23,760 research outputs found
Hydrogeochemical changes before and during the 2016 Amatrice-Norcia seismic sequence (central Italy)
Seismic precursors are an as yet unattained frontier in earthquake studies. With the aim of making a
step towards this frontier, we present a hydrogeochemical dataset associated with the 2016 Amatrice- Norcia seismic sequence (central Apennines, Italy), developed from August 24th, with an Mw 6.0 event, and culminating on October 30th, with an Mw 6.5 mainshock. The seismic sequence occurred during a seasonal depletion of hydrostructures, and the four strongest earthquakes (Mw ≥ 5.5) generated an abrupt uplift of the water level, recorded up to 100 km away from the mainshock area. Monitoring a set of selected springs in the central Apennines, a few hydrogeochemical anomalies were observed months before the onset of the seismic swarm, including a variation of pH values and an increase of As, V, and Fe concentrations. Cr concentrations increased immediately after the onset of the seismic sequence. On November 2016, these elements recovered to their usual low concentrations. We interpret these geochemical anomalies as reliable seismic precursors for a dilational tectonic setting
A Geological Itinerary Through the Southern Apennine Thrust-Belt (Basilicata—Southern Italy)
Open access via Springer Compact AgreementPeer reviewedPublisher PD
Geology and Jurassic paleogeography of the Mt. Primo-Mt. Castel Santa Maria ridge and neighbouring areas (Northern Apennines, Italy)
This paper presents the results of a geological mapping project across the Mt. Primo ridge and neighbouring areas (Umbria-Marche Domain – Northern Apennines), where a thick Meso-Cenozoic carbonate succession is exposed. A geological map on the 1:15,000 scale, illustrates the main stratigraphic, paleogeographic and structural features of the area. The geometries of Jurassic stratigraphic units, were mainly controlled by the complex submarine topography resulting from an Early Jurassic extensional phase. The three-dimensional distribution of Jurassic rocks in turn conditioned the structural evolution of this part of the Apennines during the chain building phase
Detrital events within pelagic deposits of the Umbria-Marche basin (Northern Apennines, Italy). Further evidence of Early Cretaceous tectonics
Re-sedimented deposits characterize different stratigraphical intervals in the pelagic successions of the
Umbria-Marche-Sabina Domain (Central and Northern Apennines, Italy). Three stratigraphic sections of the Maiolica
and Marne a Fucoidi Formations, characterized by breccias and calcarenites embedded in pelagic sediments, were sampled
across the Mt. Primo area (Umbria- Marche Ridge, Northern Apennines). Facies analysis indicates a gravity-driven origin
for the clastic levels, interpreted as debris-flows, or turbidity flows. The massive lensoid-to-tabular levels are composed of
loose shallow-water benthic material, sourced from an unknown carbonate platform, associated with: i) lithoclasts made
of Lower Jurassic and Lower Cretaceous shallow-water carbonates; ii) Jurassic mudstones and wackestones referable to the
pelagic succession; iii) calpionellid/radiolarian-rich soft pebbles (Maiolica-type facies). The compositional features of the
studied detrital deposits imply submarine exposure and dismantling of portions of the stratigraphic succession older than
the Barremian/Aptian, which had to be buried in the late Early Cretaceous. Such evidence led us to refer the investigated
clastic event to an extensional tectonic phase. Our interpretation well fits with data coming from different geological
settings of Italy, strongly suggesting the occurrence of a widespread extensional phase in the late Early Cretaceous
Geology of the Mt. Cosce sector (Narni Ridge, Central Apennines, Italy)
This paper is companion to a 1:15,000 scale geological map of the southern sector of the Narni
Range in Central Italy. This sector of the Apenninic Chain was affected by the western Tethyan
rifting stage during the Early Jurassic, and the inherited architectural setting in turn influenced
the Mesozoic stratigraphy and the Neogene-Quaternary tectonic evolution of the area. Based on
stratigraphic and structural field evidence, a Jurassic structural high has been identified in the
Mt. Cosce sector, flanked northward and westward by deeper basins. The basin that had to exist
to the east, as well as the top of the horst-block, cannot be observed due to recent erosion and
orogenic deformation. The western margin of the Mt. Cosce High was rejuvenated during an
extensional tectonic phase which took place in the late Early Cretaceous. This synsedimentary
faulting is reported in this area for the first time, and is documented by a
sedimentary breccia (Mt. Cosce Breccia) resting unconformably on the Jurassic footwall-block
Distribution of the brown bear (Ursus arctos marsicanus) in the Central Apennines, Italy, 2005-2014
Despite its critical conservation status, no formal estimate of the Apennine brown bear (Ursus arctos marsicanus) distribution has ever been attempted, nor a coordinated effort to compile and verify all recent occurrences has ever been ensured. We used 48331 verified bear location data collected by qualified personnel from 20052014 in the central Apennines, Italy, to estimate the current distribution of Apennine brown bears. Data sources included telemetry relocations, scats and DNA-verified hair samples, sightings, indirect signs of presence, photos from camera traps, and damage to properties. Using a grid-based zonal analysis to transform raw data density, we applied ordinary kriging and estimated a 4923 km2 main bear distribution, encompassing the historical stronghold of the bear population, and including a smaller (1460 km2) area of stable occupancy of reproducing female bears. National and Regional Parks cover 38.8% of the main bear distribution, plus an additional 19.5% encompassed by the Natura 2000 network alone. Despite some methodological and sampling problems related to spatial and temporal variation in sampling effort at the landscape scale, our approach provides an approximation of the current bear distribution that is suited to frequently update the distribution map. Future monitoring of this bear population would benefit from estimating detectability across a range on environmental and sampling variables, and from intensifying the collection of bear presence data in the peripheral portions of the distribution
Diurnal and semidiurnal cyclicity of Radon (222Rn) in groundwater, Giardino Spring, Central Apennines, Italy
Understanding natural variations of Rn (222Rn) concentrations is the fundamental
prerequisite of using this radioactive gas as a tracer, or even precursor, of natural processes, including
earthquakes. In this work, Rn concentrations in groundwater were continuously measured over
a seven-month period, during 2017, in the Giardino Spring, Italy, together with groundwater levels
in a nearby well installed into a fractured regional aquifer. Data were processed to reduce noise,
and then analyzed to produce the Fourier spectra of Rn concentrations and groundwater levels.
These spectra were compared with the spectrum of tidal forces. Results showed that diurnal and
semidiurnal cycles of Rn concentrations, and filtered oscillations of groundwater levels, in the nearby
well, are correlated with solar and luni-solar components of tidal forces, and suggested no correlation
with the principal lunar components. Therefore, influencing factors linked to solar cycles, such as
daily oscillations of temperature and atmospheric pressure, and related rock deformations, may have
played a role in Rn concentrations and groundwater levels. An open question remains regarding the
correlation, which is documented elsewhere, of Rn concentrations and groundwater levels with the
lunar components of the solid Earth tides
Geology of the Northern Simbruini Mts. (Abruzzo – Italy)
This paper presents the results of a geological mapping project across the northern portion of
the Simbruini Mts. (Latium-Abruzzi Domain – Central Apennines), where a thick Cretaceous and
Miocene carbonate succession, followed by a thick upper Miocene terrigenous foredeep
succession, is exposed. The terrigenous succession also includes a peculiar lithoclastic unit
(‘brecce della Renga fm.’), whose sedimentation is linked to pre-orogenic (TortonianMessinian) extensional tectonics. The study area experienced late Messinian-early Pliocene
compression, which is the Apennine chain building phase, followed by Quaternary postorogenic extension, related to the opening of the Tyrrhenian basin. A geological map, at
1:20,000 scale, illustrates the main stratigraphic and structural features of the area
U and Th content in the Central Apennines continental crust: a contribution to the determination of the geo-neutrinos flux at LNGS
The regional contribution to the geo-neutrino signal at Gran Sasso National
Laboratory (LNGS) was determined based on a detailed geological, geochemical
and geophysical study of the region. U and Th abundances of more than 50
samples representative of the main lithotypes belonging to the Mesozoic and
Cenozoic sedimentary cover were analyzed. Sedimentary rocks were grouped into
four main "Reservoirs" based on similar paleogeographic conditions and
mineralogy. Basement rocks do not outcrop in the area. Thus U and Th in the
Upper and Lower Crust of Valsugana and Ivrea-Verbano areas were analyzed. Based
on geological and geophysical properties, relative abundances of the various
reservoirs were calculated and used to obtain the weighted U and Th abundances
for each of the three geological layers (Sedimentary Cover, Upper and Lower
Crust). Using the available seismic profile as well as the stratigraphic
records from a number of exploration wells, a 3D modelling was developed over
an area of 2^{\circ}x2^{\circ} down to the Moho depth, for a total volume of
about 1.2x10^6 km^3. This model allowed us to determine the volume of the
various geological layers and eventually integrate the Th and U contents of the
whole crust beneath LNGS. On this base the local contribution to the
geo-neutrino flux (S) was calculated and added to the contribution given by the
rest of the world, yielding a Refined Reference Model prediction for the
geo-neutrino signal in the Borexino detector at LNGS: S(U) = (28.7 \pm 3.9) TNU
and S(Th) = (7.5 \pm 1.0) TNU. An excess over the total flux of about 4 TNU was
previously obtained by Mantovani et al. (2004) who calculated, based on general
worldwide assumptions, a signal of 40.5 TNU. The considerable thickness of the
sedimentary rocks, almost predominantly represented by U- and Th- poor
carbonatic rocks in the area near LNGS, is responsible for this difference.Comment: 45 pages, 5 figures, 12 tables; accepted for publication in GC
On the peritidal cycles and their diagenetic evolution in the Lower Jurassic carbonates of the Calcare Massiccio Formation (Central Apennines)
This paper shows the environmental changes and high-frequency cyclicity recorded by Lower Jurassic shallow- water carbonates known as the Calcare Massiccio Formation which crop out in the central Apennines of Italy. Three types of sedimentary cycle bounded by subaerial erosion have been recognized: Type I consists of a shallowing upward cycle with oncoidal floatstones to rudstones passing gradationally up into peloidal packstone alternating with cryptoalgal laminites and often bounded by desiccation cracks and pisolitic-peloidal wackestones indicating a period of
subaerial exposure. Type II shows a symmetrical trend in terms of facies arrangement with peloidal packstones and cryptoalgal laminites present both at the base and in the upper portion of the cycle, separated by oncoidal floatstones to rudstones. Type III displays a shallowing upward trend with an initial erosion surface overlain by oncoidal floatstones to rudstones that, in turn, are capped by pisolitic-peloidal wackestones and desiccation sheet cracks. Sheet cracks at the top of cycles formed during the initial phase of subaerial exposure were successively enlarged by dissolution during prolonged subaerial exposure. The following sea-level fall produced dissolution cavities in subtidal facies, while the
successive sea-level rise resulted in the precipitation of marine cements in dissolution cavities. Spectral analysis revealed six peaks, five of which are consistent with orbital cycles. While a tectonic control cannot be disregarded, the main signal recorded by the sedimentary succession points toward a main control related to orbital forcing. High frequency sea-level fluctuations also controlled diagenetic processes
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