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Made available in DSpace on 2021-06-25T11:51:43Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-03-15 Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) FINEP Brazilian agency FAPEG Brazilian agency FUNAPE Brazilian agency The crystalline Bi6Te2O15 and Bi6Te2O13 phases with orthorhombic and cubic symmetries, respectively, were synthesized by solid-state reaction synthesis. A study of the thermal stability of both phases was carried out, being verified that the high temperature cubic phase can be kept at room temperature in a metastable condition during long time. The Raman scattering spectrum, optical reflectivity and photoluminescence emission of these phases were measured for the first time. The optical band gaps E-g = 3.29eV, for the orthorhombic phase, and E-g = 3.08eV, for the cubic phase, were calculated from the reflectivity spectra. Using the brick-layer model the electrical conductivity of a dense ceramic of Bi6Te2O15 was measured, taking in account the grain and grain-boundary effects. Univ Fed Goias, Inst Quim, Goiania, Go, Brazil Univ Fed Goias, Inst Fis, Goiania, Go, Brazil Univ Estadual Paulista, Fac Engn Ilha Solteira, Botucatu, SP, Brazil Univ Estadual Paulista, Fac Engn Ilha Solteira, Botucatu, SP, Brazil

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Submarine geohazards, are exceptional events capable of producing large-volume turbidites that result from catastrophic slope failures and the associated downslope mass transport of enormous quantities of sediment from continental shelves and slopes to the deep sea. We are investigating the effects of italian earthquakes and tsunamis on the sedimentary record of the Ionian Sea, through a multi-proxy analysis of turbidite deposits. A comparison between radiometric dating and historical earthquake catalogs suggests that turbidite emplacement triggered by major earthquakes (i.e. AD 1908, 1693 and 1169) represents over 90% of the deposits during the last millennia (Polonia et al., 2013a; 2013b). Although the average recurrence time of single events is about 500 yrs, age modelling indicates that their occurrence is not periodic, but rather varies between 100 and 700 yrs, with clusters of higher frequency (Polonia et al., 2015). Seismic reflection images show that some turbidite beds are very thick and marked by acoustic transparent homogenite mud layers at their top. Based on a high-resolution study of the most recent of such megabeds, the Homogenite/Augias turbidite (Kastens and Cita, 1981; Cita and Aloisi, 2000; Hieke and Werner, 2000), we show that it was not triggered by the Santorini caldera collapse but by giant turbidity flows triggered by the AD 365 earthquake and tsunami (Polonia et al., 2013b; 2016). Backwash flows and related gravity-driven processes are the primary means of downslope sediment transport, confirming that the HAT is a unique instance of thick deep sea tsunami deposit. An older similar deep sea megaturbidite was deposited about 15,000 years BP, implying a large recurrence time of such extreme sedimentary events in the Mediterranean Sea. Marine sediments may thus be considered as seabed archives of paleo-earthquakes capable of reconstructing seismicity back in time, during several earthquake cycles.

We are investigating the effects of earthquakes and tsunamis on the sedimentary record in the Ionian Sea through the analysis of turbidite deposits. A comparison between radiometric dating and historical earthquake catalogs suggests that turbidite emplacement triggered by great earthquakes represents over 90% of the deposits in this region. Seismo-turbidite beds can be correlated with major earthquakes such as the AD 1908 Messina, AD 1693 Catania, AD 1169 Eastern Sicily and AD 365 Crete earthquakes.

Ferromanganese carbonate concretions of extremely variable compositions mineralogical, petrographic and geochemical features. The obtained results lead to a genetic model by which concretions appear to be diagenetic rather than hydrogenic or hydrothermal. This origin is particularly supported by trace metal concentrations, REE patterns and stable isotope compositions.

At Monte Cavaloro near Bologna, outcrops a small olistolith of the ophiolite sequences of the Northern Apeninnes. This small outcrop is known in the geological literature as Bombicci (1868) find out a new type of rock which he named "oligoclasite". Cappellini (1878) studying the same outcrop, named the rock "Cavalorite". These two terms are still present (although obsclete) in the geological nomenclature. The same outcrop was studied by various authors which gave contrasting description of the mineralogy and recognized different rock types, from oligoclase bearing gabbro to quartzdiorite. The last study was by Gazzi (1961) who recognized the presence of stilpnomelane and classified the rock as stilpnomelane-oligoclase bearing gabbro. The present work lead us to the finding of several litothypes in the Monte Cavaloro olistolith: Fe-gabbros, Fe-gabbrobrodiorites, Fe-Ti-P diorites, Fe-Ti-P meladiorites, quartzdiorites and amphibole bearing albitite dikes. The Fe-Ti-P diorites are made up by oligoclase, ferroaugite, ferrohortonolite, ferrosilite, apatite, titanomagnetite and Fe-edenite and appear to be the product of cumulus processes from Fe-rich andesitic magmas which concentrate Fe-Ti oxides when apatite appeared as a liquidus phase. The other associated rocks are genetically linked through flow differentiation processes which generated the Fe-Ti-P meladiorites and the zircon rich quartzdiorites. The differentiation processes, took place in a closed system under low oxygen fugacity; during the late magmatic stages the high volatile content promoted the formation of hydrous minerals (mainly amphiboles) and the peculiar association biotite, cummingtonite-grunerite, stilpnomelane, chlorite. Stilpnomelane is variable in composition and in spite of its chemical features, it may correspond to that find in late stage granophyre of the Skaergaard pluton. This fact is a clear indication of the highly evoluted nature of our stilpnomelane bearing rock in keeping with the presence of stilpnomelane relics in the quartzdiorites. REE and trace elements abundances and composition of apatites and titano-magnetites agree with this genetic interpretation. Liquid immiscibility, as responsible of Fe-Ti-P rock, would seem to be not a viable genetic mechanism. The amphibole bearing albitite dikes represent a late injection of a slightly evolved gabbric magma.

The plutonic complex of Cima d'Asta is an example of hybrid magmatism, due to the interaction of mafic magmas of mantle origin and felsic crustal magmas, in a post-orogen extensional regime (lower Permian). Micro-granular mafic enclaves (IFM) of magmatic origin occur within the main pluton (monzogranite), and are concentrated into a narrow area near the top of Cima d'Asta pluton. The upper portion of the pluton is characterised by wide-spread alteration, detectable both in the monzogranite and in the IFM. The composition of IFM ranges from tonalite to granodiorite, rarely quartzdiorite. Their textures vary from pseudodoleritic to porphyritic and/or ocellar, because of xenocrysts from the granitic magma. The geochemistry of major and trace elements is typical of IFM-bearing granitoid rocks originated through complex interaction of coeval mafic and felsic magmas. The isotopic composition of Sr and the REE distribution are compatible with mingling and mixing mechanisms. The latter is meaningful also because rock with quite different evolution (SiO2 = 55-60% for IFM vs. 70% for monzogranites) show similar REE patterns, suggesting that in places an equilibrium between mafic blobs (enclaves) and monzogranite (matrix) was reached. Based on the whole data set, the IFM are interpreted as fragments of basic dikes intruded into the solidifying monzogranitic magma. The partially molten condition of the IFM during their incorporation into the granitic body is testified by their lobate shapes with small-scale crenulation and by the occurrence of partially resorbed quartz xenocrysts with ocellar texture. Mingling processes involving granitic and mafic magmas are documented also by the heterogeneity of IFM size, broken during the intrusion, and by quenching textures (acicular apatite and fine grain size in the IFM), caused by rapid cooling of the mafic magmas. Besides mechanical interactions, also chemical exchanges, up to a true hybridization, are suggested by the occurrence in places of a melanogranodiorite facies, with compositional characters intermediate between monzogranite and IFM. Moreover, the variability of the textural and compositional features of the IFM (still at the outcrop scale) and their occurrence as enclaves also within the melanogranodiorite facies, suggest that interaction and the hybridization developed through multiple and repeated intrusions of mafic magmas at different degree of evolution. Further evidence of chemical exchanges (migration of Si and K) are suggested by the occurrence in the IFM of poikilitic quartz and K-feldspar and by the abundance of biotite. The widespread alteration detected in the Vetta zone is not pervasive and have low intensity, suggesting that an opening of the system is not reliable. As a matter of fact the main mineralogical feature is the transformation of biotite into chlorite (and rare pyroxene into actinolitic horneblende), but the biotite is still present also in the most altered rocks. Moreover, no geochemical and isotopic (Sr) variations are detectable between rocks with different degrees of alteration. Such characteristics can easily be related to a late-post magmatic deuteric mechanism, that can be particularly active near the Vetta area, that represents the upper portion of the pluton.

The sandstone of the Macigno Formation quarried along the Fontanella stream near Montereggio (Lunigiana - NW Italy) has been used in XVI-XVII century for the construction of important architectural elements such as ashlar portals in the fortified palace of the Malaspina and in Montereggio village. It is a fine-to coarse- grained feldspathic-lithic sandstone with scarce carbonatic cement and sporadic clay minerals consisting of illite. When exposed to the ravages of time, these artifacts undergo a physical degradation mainly consisting of a superficial exfoliation due either to direct causes i.e. thermoclastic and cryoclastic process or to physical indirect causes related to the presence of ashlar workmanships which leads to an increase of surface microfissuring and water absorption. Phenomena of disgregation with intergranular decohesion are not observed; electron microscopy analysis reveals only superficial corrosion of the mineral phases that acquire rounded morphology and become covered by neck-shaped, thread-like and rose-cut patinas of exclusively Si-Al composition. These latter, together with hollow micrometric spheres of analogous composition, represent the product of firewood combustion. This produces also carbonaceous matter, but not in such quantity to induce the formation of black crusts; conversely, the products of combustion of coal and mineral oils, are very scarce or almost totally absent. Although we do not observe significant effects of weathering, the increase of sandstone microporosity can be chiefly attributed to biotic-related agents such as lichens and musks. The sandstones of the ancient quarry located along the Fontanella stream have been submitted to physical-mechanical tests in order to compare them with known litotypes and to choice the most appropriate products for consolidation and protection in view of possible preservative restoration. These tests show that the sandstones of Montereggio are characterized by low porosity and low water absorption coefficient, excellent values of compressive strength, both under dry conditions and after cycles of freezing, and excellent resistence to flexural strength under concentrated load. All these characteristics make these rocks suitable in load-bearing structures such as the studied portals. Our study led us to conclude that the most important physical parameter is the thermal dilatation coefficient, because it qualifies the choice of reinforcing and waterproofing products used to prevent further alteration of the stone surface. We recommend that this coefficient is kept constant, otherwise the detatchment of the superficially consolidated layer from the substratum would be unavoidable.

Finds of basalt orthostats and mud building components from the archaeological site of Tilmen Höyük (south-eastern Turkey, early 2nd Millenium BC) preserve a glassy crust formed by vitrification of the material. It is proposed that such features are related to destructive fire events, which destroyed the wooden building elements and burned natural stones. The geoarchaeological and experimental approach confirms this hypothesis. The geochemical composition of experimental melts is comparable to that of natural basalts. Spot analyses evidence the heterogeneity of the melts, especially for mudbricks and ceiling plasters. It is concluded that the investigated finds were subjected to strong burning under oxidising conditions reached during a violent fire. Temperatures similar to those derived by experimental melting (1180-1195°C) were likely reached in the fire at Tilmen in order to produce the glass observed

Sammardenchia is an important early Neolithic site in northern Italy. It is extremely rich in polished stone with 291 findings consisting of axes, chisels, ornaments, other instruments, pebbles and undetermined fragments, all of which have been studied and which form the basis of the enclosed petrographic catalogue with the essential information relative to each find, the analyses carried out, the texture and mineralogy. The most numerous lithogies are alpine eclogites (36%) and jades or Na-pytoxenites (22.5%) which, together with other high pressure (HP) minor metaphiolites and some paragonite micashicists, usedd for rings, constitute the dominant lithic supergroup (62% of the total), which is evidence of a provenance from the western Italian Alps, similar to the other neolithic sites in northern Italy and Provence. This is a highly structured supergroup, dealth with in various points of the article. A minor supergroup (with acid cinerites/tuffites - 18.5% - and minor sandstones, slates and basalts) represents 22.5% of the lithogies, which are local in origin, from the pebbles of the Fruili plain. A smaller supergroup (10.5%) is represented by metaultramafitic lithologies (serpentines, chloriteschists/fels and nephrites); their provenance is more uncertain and probably diversified. The serpentines are probably partly connected to the HP metaophiolites from the western Alps, and in part from the eastern Alps or Dinarides. The remaining 5% of the materials can be attributed to Carpathian provenance, certain for two silexites and one vitrixc cinerite, less certain and requiring confirmation for a more consistent group of dacites/andesites. The association of these lithologies and some types of artefact forms define the lithic physiognomy of Sammardenchia, which at the moment seems to be unique in Italy. A petrographic summary and a brief discussion is given for all the lithogies, above all from the archeometric aspect. Chemical (XRD and AAS) and minero-chemical analyses by EDS are reported and discussed for a good number of samples. In particular, for the HP metaophiolites a clear distinction was found between the more abundant Fe-ecologites and the less numerous Mg-eclogites, corresponding perfectly with what is geologically known in the western Alps. Among the jades, the Fe-jadeitites (a substantial group here, but not yet known in the literature) seem to be genetically linked to the Fe-eclogites, while a good part of the mixed jades and the omphacitites, probably together with the jadeitites, seem instead to be linked to the Mg-eclogites. The definition of these links is new and must be verified for the archeometric applications and the petrological meaning in future studies.

The studied contacts outcrop in the upper part of the Toal del Mason and consist of two of high-temperature minerral associations, developed at the contact between the Monzoni pluton and the sedimentary country rocks of Werfenian-Anisian age. The contact metamorphites are forsterite-bearing marbles and monticellite-bearing Ca-Mg hornfels which pass to a carbonatic Ca-Mg hornfels. The whole rock and mineral phase chemistry is generally simple, with modest concentrations of trace elements which are always correlated with the crystal chemistry of the mineral phases: the main conclusion is that the metamorphic system, on the whole, was virtually closed and that the mobilisation of elements was limited to small distances involving almost exclusively the original sedimentary rocks. -from English summary

Mineral chemistry data from lavas recovered over a large depth interval of the deep-water volcano of Marsili (Aeolian back-arc, SE Tyrrhenian Sea) are presented. The volcano is built up by products of calcalkaline affinity with the only exception of one outcrop of sub-alkaline, within plate basalts in the crestal area. On the whole, the calcalkaline lavas of Marsili have bimodal composition, and consist of basalts and andesites with, respectively, calcalkaline and high-K serial affinity. The andesites mark a change in the geodynamic conditions that is reflected by the clockwise rotation of the seamount rifting from the early NNE-SSE orientation, associated with the extrusion of the basalts, to a dominant tensional regime trending almost NE-SW. This evolution is discussed in the context of some magmatic-structural features in the southest Tyrrhenian volcanic area. -from Authors

Middle Triassic magmatic products in the Cima Pape area (Eastern Dolomites) are examined. Stratigraphically the volcanic rocks are placed between the Livinallongo formation and the "Conglomerato della Marmolada' formation. The succession starts with the "agglomerati' (a tabular sheet of chaotic deposits derived from submarine slidings) followed by pillow lavas, pillow breccias and small subvolcanic bodies. A thick hyaloclastite sequence marks the end of volcanic activity. A sill varying in thickness from 50 to 300 m is injected inside the Livinallongo formation and controls the distribution of the overlying volcanics. The sill has undergone important differentiation. The chemical characteristics of the volcanic rocks show a clear affinity with shoshonitic series. The rocks could be derived from high alumina basalt primary magmas by high-pressure fractional crystallisation near the base of a thick crust. The "Conglomerato della Marmolada' is a thick conglomeratic sequence made almost exclusively of volcanic elements. This formation marks the end of an upper-Ladinian tectonic phase with extensive uplifting, faulting and erosions. -from English summary