Three major types of subcontinental lithospheric mantle beneath the Variscan orogen in Europe

Puziewicz, Jacek; Matusiak‐Małek, Magdalena; Ntaflos, Theodoros; Grégoire, Marilaure; Kaczmarek, Mary-Alix; Aulbach, Sonja; Ziobro, Małgorzata; Kukuła, Anna

doi:10.1016/j.lithos.2020.105467

Cited by 19 publications

(15 citation statements)

References 69 publications

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“…However, rather than representing mantle that experienced a small degree of depletion, these lherzolites originated by refertilization by a depleted basaltic melt, similar to MORB. Thus, the Befang mantle section belongs to the group of mantle domains refertilised by DMM-derived melts, defined as "type 3" by Puziewicz et al (2020).…”

Section: Discussionmentioning

confidence: 99%

“…Lenoir et al (2000) suggest that LREE-depleted lherzolites of the southern domain of the French Massif Central could have originated in this way. More specifically, Puziewicz et al (2020) showed that lherzolites forming the southern part of the French Massif Central originated by refertilization by MORB-like melts of a protolith that originally was depleted in magmaphile elements.…”

Section: Introductionmentioning

confidence: 99%

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Lithospheric mantle refertilization by DMM-derived melts beneath the Cameroon Volcanic Line—a case study of the Befang xenolith suite (Oku Volcanic Group, Cameroon)

Tedonkenfack

Puziewicz

Aulbach

et al. 2021

Contrib Mineral Petrol

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The origin and evolution of subcontinental lithospheric mantle (SCLM) are important issues of Earth’s chemical and physical evolution. Here, we report detailed textural and chemical analyses on a mantle xenolith suite from Befang (Oku Volcanic Group, Cameroon Volcanic Line), which represents a major tectono-magmatic structure of the African plate. The samples are sourced from spinel-facies mantle and are dominated by lherzolites. Their texture is cataclastic to porphyroclastic, and foliation defined by grain-size variation and alignment of spinel occurs in part of peridotites. Spinel is interstitial and has amoeboidal shape. Clinopyroxene REE patterns are similar to those of Depleted MORB Mantle (DMM) except LREEs, which vary from depleted to enriched. The A-type olivine fabric occurs in the subset of one harzburgite and 7 lherzolites studied by EBSD. Orthopyroxene shows deformation consistent with olivine. The fabric of LREE-enriched clinopyroxene is equivalent to those of orthopyroxene and olivine, whereas spinel and LREE-depleted clinopyroxene are oriented independently of host rock fabric. The textural, chemical and thermobarometric constraints indicate that the Befang mantle section was refertilised by MORB-like melt at pressures of 1.0–1.4 GPa and temperatures slightly above 1200–1275 °C. The olivine-orthopyroxene framework and LREE-enriched clinopyroxene preserve the protolith fabric. In contrast, the LREE-depleted clinopyroxene, showing discordant deformation relative to the olivine-orthopyroxene protolith framework, and amoeboidal spinel crystallized from the infiltrating melt. The major element and REEs composition of minerals forming the Befang peridotites indicate subsequent reequilibration at temperatures 930–1000 °C. This was followed by the formation of websterite veins in the lithospheric mantle, which can be linked to Cenozoic volcanism in the Cameroon Volcanic Line that also brought the xenoliths to the surface. This study therefore supports the origin of fertile SCLM via refertilization rather than by extraction of small melt fractions, and further emphasizes the involvement of depleted melts in this process.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Lithospheric mantle refertilization by DMM-derived melts beneath the Cameroon Volcanic Line—a case study of the Befang xenolith suite (Oku Volcanic Group, Cameroon)

Tedonkenfack

Puziewicz

Aulbach

et al. 2021

Contrib Mineral Petrol

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“…There is a difficulty in comparing CPOs of different peridotite xenoliths because the orientations of thin sections are random. Orthopyroxene grains are abundant in all samples, where (100) OPX [001] OPX is well‐developed in peridotites (Cao et al., 2015; Jung et al., 2010; Manthilake et al., 2013; Nazé et al., 1987; Soustelle & Manthilake, 2017) and it can provide a good reference frame for CPO presentation (Puziewicz et al., 2020; Yu et al., 2019). Therefore, to make comparison of CPOs easier, we rotated the orientations for each xenolith so that the [100] OPX and [001] OPX maxima are aligned with the Z ‐axis and X ‐axis, respectively (e.g., Puziewicz et al., 2020; Yu et al., 2019).…”

Section: Methodsmentioning

confidence: 99%

“…The discussion in Section 6 suggests that the CPO formation is most likely at high temperatures predating the mid‐Cenozoic mantle metasomatism, decompression and cooling. Integration of the subgrain trace analysis, misorientation data and the CPO data (Section 6) suggests that the alignment of the olivine CPOs using the orthopyroxene CPO as a reference frame (Puziewicz et al., 2020; Yu et al., 2019) provides a good kinematic reference frame for these samples. The [100] OL maxima, subparallel to X, represent the flow or extension direction and olivine (010) OL maxima, subparallel to Z, the pole to foliation (Hidas et al., 2016; Vauchez et al., 2012).…”

Section: Timing and Kinematics Of Cpo Formationmentioning

confidence: 99%

Pre‐Alpine Fault Fabrics in Mantle Xenoliths From East Otago, South Island, New Zealand

et al. 2020

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In the last century geophysicists discovered that seismic velocity in the Earth's upper mantle is anisotropic and inferred that the crystallographic preferred orientations (CPOs) of olivine in the subcontinental lithospheric mantle (SCLM) contributes significantly to this anisotropy (Hess, 1964; Nicolas & Christensen, 1987). During the last two decades, measurements of the CPOs of natural samples (orogenic mantle slices and mantle xenoliths) and the products of laboratory experiments have established a framework of olivine CPO types and understanding of how these CPOs relate to deformation processes and how they contribute to seismic anisotropy (

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“…The involvement of enriched lithospheric mantle sources during the Cadomian and Variscan magmatism indicates the existence of an older (Proterozoic?) SCLM beneath central Iberia [63]. The SCLM beneath these tectonic zones of Iberia is characterized by positive εNd(t) values and isotopic model ages ranging from 1100 Ma to 800 Ma [59].…”

Section: Tournaisian: Earliest Stage Of Arc-magmatismmentioning

confidence: 99%

Changing Carboniferous Arc Magmatism in the Ossa-Morena Zone (Southwest Iberia): Implications for the Variscan Belt

et al. 2022

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Carboniferous magmatism in southwestern Iberia was continuously active for more than 60 m.y. during the development of the Appalachian-Variscan belt of North America, North Africa and Western-Central Europe. This collisional orogen that records the closure of the Rheic Ocean is essential to understanding the late Paleozoic amalgamation of the Pangea supercontinent. However, the oblique convergence between Laurussia and Gondwana that lasted from the Devonian to the Carboniferous was likely more complex. Recently, a new tectonic model has regarded the Iberia Variscan belt as the site of coeval collisional and accretionary orogenic processes. Early Carboniferous plutonic rocks of southwest Iberia indicate arc magmatism in Gondwana. The Ossa-Morena Zone (OMZ) acted as the upper plate in relation to the geometry of the Paleotethys subduction. This active accretionary-extensional margin was progressively involved in a collisional phase during the Late Carboniferous. Together, the Évora Massif and the Beja Igneous Complex include three successive stages of bimodal magmatism, with a chemical composition indicative of a long-lived subduction process lasting from the Tournaisian to the Moscovian in the OMZ. The earliest stage of arc magmatism includes the Tournaisian Beja and Torrão gabbro-dioritic rocks of the Layered Gabbroic Sequence. We present new geochemical and Nd isotopic and U-Pb geochronological data for magmatic rocks from the Main (Visean-Serpukhovian) and Latest (Bashkirian-Moscovian) stages of arc magmatism. Visean Toca da Moura trachyandesite and rhyolites and Bashkirian Baleizão porphyries and Alcáçovas quartz diorite share enriched, continental-crust like characteristics, as indicated by major and trace elements, mainly suggesting the addition of calc-alkaline magma extracted from various mantle sources in a subduction-related setting (i.e., Paleotethys subduction). New U-Pb zircon geochronology data have allowed us to establish a crystallization age of 317 ± 3 Ma (Bashkirian) for Alcáçovas quartz diorite that confirms a temporal link with Baleizão porphyry. Positive εNd(t) values for the Carboniferous igneous rocks of the Beja Igneous Complex and the Évora gneiss dome indicate production of new juvenile crust, whereas negative εNd(t) values also suggest different grades of magma evolution involving crustal contamination. The production and evolution of Carboniferous continental crust in the OMZ was most likely associated with the development of an active continental margin during the convergence of the Paleotethys Ocean with Gondwana, involving juvenile materials and different grades of crustal contamination.

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Three major types of subcontinental lithospheric mantle beneath the Variscan orogen in Europe

Cited by 19 publications

References 69 publications

Lithospheric mantle refertilization by DMM-derived melts beneath the Cameroon Volcanic Line—a case study of the Befang xenolith suite (Oku Volcanic Group, Cameroon)

Lithospheric mantle refertilization by DMM-derived melts beneath the Cameroon Volcanic Line—a case study of the Befang xenolith suite (Oku Volcanic Group, Cameroon)

Pre‐Alpine Fault Fabrics in Mantle Xenoliths From East Otago, South Island, New Zealand

Changing Carboniferous Arc Magmatism in the Ossa-Morena Zone (Southwest Iberia): Implications for the Variscan Belt

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