Petrology and geochemistry of potassic and ultrapotassic volcanism in central Italy; petrogenesis and inferences on the evolution of the mantle sources

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doi: 10.1016/0024-4937(92)90008-M
Authors:Conticelli, S.; Peccerillo, A.
Author Affiliations:Primary:
Univ. Studi Firenze, Dip. Sci. Terra, Florence, Italy
Volume Title:Potassic and ultrapotassic magmas and their origin; Sixth meeting of the European Union of Geosciences (EUG VI)
Volume Authors:Foley, S., editor
Source:Lithos (Oslo), 28(3-6), p.221-240; Sixth meeting of the European Union of Geosciences; Potassic and ultrapotassic magmas and their origin, Strasbourg, France, March 1991, edited by S. Foley and A. Peccerillo. Publisher: Elsevier, Amsterdam, International. ISSN: 0024-4937
Publication Date:1992
Note:In English; illus. incl. 37 anals., 4 tables, geol. sketch map
Summary:Major, trace element, Sr isotopic and mineral chemical data are reported for mafic volcanic rocks from the northern-central sector of the potassic volcanic belt of central Italy. The rocks range from potassic series and high-K series to lamproitic and kamafugitic through a transitional series, thus covering the entire compositional spectrum of potassic and ultrapotassic magmas. Geochemical and isotopic data for the most primitive of these rocks support the hypothesis that the interaction between crustal and mantle reservoirs was a main process in the genesis of Italian potassic magmatism. Simple mass-balance calculations exclude, however, an important role of crustal assimilation during ascent of subcrustal magmas to the surface and indicate that the sources of central Italy volcanics underwent contamination with fluids and/or melts released by upper crustal material previously brought into the mantle by subduction processes. Different trends of incompatible elements vs K2O in these rocks suggest distinct metasomatic processes for their magma sources. Liquids derived by bulk melting of pelitic sediments are believed to be the most likely contaminants of the source of lamproitic rocks. Fluids or melts rich in Ca, Sr and with Sr isotopic composition around 0.710 are the most likely contaminant of the source region of the other volcanics. Variations in CaO, Na2O and ferromagnesian element abundances and ratios suggest that, in some zones, the mantle source of potassic magmas experienced partial melting with extraction of basaltic liquids prior to metasomatism. [G.R.]
Subjects:Alkaline earth metals; Cenozoic; Chemical ratios; Electron probe data; Igneous rocks; Isotopes; Magmas; Major elements; Metals; Neogene; Partial melting; Pleistocene; Pliocene; Pollution; Potassic composition; Quaternary; Sr-87/Sr-86; Stable isotopes; Strontium; Tertiary; Trace elements; Ultrapotassic composition; Volcanic rocks; Europe; Italy; Latium Italy; Southern Europe; Tuscany Italy; Central Italy
Abstract Numbers:94M/3657
Record ID:1993036164
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom, Reference includes data from PASCAL, Institute de l'Information Scientifique et Technique
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