Search results for "Plutonism"
showing 4 items of 4 documents
Early Pan-African evolution of the basement around Elat, Israel,and the Sinai Peninsula revealed by single-zircon evaporation dating, and implication…
1990
We report 2<r7Pb/206Pb single-zircon evaporation ages for early Pan-African rocks from southern Israel and the northeastern Sinai Peninsula, the northernmost extension of the Arabian-Nubian shield. The oldest rocks are metamorphic schists of presumed island-arc derivation; detrital zircons date the source terrain at ca. 800-820 Ma. A major phase of tonalite-trondhjemite plutonism occurred at ca. 760-780 Ma; more evolved granitic rocks were emplaced at about 745 Ma. A metagabbro-met adiorite complex reflects the youngest igneous phase at ca. 640 Ma. We Find no evidence for pre-Pan-African crust, and our data document important crust-forming events that correlate with similar episodes elsewhe…
Pb–Pb age, stable isotope and chemical composition of Archaean magnesite, Barberton Greenstone Belt, South Africa
2010
International audience; Trace-element, carbon, oxygen and lead-isotope analyses were carried out to determine the formation mode and crystallization age of magnesite from the Budd ultramafic complex of the Archaean Barberton Greenstone Belt, South Africa. Its significantly high Ti contents probably relate to a soluble Ti-rich accessory mineral, probably dissolved during magnesite precipitation. Primitive mantle-normalized REE patterns of the magnesite show negative Ce and Eu anomalies induced by two events: (1) the Eu anomaly indicates reducing conditions probably induced by the emplacement of the ultramafic source rock; (2) the Ce anomaly implies oxidizing conditions, probably during a hyd…
Kinematics, deformation partitioning and late Variscan magmatism in the Agly massif, Eastern Pyrenees, France
2020
International audience; In order to constrain the finite deformation pattern of the Variscan basement of the Agly massif, a detailed structural analysis over the whole Agly massif was performed. Our investigation combined geological mapping, reappraisal of published and unpublished data completed with our own structural work. Results are provided in the form of new tectonic maps and series of regional cross-sections through the Agly massif. At variance from previous studies, we identified three deformation fabrics named D1, D2 and D3. The D1 deformation is only relictual and characterized by a broadly northwest-southeast striking and eastward dipping foliation without any clear mineral and …
Geochemistry, single zircon ages and Sm–Nd systematics of granitoid rocks from theGóry Sowie (Owl Mts), Polish West Sudetes: evidence for earlyarc-re…
1998
Granitoid gneisses as well as their migmatitic and anatectic derivates were investigated from theGory Sowie (Owl Mts) Massif of SW Poland in the central West Sudetes. The gneisses and migmatites aretectonically interlayered with paragneisses, and experienced several consecutive tectono-metamorphicevents. Geochemically, the granitoid gneisses are calc-alkaline and similar to orogenic granite suites, whichtherefore lends support to a subduction-related origin. Single zircon Pb–Pb evaporation ages suggest that the gneiss precursors were emplaced between 473 and488 Ma, and most samples analysed contain zircon xenocrysts with minimum ages between 1124 and2620 Ma. An early phase of high-grade met…