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Tertiary volcanism in the Northern Apennines (Italy): evidences from the Canetolo Unit and buried volcanic bodies
No full textMineralogical dataset of natural zeolites from Lessini Mounts, Northern Italy: Analcime, natrolite, phillipsite and harmotome chemical composition
Full text linkThis dataset article contains mineralogical and chemical data of some natural zeolites such as analcime, natro- lite, phillipsite and harmotome. These minerals were found as secondary phases within vesicles and veins in the basaltic rocks of the Lessini Mounts, Northern Italy. Meth- ods for obtaining the datasets include optical microscopy, X-ray diffraction, scanning electron microscopy and elec- tron probe microanalysis. Analcime forms well-developed, transparent to milky crystals with a typical icositetrahe- dron habit. The average composition of analcime is calcu- lated as Na 13.79 Ca 0.01 K 0.03 Ba 0.03 [Al 14.28 Si 33.82 O 96 ] 16H 2 O, with all of the extra-framework sites occupied by sodium. Na- trolite usually forms hemispherical aggregates with glassy, colourless to white thin prismatic crystals, which generally radiate from a central point. The average chemical compo- sition of natrolite is Na 14.28 Ca 0.14 K 0.01 [Al 15.60 Si 24.59 O 80 ] 16H 2 O. Crystals of phillipsite-harmotome serie occur in a variety of forms and display a highly variable chemical composi- tion, from almost pure compositions to intermediate values. Phillipsite is more common and its average chemical com- position is Ca 1.40 Na 0.29 K 1.08 Ba 0.27 [Al 4.68 Si 11.28 O 32 ] 12H 2 O, while harmotome is rare and has an average chemical composition of Ca 0.97 Na 0.20 K 0.36 Ba 0.91 [Al 4.60 Si 11.46 O 32 ] 12H 2 O. The obtained dataset can be used for various purposes: it can be used by other authors to compare morphological features and chem- ical compositions of similar zeolites crystals discovered in other parts of the world, it can be compared with those ob- tained from similar geologic environments encouraging stud- ies on hydrothermal processes, and it could represent the starting point for a potential exploration of zeolites from an industrial point of view
Le vulcaniti dell’unità di Canetolo nel quadro del magmatismo cenozoicodell’area circum-mediterranea
No full textVolcanogenic sediments are widespread in the Tertiary litostratigraphic
units of the circum-mediterranean area and they are representative
of periods of intense volcanically-induced sedimentation, penecontemporaneous
to the development of calcalkaline arc systems. With
regard to the Northern Apennine, only few scattered remnants of the
volcanic activity that developed during Tertiary time are actually preserved.
The volcanic clasts within the Canetolo Unit represent one of
these coarse remnants and provide a good chance to investigate the
petrological and geochemical features of Tertiary magmatism associated
with the apenninic subduction/collisional system.
This work focus on the petrography and geochemistry of the volcanic
clasts from the Aveto-Petrignacola Formation (Canetolo Unit), in the
internal part of the apenninic chain, with emphasis on the possible
relationships between geochemical affinities of the magmas and the
circum-mediterranean geodynamic context. The Aveto-Petrignacola
Formation consists of a thick sedimentary sequence of prevailing
redeposited volcaniclastic rocks. Lithic fragments of volcanic origin
are dominant (65-80 vol.%), whereas other lithologies (plutonic,
metamorphic and sedimentary rocks) are subordinate and essentially
derived from the erosion of a basement and a sedimentary cover. The
Aveto-Petrignacola volcanic suite includes basalt, basaltic andesite,
andesite, dacite lavas, and dacite to rhyolite ignimbrites. Geochemically,
the Aveto-Petrignacola suite forms a continuum in composition
with a wide range of SiO2 (48-73 wt.%) and all lithologies could be
considered co-magmatic. The rocks seem to be related to an orogenic
calc-alkaline volcanism and was produced in a subduction-related
tectonic environment
The Ponticello eruption: a sequence of plinian fall deposits from Bolsena Volcanic Complex (Vulsini Volcanic District, Central Italy)
No full textEvolution of the Sabatinian Volcanic District (central Italy) as inferred by stratigraphic successions of its northern sector and geochronological data.
No full textThe Sabatinian Volcanic District (central Italy) consists of a system of several vents clustered around the lake-filled Bracciano volcano- tectonic depression. Its activity spans between 0.8 My and 0.04 My and overlaps that of the neighbouring Vico and Alban Hills Volcanoes in time and space. A field survey of the northern sector together with new geochronological and geochemical data allows us to reconstruct the stratigraphy and volcanic evolution of the Sabatinian Volcanic District. Six main phases of activity have been recognised on the basis of geological data, following the UBSU criteria. The presence of three unconformities of regional significance also enables us to distinguish three different synthems, representing the main stages in the volcanic evolution of the Sabatinian District. The initial phases of activity (from I to IV) are within the Barca di Parma Synthem (800-200 ky) and are dominated by pyroclastic fall and flow deposits and subordinate phonolitic tephritic lava flows. The phase V is related to the Archi di Pontecchio Synthem (200-155 ky) and characterised by prevailing strombolian deposits with a composition ranging from phonolitic tephrite to tephrite. During the phase VI (Casalone Synthem) both magmatic and phreatomagmatic eruptive cycles occurred in the northern sector. The magmatic cycle (154-134 ky) is dominated by pyroclastic fall and lava flows with a variable composition from phonolitic tephrite to potassic trachibasalt. The phreatomagmatic cycle marked the end of the volcanic activity (<134ky) in the northern sector of the Sabatinian District and produced small, single eruptive centres (maars) or coalescent craters which are aligned in a NW-SE regional fracture system at a right angle to the tectonic orientation of the initial Sabatinian Volcanic activity. This fracture system could be connected to the main regional tectonic line that crosses the Vico Volcano and the eastern Sabatinian District
Petrology, geochemistry and age of the volcanic clasts from the Canetolo Unit (Northern Apennines, Italy)
No full textSecondary mineral assemblages as indicators of multistage alteration processes in basaltic lava flows: evidence from the Lessini Mountains, Veneto Volcanic Province, Northern Italy
No full textThe secondary mineral assemblages in the Tertiary basalts from the Lessini Mountains are mainly clay minerals and zeolites, and result from multistage alteration processes. In the earliest Stage I, clay and silica minerals precipitate along the inner walls of the vesicles, followed by the deposition of the fine-grained zeolites of the Stage II (erionite, offretite, analcime, natrolite, heulandite and stilbite). The final Stage III is marked by a new generation of large, well-shaped zeolites (phillipstite-harmotomo, gmelinite, chabazite, willhendersonite and yugawaralite), followed by extensive crystallization of calcite. New morphological and chemical data are presented herein in order to reveal the chemical compositions of Lessini zeolite species, which have never been analyzed before. Textural and chemical observations indicate that the chemical elements for Stage I and II alteration minerals derived from the alteration of the basaltic glass and the primary phases in the volcanic host rocks. The final mineral assemblages of the Stage III suggest a variation in the crystallization conditions, probably related to the presence of new, late-stage fluids enriched in Ca and (CO3)2-, leached from the surrounding calcareous rocks
Geochemical features of the Tertiary buried Mortara volcanic body (Northern Apennines, Italy)
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Volcanic source areas of the Upper Oligocene-Lower Miocene volcanogenic sediments along the Western Mediterranean chains: an overview.
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