Chemical and Os isotopic study of Cretaceous potassic rocks from Southern Brazil

Article Abstract:

The low Os isotopic content of the kimberlitic and lamproitic rocks of the Alto Paranaiba province, Brazil, suggest that these late-Cretaceous mafic potassic rocks have been formed from peridotitic lithospherical mantle magmas. Melt removal during the late Archean and mid-Proterozoic era decreased the peridotite Re content. The peridotites underwent LIL-element enrichment due to fluid and melt metasomatism almost one Ga ago. The Sr, Nd and Pb isotopic content of the rocks is similar to that of the oceanic basalts of the Walvis Ridge hot spot.

Brazil, Cretaceous period

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The evolution of the lithospheric mantle along the N. African Plate: geochemical and isotopic evidence from the tholeiitic and alkaline volcanic rocks of the Hyblean plateau, Italy

Article Abstract:

A study was conducted to examine the Plio-Pleistocene volcanic activity of the Hyblean plateau which occurred along a system of fractures located at the edge of the North African Plate. The volcanism of the Hyblean plateau located at Sicily, Italy, was characterized by coeval eruption of tholeiites and alkaline basalts which were composed of varying trace elements. These chemical and radiogenic isotopic trace elements required various degrees of melting from different mantle sources.

Analysis, Ice age, Geochemistry, Volcanism, Northern Africa

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The role of the crust in the magmatic evolution of the island of Lipari (Aeolian Islands, Italy)

Article Abstract:

An analysis of the volcanic rock formations which compose the Lipari island is presented. It is shown that the islands present Sr, Nd and Pb isotpoic compositions. The evolution of volcanic rocks with crustal values support findings that geochemical characteristics in lavas are products of crustal contamination and mixing. The intrusion of an MORB-type mantle into a cooler formation yielded lava variability in isotopic composition and budget of alkalis.

Earth, Crust (Geology), Lipari Islands

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