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

Kód výsledku v 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>

Výsledek na webu

<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>

Jazyk výsledku

angličtina

Název v původním jazyce

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

Popis výsledku v původním jazyce

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, &quot;MECS&quot; (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 &amp; 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 &amp; DEG;C, which is consistent with the standard oceanic subduction palaeo-geotherm. These new data suggest that eclogites recognized in the &quot;MECS&quot; Variscan microplate represent the closure of oceanic domains of different ages (Cambrian or Ordovician).

Název v anglickém jazyce

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

Popis výsledku anglicky

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, &quot;MECS&quot; (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 &amp; 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 &amp; DEG;C, which is consistent with the standard oceanic subduction palaeo-geotherm. These new data suggest that eclogites recognized in the &quot;MECS&quot; Variscan microplate represent the closure of oceanic domains of different ages (Cambrian or Ordovician).

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10505 - Geology

Projekt

—

Návaznosti

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Rok uplatnění

2023

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

BSGF- Earth Sciences Bulletin

ISSN

0037-9409

e-ISSN

1777-5817

Svazek periodika

194

Číslo periodika v rámci svazku

10

Stát vydavatele periodika

FR - Francouzská republika

Počet stran výsledku

29

Strana od-do

—

Kód UT WoS článku

001019500100001

EID výsledku v databázi Scopus

2-s2.0-85165571025