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Wijbrans, J. R.
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Wijbrans, J. R.
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- PublicationRestricted40Ar/39Ar geochronology of Holocene basalts; examples from Stromboli, Italy(2011)
; ; ; ; ; ; ; ; ; ;Wijbrans, J. ;Schneider, B. ;Kuiper, K. ;Calvari, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Branca, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;De Beni, E.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Norini, G. ;Corsaro, R. A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Miraglia, L.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ; ; ;; ; ; ;; Absolute chronologies of active volcanoes and consequently timescales for eruptive behaviour and magma production form a quantitative basis for understanding the risk of volcanoes. Surprisingly, the youngest records in the geological timescale often prove to be the most elusive when it comes to isotopic dating. Absolute Holocene volcanic records almost exclusively rely on 14C ages measured on fossil wood or other forms of biogenic carbon. However, on volcanic flanks, fossil carbon is often not preserved, and of uncertain origin when present in paleosols. Also, low 14C-volcanic CO2 may have mixed with atmospheric and soil 14C-CO2, potentially causing biased ages. Even when reliable data are available, it is important to have independent corroboration of inferred chronologies as can be obtained in principle using the 40K/40Ar decay system. Here we present results of a 40Ar/39Ar dating study of basaltic groundmass in the products from the Pleistocene e Holocene boundary until the beginning of the historic era for the north-northeastern flank of Stromboli, Aeolian Islands, Italy, identifying a short phase of intensified flank effusive activity 7500 500 a ago, and a maximum age of 4000 900 a for the last flank collapse event that might have caused the formation of the Sciara del Fuoco depression. We expect that under optimum conditions 40Ar/39Ar dating of basaltic groundmass samples can be used more widely for dating Holocene volcanic events.504 24 - PublicationRestrictedGeological evolution of Mount Etna volcano (Italy) from earliest products until the first central volcanism (between 500 and 100 ka ago) inferred from geochronological and stratigraphic data(2007)
; ; ; ; ;Branca, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Coltelli, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;De Beni, E.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Wijbrans, J.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; ; ; We present an updated geological evolution of Mount Etna volcano based on new 40Ar/39Ar age determinations and stratigraphic data integrating the previous K/Ar ages. Volcanism began at about 500 ka ago through submarine eruptions on the Gela–Catania Foredeep basin. About 300 ka ago fissure-type eruptions occurred on the ancient alluvial plain of the Simeto River forming a lava plateau. From about 220 ka ago the eruptive activity was localised mainly along the Ionian coast where fissure-type eruptions built a shield volcano. Between 129 and 126 ka ago volcanism shifted westward toward the central portion of the present volcano (Val Calanna–Moscarello area). Furthermore, scattered effusive eruptions on the southern periphery of Etna edifice occurred until about 121 ka ago. The stabilization of the plumbing system on the Valle del Bove area is marked by the building of two small polygenic edifices, Tarderia and Rocche volcanoes. Their eruptive activity was rather coeval ending 106 and 102 ka ago, respectively. During the investigated time-span volcanism in Etna region was controlled by a main E–W extensional tectonic related to the reactivation of Malta Escarpment fault system in eastern Sicily.359 34 - PublicationRestrictedThe Mt. Moio eruption (Etna): Stratigraphy, petrochemistry and 40Ar/39Ar age determination with inferences on the relationship between structural setting and magma intrusion(2012-10-01)
; ; ; ; ; ;Del Carlo, P.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Pisa, Pisa, Italia ;Branca, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;De Beni, E.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Lo Castro, M. D.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Wijbrans, J. R.; Faculteit Aard-en Levenswetenschappen, Vrije Universiteit, Amsterdam, The Netherlands; ; ; ; Mt. Moio is the most peripheral scoria cone of Etna volcano and rises above the Peloritani Mountains sedimentary basement, 18 km north of the volcano summit. Geological and tephrostratigraphic studies and 40Ar/39Ar age determinations were used to characterize the eruption and constrain its occurrence to ~ 29 ka ago, during the activity of the Ellittico volcano, the volcanic edifice active before the actual one, the Mongibello volcano. The Mt. Moio eruption formed a large scoria cone and a widespread tephra fallout deposit, indicating that vigorous explosive activity produced an eruptive plume; minor effusive activity produced a small lava flow at the end of the eruption. Geochemical data indicate that the composition of erupted magma became less evolved during the eruption (mugearite → basalt–hawaiite); thus Mt. Moio deposits have been divided into Lower and Upper Sequences characterized by similar depositional facies. Based on the classification of Etna flank eruptions available in the literature, Mt. Moio can be classed as an eccentric (sensu Rittmann) and Class B eruption. Historic flank eruptions (e.g. 1669, 1763, 2001, 2002–03) formed deposits that are petrochemically and stratigraphically similar to those of Mt. Moio. The general trend of the Mt. Moio eruptive fissure corresponds to that of extensional neotectonic lineaments in the Apenninic–Maghrebian Chain, indicating that the structure of the basement played a role in controlling the ascent of the volatile-rich magma during Ellittico volcano activity.657 34 - PublicationEmbargoCoupled U–Pb and 40Ar/39Ar chronology of late‐stage intrusions at Elba Island (Italy) supports late Miocene long‐lived magma reservoirs in the Tyrrhenian upper crust(2024-02-07)
; ; ; ; ; ; ; ; ; ; ; The late Miocene Monte Capanne and Porto Azzurro plutons are investigated by means of coupled U-Pb zircon and 40Ar/39Ar white mica dating to test the occurrence of long-lived magmatic systems in the upper crust. Zircon crystallized for > 1 Myr in both plutonic systems, with supersolidus conditions overlapping for ~220 kyr indicating previously unrecognized co-existence of the two reservoirs. The development of the Porto Azzurro high T-aureole is post-dated by continuous igneous zircon crystallization until ~ 6.0 Ma. By linking crystallization to post-emplacement cooling of late-stage pulses in both western and eastern Elba we constrain long-lived sizeable reservoirs (possibly the same reservoir) in the Tyrrhenian upper crust between ~8 and 6 Ma.46 16 - PublicationRestrictedReconstruction of the eruptive activity on the NE sector of Stromboli volcano: timing of flank eruptions since 15 ka(2011-01)
; ; ; ; ; ; ; ; ;Calvari, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Branca, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Corsaro, R. A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;De Beni, E.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Miraglia, L.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Norini, G. ;Wijbrans, J. ;Boschi, E.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; ; ; ; ; ; ;A multidisciplinary geological and compositional investigation allowed us to reconstruct the occurrence of flank eruptions on the lower NE flank of Stromboli volcano since 15 ka. The oldest flank eruption recognised is Roisa, which occurred at ~15 ka during the Vancori period, and has transitional compositional characteristics between the Vancori and Neostromboli phases. Roisa was followed by the San Vincenzo eruption that took place at ~12 ka during the early stage of Neostromboli period. The eruptive fissure of San Vincenzo gave rise to a large scoria cone located below the village of Stromboli, and generated a lava flow, most of which lies below sea level. Most of the flank eruptions outside the barren Sciara del Fuoco occurred in a short time, between ~9 and 7 ka during the Neostromboli period, when six eruptive events produced scoria cones, spatter ramparts and lava flows. The Neostromboli products belong to a potassic series (KS), and cluster in two differently evolved groups. After an eruptive pause of ~5,000 years, the most recent flank eruption involving the NE sector of the island occurred during the Recent Stromboli period with the formation of the large, highly K calc-alkaline lava flow field, named San Bartolo. The trend of eruptive fissures since 15 ka ranges from N30°E to N55° E, and corresponds to the magma intrusions radiating from the main feeding system of the volcano.559 26 - PublicationRestrictedThe occurrence of Mt Barca flank eruption in the evolution of the NW periphery of Etna volcano (Italy)(2009-01)
; ; ; ; ; ;Branca, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Del Carlo, P.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Pisa, Pisa, Italia ;Lo Castro, D.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;De Beni, E.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Wijbrans, J.; Faculteit Aard-en Levenswetenschappen, Vrije Universiteit, Amsterdam, The Netherlands; ; ; ; Geological surveys, tephrostratigraphic study, and 40Ar/39Ar age determinations have allowed us to chronologically constrain the geological evolution of the lower NW flank of Etna volcano and to reconstruct the eruptive style of the Mt Barca flank eruption. This peripheral sector of the Mt Etna edifice, corresponding to the upper Simeto valley, was invaded by the Ellittico volcano lava flows between 41 and 29 ka ago when the Mt Barca eruption occurred. The vent of this flank eruption is located at about 15 km away from the summit craters, close to the town of Bronte. The Mt Barca eruption was characterized by a vigorous explosive activity that produced pyroclastic deposits dispersed eastward and minor effusive activity with the emission of a 1.1-km-long lava flow. Explosive activity was characterized by a phreatomagmatic phase followed by a magmatic one. The geological setting of this peripheral sector of the volcano favors the interaction between the rising magma and the shallow groundwater hosted in the volcanic pile resting on the impermeable sedimentary basement. This process produced phreatomagmatic activity in the first phase of the eruption, forming a pyroclastic fall deposit made of high-density, poorly vesicular scoria lapilli and lithic clasts. Conversely, during the second phase, a typical strombolian fall deposit formed. In terms of hazard assessment, the possible occurrence of this type of highly explosive flank eruption, at lower elevation in the densely inhabited areas, increases the volcanic risk in the Etnean region and widens the already known hazard scenario.482 23 - PublicationRestrictedNew results of 40Ar/39Ar dating constrain the timing of transition from fissure-type to central volcanism at Mount Etna (Italy)(2005-05-06)
; ; ; ; ; ;De Beni, E.; Dipartimento di Scienze Geologiche, Universita` di Catania, Italy ;Wijbrans, J. R.; Faculteit der Aardwetenschappen, Vrije Universiteit, Amsterdam, The Netherlands ;Branca, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Coltelli, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Groppelli, G.; Istituto per la Dinamica dei Processi Ambientali-Sezione di Milano, CNR, via Mangiagalli 34, 20133 Milano, Italy; ; ; ; Recent geological studies performed at Etna allow reassessing the stratigraphic frame of the volcano where distinct evolutionary phases are defined. This stratigraphic reconstruction was chronologically constrained on the basis of a limited number of U–Th and K–Ar age determinations whose uncertainty margins are sometimes too wide. For this reason, we successfully adopted at Etna the 40Ar/39Ar technique that allowed obtaining more precise age determinations. The incremental heating technique also gives information on sample homogeneity, and potential problems of trapped argon. Five samples were collected from stratigraphically well-controlled volcanic units in order to chronologically define the transition between the fissure-type volcanism of the Timpe phase to the central volcanism of the Valle del Bove Centers. Isotopic ages with an uncertainty margin of 2–4% have been obtained emphasizing that this transition occurred (130– 126 ka) without significant temporal hiatus.373 28 - PublicationRestricted40Ar/39Ar isotopic dating of Etna volcanic succession(2011)
; ; ; ; ; ;De Beni, E.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Branca, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Coltelli, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Groppelli, G.; C.N.R - Istituto per la Dinamica dei Processi Ambientalisezione ;Wijbrans, J. R.; Faculty of Earth and Life Sciences, VU University, Am -; ; ; ; Since the 1970’s, about 50 radio-isotopic ages have been determined on Etna volcanics using different techniques: Th-U and K/Ar. Unfortunately, these ages cannot be readily used to constrain the new stratigraphic setting of the volcano, because of the uncertainty in sample locations or, sometimes, the large errors affecting the calculated ages. For this reason a program of radio-isotopic dating applying the 40Ar/39Ar incremental heating technique to date the groundmass of basaltic samples has been carried out from 2002. Forty samples (22 of which are of new publication) were collected from key outcrops on Etna volcano, selected on the basis of their stratigraphic position, while one sample was collected from the Hyblean plateau volcanics. We have obtained reliable results from all volcanics analysed from 542 ka up to 10 ka with the MSWD’s (Mean Square of Weighted Deviates) ranging from 0.03 up to 1.7 excluding IS sample (MSWD = 6.28). These new results allow us to: i) assign an age to 19 of the 25 lithostratigraphic units defined in the new geological map of Etna volcano; ii) clarify the uncertain stratigraphic position of isolated volcanic units; iii) constraint the temporal hiatus that matches the main unconformities; iv) outline the lapse of time between the end of the Hyblean volcanism and the beginning of eruptive activity in the Etna region.593 63