U–Th–Pb geochronology of zircon and monazite from syenite and pincinite xenoliths in Pliocene alkali basalts of the intra-Carpathian back-arc basin

Deciphering Variscan versus Alpine history in the Internal Rif system is a key to constrain the tectonic evolution of the Alboran domain and hence the geodynamics of the western Mediterranean system during the Cenozoic. This study focuses on the evolution of the metamorphic envelope of the Beni Bousera massif and its relation to the underlying peridotites. Combining structural geology, metamorphic petrology, and laser ablation inductively coupled plasma mass spectrometry U-Th-Pb dating of monazite, this study contributes to the understanding of the tectonic history of the western Internal Rif. The regional foliation (S2) is characterized by low pressure-high temperature (LP-HT) mineral assemblages and obliterates a former foliation (S1) developed along a Barrovian (medium pressure-medium temperature, MP-MT) metamorphic gradient. The dating of some metamorphic monazite grains from a micaschist and a migmatitic gneiss demonstrates that the crustal envelope of the peridotite recorded two distinct tectonometamorphic episodes. Data from monazite inclusions in S1 garnet suggest that the first event, D1, is older than 250-170 Ma and likely related to the Variscan collision, in agreement with the Barrovian type of the metamorphic gradient. The second event, D2, is Alpine in age (at circa 21 Ma) and corresponds to a strong lithosphere thinning allowing subsequent subcontinental mantle exhumation. Such a tectonic context provides an explanation for the LP-HT metamorphic gradient that is recorded in the regional foliation of the western Betic-Rif system. This extension is probably related to a subduction slab rollback in the western end of the Mediterranean realm during the Oligo-Miocene times. No evidence for a Tertiary high pressure/low temperature metamorphism has been identified in the studied area.

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“…Further information on the instrumentation and the analytical technique is detailed in Hurai et al . [].…”

Section: Geochronolgymentioning

confidence: 99%

Oligo-Miocene thinning of the Beni Bousera peridotites and their Variscan crustal host rocks, Internal Rif, Morocco

Gueydan

Pitra

Afiri³

et al. 2015

Tectonics

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“…Ablation spot diameters of 26 m and 7 m with repetition rates of 3 Hz and 1 Hz were used for zircon and monazite, respectively. Full details on the instrumentation used and the method are given in Hurai et al (2010). Separated zircon grains from sample GUI14 were analyzed using the SHRIMP II at the Research School of Earth Sciences, Australian National University, Canberra, in order to complete the LA-ICP-MS dataset.…”

Section: U-pb Geochronologymentioning

confidence: 99%

Mylonites of the South Armorican Shear Zone: Insights for crustal-scale fluid flow and water–rock interaction processes

Tartèse

Boulvais

Poujol

et al. 2012

Journal of Geodynamics

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“…Interestingly, systematic study of zircons in primary pyroclastic deposits of the Pinciná, Fiľakovo -Hradný vrch, Hodejov, and Gemerské Dechtáre maars (Hurai et al 2010(Hurai et al , 2013 and in redeposited sediments of the Hajnáčka -Kostná dolina maar (Hurai et al 2012) did not provide any evidence for zircons inherited from proximal or distal pre-Tertiary sources. In turn, all investigated volcanic structures only contained populations of very young (2-5 Ma) magmatic zircons derived from A-type granite/syenite melts produced by advanced fractional crystallization of underplated alkali basalt (e.g., Huraiová et al 1996Huraiová et al , 2017 and entrained in younger basalt portions as zircon-bearing xenoliths or isolated zircon xenocrysts.…”

Section: Proximal Versus Distal Origin Of Heavy Minerals?mentioning

confidence: 95%

“…Products of the Late Miocene volcanic activity are affiliated with the Podrečany Basalt Formation (Balogh et al 1981;Vass & Kraus 1985). Recent U-Pb and U-Th(He) data on zircon and apatite from Jelšovec and Pinciná maars, however, indicate their Late Pliocene ages (Hurai et al 2010(Hurai et al , 2013.…”

Section: Neogene Andesites and Rhyolitesmentioning

confidence: 99%

Provenance study of detrital garnets and rutiles from basaltic pyroclastic rocks of Southern Slovakia (Western Carpathians)

Nemec¹,

Huraiová²

2018

Geologica Carpathica

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Detrital garnets and rutiles have been recovered from basaltic pyroclastic rocks in the northern part of the Pannonian Basin and characterized using electron probe microanalysis and imaging. All garnets are dominated by the almandine component, except for one sample dominated by spessartine. A total of three garnet groups have been distinguished according to the increased contents of grossular (Group I), pyrope (Group II) and spessartine components (Group III). Compositions of the group I and II garnets with fluctuating Ca-and relatively low Mg contents are consistent with low-to medium-grade metasediments and/or metabasites. Locally increased Mg contents could indicate higher P-T metamorphic overprint. The dominantly metamorphic origin of the Group I and II garnets (composed of > 99 % of samples) is also corroborated by chlorite, tourmaline, staurolite, ilmenite and andalusite inclusions. Spessartine-rich garnets (Group III composed of < 1 % of samples) could be genetically linked with granitoids. Detrital rutiles invariably plot within the field of metasediments metamorphosed under amphibolite-facies conditions. Possible proximal (subjacent basement sampled by ascending lava) or distal sources (catchment sediments from uplifted Central Carpathian basement) of heavy mineral assemblages are discussed.

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U–Th–Pb geochronology of zircon and monazite from syenite and pincinite xenoliths in Pliocene alkali basalts of the intra-Carpathian back-arc basin

Cited by 83 publications

References 29 publications

Oligo-Miocene thinning of the Beni Bousera peridotites and their Variscan crustal host rocks, Internal Rif, Morocco

Oligo-Miocene thinning of the Beni Bousera peridotites and their Variscan crustal host rocks, Internal Rif, Morocco

Mylonites of the South Armorican Shear Zone: Insights for crustal-scale fluid flow and water–rock interaction processes

Provenance study of detrital garnets and rutiles from basaltic pyroclastic rocks of Southern Slovakia (Western Carpathians)

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