism; Kübler indices of illite and Árkai indices of chlorite in mudstone record diagenetic to high anchizone metapelitic conditions; and the color of organic matter (i.e., the Thermal Alteration Index of palynomorphs and the Conodont Alteration Index) and pyrolysis of organic matter in mudstone and hemipelagite beds document thermal maturation at catagenesis to mesogenesis stages. Collectively, the mineralogic and organic thermal indicators in the Dezadeash Formation suggest that strata experienced maximum pressure-temperature conditions of 2.5 ± 0.5 kbar and 250 ± 25 ℃ in the Early Cretaceous. The inferred tectonometamorphic evolution of the Dezadeash Formation does not support the northern part of the Gravina-Nutzotin belt being underthrust > 20 km beneath the western margin of North America in mid-Cretaceous time, thus contrasting sharply with the Gravina sequence and Gravina belt in the southern part of the Gravina-Nutzotin belt. The diverse tectonometamorphic histories recorded by the southern and northern parts of the Gravina-Nutzotin belt may be a manifestation of oblique collision and diachronous south-to-north accretion of the Wrangellia composite terrane to North America.</p> </abstract>

Validating Structural Styles in the Flysch Basin Northern Rif (Morocco) by Means of Thermal Modeling

Vitrinite reflectance and a micro-Raman spectroscopy parameters data set have been acquired on dispersed organic matter of the Maghrebian flysch basin and the Tangiers unit across a NE-SW section in the north-western Rif belt (North Morocco). Thermal maturity shows increasing values from the hinterland to the external unit (from NE to SW). Paleo-thermal indicators show that the internal flysch basin (i.e., the Mauretanian unit) is less mature than the external one, (i.e., the Massylian unit), with Ro% and Ro eq. Raman values ranging from 0.64% to 1.02% (from early mature to late mature stages of hydrocarbon generation). 1D thermal modeling estimates the overburden now totally eroded ranging from 3.1 km to 6.0 km, and has been used as constraint to reconstruct the complete thrust wedge geometry in Miocene times. The reconstructed geometry accounts for high shortening (about 63%) due to the development of an antiformal stack in the frontal part of the wedge made up by the flysch succession. This stacking is interpreted as a consequence of the western translation of the Alboran Domain in the core of the Betic-Rif orogenic system.

Tectono‐Stratigraphic and Thermal Evolution of the Western Betic Flysch: Implications for the Geodynamics of South Iberian Margin and Alboran Domain

AbstractThe Betic‐Rif orogen is a key region to understand the evolution of the plate boundary between Africa and Iberia/Europe. This study focuses on the Flysch Complex, which is considered the sedimentary cover of a domain originally positioned between the Iberian and Alboran margins. Based on stratigraphic and depositional evolution constraints, evidence for salt tectonics, combined with new apatite fission‐tracks (AFT) and (U‐Th‐Sm)/He ages from the Flysch Complex and the Subbetic Zone, we propose a geodynamic interpretation for the formation of the Betic Cordillera, accounting for moderate N‐directed transport of the Flysch Complex and synchronous exhumation between External and Internal Zones of the Betic. Early contraction between Africa and Iberia/Europe is reflected in the Cretaceous Flysch basin by a prolonged period of residence in the partial annealing zone for AFT and onset of foreland subsidence at 50 Ma. This stage lasted until the Early to Middle Miocene (20–15 Ma), marked by the rapid succession, in less than 5 Ma, of the deposition of Cenozoic flysch and their rapid exhumation. This event is interpreted to reflect the W‐directed retreating mantle delamination between Africa and Iberia margins at the origin of the collapse of the proto‐Betic orogenic domain and formation of the Alboran domain.