Hercynian, Pan-African, Proterozoic and Archean ion-microprobe zircon ages for a Betic-Rif core complex, Alpine belt, W Mediterranean - consequences for its P-T-t path

Article Abstract:

A Hercynian age of 285 +/- 5 (2 omega) Ma was observed for euhedral rims. The age was derived after an ion-microprobe analysis of zircons from an andalusite-bearing orthogneiss within the major Alpujarride nappe complex in Betic Cordilleras' central part was undertaken. Paleozoic sedimentation age for the parent material for the anatectic source rock was implied by the Zircon age zoning systematics. Meanwhile, ambiguous result may be obtained from thermobarometry of rock complexes when it is solely based on field observations and petrography.

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Detrital zircon ages from southern Norway - implications for the Proterozoic evolution of the southwestern Baltic Shield

Article Abstract:

Four specimen from Precambrian metasediments from the Bamble Sector in souther Norway were investigated via SIMS ion-microprode U-Pb zircon dating to elucidate the geochronology of the area, the evolution of the southwestern Baltic Shield and the relationship of the area's history on the domains in central and south Sweden. The results of the composite detrital-metamorphic zircon analyses revealed erratic 206Pb/238U versus 207Pb/235U ratios. The findings also provide evidence that a protocrust of 1.7 to 2.0 GPa existed in the Baltic Shield.

Usage, Sweden, Natural history, Geology, Stratigraphic, Stratigraphy, Proterozoic Eon, Geological time, Geochronology, Microprobe analysis, Baltic Shield

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Growth, annealing and recrystallization of zircon and preservation of monazite in high-grade metamorphism: conventional and in-situ U-Pb isotope, cathodoluminescence and michrochemical evidence

Article Abstract:

The use of spot U-Pb age determinations of zircon and monazite and high-quality conventional single-grain was vital in determining the evolution of granulite to amphibolite-facies terrains in the Vosges mountains. Together with the use of careful cathodoluminescence imaging and michrochemical probing, the process revealed that it was during subsolidus growth when round-shaped zircons with resorbed surface were created. The formation of a euhedral equant or prismic zircon morphology can be traced to intergranular fluid or melt phase growth.

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