Search results for "Geophysic"
showing 10 items of 2684 documents
High‐Resolution Proxy Records From Two Simultaneously Grown Stalagmites From Zoolithencave (Southeastern Germany) and their Potential for Palaeoclima…
2020
Two small annually laminated stalagmites from Zoolithencave (southeastern Germany) grew between CE 1821 and 1970 (Zoo‐rez‐1) and CE 1835 and 1970 (Zoo‐rez‐2), respectively. Trace element concentrations were determined by Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA‐ICP‐MS). Samples for δ13C and δ18O analyses were micromilled on annual and subannual resolution. Soil and host rock samples were analyzed by X‐Ray Diffraction (XRD) and their elemental concentrations determined via inductively coupled plasma optical emission spectrometer (ICP‐OES). Trace element concentrations in the stalagmites show two groups in the principal component analyses: one with Mg, Ba, and Sr and an…
U-Pb zircon and Sm-Nd model ages of high-grade Moldanubian metasediments, Bohemian Massif, Czechoslovakia
1988
We report single grain U-Pb ion-microprobe as well as conventional bulk size fraction ages for zircons from 3 metasediment samples of the Moldanubian Complex, Bohemian Massif, one of the largest crystalline complexes of the Hercynian foldbelt in Europe. These are complemented by whole-rock Sm-Nd model ages. The metasediments are of upper amphibolite to granulite grade and come from the Bory Massif in Moravia, NW of Brno (sample AA-1) and from the Varied Group (AA-2) and Monotonous Group (AA-3) in the Ceske Budejovice region of SW Bohemia.
Preliminary geochemical characterization of the Mts. Simbruini karst aquifer (Central Italy)
2021
Mts. Simbruini karst aquifer feeds important springs whose capture contributes to the water supply of Rome City. To improve the geochemical characterization of this aquifer, we analyzed 36 groundwater samples, 29 from springs and 7 from shallow wells, collected in 1996 and 2019. Atomic adsorption spectroscopy, tritration, ionic chromatography and mass spectrometry were the used analytical methods. Ground waters are bicarbonate alkaline-earth type and HCO3 dominance confirms that the aquifer is hosted in carbonate rocks. Total alkalinity vs. cations plot indicates that CO2 driven weathering controls the water chemistry. The probability plots of HCO3, cations and Ca2+ +Mg2+ indicate four grou…
Mount Etna: Geochemical signals of magma ascent and unusually extensive plumbing system
2003
] FiveyearsofgasmonitoringfromselectedsitessuggestthatMtEtna’splumbingsystemismuchmoreextensivethanpreviously reported. It extends at least 40 km SW from thevolcano’s boundary along the NE-SW regional fault, whereit discharges about 200 tons/day of gas, containing heliumwith mantle-type isotopic composition. Synchronousvariations of
Investigation of Surface Geology and Intensity Variability in the Palermo, Italy, Urban Area after the 6 September 2002 Earthquake
2005
For the first time, a high-density macroseismic survey has been carried out in the city of Palermo, Italy, after the 6 September 2002, Mw 5.9 earthquake. The aim was to investigate the spatial relationships and correlations between intensity data and surface geology. A very dense database has been created to store a large amount of macroseismic, stratigraphic, and geotechnical information. A Geographic Information Systems (gis) tool, called City-gis, enables data processing by instruments and research keys devoted to seismic hazard. The results show the feasibility of such procedures, especially for large cities where the surface geology critically influences the ground motion. Our analysis…
Integrated geophysical survey for 3D modelling of a coastal aquifer polluted by seawater
2013
Geophysical surveys are carried out in the coastal area of Petrosino (south-western Sicily) to study the time evolution of seawater contamination of the coastal aquifer, probably increased due to human impact. The overexploitation of the aquifer, due to an intensive agricultural use has affected significantly the natural hydro-geochemical state of the basin. The study is based on a processing and integrated analysis of hydrogeological, geochemical and geophysical data. In particular in the last two years seasonal time-lapse electrical resistivity tomographies (ERT), new TDEM soundings and Multi-Analysis Surface Wave soundings (MASW) have been carried out. The interpretation of the total set…
Geophysical investigations in the Flumendosa River Delta, Sardinia (Italy) — Seismic reflection imaging
2006
A geophysical investigation that included seismic-reflection surveying and time-domain electromagnetics (EM) was carried out in the Flumendosa River Delta plain in southeastern Sardinia, Italy. The objective was to improve knowledge of geologic and hydrogeologic controls on a highly productive aquifer hosted in thick Quaternary deposits and known to be affected by an extensive saltwater intrusion. The seismic reflection survey, whose results are reported here, aimed to image the Paleozoic bedrock topography and to obtain detailed structural and stratigraphic information on the sequence of largely fluvial sediments extending from the surface down to bedrock. The survey consisted of two inli…
Exceptional mobility of an advancing rhyolitic obsidian flow at Cordón Caulle volcano in Chile
2013
The emplacement mechanisms of rhyolitic lava flows are enigmatic and, despite high lava viscosities and low inferred effusion rates, can result in remarkably, laterally extensive (30 km) flow fields. Here we present the first observations of an active, extensive rhyolitic lava flow field from the 2011-2012 eruption at Cordón Caulle, Chile. We combine high-resolution four-dimensional flow front models, created using automated photo reconstruction techniques, with sequential satellite imagery. Late-stage evolution greatly extended the compound lava flow field, with localized extrusion from stalled, ~35 m-thick flow margins creating80 breakout lobes. In January 2013, flow front advance continu…
The emissions of CO2 and other volatiles from the world’s subaerial volcanoes
2019
AbstractVolcanoes are the main pathway to the surface for volatiles that are stored within the Earth. Carbon dioxide (CO2) is of particular interest because of its potential for climate forcing. Understanding the balance of CO2 that is transferred from the Earth’s surface to the Earth’s interior, hinges on accurate quantification of the long-term emissions of volcanic CO2 to the atmosphere. Here we present an updated evaluation of the world’s volcanic CO2 emissions that takes advantage of recent improvements in satellite-based monitoring of sulfur dioxide, the establishment of ground-based networks for semi-continuous CO2-SO2 gas sensing and a new approach to estimate key volcanic gas param…
Tropical Atlantic temperature seasonality at the end of the last interglacial
2015
The end of the last interglacial period, ~118 kyr ago, was characterized by substantial ocean circulation and climate perturbations resulting from instabilities of polar ice sheets. These perturbations are crucial for a better understanding of future climate change. The seasonal temperature changes of the tropical ocean, however, which play an important role in seasonal climate extremes such as hurricanes, floods and droughts at the present day, are not well known for this period that led into the last glacial. Here we present a monthly resolved snapshot of reconstructed sea surface temperature in the tropical North Atlantic Ocean for 117.7±0.8 kyr ago, using coral Sr/Ca and δ18O records. W…