Search results for "Deposit"
showing 10 items of 1447 documents
Late-glacial to Holocene aeolian deposition in northeastern Europe - The timing of sedimentation at the Iisaku site (NE Estonia)
2015
Abstract The Late-glacial and Holocene aeolian inland dune complex at Iisaku (NE Estonia) has been investigated using an accurate and detailed compilation of the sedimentary properties and chronological framework. The quartz grains forming the dunes are very variable, reflecting aeolian, weathering, and periglacial conditions, both prior and after deposition. Although the morphological forms and the sedimentary record point to a dune-like environment, the transport record reflects either a short transport time or/and distance, and a contribution from neighbouring sedimentary environments. Dune development in the area was strongly controlled by the formation of the Baltic Ice Lake (BIL) in f…
Diagenesis of speleothems and its effect on the accuracy of 230 Th/U-ages
2014
Abstract Speleothems can be precisely dated by U-series disequilibrium methods. One basic assumption of the 230Th/U-dating method is that the system remains closed and U and Th isotopes are neither lost nor added after deposition. For stalagmites, this requirement is usually fulfilled due to their protected environment in caves. However, undersaturated drip water may lead to diagenesis of speleothem CaCO3 and altered 230Th/U-ages. Here we present a detailed petrographic investigation using thin sections and 230Th/U-ages of a stalagmite from the Riesenberghohle, northern Germany, which grew during Marine Isotope Stages 5e, c and a. The occurrence of a mosaic fabric in large parts of the stal…
Inner vs. outer wedge-top depozone “sequences” in the Late Miocene (late Tortonian–early Messinian) Sicilian Foreland Basin System; new data from the…
2012
Abstract The wedge-top depozone belongs to the innermost portion of a Foreland Basin System (FBS) ( DeCelles and Giles, 1996 ) and includes all sediments, typically coarse-grained proximal facies, that bury the active frontal part of a fold and thrust belt. The Terravecchia Formation ( Flores, 1959 , Schmidt Di Friedberg, 1962 , Schmidt Di Friedberg, 1964 , Catalano, 1979 ) is a composite lithostratigraphic unit widespread in Sicily (southern Italy) which has been recently considered ( Gugliotta, 2010 ) as a part of the stratigraphic record of the Late Miocene (late Tortonian to early Messinian) Sicilian wedge-top depozone and represent the main object of this paper. Two end-member wedge-to…
Major-ion bulk deposition around an active volcano (Mt. Etna, Italy)
2005
Bulk atmospheric deposition of major cations (Na, K, Ca, Mg) and anions (Cl, F, SO4) were measured at 15 sites around an active volcano, Mount Etna, from 2001 to 2003. Their composition indicates several natural sources, among which deposition of plume-derived volcanogenic gas compounds is prevalent for F, Cl and S. Plume-derived acidic compounds are also responsible for the prevailing acidic composition of the samples collected on the summit of the volcano (pH in the 2.45–5.57 range). Cation species have complex origin, including deposition of plume volcanogenic ash and aerosols and soil-dust wind re-suspension of either volcanic or carbonate sedimentary rocks. Variation of the deposition …
Reconstruction of the Holocene palaeoenvironmental conditions accordingly to the multiproxy sedimentary records from Lake Pilvelis, Latvia
2015
Abstract Reconstruction of the Holocene palaeoenvironment conditions in Southeastern Latvia is based on multiproxy records from Lake Pilvelis: pollen, plant macrofossil and microfossil analysis; loss-on-ignition (LOI) measurements; 14 C dating; humic substances content; humification index; and elemental composition of gyttja organic mass. The data complex obtained in the result of multiproxy studies of sediments in Lake Pilvelis indicates significant changes in the depositional environment during the lake development. Data from Lake Pilvelis show that the start of organic-rich sediments formation before approximately 9750 cal BP, when birch–pine forest dominated in the surrounding landscape…
Rapid oxidation of mercury (Hg) at volcanic vents: Insights from high temperature thermodynamic models of Mt Etna's emissions
2011
A major uncertainty regarding the environmental impacts of volcanic Hg is the extent to which Hg is deposited locally or transported globally. An important control on dispersion and deposition is the oxidation state of Hg compounds: Hg(0) is an inert, insoluble gas, while Hg(II) occurs as reactive gases or in particles, which deposit rapidly and proximally, near the volcanic vent. Using a new high temperature thermodynamic model, we show that although Hg in Etna's magmatic gases is almost entirely Hg(0) (i.e., gaseous elemental mercury), significant quantities of Hg(II) are likely formed at Etna's vents as gaseous HgCl2, when magmatic gases are cooled and oxidised by atmospheric gases. Thes…
Volcanic SiO2-cristobalite: A natural product of chemical vapor deposition
2020
Abstract Cristobalite is a low-pressure, high-temperature SiO2 polymorph that occurs as a metastable phase in many geologic settings, including as crystals deposited from vapor within the pores of volcanic rocks. Such vapor-phase cristobalite (VPC) has been inferred to result from silica redistribution by acidic volcanic gases but a precise mechanism for its formation has not been established. We address this by investigating the composition and structure of VPC deposited on plagioclase substrates within a rhyolite lava flow, at the micrometer to nanometer scale. The VPC contains impurities of the form [AlO4/Na+]0—coupled substitution of Al3+ charge-balanced by interstitial Na+—which are ty…
Vertical movements in NE Sicily and its offshore: Outcome of tectonic uplift during the last 125 ky
2013
New data in the coastal area between Acquedolci and Patti (northeastern Sicily, Italy) have been collected to calculate vertical tectonic rates in a key sector between the Kabilian-Calabrian and the Sicilian-Maghrebian chain. The comparison among marine geology data (multibeam and seismic reflection profiles) on the continental shelf-slope system and the radiocarbon ages on geomorphological markers collected during a coastal survey, provided new stratigraphic, geomorphological and biological data, contributing to the knowledge of the geological evolution of this sector for the last 125 ky.This coastal area is framed between two main structural features active during the Pleistocene in north…
Ash resuspension related to the 2011–2012 Cordón Caulle eruption, Chile, in a rural community of Patagonia, Argentina
2017
Abstract The 2011–2012 Cordon Caulle eruption emitted about 1 km3 of rhyodacitic tephra. Dominant westerly winds in the region caused most of the primary tephra to deposit in neighboring Argentina. In addition to the impact of widespread dispersal and fallout of primary tephra during the eruption, Argentina was also significantly affected by remobilization of the primary ash even several years after the climactic phase of the eruption. In this mixed methods study, we combine aspects of natural and social sciences to characterize the ash resuspension events associated with the 2011–2012 Cordon Caulle deposits and assess the impacts on the Argentinian farming community of Ingeniero Jacobacci …
The “Camporeale wedge-top Basin” (NW Sicily; Italy) in the frame of the Late Miocene Sicilian Foreland Basin System; Inferences from the Upper Torton…
2011
Abstract Since the latest Oligocene–earliest Miocene the building of the Sicilian fold and thrust belt has been accompanied by development of a “peripheral” foreland basin system which migrated toward the foreland. In north-western Sicily, the sedimentary record of the foreland basin system migration is represented by a stratigraphic succession made up of several lithostratigraphic units, bounded by regional unconformity surfaces, deposited recording at least four main sedimentary phases, each characterized by the development of different types of syntectonic basins. In particular, during the Late Miocene (Late Tortonian to Early Messinian) a wide wedge-top depozone developed in the innermo…