The “Umbria-Latium ultra-alkaline district” (ULUD), central Italy, consists of numerous, generally monogenetic igneous centres, all of which are Late Pleistocene in age. They show strong peculiarities in both volcanic behaviour and chemical characteristics. The igneous centres occur as cinder cones, lava flows, dykes, maars and diatremes along the Plio-Pleistocene graben faults and adjoining blocks. The existing subvolcanic rocks and lavas display rare mineral assemblages including melilite, leucite, kalsilite, monticellite, wollastonite, perovskite and Ba-Sr-rich calcite. In addition, they contain very unusual Ti-rich garnet and Zr-Ca-Ti minerals, which are generally confined to carbonate-rich magmatic rocks. These rock types range from near-agpaitic melilitolite and melilitite to calcium-carbonatite. The pyroclastics commonly contain feldspars, mostly sanidine, and like the ULUD sub-volcanic rocks and lavas, commonly contain diopside, phlogopite, olivine and mantle micro-nodules. The pyroclastic rocks range from melilitite-carbonate tuffs to sanidine-bearing tuffs. In the ULUD, volcanic activity and rock types strongly resemble those generally observed in classical, continental-rift-related magmatic provinces. The affinity between the ULUD rocks and the Roman Campanian Province “High-Potassium Series” rocks helps in interpreting the magmatism developed at the Tyrrhenian eastern border as intra-continental and rift-related.

Late Pleistocene ultra-alkaline magmatic activity in the Umbria-Latium region (Italy) : an overview

STOPPA, Francesco;LAVECCHIA, Giuseppina
1992-01-01

Abstract

The “Umbria-Latium ultra-alkaline district” (ULUD), central Italy, consists of numerous, generally monogenetic igneous centres, all of which are Late Pleistocene in age. They show strong peculiarities in both volcanic behaviour and chemical characteristics. The igneous centres occur as cinder cones, lava flows, dykes, maars and diatremes along the Plio-Pleistocene graben faults and adjoining blocks. The existing subvolcanic rocks and lavas display rare mineral assemblages including melilite, leucite, kalsilite, monticellite, wollastonite, perovskite and Ba-Sr-rich calcite. In addition, they contain very unusual Ti-rich garnet and Zr-Ca-Ti minerals, which are generally confined to carbonate-rich magmatic rocks. These rock types range from near-agpaitic melilitolite and melilitite to calcium-carbonatite. The pyroclastics commonly contain feldspars, mostly sanidine, and like the ULUD sub-volcanic rocks and lavas, commonly contain diopside, phlogopite, olivine and mantle micro-nodules. The pyroclastic rocks range from melilitite-carbonate tuffs to sanidine-bearing tuffs. In the ULUD, volcanic activity and rock types strongly resemble those generally observed in classical, continental-rift-related magmatic provinces. The affinity between the ULUD rocks and the Roman Campanian Province “High-Potassium Series” rocks helps in interpreting the magmatism developed at the Tyrrhenian eastern border as intra-continental and rift-related.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11564/121958
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