排序方式: 共有51条查询结果,搜索用时 31 毫秒
21.
Giusj Valentina Fichera Cristina Maria Belfiore Mauro Francesco La Russa Silvestro Antonio Ruffolo Donatella Barca Riccardo Frontoni Giuliana Galli Antonino Pezzino 《Geoarchaeology》2015,30(2):79-99
Roman mortars were collected from the Villa dei Quintili in Rome, an archaeological site consisting of numerous edifices from nine construction phases dating from the 2nd century A.D. to modern times. A multianalytical approach was used on 34 mortar samples to infer the evolution of production techniques over time and to identify the source area of calcareous raw materials used in the preparation of the lime. Optical microscopy, scanning electron microscopy coupled with an energy‐dispersive system, and laser ablation inductively coupled plasma mass spectrometry were used to study the samples. The major and trace element data were compared with the compositions of two types of limestone samples (Calcare Massiccio and Calcare Maiolica) collected from the Cornicolani Mountains. The results suggest that the technological practices and the calcareous raw materials used for lime production remained unchanged over the time period considered (2nd century A.D. to 3rd century A.D.). The compositions of lime‐related particles in the mortars match those of Calcare Maiolica, which suggests its use as raw material for lime production. On the whole, the results are in agreement with data from existing literature regarding both the use by Roman builders of specific raw materials for the mortars’ production and the relative supply area. 相似文献
22.
Pietro Carveni Giuliana Mele Santo Benfatto Sebastiano Imposa Maria Salleo Puntillo 《Bulletin of Volcanology》2011,73(9):1155-1162
The row of pyroclastic cones named Mts. Sartorius, outcropping on the NE flank of Etna, formed in 1865 during a lateral eruption
that lasted about 6 months. The event was eye witnessed and described by numerous scientists and reporters. In this work,
we use their observations to reconstruct the eruption chronology and scenario, and carry out a detailed geomorphologic survey
to identify the eruptive features and pyroclastic deposits. The 1865 eruption began on 29 January along a segment of the main
system of fractures oriented ENE–WSW, radial to the central conduit. After 30 January, a secondary system of fractures trending
NNW–SSE was simultaneously active. The six larger Mts. Sartorius cones developed since 3 February along the lower extension
of the radial system. They are markedly asymmetric due to the persistent winds blowing at the time and to the pre-existing
topography formed on underlying deposits, previously unreported, that we have recognized. Now, about 150 years after the eruption,
most of the eruptive vents and fractures are no longer observable in the field, being mostly hidden by products of subsequent
phases of the eruption and by younger epiclastic deposits. 相似文献
23.
24.
25.
26.
Maria Letizia Amadori Habib Belayouni Francesco Guerrera Manuel Martín-Martín Iván Martin-Rojas Crina Micl?u? Giuliana Raffaelli 《International Journal of Earth Sciences》2012,101(6):1599-1623
A study has been performed on the Cretaceous to Early Miocene succession of the Vrancea Nappe (Outer Carpathians, Romania), based on field reconstruction of the stratigraphic record, mineralogical-petrographic and geochemical analyses. Extra-basinal clastic supply and intra-basinal autochthonous deposits have been differentiated, appearing laterally inter-fingered and/or interbedded. The main clastic petrofacies consist of calcarenites, sub-litharenites, quartzarenites, sub-arkoses, and polygenic conglomerates derived from extra-basinal margins. An alternate internal and external provenance of the different supplies is the result of the paleogeographic re-organization of the basin/margins system due to tectonic activation and exhumation of rising areas. The intra-basinal deposits consist of black shales and siliceous sediments (silexites and cherty beds), evidencing major environmental changes in the Moldavidian Basin. Organic-matter-rich black shales were deposited during anoxic episodes related to sediment starvation and high nutrient influx due to paleogeographic isolation of the basin caused by plate drifting. The black shales display relatively high contents in sub-mature to mature, Type II lipidic organic matter (good oil and gas-prone source rocks) constituting a potentially active petroleum system. The intra-basinal siliceous sediments are related to oxic pelagic or hemipelagic environments under tectonic quiescence conditions although its increase in the Oligocene part of the succession can be correlated with volcanic supplies. The integration of all the data in the “progressive reorientation of convergence direction” Carpathian model, and their consideration in the framework of a foreland basin, led to propose some constrains on the paleogeographic-geodynamic evolutionary model of the Moldavidian Basin from the Late Cretaceous to the Burdigalian. 相似文献
27.
28.
29.
Ricardo Henrique Moreton Godoi Patricia Y. Hirata Andre V. L. Bitterncourt Ana F. L. Godoi Miguel Jafelicci Jr Francisco J. dos Santos Rafael Bini Liuz F. Zara Cynara L. N. Cunha Ana P. K Soares Eduardo F. Gobbi Sanja Potgieter‐Vermaak José E. F. C. Gardolinski José M. Reis Neto Giuliana Gatto Rotondo Rene van Grieken 《洁净——土壤、空气、水》2012,40(4):364-372
Suspended particles and dissolved substances in water provide reactive surfaces, influence metabolic activity and contribute to the net sediment deposition. It therefore plays an important part in the ecology and quality of the water mass. The water quality in reservoirs is crucial and it is naturally maintained by flushing and sedimentation, which continuously remove phosphorus from the water. In some reservoirs, however, these removal processes are countered by recycling of ions which could play a key role to start and/or maintain the eutrophic state. The combination of macro‐, trace‐ and microanalysis techniques can be useful to trace pollution sources through a chemical fingerprint, whether be during an acute environmental disaster or a long‐term release of pollutants. The water quality and total metal content of reservoir sediments were assessed in a reservoir, situated in the capital of the Paraná State, in the South‐Eastern part of Brazil. The goal of this paper was to determine the metal presence in the sediment and metal and ionic speciation in the Green River reservoir water. Water and bed sediment samples, collected from various sites during 2008 and 2009, were investigated using XRF, ICP‐OES, ICP‐MS, XRD and zeta potential measurements. Based on the results, the heavy metal concentration and chemical composition of the suspended matter in the water samples, as well as the sediment's chemical composition will be discussed. 相似文献
30.
Ground survey within the Nature Park Lonjsko Polje, placed in the middle-northern Croatia was performed during the time interval
2007–2010 in order to find the best location for installing the geomagnetic observatory. The total magnetic field has been
measured a few times using the Overhauser proton magnetometers. The horizontal and vertical gradients of the total field,
and its temporal behaviour were investigated over the restricted region that we estimated as suitable for the observatory.
The results obtained from thoroughly conducted measurements allowed us to find definitive positions for the instrument pillars.
These results are in agreement with previously suggested location found based on combination of Comprehensive CM4 model prediction
and measurements conducted from 2003 to 2005. This study contributes to the development of geomagnetism in Croatia and paves
a way to install the first geomagnetic observatory in Croatia. 相似文献