Samples of table and cooking ware, dating back to the Byzantine period of the ancient Greek colon... more Samples of table and cooking ware, dating back to the Byzantine period of the ancient Greek colony of Cuma, were analysed by optical microscopy, X-ray diffraction, X-ray fluorescence and scanning electron microscopy, in order to reconstruct the main technological properties of these manufactures. The comparison of minero-petrographical data from these samples with those of some kiln wastes allowed us to hypothesize a local manufacture for most of the investigated specimens and to confirm the relative reference groups. A restricted number of samples did not link with the main groups, indicating a regional (or maybe extra-regional) production, in agreement with the widespread circulation of this high-medieval ceramic production in southern Italy.
Late Miocene basanites of Nosy Be and Nosy Sakatia islands (Nosy Be Archipelago, northern Madagas... more Late Miocene basanites of Nosy Be and Nosy Sakatia islands (Nosy Be Archipelago, northern Madagascar) carry spinel-facies anhydrous ultramafic xenoliths (lherzolites, harzburgites and wehrlites). Geothermobarometric estimates indicate that these xenoliths derive from shallow mantle depths of 35e40 km, with those from Nosy Be island showing equilibration T (averages in the range of 945e985 C) lower than the Nosy Sakatia analogues (averages ranging from 1010 to 1110 C). One Nosy Sakatia mantle xenolith exhibits relatively fertile lherzolite composition, with trace and major element mineral chemistry consistent with a residual character after low degrees (1e2%) of mafic melt extraction. We interpret this composition as that resembling a depleted mantle (DM)-like lithospheric composition before metasomatic overprints. The other lherzolites and harzburgites display petrochemical characters consistent with variable extent of partial melting (up to 18%), associated with pronounced metasomatic overprints caused by migrating melts, as highlighted by enrichments in highly incompatible trace elements (e.g. light rare earth elements, LREE and Sr), together with the abundant occurrence of wehrlitic lithologies.
Journal of Archaeological Science, Volume 40, Issue 2, February 2013, Pages 810-826, Jan 1, 2012
The Via Lepanto site is one of the best examples showing how the Vesuvian region was partially re... more The Via Lepanto site is one of the best examples showing how the Vesuvian region was partially reconstructed and earlier re-occupied after Vesuvius's eruption in the year 79 AD. The large amount of ceramic finds illustrates the typology in use in this area during the IV and V century AD. Analyses were focused on table and cooking ware productions. Archaeometric data were obtained using chemical and minero-petrographical methods (OM, XRD, XRF and SEM). Grain size measurements using Image Analyses on thin sections and a geochemical comparison with clayey deposits outcropping in the Campania region permitted the identification of the raw materials used for these pottery productions. XRD and SEM completed the data set, establishing the protocols used for pottery production in the Pompeii area during Late Roman period. The Via Lepanto site was part of an exchange network of markets with a periodic frequency, where locally produced and imported pottery was sold, indicating a flourishing network of exchanges spanning short, medium and long distances.► Via Lepanto site is an examples testifying the early reconstruction and occupation of Vesuvian region after 79 AD eruption. ► Via Lepanto site was a part of a Late Roman exchange network, here pottery was individually distributed. ► Potters exploited low-CaO clays mixed with selected volcanics to produce high quality ceramics. ► Use of different protocols aimed at achieving the same product with different quality and costs.
This study deals with the characterization of ancient seawater concretes from the Roman harbour o... more This study deals with the characterization of ancient seawater concretes from the Roman harbour of Soli-Pompeiopolis, 1 st century B.C., at Mersin in Turkey, drilled by the ROMACONS (Roman Maritime Concrete Study) team in 2009. This research activity was performed in collaboration with the Laboratories Department of CTG Italcementi Group and the Earth Sciences Department of the University "Federico II" of Naples. Results confirmed that the Roman engineers extensively used coarse tuff aggregate, lime hydrated in seawater, and pozzolanic volcanic fine sand, the so-called pulvis puteolanus of Vitruvius's treatise De Architectura (1 st century B.C.). The typical mineralogical association of phillipsite > chabazite > analcime, in particular points out the provenance for the tuff aggregate from the Yellow Neapolitan Tuff (NYT) formation, which is connected to the Campi Flegrei volcanic activity, dated back to 15.000 years ago. As far as the fine pozzolanic sand, of which just some scoria relics have been observed, can be ascribed to the same formation, or, probably, to the pozzolan stricto sensu pyroclastic flow from the Campi Flegrei area, as well. EDS microanalyses of different phillipsite crystals showed that the content of major alkaline and alkaline-earth metals was very close to those of phillipsite crystals from NYT, with K higher than Na and Ca, as previously reported in the literature. This fact clearly attests that zeolites were not involved in cation exchange processes within the seawater, despite of their long time curingapproximately two thousand years -in the marine environment.
Detailed micropalaeontological and petrochemical analyses of rock samples from two boreholes dril... more Detailed micropalaeontological and petrochemical analyses of rock samples from two boreholes drilled at the archaeological excavations of Herculaneum,~7 km west of the Somma-Vesuvius crater, allowed reconstruction of the Late Quaternary palaeoenvironmental evolution of the site. The data provide clear evidence for ground uplift movements involving the studied area. The Holocenic sedimentary sequence on which the archaeological remains of Herculaneum rest has risen several meters at an average rate of~4 mm/yr. The uplift has involved the western apron of the volcano and the Sebeto-Volla Plain, a populous area including the eastern suburbs of Naples. This is consistent with earlier evidence for similar uplift for the areas of Pompeii and Sarno valley (SE of the volcano) and the Somma-Vesuvius eastern apron. An axisimmetric deep source of strain is considered responsible for the long-term uplift affecting the whole Somma-Vesuvius edifice. The deformation pattern can be modeled as a single pressure source, sited in the lower crust and surrounded by a shell of Maxwell viscoelastic medium, which experienced a pressure pulse that began at the Last Glacial Maximum.
Page 1. Geol. Mag.: page 1 of 19. c Cambridge University Press 2011 1 doi:10.1017/ S0016756811000... more Page 1. Geol. Mag.: page 1 of 19. c Cambridge University Press 2011 1 doi:10.1017/ S0016756811000902 Evidence of crystallization in residual, Cl–F-rich, agpaitic, trachyphonolitic magmas and primitive Mg-rich basalt–trachyphonolite interaction in the lava domes of the ...
During Early Miocene northwestern Sardinia was interested by widespread volcanic activity belongi... more During Early Miocene northwestern Sardinia was interested by widespread volcanic activity belonging to the calcalkaline to high-K calcalkaline "orogenic" Sardinian cycle. The peak of activity is recorded in the ~ 22-18 Ma time span and it is mostly concentrated along the Fossa Sarda graben, an Oligo-Miocene rift system cutting the western Sardinia from north to south. The northwestern Sardinia volcanic rocks crop out in the districts of Bosa-Alghero, Anglona, Logudoro, Mulargia-Macomer and Ottana graben, ranging in composition from rare high alumina basalt lavas to rhyolitic ignimbrites (welded and unwelded) and lava flows, through basaltic andesites, andesites and dacitic domes, with the most evolved rocks (dacites and rhyolites) being volumetrically predominant.
Two stratigraphic sections (Palazzo Reale and Castel Nuovo), found in Naples during archaeologica... more Two stratigraphic sections (Palazzo Reale and Castel Nuovo), found in Naples during archaeological excavations, were investigated from the geochemical and volcanological points of view.
Abstract Petrographical, geochemical and mineralogical analyses have been performed on metabasalt... more Abstract Petrographical, geochemical and mineralogical analyses have been performed on metabasalt samples collected in middle triassic to middle miocene sediments from Campanian and Lucan Apennines. These sediments have been referred (Carta Tettonica ...
Detailed stratigraphical, archaeological, micropalaeontological, archaeometrical and petrochemica... more Detailed stratigraphical, archaeological, micropalaeontological, archaeometrical and petrochemical analyses of samples from trenches and boreholes at insula of Casti Amanti, in Pompeii, allowed a faithful reconstruction of the recent environmental evolution of the site. The present data clearly indicate the alternation of both subaerial and shallow marine conditions during Holocene times. Taking into account the relative local sea level variations, a~30 m ground uplift event in the last 6 kyr (with an average vertical uplift rate of~5 mm/yr) was inferred for the first time.
The Cretaceous flood basalts of northern Madagascar range in composition from picritic basalt to ... more The Cretaceous flood basalts of northern Madagascar range in composition from picritic basalt to basaltic andesite with a serial affinity ranging from tholeiitic to slightly alkaline. Rare, more evolved rocks are represented by peraluminous rhyodacites and peralkaline rhyolites. The intrusive complexes have a large range of lithologies, from ultramafic (dunites, wehrlites, clinopyroxenites) to felsic (leucogabbros, syenites). We report here the chemical composition of olivine, Ca-rich and Capoor pyroxene, feldspar, Fe-Cr-Ti oxide, amphibole, glass and accessory phases; the significance of their variations for what concerns geothermobarometry and regional chemical correlations is also discussed.
L ORENZO FEDELE, VINCENZO MORRA, ANNAMARIA PERROTTA, CLAUDIO SCARPATI stratifi cata per densità. ... more L ORENZO FEDELE, VINCENZO MORRA, ANNAMARIA PERROTTA, CLAUDIO SCARPATI stratifi cata per densità. L'esistenza di simili strutture è stata già in precedenza proposta da altri autori per altre eruzioni dei Campi Flegrei, e pertanto sembrerebbe che lo sviluppo di tali camere magmatiche costituisca un processo molto ricorrente ed importante nell'ambito dell'evoluzione del sistema magmatico fl egreo.
The Cenozoic ankaratrites of the Alaotra, Takarindoha-Vatomandry and Votovorona (NE Ankaratra) vo... more The Cenozoic ankaratrites of the Alaotra, Takarindoha-Vatomandry and Votovorona (NE Ankaratra) volcanic fields, Madagascar, range from olivine (± monticellite) melilitites, through olivine-melilite nephelinites to olivine (± leucite) nephelinites. The rocks show significant compositional ranges in their coexisting magmatic minerals (olivine-group minerals, melilite, clinopyroxene, nepheline, leucite, Ba-phlogopite, perovskite, ilmenite, spinels, apatite), and evidence of distinct parental magmas, often in different facies of the same vent. Primitive compositions (high Mg#, Cr and Ni concentrations) are found in each volcanic district, and a few lavas contain mantle xenoliths or xenocrysts. The rocks show enrichment in the most strongly incompatible elements (e.g., Ba and Nb up to 200 times primitive mantle, La/Yb n = 24 to 40), with troughs at K and smooth, decreasing patterns towards the least incompatible elements in mantle-normalized diagrams. The Nd-Pb-Sr isotope geochemistry indicates a marked heterogeneity of the mantle sources of the various districts (e.g., 206 Pb/ 204 Pb = 18.68-18.77, 87 Sr/ 86 Sr = 0.704011-0.704207 for the Alaotra-Votovorona districts; 206 Pb/ 204 Pb = 19.04-19.14, 87 Sr/ 86 Sr = 0.703544-0.704017 for the Takarindoha-Vatomandry districts), with significant differences to other Cenozoic mafic volcanic rocks of northern Madagascar. The genesis of the Madagascan ankaratrites is related to rifting events which triggered low-degree partial melting of a garnet peridotite enriched in dolomite and incompatible-element-rich phases, in the lowermost lithosphere. Despite marked geochemical similarities, the source of the Madagascan melilitites bears no isotopic similarity to the HIMU-related sources of melilitites of eastern and southern Africa.
a b s t r a c t The Karoo volcanic sequence in the southern Lebombo monocline in Mozambique conta... more a b s t r a c t The Karoo volcanic sequence in the southern Lebombo monocline in Mozambique contains different silicic units in the form of pyroclastic rocks, and two different basalt types. The silicic units in the lower part of the Lebombo sequence are formed by a lower unit of dacites and rhyolites (67-80 wt.% SiO 2 ) with high Ba (990-2500 ppm), Zr (800-1100 ppm) and Y (130-240 ppm), which are part of the Jozini-Mbuluzi Formation, followed by a second unit, interlayered with the Movene basalts, of high-SiO 2 rhyolites (76-78 wt.%; the Sica Beds Formation), with low Sr (19-54 ppm), Zr (340-480 ppm) and Ba (330-850 ppm) plus rare quartz-trachytes (64-66 wt.% SiO 2 ), with high Nb and Rb contents (240-250 and 370-381 ppm, respectively), and relatively low Zr (450-460 ppm). The mafic rocks found at the top of the sequence are basalts and ferrobasalts belonging to the Movene Formation. The basalts have roughly flat mantle-normalized incompatible element patterns, with abundances of the most incompatible elements not higher than 25 times primitive mantle. The ferrobasalt has TiO 2 $ 4.7 wt.%, Fe 2 O 3t = 16 wt.%, and high Y (100 ppm), Zr (420 ppm) and Ba (1000 ppm). The Movene basalts have initial (at 180 Ma) 87 Sr/ 86 Sr = 0.7052-0.7054 and 143 Nd/ 144 Nd = 0.51232, and the Movene ferrobasalt has even lower 87
Trace element partition coefficients between clinopyroxenes and associated glassy matrix ( Cpx/L ... more Trace element partition coefficients between clinopyroxenes and associated glassy matrix ( Cpx/L D) have been determined for 13 REE, HFSE 4?,5? , U, Th, Sr, Pb, Sc and V from combined LA-ICP-MS/EMP analyses in selected trachytes and trachyphonolites from Campi Flegrei. Composition of clinopyroxene and glass is pretty homogeneous in the trachyphonolites, pointing to an overall attainment of the equilibrium conditions. In trachytes, conversely, phases show some compositional heterogeneity (due to the presence of clinopyroxene xenocrysts) that requested a more careful petrographic and geochemical inspection of the samples to assess the equilibrium clinopyroxene composition. In the trachyte clinopyroxenes, REE are compatible from Nd to Lu ( Cpx/L D up to 2.9), like Y, Ti, Sc and V. The Cpx/L D for Eu is lower than those of the adjacent REE, highlighting Eu 2? contribution. High D values are also shown by U, Th, Pb, Zr, Hf, Nb and Ta relatively to basaltic and andesitic systems, whereas the D Sr is roughly similar to that found for less evolved magmas. Trachyphonolites are characterized by an overall decrease of the Cpx/L D for highly-charged cations (with the exception of V), and by a slight increase of D Sr . REE are still compatible from Nd to Lu ( Cpx/L D up to 2.1), like Ti, Y, Sc and V. This variation is also predicted for REE and Y by models based on the elastic strain theory, being consistent with the slightly lower polymerization degree estimated for the trachyphonolites. However, the observed Cpx/L D (REE,Y) are matched by the modelled ones only considering very low T (B825°C), which are believed unlikely. This mismatch cannot be attributed to effects induced by the water-rich composition of the trachytetrachyphonolite suite, since they would lower the observed Cpx/L D (REE,Y) . Moreover, the anomalous inflections of measured Cpx/L D for HREE suggests some crystal-chemical control, such as the entrance of these elements in a site distinct from M2. It is concluded that the large Cpx/L D determined for trachytes and trachyphonolites are likely induced by hitherto unconstrained changes of the Z 3? activities related to the composition of melt and/or solid. All these considerations strongly highlight the importance of a direct characterization of trace element partitioning in natural samples from magmatic systems poorly characterized by experimental studies.
Abstract During the Oligo-Miocene, the Island of Sardinia was covered by the products of volumino... more Abstract During the Oligo-Miocene, the Island of Sardinia was covered by the products of voluminous magmatic activity, with a typical subduction-related signature. The mafic rocks of the Montresta (north) and Arcuentu (south) volcanic districts include primitive high MgO ...
Samples of table and cooking ware, dating back to the Byzantine period of the ancient Greek colon... more Samples of table and cooking ware, dating back to the Byzantine period of the ancient Greek colony of Cuma, were analysed by optical microscopy, X-ray diffraction, X-ray fluorescence and scanning electron microscopy, in order to reconstruct the main technological properties of these manufactures. The comparison of minero-petrographical data from these samples with those of some kiln wastes allowed us to hypothesize a local manufacture for most of the investigated specimens and to confirm the relative reference groups. A restricted number of samples did not link with the main groups, indicating a regional (or maybe extra-regional) production, in agreement with the widespread circulation of this high-medieval ceramic production in southern Italy.
Late Miocene basanites of Nosy Be and Nosy Sakatia islands (Nosy Be Archipelago, northern Madagas... more Late Miocene basanites of Nosy Be and Nosy Sakatia islands (Nosy Be Archipelago, northern Madagascar) carry spinel-facies anhydrous ultramafic xenoliths (lherzolites, harzburgites and wehrlites). Geothermobarometric estimates indicate that these xenoliths derive from shallow mantle depths of 35e40 km, with those from Nosy Be island showing equilibration T (averages in the range of 945e985 C) lower than the Nosy Sakatia analogues (averages ranging from 1010 to 1110 C). One Nosy Sakatia mantle xenolith exhibits relatively fertile lherzolite composition, with trace and major element mineral chemistry consistent with a residual character after low degrees (1e2%) of mafic melt extraction. We interpret this composition as that resembling a depleted mantle (DM)-like lithospheric composition before metasomatic overprints. The other lherzolites and harzburgites display petrochemical characters consistent with variable extent of partial melting (up to 18%), associated with pronounced metasomatic overprints caused by migrating melts, as highlighted by enrichments in highly incompatible trace elements (e.g. light rare earth elements, LREE and Sr), together with the abundant occurrence of wehrlitic lithologies.
Journal of Archaeological Science, Volume 40, Issue 2, February 2013, Pages 810-826, Jan 1, 2012
The Via Lepanto site is one of the best examples showing how the Vesuvian region was partially re... more The Via Lepanto site is one of the best examples showing how the Vesuvian region was partially reconstructed and earlier re-occupied after Vesuvius's eruption in the year 79 AD. The large amount of ceramic finds illustrates the typology in use in this area during the IV and V century AD. Analyses were focused on table and cooking ware productions. Archaeometric data were obtained using chemical and minero-petrographical methods (OM, XRD, XRF and SEM). Grain size measurements using Image Analyses on thin sections and a geochemical comparison with clayey deposits outcropping in the Campania region permitted the identification of the raw materials used for these pottery productions. XRD and SEM completed the data set, establishing the protocols used for pottery production in the Pompeii area during Late Roman period. The Via Lepanto site was part of an exchange network of markets with a periodic frequency, where locally produced and imported pottery was sold, indicating a flourishing network of exchanges spanning short, medium and long distances.► Via Lepanto site is an examples testifying the early reconstruction and occupation of Vesuvian region after 79 AD eruption. ► Via Lepanto site was a part of a Late Roman exchange network, here pottery was individually distributed. ► Potters exploited low-CaO clays mixed with selected volcanics to produce high quality ceramics. ► Use of different protocols aimed at achieving the same product with different quality and costs.
This study deals with the characterization of ancient seawater concretes from the Roman harbour o... more This study deals with the characterization of ancient seawater concretes from the Roman harbour of Soli-Pompeiopolis, 1 st century B.C., at Mersin in Turkey, drilled by the ROMACONS (Roman Maritime Concrete Study) team in 2009. This research activity was performed in collaboration with the Laboratories Department of CTG Italcementi Group and the Earth Sciences Department of the University "Federico II" of Naples. Results confirmed that the Roman engineers extensively used coarse tuff aggregate, lime hydrated in seawater, and pozzolanic volcanic fine sand, the so-called pulvis puteolanus of Vitruvius's treatise De Architectura (1 st century B.C.). The typical mineralogical association of phillipsite > chabazite > analcime, in particular points out the provenance for the tuff aggregate from the Yellow Neapolitan Tuff (NYT) formation, which is connected to the Campi Flegrei volcanic activity, dated back to 15.000 years ago. As far as the fine pozzolanic sand, of which just some scoria relics have been observed, can be ascribed to the same formation, or, probably, to the pozzolan stricto sensu pyroclastic flow from the Campi Flegrei area, as well. EDS microanalyses of different phillipsite crystals showed that the content of major alkaline and alkaline-earth metals was very close to those of phillipsite crystals from NYT, with K higher than Na and Ca, as previously reported in the literature. This fact clearly attests that zeolites were not involved in cation exchange processes within the seawater, despite of their long time curingapproximately two thousand years -in the marine environment.
Detailed micropalaeontological and petrochemical analyses of rock samples from two boreholes dril... more Detailed micropalaeontological and petrochemical analyses of rock samples from two boreholes drilled at the archaeological excavations of Herculaneum,~7 km west of the Somma-Vesuvius crater, allowed reconstruction of the Late Quaternary palaeoenvironmental evolution of the site. The data provide clear evidence for ground uplift movements involving the studied area. The Holocenic sedimentary sequence on which the archaeological remains of Herculaneum rest has risen several meters at an average rate of~4 mm/yr. The uplift has involved the western apron of the volcano and the Sebeto-Volla Plain, a populous area including the eastern suburbs of Naples. This is consistent with earlier evidence for similar uplift for the areas of Pompeii and Sarno valley (SE of the volcano) and the Somma-Vesuvius eastern apron. An axisimmetric deep source of strain is considered responsible for the long-term uplift affecting the whole Somma-Vesuvius edifice. The deformation pattern can be modeled as a single pressure source, sited in the lower crust and surrounded by a shell of Maxwell viscoelastic medium, which experienced a pressure pulse that began at the Last Glacial Maximum.
Page 1. Geol. Mag.: page 1 of 19. c Cambridge University Press 2011 1 doi:10.1017/ S0016756811000... more Page 1. Geol. Mag.: page 1 of 19. c Cambridge University Press 2011 1 doi:10.1017/ S0016756811000902 Evidence of crystallization in residual, Cl–F-rich, agpaitic, trachyphonolitic magmas and primitive Mg-rich basalt–trachyphonolite interaction in the lava domes of the ...
During Early Miocene northwestern Sardinia was interested by widespread volcanic activity belongi... more During Early Miocene northwestern Sardinia was interested by widespread volcanic activity belonging to the calcalkaline to high-K calcalkaline "orogenic" Sardinian cycle. The peak of activity is recorded in the ~ 22-18 Ma time span and it is mostly concentrated along the Fossa Sarda graben, an Oligo-Miocene rift system cutting the western Sardinia from north to south. The northwestern Sardinia volcanic rocks crop out in the districts of Bosa-Alghero, Anglona, Logudoro, Mulargia-Macomer and Ottana graben, ranging in composition from rare high alumina basalt lavas to rhyolitic ignimbrites (welded and unwelded) and lava flows, through basaltic andesites, andesites and dacitic domes, with the most evolved rocks (dacites and rhyolites) being volumetrically predominant.
Two stratigraphic sections (Palazzo Reale and Castel Nuovo), found in Naples during archaeologica... more Two stratigraphic sections (Palazzo Reale and Castel Nuovo), found in Naples during archaeological excavations, were investigated from the geochemical and volcanological points of view.
Abstract Petrographical, geochemical and mineralogical analyses have been performed on metabasalt... more Abstract Petrographical, geochemical and mineralogical analyses have been performed on metabasalt samples collected in middle triassic to middle miocene sediments from Campanian and Lucan Apennines. These sediments have been referred (Carta Tettonica ...
Detailed stratigraphical, archaeological, micropalaeontological, archaeometrical and petrochemica... more Detailed stratigraphical, archaeological, micropalaeontological, archaeometrical and petrochemical analyses of samples from trenches and boreholes at insula of Casti Amanti, in Pompeii, allowed a faithful reconstruction of the recent environmental evolution of the site. The present data clearly indicate the alternation of both subaerial and shallow marine conditions during Holocene times. Taking into account the relative local sea level variations, a~30 m ground uplift event in the last 6 kyr (with an average vertical uplift rate of~5 mm/yr) was inferred for the first time.
The Cretaceous flood basalts of northern Madagascar range in composition from picritic basalt to ... more The Cretaceous flood basalts of northern Madagascar range in composition from picritic basalt to basaltic andesite with a serial affinity ranging from tholeiitic to slightly alkaline. Rare, more evolved rocks are represented by peraluminous rhyodacites and peralkaline rhyolites. The intrusive complexes have a large range of lithologies, from ultramafic (dunites, wehrlites, clinopyroxenites) to felsic (leucogabbros, syenites). We report here the chemical composition of olivine, Ca-rich and Capoor pyroxene, feldspar, Fe-Cr-Ti oxide, amphibole, glass and accessory phases; the significance of their variations for what concerns geothermobarometry and regional chemical correlations is also discussed.
L ORENZO FEDELE, VINCENZO MORRA, ANNAMARIA PERROTTA, CLAUDIO SCARPATI stratifi cata per densità. ... more L ORENZO FEDELE, VINCENZO MORRA, ANNAMARIA PERROTTA, CLAUDIO SCARPATI stratifi cata per densità. L'esistenza di simili strutture è stata già in precedenza proposta da altri autori per altre eruzioni dei Campi Flegrei, e pertanto sembrerebbe che lo sviluppo di tali camere magmatiche costituisca un processo molto ricorrente ed importante nell'ambito dell'evoluzione del sistema magmatico fl egreo.
The Cenozoic ankaratrites of the Alaotra, Takarindoha-Vatomandry and Votovorona (NE Ankaratra) vo... more The Cenozoic ankaratrites of the Alaotra, Takarindoha-Vatomandry and Votovorona (NE Ankaratra) volcanic fields, Madagascar, range from olivine (± monticellite) melilitites, through olivine-melilite nephelinites to olivine (± leucite) nephelinites. The rocks show significant compositional ranges in their coexisting magmatic minerals (olivine-group minerals, melilite, clinopyroxene, nepheline, leucite, Ba-phlogopite, perovskite, ilmenite, spinels, apatite), and evidence of distinct parental magmas, often in different facies of the same vent. Primitive compositions (high Mg#, Cr and Ni concentrations) are found in each volcanic district, and a few lavas contain mantle xenoliths or xenocrysts. The rocks show enrichment in the most strongly incompatible elements (e.g., Ba and Nb up to 200 times primitive mantle, La/Yb n = 24 to 40), with troughs at K and smooth, decreasing patterns towards the least incompatible elements in mantle-normalized diagrams. The Nd-Pb-Sr isotope geochemistry indicates a marked heterogeneity of the mantle sources of the various districts (e.g., 206 Pb/ 204 Pb = 18.68-18.77, 87 Sr/ 86 Sr = 0.704011-0.704207 for the Alaotra-Votovorona districts; 206 Pb/ 204 Pb = 19.04-19.14, 87 Sr/ 86 Sr = 0.703544-0.704017 for the Takarindoha-Vatomandry districts), with significant differences to other Cenozoic mafic volcanic rocks of northern Madagascar. The genesis of the Madagascan ankaratrites is related to rifting events which triggered low-degree partial melting of a garnet peridotite enriched in dolomite and incompatible-element-rich phases, in the lowermost lithosphere. Despite marked geochemical similarities, the source of the Madagascan melilitites bears no isotopic similarity to the HIMU-related sources of melilitites of eastern and southern Africa.
a b s t r a c t The Karoo volcanic sequence in the southern Lebombo monocline in Mozambique conta... more a b s t r a c t The Karoo volcanic sequence in the southern Lebombo monocline in Mozambique contains different silicic units in the form of pyroclastic rocks, and two different basalt types. The silicic units in the lower part of the Lebombo sequence are formed by a lower unit of dacites and rhyolites (67-80 wt.% SiO 2 ) with high Ba (990-2500 ppm), Zr (800-1100 ppm) and Y (130-240 ppm), which are part of the Jozini-Mbuluzi Formation, followed by a second unit, interlayered with the Movene basalts, of high-SiO 2 rhyolites (76-78 wt.%; the Sica Beds Formation), with low Sr (19-54 ppm), Zr (340-480 ppm) and Ba (330-850 ppm) plus rare quartz-trachytes (64-66 wt.% SiO 2 ), with high Nb and Rb contents (240-250 and 370-381 ppm, respectively), and relatively low Zr (450-460 ppm). The mafic rocks found at the top of the sequence are basalts and ferrobasalts belonging to the Movene Formation. The basalts have roughly flat mantle-normalized incompatible element patterns, with abundances of the most incompatible elements not higher than 25 times primitive mantle. The ferrobasalt has TiO 2 $ 4.7 wt.%, Fe 2 O 3t = 16 wt.%, and high Y (100 ppm), Zr (420 ppm) and Ba (1000 ppm). The Movene basalts have initial (at 180 Ma) 87 Sr/ 86 Sr = 0.7052-0.7054 and 143 Nd/ 144 Nd = 0.51232, and the Movene ferrobasalt has even lower 87
Trace element partition coefficients between clinopyroxenes and associated glassy matrix ( Cpx/L ... more Trace element partition coefficients between clinopyroxenes and associated glassy matrix ( Cpx/L D) have been determined for 13 REE, HFSE 4?,5? , U, Th, Sr, Pb, Sc and V from combined LA-ICP-MS/EMP analyses in selected trachytes and trachyphonolites from Campi Flegrei. Composition of clinopyroxene and glass is pretty homogeneous in the trachyphonolites, pointing to an overall attainment of the equilibrium conditions. In trachytes, conversely, phases show some compositional heterogeneity (due to the presence of clinopyroxene xenocrysts) that requested a more careful petrographic and geochemical inspection of the samples to assess the equilibrium clinopyroxene composition. In the trachyte clinopyroxenes, REE are compatible from Nd to Lu ( Cpx/L D up to 2.9), like Y, Ti, Sc and V. The Cpx/L D for Eu is lower than those of the adjacent REE, highlighting Eu 2? contribution. High D values are also shown by U, Th, Pb, Zr, Hf, Nb and Ta relatively to basaltic and andesitic systems, whereas the D Sr is roughly similar to that found for less evolved magmas. Trachyphonolites are characterized by an overall decrease of the Cpx/L D for highly-charged cations (with the exception of V), and by a slight increase of D Sr . REE are still compatible from Nd to Lu ( Cpx/L D up to 2.1), like Ti, Y, Sc and V. This variation is also predicted for REE and Y by models based on the elastic strain theory, being consistent with the slightly lower polymerization degree estimated for the trachyphonolites. However, the observed Cpx/L D (REE,Y) are matched by the modelled ones only considering very low T (B825°C), which are believed unlikely. This mismatch cannot be attributed to effects induced by the water-rich composition of the trachytetrachyphonolite suite, since they would lower the observed Cpx/L D (REE,Y) . Moreover, the anomalous inflections of measured Cpx/L D for HREE suggests some crystal-chemical control, such as the entrance of these elements in a site distinct from M2. It is concluded that the large Cpx/L D determined for trachytes and trachyphonolites are likely induced by hitherto unconstrained changes of the Z 3? activities related to the composition of melt and/or solid. All these considerations strongly highlight the importance of a direct characterization of trace element partitioning in natural samples from magmatic systems poorly characterized by experimental studies.
Abstract During the Oligo-Miocene, the Island of Sardinia was covered by the products of volumino... more Abstract During the Oligo-Miocene, the Island of Sardinia was covered by the products of voluminous magmatic activity, with a typical subduction-related signature. The mafic rocks of the Montresta (north) and Arcuentu (south) volcanic districts include primitive high MgO ...
Colorimetry and accelerated aging tests were performed on ceramics prepared using two clays from ... more Colorimetry and accelerated aging tests were performed on ceramics prepared using two clays from the Bay of Naples (Ischia and Sorrento Peninsula). Visible-near infrared spectroscopy was applied in order to acquire further information on color and composition of ceramics. Different mix designs and firing dynamics were adopted in order to provide information on the control of aesthetic features of ancient building ceramics. Color depends on firing temperature and physical-chemical composition of the raw materials. Low-CaO concentration provided a more intense reddish hue at high temperatures (over 950 °C). Black core developed in high-CaO ceramic samples fired at low temperatures, except for those containing high temper amounts. Salt crystallization test showed that high-CaO ceramics are more durable starting from relatively low firing temperatures (over 850 °C).
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Color depends on firing temperature and physical-chemical composition of the raw materials. Low-CaO concentration provided a more intense reddish hue at high temperatures (over 950 °C). Black core developed in high-CaO ceramic samples fired at low temperatures, except for those containing high temper amounts.
Salt crystallization test showed that high-CaO ceramics are more durable starting from relatively low firing temperatures (over 850 °C).