Geochemical and Sr–Nd isotopic features of the Zaro volcanic complex: insights on the magmatic processes triggering a small-scale prehistoric eruption at Ischia island (south Italy)

Abstract The prehistoric (< 7 ka) Zaro eruption at Ischia island (Southern Italy) produced a lava complex overlaying a pyroclastic deposit. Although being of low energy, the Zaro eruption might have caused casualties among the neolithic population that inhabited that area of Ischia, and damages to their settlements. A similar eruption at Ischia with its present-day population would turn into a disaster. Therefore, understanding the magmatic processes that triggered the Zaro eruption would be important for volcanic hazard assessment and risk mitigation, so as to improve a knowledge that can be applied to other active volcanic areas worldwide. The main Zaro lava body is trachyte and hosts abundant mafic and felsic enclaves. Here all juvenile facies have been fully characterized from petrographic, geochemical and isotopic viewpoints. The whole dataset (major and trace element contents; Sr–Nd isotopic composition) leads to rule out a genetic link by fractional crystallization among the variable facies. Thus, we suggest that the Zaro mafic enclaves could represent a deep-origin mafic magma that mingled/mixed with the main trachytic one residing in the Ischia shallow magmatic system. The intrusion of such a mafic magma into a shallow reservoir filled by partly crystallized, evolved magma could have destabilized the magmatic system presumably acting as a rapid eruption trigger. The resulting processes of convection, mixing and rejuvenation have possibly played an important role in pre- and syn-eruptive phases also in several eruptions of different sizes in the Neapolitan area and elsewhere in the world.

Download Full-text

Small-scale spatial and temporal variations in mid-ocean ridge crest magmatic processes

Geology ◽

10.1130/0091-7613(1994)022<0375:sssatv>2.3.co;2 ◽

1994 ◽

Vol 22 (4) ◽

pp. 375-379 ◽

Cited By ~ 152

Author(s):

M. R. Perfit ◽

D. J. Fornari ◽

M. C. Smith ◽

J. F. Bender ◽

C. H. Langmuir ◽

...

Keyword(s):

Temporal Variations ◽

Spatial And Temporal Variations ◽

Small Scale ◽

Ridge Crest ◽

Mid Ocean Ridge ◽

Magmatic Processes ◽

Ocean Ridge

Download Full-text

Multifractal analysis of radar rainfall fields over the area of Rome

Advances in Geosciences ◽

10.5194/adgeo-2-293-2005 ◽

2005 ◽

Vol 2 ◽

pp. 293-299 ◽

Cited By ~ 5

Author(s):

G. Calenda ◽

E. Gorgucci ◽

F. Napolitano ◽

A. Novella ◽

E. Volpi

Keyword(s):

Scale Invariance ◽

Large Scale ◽

Doppler Radar ◽

Risk Mitigation ◽

Small Scale ◽

Radar Rainfall ◽

Invariance Properties ◽

Meteorological Radar ◽

Using Data ◽

Precipitation Events

Abstract. A scale-invariance analysis of space and time rainfall events monitored by meteorological radar over the area of Rome (Italy) is proposed. The study of the scale-invariance properties of intense precipitation storms, particularly important in flood forecast and risk mitigation, allows to transfer rainfall information from the large scale predictive meteorological models to the small scale hydrological rainfall-runoff models. Precipitation events are monitored using data collected by the polarimetric Doppler radar Polar 55C (ISAC-CNR), located 15 km Southeast from downtown. The meteorological radar provides the estimates of rainfall intensity over an area of about 10 000 km2 at a resolution of 2×2 km2 in space and 5 min in time. Many precipitation events have been observed from autumn 2001 up to now. A scale-invariance analysis is performed on some of these events with the aim at exploring the multifractal properties and at understanding their dependence on the meteorological large-scale conditions.

Download Full-text

Tectono-magmatic evolution of the younger Gardar southern rift, South Greenland

Geological Survey of Denmark and Greenland Bulletin ◽

10.34194/geusb.v29.4692 ◽

2013 ◽

Vol 29 ◽

pp. 1-24 ◽

Cited By ~ 16

Author(s):

Brian G.J. Upton

Keyword(s):

Mafic Magma ◽

Dyke Swarm ◽

Small Scale ◽

Alkaline Magmatism ◽

East African ◽

The North ◽

Intrusive Rocks ◽

Alkali Granites ◽

African Rift ◽

Very High

The 1300–1140 Ma Gardar period in South Greenland involved continental rifting, sedimentation and alkaline magmatism. The latest magmatism was located along two parallel rift zones, Isortoq–Nunarsuit in the north and the Tuttutooq–Ilimmaasaq–Narsarsuaq zone in the south addressed here. The intrusive rocks crystallised at a depth of troctolitic gabbros. These relatively reduced magmas evolved through marked iron enrichment to alkaline salic differentiates. In the Older giant dyke complex, undersaturated augite syenites grade into sodalite foyaite. The larger, c . 1163 Ma Younger giant dyke complex (YGDC) mainly consists of structureless troctolite with localised developments of layered cumulates. A layered pluton (Klokken) is considered to be coeval and presumably comagmatic with the YGDC. At the unconformity between the Ketilidian basement and Gardar rift deposits, the YGDC expanded into a gabbroic lopolith. Its magma may represent a sample from a great, underplated mafic magma reservoir, parental to all the salic alkaline rocks in the southern rift. The bulk of these are silica undersaturated; oversaturated differentiates are probably products of combined fractional crystallisation and crustal assimilation. A major dyke swarm 1–15 km broad was intruded during declining crustal extension, with decreasing dyke widths and increasing differentiation over time. Intersection of the dyke swarm and E–W-trending sinistral faults controlled the emplacement of at least three central complexes (Narssaq, South Qôroq and early Igdlerfigssalik). Three post-extensional complexes (Tugtutôq, Ilímaussaq and late Igdlerfigssalik) along the former rift mark the end of magmatism at c . 1140 Ma. The latter two complexes have oblate plans reflecting ductile, fault-related strain. The Tugtutôq complex comprises quartz syenites and alkali granites. The Ilímaussaq complex mainly consists of nepheline syenite crystallised from highly reduced, Fe-rich phonolitic peralkaline (agpaitic) magma, and resulted in rocks with very high incompatible element concentrations. Abundant anorthositic xenoliths in the mafic and intermediate intrusions point to a large anorthosite protolith at depth which is considered of critical importance in the petrogenesis of the salic rocks. Small intrusions of aillikite and carbonatite may represent remobilised mantle metasomites. The petrological similarity between Older and Younger Gardar suites implies strong lithospheric control of their petrogenesis. The parental magmas are inferred to have been derived from restitic Ketilidian lithospheric mantle, metasomatised by melts from subducting Ketilidian oceanic crust and by small-scale melt fractions associated with Gardar rifting. There are numerous analogies between the southern Gardar rift and the Palaeogene East African rift.

Download Full-text

Revisiting currency swaps: hedging real estate investments in global city markets

Journal of Property Investment and Finance ◽

10.1108/jpif-04-2017-0026 ◽

2018 ◽

Vol 36 (2) ◽

pp. 191-209

Author(s):

Philipp Bejol ◽

Nicola Livingstone

Keyword(s):

Real Estate ◽

Foreign Currency ◽

Risk Mitigation ◽

Sampling Technique ◽

Real Estate Market ◽

Small Scale ◽

Negative Consequences ◽

Content Type ◽

Net Worth ◽

Individual Asset

Purpose The purpose of this paper is to re-examine currency swaps as an effective hedging technique for individual asset performance in today’s global real estate market, by considering hypothetical prime office investments across six different cities and five currency pairs. The perspective of a risk-averse, high net worth, non-institutional, smaller-scale Swiss investor is paired with investors from five additional national markets. Design/methodology/approach The study examines currency swaps in key office markets across three continents (Frankfurt, London, New York, Sydney, Warsaw and Zurich) and extends previous work on the topic by adopting both Monte Carlo (MC) and Latin Hypercube (LH) techniques to create stochastic samples for individual asset performance analyses. This is the first paper to apply LH sampling to currency swaps with underlying real estate assets, and the validity of this method is compared with that of MC. Four models are presented: the experience of the domestic investor (no exchange rate (ER) fluctuations); an unhedged direct foreign investment; hedging rental income and initial purchase price via a currency swap; and hedging rental income and anticipated terminal value. Findings The efficacy of a swap depends on the historical framework of the ERs. If the foreign currency depreciates against the domestic one, hedging the repatriated cash flow of a property investment proved superior to the unhedged strategy (EUR, GBP, PLN and USD to the CHF). An investor would benefit from exposure to an appreciating foreign currency (CHF to the EUR, GBP, PLN and USD), with an unhedged strategy clearly outperforming the currency swap as well as the domestic investor’s performance, while a historically sideways fluctuating ER (AUD to the CHF) also favours an unhedged approach. In all scenarios, unexpected economic or market shocks could cause negative consequences on the repatriated proceeds. Practical implications This research is of interest to small-scale, non-institutional investors aiming to develop strategies for currency risk mitigation in international investments for individual assets; however, tax-optimising strategies and the implications on a larger portfolio have not been taken into account. Originality/value There is no recent academic work on the efficacy of currency swaps in today’s global office market, nor has the position of smaller-scale high net worth investors received much academic attention. This research revisits the discussion on their validity, providing contemporary insight into the performance of six markets using LH as an alternative and original sampling technique.

Download Full-text

Evolution of the Kara Ore-Magmatic System (Eastern Transbaikalia, Russia): Experience in Applying Small-Scale Geochemical Survey

Geology of Ore Deposits ◽

10.1134/s1075701521030041 ◽

2021 ◽

Vol 63 (3) ◽

pp. 257-268

Author(s):

S. V. Efremov ◽

A. M. Spiridonov ◽

N. A. Goryachev ◽

A. E. Budyak

Keyword(s):

Small Scale ◽

Magmatic System ◽

Geochemical Survey ◽

Eastern Transbaikalia

Download Full-text

Prevalence and risk factors associated with Campylobacter spp. and Salmonella enterica in livestock raised on diversified small-scale farms in California

Epidemiology and Infection ◽

10.1017/s095026881900205x ◽

2019 ◽

Vol 147 ◽

Cited By ~ 1

Author(s):

A. F. A. Pires ◽

L. Patterson ◽

E. A. Kukielka ◽

P. Aminabadi ◽

N. Navarro-Gonzalez ◽

...

Keyword(s):

Risk Factors ◽

Salmonella Enterica ◽

Management Practices ◽

Risk Mitigation ◽

Significant Risk ◽

Mitigation Strategies ◽

Farm Size ◽

Small Scale ◽

Animal Products ◽

Factors Associated

Abstract Diversified farms are operations that raise a variety of crops and/or multiple species of livestock, with the goal of utilising the products of one for the growth of the other, thus fostering a sustainable cycle. This type of farming reflects consumers' increasing demand for sustainably produced, naturally raised or pasture-raised animal products that are commonly produced on diversified farms. The specific objectives of this study were to characterise diversified small-scale farms (DSSF) in California, estimate the prevalence of Salmonella enterica and Campylobacter spp. in livestock and poultry, and evaluate the association between farm- and sample-level risk factors and the prevalence of Campylobacter spp. on DSSF in California using a multilevel logistic model. Most participating farms were organic and raised more than one animal species. Overall Salmonella prevalence was 1.19% (95% confidence interval (CI95) 0.6–2), and overall Campylobacter spp. prevalence was 10.8% (CI95 = 9–12.9). Significant risk factors associated with Campylobacter spp. were farm size (odds ratio (OR)10–50 acres: less than 10 acres = 6, CI95 = 2.11–29.8), ownership of swine (OR = 9.3, CI95 = 3.4–38.8) and season (ORSpring: Coastal summer = 3.5, CI95 = 1.1–10.9; ORWinter: Coastal summer = 3.23, CI95 = 1.4–7.4). As the number of DSSF continues to grow, evaluating risk factors and management practices that are unique to these operations will help identify risk mitigation strategies and develop outreach materials to improve the food safety of animal and vegetable products produced on DSSF.

Download Full-text

Seismic risk mitigation at Ischia island (Naples, Southern Italy): An innovative approach to mitigate catastrophic scenarios

Engineering Geology ◽

10.1016/j.enggeo.2019.105285 ◽

2019 ◽

Vol 261 ◽

pp. 105285 ◽

Cited By ~ 1

Author(s):

Giuseppe De Natale ◽

Stefano Petrazzuoli ◽

Fabio Romanelli ◽

Claudia Troise ◽

Franco Vaccari ◽

...

Keyword(s):

Seismic Risk ◽

Southern Italy ◽

Risk Mitigation ◽

Innovative Approach ◽

Ischia Island ◽

Seismic Risk Mitigation

Download Full-text

Evolution of a non-resurgent cauldron: the Late Permian Coombadjha Volcanic Complex, northeastern New South Wales, Australia

Geological Magazine ◽

10.1017/s0016756800034749 ◽

1986 ◽

Vol 123 (3) ◽

pp. 257-277 ◽

Cited By ~ 8

Author(s):

J. McPhie

Keyword(s):

New England ◽

Magma Source ◽

Small Scale ◽

Volcanic Complex ◽

Late Permian ◽

South Wales ◽

Igneous Activity ◽

Homogeneous Crystal ◽

Volcaniclastic Rocks ◽

Fault Displacement

AbstractThe Coombadjha Volcanic Complex is the remnant of a Late Permian cauldron. It is part of an extensive sequence of silicic calc-alkaline volcanics that covers the southeastern portion of the New England Orogen in NSW. The Complex is elliptical, measuring 15 × 24 km, and is outlined by a ring pluton and an arcuate fault. Bedding in the volcanic units of the Complex defines a structural basin, with steep inward dips at the monoclinal rim and gentle to horizontal orientations near the centre. An older group of outflow ignimbrites, lavas, breccias and volcaniclastic rocks at least 1500 m thick, is conformably overlain by more than 500 m of texturally homogeneous, crystal-rich, dacitic ignimbrite. Ignimbrites of the older group are the products of several discrete eruptions from separate vents, all of which were situated outside the Coombadjha area. Silicic lava domes with volcaniclastic aprons, and a tuff ring, mark the positions of local vents active on a small scale during intervals between the emplacement of the outflow ignimbrites. No significant subsidence occurred, nor did a caldera exist at this stage. Cauldron subsidence occurred in response to the large magnitude eruption that produced the crystal-rich ignimbrite. The central cauldron block was lowered at least 2000 m by downwarping and fault displacement, and remained largely intact. There is no evidence for resurgent doming of the cauldron after subsidence, although igneous activity continued with intrusion of an adamellite ring pluton along much of the cauldron margin. The crystal-rich ignimbrite and the ring pluton are similar in composition and may have been successive products of a common magma source that sustained this simple, single cauldron cycle.

Download Full-text

The ’Little’ Fish Canyon Tuff in Romania: Rejuvenation of granodioritic crystal mush resulting in homogeneous dacite recorded by the Haramul Mic lava dome (Ciomadul)

10.5194/egusphere-egu2020-19689 ◽

2020 ◽

Author(s):

Emese Pánczél ◽

Maurizio Petrelli ◽

Réka Lukács ◽

Szabolcs Harangi

Keyword(s):

Lava Dome ◽

Thermal Evolution ◽

Bulk Composition ◽

Volcanic Complex ◽

Bulk Rock ◽

Crystal Mush ◽

Magmatic System ◽

Zircon Core ◽

Accessory Zircon ◽

Zircon Crystallization

Long-dormant volcanoes (quiescence time is several 100&#8217;s to 10&#8217;s thousand years between eruptions) pose a particular hazard, since the long repose time decreases the awareness and there is mostly a lack of monitoring. The Haramul Mic, a pancake-shaped flat dacitic lava dome is part of the Ciomadul Volcanic Complex in eastern-central Europe (Romania) and serves as an excellent example of such volcanoes. The Haramul Mic lava dome is the earliest product of the Young Ciomadul Eruption Period (YCEP), when the activity recrudesced in the area after about 200.000 years quiescence time. Eruption age of the dome determined by (U-Th)/He dating on zircon gave 154 +/- 16 ka that is in agreement with the youngest zircon U-Th outer rim date (142 +18/-16 ka). In the YCEP zircon crystallization dates record typically long, up to 350-400 kyr lifetime of the magmatic plumbing system, in case of &#160;Haramul Mic the oldest zircon core is 306 +/- 37 ka old.The 880.7 m high lava dome covers an area of 1.1 km2 and has a volume of ~0.15 km3. It is composed of crystal-rich homogeneous high-K dacite. The average crystal content is 35-40% and consists of plagioclase, amphibole, biotite and accessory zircon, apatite, titanite and Fe-Ti oxides. The groundmass is mainly built up by perlitic glass with some microlites. The dacite includes mafic enclaves having plagioclase and amphibole besides a large amount of biotite crystals, that eventuates K-rich, shoshonitic bulk composition. The dacite contains abundant felsic crystal clots which comprise plagioclase, amphibole, biotite and interstitial vesicular glass.Amphiboles are relatively homogeneous in chemical composition. They are low-Al hornblendes suggesting 700-800 oC crystallization condition at 200-300 MPa compared with experimental data. Al-in-hornblende geobarometer and amphibole-plagioclase geothermometer calculations give results reproducing these temperature and pressure ranges. Although the Kis-Haram dacite is fairly rich in 25-45 anorthite mol% plagioclase, no negative Eu anomaly can be observed in the bulk rock and the glass. Similarities between Fish Canyon Tuff and Kis-Haram rocks can be strikingly noted regarding the major and trace element contents of mineral phases, glass and bulk rock that all refer to a wet oxidised calc-alkaline magmatic system. The relatively small volume Kis-Haram lava dome represents a rejuvenated low-temperature granodioritic crystal mush having similar features as the large volume silicic eruption of Fish Canyon Tuff. Their recorded almost similarly long zircon crystallization intervals give an interesting aspect with regard to the thermal evolution of the magmatic system and eruption volumes.This research was financed by the Hungarian National Research, Development and Innovation Fund (NKFIH) within No. K116528 project and was supported by the &#218;NKP-19-1 New National Excellence Program of the Ministry for Innovation and Technology.

Download Full-text