Search results for "petrography"
showing 10 items of 138 documents
Are highly siderophile elements (PGE, Re and Au) fractionated in the upper mantle of the earth? New results on peridotites from Zabargad
2000
Abstract Seven peridotite samples from Zabargad Island (Red Sea) were analyzed for highly siderophile elements (HSE), including five platinum-group elements (PGE: Os, Ir, Ru, Rh, Pd) and Re and Au. Petrography and chemical composition of the samples had been published earlier [Kurat, G., Palme, h., Embey-Isztin, A., Touret, J., Ntaflos, T., Spettel, B., Brandstatter, F., Palme, C., Dreibus, G., Prinz, m., 1993. Petrology and geochemistry of peridotites and associated vein rocks of Zabargad Island, Red Sea, Egypt. Mineralogy and Petrology 48, 309–341]. Five samples with chemical compositions typical of upper mantle rocks, from fertile to increasingly depleted mantle (CaO: 3.39 to 0.21%), hav…
Evaluation of accelerated weathering effects on the surface of two coloured sicilian building stones
2007
The dark grey Breccia di Billiemi and the Ammonitico Rosso of Piana degli Albanesi, widely employed outdoor and indoor in monuments in Sicily, undergo significant alteration processes, affecting not only the chromatic aspect but also the state of aggregation. In a previous paper [1] the effects of accelerated weathering in laboratory was compared with natural ageing in the urban environment. The study included the description of lithofacies, the characterisation by means of petrographic and physical-chemical techniques and accelerated weathering experiments on both lithotypes.
THE PETROGRAPHY AND CHEMISTRY OF THIN-WALLED WARE FROM AN HELLENISTIC- ROMAN SITE AT SEGESTA (SICILY)*
2003
Samples of Roman thin-walled ware from Segesta (northwestern Sicily), dating back to the early Imperial period, were studied by optical microscopy (OM) and Neutron Activation Analysis (NAA). Up to now, this class of Roman fine tableware has only occasionally been evaluated archaeometrically. Nevertheless, numerous production centres are believed to have been simultaneously active in the western Mediterranean area. Petrographic and chemical data seem to be in agreement with the archaeological hypothesis of local manufacture in Segesta for most of the analysed samples, through a comparison with kiln wasters and local raw materials. The effectiveness of thin-section petrography for determining…
Petrographic and geochemical characterization of Archaic-Hellenistic tableware production at Solunto, Sicily
2009
A selected assortment of Archaic-Hellenistic tableware samples from Solunto, a Phoenician-Punic site located 20 km east of Palermo (Sicily), has been subjected to thin-section petrography and chemical analysis (XRF). In this settlement several ceramic kilns remained operative over a long time period (7th to 3rd century B.C.). The main goal of this analytical study is to distinguish the ceramics manufactured locally from regional and off-island imports. Analytical results were matched to similar data concerning local natural clay sources and to coeval tableware productions from other sites in the same area. The ceramic pastes used by the ancient craftsmen of Solunto in the case of this class…
Preliminary petrographic and geochemical considerations on the precambrian mafic dykes of the Ilhéus-Olivença area, Bahia
1989
Fe–Mn-encrusted “Kamenitza” and associated features in the Jurassic of Monte Kumeta (Sicily): subaerial and/or submarine dissolution?
2000
Abstract An unusually jagged dissolution surface, capped by a thick Fe–Mn crust is well exposed in small quarry-cuts of the Jurassic of Monte Kumeta. It was formed on a crinoidal limestone substrate of Pliensbachian age, and is covered by Upper Bajocian Ammonitico Rosso-type sediments, all cross-cut by several generations of neptunian dykes. This peculiar surface is more or less coeval with hardgrounds, Fe–Mn-capped dissolution surfaces and associated neptunian dykes described from other localities of the Western Tethys and currently subject to fierce debates as to their purely submarine (or perhaps partly subaerial) origin. The major goal of this paper is to add new arguments to this debat…
Petrogenesis of tourmaline rocks associated with Fe-carbonate-graphite metapelite, metabasite and strata-bound polymetallic sulphide mineralisation, …
2007
Abstract Tourmalinite and tourmaline-rich rocks associated with Fe-carbonate–graphite phyllite, strata-bound polymetallic sulphide deposits, metabasite and marble were studied, for information on the mechanism of tourmaline formation in the pre-Hercynian low-grade metamorphic sequence of the Mandanici Unit in the Peloritani Mountains of Sicily, southern Italy. The major and trace element compositions of the tourmaline rocks suggest the existence of a sedimentary protolith with pre-metamorphic black shale and bedded chert. Boron was interpreted to be accumulated in a restricted sedimentary basin, between platform carbonate formations, with abundant organic matter and Fe–Al–Ti-rich laterite–b…
Dissolution Process: When Does the Process Start
2019
Dissolution process is a complex phenomenon controlled by several factors as like lithology, porosity, stress orientation, environmental conditions and networks of fractures. Then, fault zone and fractures play an important role in fluid circulation and in dissolution, acting as barriers or conduits. In fact, the fault zone has a high permeability only in the early stages of the movement, but shortly the process of recrystallization and reprecipitation reduces the permeability greatly within them. Despite this, traditionally (Cucchi and Forti in In Att. e Mem. Comm. Grotte “E: Boegan” 87–93, 1988; Bini et al. in Varese Lake and the Quaternary 6:3–14, 1993; Ferrarese and Meneghel in Aspetti …
Social and technological changes in the ceramic production of the Northern Levant during the LBA/IA transition: New evidence about the Sea People iss…
2019
Abstract The transition from the Late Bronze Age (LBA) to the Iron Age (IA) in the Levant is marked by the collapse of the Egyptian and Hittite empires, which dominated the political scene of the 14th–13th century BCE. The role of the Sea People, groups of migrants who were defeated by the Egyptian king Ramses III around 1175 BCE, is the focal point concerning this period. After the collapse of the LBA empires, written sources disappeared, and the archaeologists’ primary tool to define cultural processes is to analyze the evolution of pottery. Because of this, studies about the distribution of Aegeanizing ceramic production, considered here to have derived from the Sea People culture, can p…