Deciphering the nature and age of the protoliths and peak P-T conditions in retrogressed mafic eclogites from the Maures-Tannneron Massif (SE France) and implications for the southern European Variscides
The result's identifiers
Result code in IS VaVaI
<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00025798%3A_____%2F23%3A10168716" target="_blank" >RIV/00025798:_____/23:10168716 - isvavai.cz</a>
Result on the web
<a href="https://doi.org/10.1051/bsgf/2023006" target="_blank" >https://doi.org/10.1051/bsgf/2023006</a>
DOI - Digital Object Identifier
<a href="http://dx.doi.org/10.1051/bsgf/2023006" target="_blank" >10.1051/bsgf/2023006</a>
Alternative languages
Result language
angličtina
Original language name
Deciphering the nature and age of the protoliths and peak P-T conditions in retrogressed mafic eclogites from the Maures-Tannneron Massif (SE France) and implications for the southern European Variscides
Original language description
We present new constraints on the age, nature, and tectonic setting of mafic eclogite protoliths from the Maures-Tanneron Massif, southern Variscan belt. Whole-rock major and trace element geochemistry was combined with zircon dating using Pb-206/U-238 by LA-ICP-MS to improve the understanding of this key-target of the European Southern Variscides. Geochemical data show that protoliths of the mafic eclogites are typical MORBs, while REE and HFSE patterns suggest an E-MORB affinity. However, the geochemical study shows several signs of crustal contamination that increases with the degree of retrogression. A comparison with Sardinian eclogites, which belong to the same Variscan microplate, namely, "MECS" (Maures-Esterel-Corsica-Sardinia), demonstrates that the eclogites are included in migmatites, which is the case for the studied samples, are the most contaminated. The Maures-Tanneron mafic eclogites represent the remnant of an oceanic basaltic crust. Zircon cores display homogeneous Th/U ratios (0.3-0.4), which are consistent with a magmatic origin, and define an age peak at 499.5 & PLUSMN; 2.9 Ma that is interpreted as the most likely emplacement age of the basaltic protolith. This age suggests that this protolith was part of an oceanic floor that was older than the Rheic Ocean and located to the north of the Gondwana active continental margin as predicted by recent unified full plate reconstruction models. Although the studied eclogites are retrogressed, the study of mineral inclusions trapped in garnets combined with thermodynamic modelling yields a P-T range of 17.2-18.5 kbar and 640-660 & DEG;C, which is consistent with the standard oceanic subduction palaeo-geotherm. These new data suggest that eclogites recognized in the "MECS" Variscan microplate represent the closure of oceanic domains of different ages (Cambrian or Ordovician).
Czech name
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Czech description
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Classification
Type
J<sub>imp</sub> - Article in a specialist periodical, which is included in the Web of Science database
CEP classification
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OECD FORD branch
10505 - Geology
Result continuities
Project
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Continuities
I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace
Others
Publication year
2023
Confidentiality
S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů
Data specific for result type
Name of the periodical
BSGF- Earth Sciences Bulletin
ISSN
0037-9409
e-ISSN
1777-5817
Volume of the periodical
194
Issue of the periodical within the volume
10
Country of publishing house
FR - FRANCE
Number of pages
29
Pages from-to
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UT code for WoS article
001019500100001
EID of the result in the Scopus database
2-s2.0-85165571025