An accurate record of preindustrial (pre-1900 CE) sea level is necessary to contextualize modern ... more An accurate record of preindustrial (pre-1900 CE) sea level is necessary to contextualize modern global mean sea level (GMSL) rise with respect to natural variability. Precisely dated phreatic overgrowths on speleothems (POS) provide detailed rates of Late Holocene sea-level rise in Mallorca. Statistical analysis indicates that sea level rose locally by 0.12 to 0.31 m (95% confidence) from 3.26 to 2.84 thousand years (ka) ago (2σ) and remained within 0.08 m (95% confidence) of preindustrial levels from 2.84 ka to 1900 CE. This sea-level history is consistent with glacial isostatic adjustment models adopting relatively weak upper mantle viscosities of ~10 20 Pa s. There is virtual certainty (>0.999 probability) that the average GMSL rise since 1900 CE has exceeded even the high average rate of sea-level rise between 3.26 and 2.84 ka inferred from the POS record. We conclude that modern GMSL rise is anomalous relative to any natural variability in ice volumes over the past 4000 years.
<p>The Vinschgau Shear Zone (VSZ) is an E-W striking ductile shear zone dev... more <p>The Vinschgau Shear Zone (VSZ) is an E-W striking ductile shear zone developed within the central-eastern Austroalpine domain. Along the VSZ the Ötztal-Stubai nappe with an amphibolite facies Alpine metamorphism overthrusted the Campo nappe (and respectively the Engadine Dolomites) characterized by low-to-medium metamorphic conditions (Schmid and Haas, 1989). In the eastern part the shear zone involves also the Texel Unit at the base of the Ötztal nappe. Foliation gently dips (20°-30°) northward and lineation constantly strikes E-W, with kinematic indicators that point to a top-to-NW sense of shear. The VSZ, deepening to the E, developed mostly under amphibolite to greenschist-facies conditions. A remarkable variation in finite strain along its length can be observed: lenses of protomylonites are bounded by deeply sheared ultramylonites, mylonites and phyllonites, these occurring in the western part of the VSZ.</p><p>In order to fully assess the evolution of the VSZ a multidisciplinary approach based on structural and petrochronological analyses has been carried out on three representative transects of the shear zone from W to E: Eyrs, Schlanders and Juval transects.</p><p>Our fieldwork based analyses suggest that the dip of mylonitic foliation increases from W to E and the lineation dips towards the W in Schlanders and Juval, whereas towards the E in Eyrs, probably due to a folding event related to Cenozoic shortening (Pomella et al., 2016).</p><p>Chemical and microstructural analyses suggest that deformation temperatures of 350-400 °C have been reached during shearing, as testified by Ti content in biotite and by bulging and subgrain rotation as dominant recrystallization mechanisms in quartz.</p><p>Timing of deformation along the VSZ has been constrained through <sup>40</sup>Ar/<sup>39</sup>Ar dating of syn-shearing micas confirming previous geochronological data of Thöni, 1981, which reveal a Late Cretaceous age of the VSZ mylonites. A systematic younging trend of deformation towards the central part of the shear zone has been observed in the studied area. Vorticity analyses, both through shear bands and rigid porphyroclasts methods, show a clear decrease in simple shear component correlated to the younging direction of mica ages (i.e. towards the core of the shear zone). This evolution is clearly consistent with Type 2 evolution of Fossen and Cavalcante (2017), where strain localizes into the core of the shear zone during deformation.</p><p>Our data confirm the age of the VSZ only supposed on the base of indirect observations  and demonstrate that the Austroalpine domain was severely affected by W-NW verging thrust stacking much time before the Adria-Europe continental collision.</p><p> </p><p><em>References</em></p><p>Fossen, H. & Cavalcante, G.C.G., (2017) - <em>Shear zones–A review</em>. Earth-Science Reviews, <strong>171</strong>, 434-455.</p><p>Pomella, H., Flöss, D., Speckbacher, R., Tropper, P., & Fügenschuh, B. (2016) - <em>The western end of the Eoalpine High‐Pressure Belt (Texel unit, South Tyrol/Italy).</em> Terra Nova, <strong>28(1)</strong>, 60-69.</p><p>Schmid, S.M., & Haas, R. (1989) - <em>Transition from near‐surface thrusting to Intrabasement Decollement, Schlinig Thrust, eastern Alps</em>. Tectonics, <strong>8(4)</strong>, 697-718.</p><p>Thöni, M. (1981):<em> Degree and evolution of the Alpine metamorphism in the Austroalpine unit W of the Hohe </em><em>Tauern in the light of K/Ar and Rb/Sr age determinations on micas. - </em>Jb. Geol. B.A. 124, 1: 111-174.</p>
ABSTRACTThe Las Canadas Caldera corresponds to a volcanic caldera formed after a long period of e... more ABSTRACTThe Las Canadas Caldera corresponds to a volcanic caldera formed after a long period of explosive activity. The structural and lithological variations which can be observed in the caldera wall make clear the complexity of the original Las Canadas Edifice in which different eruptive centres existed. The stratigraphic and structural reconstruction of the Las Canadas Caldera indicates that the Diego Hernández wall, located at the eastern side of the caldera wall, comprises the youngest pre‐caldera deposits. Determination of their K‐Ar ages has provided the maximum age for the formation of the Las Canadas caldera. The results are internally consistent with stratigraphic relationships and allow two pre‐caldera volcanic cycles in the Diego Hernández wall to be differentiated in accordance with geological evidence. The first cycle shows imprecise age limits. The second cycle ranges from 0.35 to 0.17 Ma. This upper pre‐caldera age suggests that the Las Canadas caldera and the Teide‐...
... in sequences, because with the ages obtained, the evolution of the Diego Hernandez Formation ... more ... in sequences, because with the ages obtained, the evolution of the Diego Hernandez Formation is ... Giiimar valley) to find correlation levels between these areas and Diego Hernández Formation to ... Fuster, JM, Araña, V., Brandie, JL, Alonso, U. and Aparicio, A. (1968) Geología y ...
The Southern Tuscanv-Norrhern Latium area has been affected by a complex geological evolution dur... more The Southern Tuscanv-Norrhern Latium area has been affected by a complex geological evolution during Neogene times. Starting from Miocene, several subsidence episodes, alternated with periods of differential uplifting, brought to the development and closure of some marine and continental basins. Since Pliocene, an intense and widespread magmatic activity .has also interested this region, characterized by a space-time eastward migration of the magmatic centers and by a strong variation in time of the magma composition. Very high heat flow values are observed over the whole area, which represents one of the most interesting geothermal Italian regions. In this paper we present an attempt to combine the stratigraphical, geochronological, volcanological and geophyslcal data in an unifying picture of the regional structural evolution, and of the relationships between Neogene sedimentary basins, subsidence and uplift phases, and rnagmatic activity. New biostratigraphic datings of the Pliocene successions have been performed, together with several radiometric, K/Ar and 39Ar/40Ar, datings of Plio-Pleistocene volcanic, from samples of outcropping and subsurface sequences. The geothermal wells drilled by ENEL, and by J.V. AGIP-ENEL, integrated by results from surface survey’s, have permitted to define the present thickness of Pliocene sediments, the geometry of the bottom surface of the Plistocene volcanic cover, and the map of the present altitude of Plio-Pleistocene marine sediments reflecting the sum of the total vertical movements. The chemical composition of Pleistocene volcanic complexes of the Northern Roman Magmatic Province has been investigated, tryng to delineate its temporal evolution. The subsurface geoogy of the area has been finaly analyzed in the light of drilling results and of gravimetric and thermal data. Since Pliocene, a very intense extensional tectonics affects The investigated area. Two Pliocene sedimentary cycles can be distinguished, leading to the deposition of sedimentary successions up to two thousands meters thick. Subsidence movements appear more intense in a relatively narrow, NW-SE trending belt close to the Apennine range, while the Tyrrhenian side suffers a less developed subsidence witnessed by the deposition of several discontinuous, not very thick sedimentary piles. Pliocene magmatic activity sets up just on the Tyrrhenian border, with the emplacement of several intrusive bodies and the extrusion of prevalently acid crustal anatectic magmas and of minor subcrustal mafic melts. We suggest taht the different structure presented by the western side of the investigated area could reflect a primary role of a diffuse intrusive process in this area. Pliocene sedimentation stops in the whole area around 2 Ma b.p.; marine sedimentation resumes during lower Pleistocene, inside more eastern basins. The associated volcanic axis (defined by the Radicofani, Torre Alfina, Monti Cimini alignment) assumes a more eastern position than the preceding one, and is characterized by orenditic transitional to potassic magmas. During Pleistocene, the regional stress field undergoes a strong variation, connected to the opening of the Marsili basin in the Southern Tyrrhenian Sea. Positive vertical movements seem to prevail since Middle-Upper Pleistocene, probably linked to the strong isostatic uplift of the Apennine chain. The present geometry shown by the Neogene sediments mainly reflects this uplift phase. The potassic vo1canism of Roman Magmatic Province starts in the wholele region (and probably also further South) around 0.6 Ma b.p., showing a strict relationship with the new prevailing tectonic regime, this magmatism being distributed along the disengaging zone between the uplifting chain and the subsiding Tyrrhenian basins. A further pulse of magmatic activity occurs around 0.4-0.3 Ma b.p., wlth a very intense volcanicity affecting all the main volcanic complexes, accompanied by a maximum in the compositional spreading o f the erupted products. The time variations of magma composition and the tectonic evolution of the area, shoving a progressive deepening of magmatic sources associated to a general decreasing of extensional tectonics, seem to be strongly related. In this picture, the present heat flow anomaly would represent the residual of the thermal anomaly associated with the Neogene extensional setting
Abstract In solid-state physics and materials science Fick's Law diffusion is a well-establis... more Abstract In solid-state physics and materials science Fick's Law diffusion is a well-established process. In Earth Sciences, laboratory experiments on garnet, olivine and other anhydrous minerals do document the intra-grain element concentration gradients that follow the functional form required by Fick's Law. Natural gradients in minerals have rarely been analyzed with the necessary spatial resolution. Reports of actual observations of diffusion profiles of element concentrations are rare in the literature, and diffusion profiles of isotope ratios in minerals used for geochronology are absent. An in-depth re-examination of recent and older literature suggests that isotope transport in minerals is instead often dominated by fluid-mediated retrogression reactions. Imaging microtextures by cathodoluminescence or back-scattered electron maps provides ubiquitous evidence of patchy or dendritic replacement structures, which correspond to multiple growth stages, in zircon, monazite, muscovite, biotite, K-feldspar, etc. The U–Pb, K–Ar and Rb–Sr systems in these partly retrogressed minerals show isotopic inheritance (that survived the retrograde reactions at least in part) in close correspondence with the petrologic relicts. Depending on the relative rates of the petrological processes relevant for isotope transport, geochronometers can be grouped in two classes: Class I (thermochronometers) are those for which the diffusivity of a given radiogenic isotope is faster than the rate of dissolution and/or reprecipitation, and Class II (hygrochronometers) are those for which aqueous dissolution/reprecipitation is the faster process. All of the abovementioned geochronometers, for which patchy/dendritic textures formed by diachronous mineral generations and isotopic inheritance were observed, must be assigned to Class II. Class II samples in petrologic equilibrium can (but need not) record purely thermal diffusion of daughter isotopes. The isotope record of Class II minerals in petrologic disequilibrium, being controlled by inheritance and retrogression reactions, depends chiefly on the reaction-promoting factors, water activity and strain. The dependence of Class II mineral ages on thermal diffusion is subordinate and never unique.
An accurate record of preindustrial (pre-1900 CE) sea level is necessary to contextualize modern ... more An accurate record of preindustrial (pre-1900 CE) sea level is necessary to contextualize modern global mean sea level (GMSL) rise with respect to natural variability. Precisely dated phreatic overgrowths on speleothems (POS) provide detailed rates of Late Holocene sea-level rise in Mallorca. Statistical analysis indicates that sea level rose locally by 0.12 to 0.31 m (95% confidence) from 3.26 to 2.84 thousand years (ka) ago (2σ) and remained within 0.08 m (95% confidence) of preindustrial levels from 2.84 ka to 1900 CE. This sea-level history is consistent with glacial isostatic adjustment models adopting relatively weak upper mantle viscosities of ~10 20 Pa s. There is virtual certainty (>0.999 probability) that the average GMSL rise since 1900 CE has exceeded even the high average rate of sea-level rise between 3.26 and 2.84 ka inferred from the POS record. We conclude that modern GMSL rise is anomalous relative to any natural variability in ice volumes over the past 4000 years.
<p>The Vinschgau Shear Zone (VSZ) is an E-W striking ductile shear zone dev... more <p>The Vinschgau Shear Zone (VSZ) is an E-W striking ductile shear zone developed within the central-eastern Austroalpine domain. Along the VSZ the Ötztal-Stubai nappe with an amphibolite facies Alpine metamorphism overthrusted the Campo nappe (and respectively the Engadine Dolomites) characterized by low-to-medium metamorphic conditions (Schmid and Haas, 1989). In the eastern part the shear zone involves also the Texel Unit at the base of the Ötztal nappe. Foliation gently dips (20°-30°) northward and lineation constantly strikes E-W, with kinematic indicators that point to a top-to-NW sense of shear. The VSZ, deepening to the E, developed mostly under amphibolite to greenschist-facies conditions. A remarkable variation in finite strain along its length can be observed: lenses of protomylonites are bounded by deeply sheared ultramylonites, mylonites and phyllonites, these occurring in the western part of the VSZ.</p><p>In order to fully assess the evolution of the VSZ a multidisciplinary approach based on structural and petrochronological analyses has been carried out on three representative transects of the shear zone from W to E: Eyrs, Schlanders and Juval transects.</p><p>Our fieldwork based analyses suggest that the dip of mylonitic foliation increases from W to E and the lineation dips towards the W in Schlanders and Juval, whereas towards the E in Eyrs, probably due to a folding event related to Cenozoic shortening (Pomella et al., 2016).</p><p>Chemical and microstructural analyses suggest that deformation temperatures of 350-400 °C have been reached during shearing, as testified by Ti content in biotite and by bulging and subgrain rotation as dominant recrystallization mechanisms in quartz.</p><p>Timing of deformation along the VSZ has been constrained through <sup>40</sup>Ar/<sup>39</sup>Ar dating of syn-shearing micas confirming previous geochronological data of Thöni, 1981, which reveal a Late Cretaceous age of the VSZ mylonites. A systematic younging trend of deformation towards the central part of the shear zone has been observed in the studied area. Vorticity analyses, both through shear bands and rigid porphyroclasts methods, show a clear decrease in simple shear component correlated to the younging direction of mica ages (i.e. towards the core of the shear zone). This evolution is clearly consistent with Type 2 evolution of Fossen and Cavalcante (2017), where strain localizes into the core of the shear zone during deformation.</p><p>Our data confirm the age of the VSZ only supposed on the base of indirect observations  and demonstrate that the Austroalpine domain was severely affected by W-NW verging thrust stacking much time before the Adria-Europe continental collision.</p><p> </p><p><em>References</em></p><p>Fossen, H. & Cavalcante, G.C.G., (2017) - <em>Shear zones–A review</em>. Earth-Science Reviews, <strong>171</strong>, 434-455.</p><p>Pomella, H., Flöss, D., Speckbacher, R., Tropper, P., & Fügenschuh, B. (2016) - <em>The western end of the Eoalpine High‐Pressure Belt (Texel unit, South Tyrol/Italy).</em> Terra Nova, <strong>28(1)</strong>, 60-69.</p><p>Schmid, S.M., & Haas, R. (1989) - <em>Transition from near‐surface thrusting to Intrabasement Decollement, Schlinig Thrust, eastern Alps</em>. Tectonics, <strong>8(4)</strong>, 697-718.</p><p>Thöni, M. (1981):<em> Degree and evolution of the Alpine metamorphism in the Austroalpine unit W of the Hohe </em><em>Tauern in the light of K/Ar and Rb/Sr age determinations on micas. - </em>Jb. Geol. B.A. 124, 1: 111-174.</p>
ABSTRACTThe Las Canadas Caldera corresponds to a volcanic caldera formed after a long period of e... more ABSTRACTThe Las Canadas Caldera corresponds to a volcanic caldera formed after a long period of explosive activity. The structural and lithological variations which can be observed in the caldera wall make clear the complexity of the original Las Canadas Edifice in which different eruptive centres existed. The stratigraphic and structural reconstruction of the Las Canadas Caldera indicates that the Diego Hernández wall, located at the eastern side of the caldera wall, comprises the youngest pre‐caldera deposits. Determination of their K‐Ar ages has provided the maximum age for the formation of the Las Canadas caldera. The results are internally consistent with stratigraphic relationships and allow two pre‐caldera volcanic cycles in the Diego Hernández wall to be differentiated in accordance with geological evidence. The first cycle shows imprecise age limits. The second cycle ranges from 0.35 to 0.17 Ma. This upper pre‐caldera age suggests that the Las Canadas caldera and the Teide‐...
... in sequences, because with the ages obtained, the evolution of the Diego Hernandez Formation ... more ... in sequences, because with the ages obtained, the evolution of the Diego Hernandez Formation is ... Giiimar valley) to find correlation levels between these areas and Diego Hernández Formation to ... Fuster, JM, Araña, V., Brandie, JL, Alonso, U. and Aparicio, A. (1968) Geología y ...
The Southern Tuscanv-Norrhern Latium area has been affected by a complex geological evolution dur... more The Southern Tuscanv-Norrhern Latium area has been affected by a complex geological evolution during Neogene times. Starting from Miocene, several subsidence episodes, alternated with periods of differential uplifting, brought to the development and closure of some marine and continental basins. Since Pliocene, an intense and widespread magmatic activity .has also interested this region, characterized by a space-time eastward migration of the magmatic centers and by a strong variation in time of the magma composition. Very high heat flow values are observed over the whole area, which represents one of the most interesting geothermal Italian regions. In this paper we present an attempt to combine the stratigraphical, geochronological, volcanological and geophyslcal data in an unifying picture of the regional structural evolution, and of the relationships between Neogene sedimentary basins, subsidence and uplift phases, and rnagmatic activity. New biostratigraphic datings of the Pliocene successions have been performed, together with several radiometric, K/Ar and 39Ar/40Ar, datings of Plio-Pleistocene volcanic, from samples of outcropping and subsurface sequences. The geothermal wells drilled by ENEL, and by J.V. AGIP-ENEL, integrated by results from surface survey’s, have permitted to define the present thickness of Pliocene sediments, the geometry of the bottom surface of the Plistocene volcanic cover, and the map of the present altitude of Plio-Pleistocene marine sediments reflecting the sum of the total vertical movements. The chemical composition of Pleistocene volcanic complexes of the Northern Roman Magmatic Province has been investigated, tryng to delineate its temporal evolution. The subsurface geoogy of the area has been finaly analyzed in the light of drilling results and of gravimetric and thermal data. Since Pliocene, a very intense extensional tectonics affects The investigated area. Two Pliocene sedimentary cycles can be distinguished, leading to the deposition of sedimentary successions up to two thousands meters thick. Subsidence movements appear more intense in a relatively narrow, NW-SE trending belt close to the Apennine range, while the Tyrrhenian side suffers a less developed subsidence witnessed by the deposition of several discontinuous, not very thick sedimentary piles. Pliocene magmatic activity sets up just on the Tyrrhenian border, with the emplacement of several intrusive bodies and the extrusion of prevalently acid crustal anatectic magmas and of minor subcrustal mafic melts. We suggest taht the different structure presented by the western side of the investigated area could reflect a primary role of a diffuse intrusive process in this area. Pliocene sedimentation stops in the whole area around 2 Ma b.p.; marine sedimentation resumes during lower Pleistocene, inside more eastern basins. The associated volcanic axis (defined by the Radicofani, Torre Alfina, Monti Cimini alignment) assumes a more eastern position than the preceding one, and is characterized by orenditic transitional to potassic magmas. During Pleistocene, the regional stress field undergoes a strong variation, connected to the opening of the Marsili basin in the Southern Tyrrhenian Sea. Positive vertical movements seem to prevail since Middle-Upper Pleistocene, probably linked to the strong isostatic uplift of the Apennine chain. The present geometry shown by the Neogene sediments mainly reflects this uplift phase. The potassic vo1canism of Roman Magmatic Province starts in the wholele region (and probably also further South) around 0.6 Ma b.p., showing a strict relationship with the new prevailing tectonic regime, this magmatism being distributed along the disengaging zone between the uplifting chain and the subsiding Tyrrhenian basins. A further pulse of magmatic activity occurs around 0.4-0.3 Ma b.p., wlth a very intense volcanicity affecting all the main volcanic complexes, accompanied by a maximum in the compositional spreading o f the erupted products. The time variations of magma composition and the tectonic evolution of the area, shoving a progressive deepening of magmatic sources associated to a general decreasing of extensional tectonics, seem to be strongly related. In this picture, the present heat flow anomaly would represent the residual of the thermal anomaly associated with the Neogene extensional setting
Abstract In solid-state physics and materials science Fick's Law diffusion is a well-establis... more Abstract In solid-state physics and materials science Fick's Law diffusion is a well-established process. In Earth Sciences, laboratory experiments on garnet, olivine and other anhydrous minerals do document the intra-grain element concentration gradients that follow the functional form required by Fick's Law. Natural gradients in minerals have rarely been analyzed with the necessary spatial resolution. Reports of actual observations of diffusion profiles of element concentrations are rare in the literature, and diffusion profiles of isotope ratios in minerals used for geochronology are absent. An in-depth re-examination of recent and older literature suggests that isotope transport in minerals is instead often dominated by fluid-mediated retrogression reactions. Imaging microtextures by cathodoluminescence or back-scattered electron maps provides ubiquitous evidence of patchy or dendritic replacement structures, which correspond to multiple growth stages, in zircon, monazite, muscovite, biotite, K-feldspar, etc. The U–Pb, K–Ar and Rb–Sr systems in these partly retrogressed minerals show isotopic inheritance (that survived the retrograde reactions at least in part) in close correspondence with the petrologic relicts. Depending on the relative rates of the petrological processes relevant for isotope transport, geochronometers can be grouped in two classes: Class I (thermochronometers) are those for which the diffusivity of a given radiogenic isotope is faster than the rate of dissolution and/or reprecipitation, and Class II (hygrochronometers) are those for which aqueous dissolution/reprecipitation is the faster process. All of the abovementioned geochronometers, for which patchy/dendritic textures formed by diachronous mineral generations and isotopic inheritance were observed, must be assigned to Class II. Class II samples in petrologic equilibrium can (but need not) record purely thermal diffusion of daughter isotopes. The isotope record of Class II minerals in petrologic disequilibrium, being controlled by inheritance and retrogression reactions, depends chiefly on the reaction-promoting factors, water activity and strain. The dependence of Class II mineral ages on thermal diffusion is subordinate and never unique.
Alabaster, geologically labelled onyx marble, calcitic-alabaster or travertine, was one of the mo... more Alabaster, geologically labelled onyx marble, calcitic-alabaster or travertine, was one of the most valued ornamental stones in the Roman period. The study of its use, however, remains problematic due to two interrelated issues: the incomplete knowledge of all alabaster sources alongside the shortage of specific studies on their archaeometric characterization and the fact that only a few samples have been analysed and provenanced. While much work has been done over the last decade, including numerous papers presented at ASMOSIA (Barbieri et al. 2002; Bruno 2002; Çolak, Lazzarini 2002; Lazzarini et al. 2012; Herrmann Jr. et al. 2012; Scardozzi 2012; Barker et al. 2018), the establishment of a reliable methodology for provenancing and the collection of detailed quarry data sets are still needed. The on-going project, 'Alabaster:' Quarrying and Trade in the Roman World, seeks to contribute to the discussion by building quarry datasets and promoting novel scientific methods for provenancing alabaster artefacts. For example, previous testing of Egyptian, North African, Turkish, Cretan and Italian alabasters (Antonelli et al. 2010; Barbieri et al. 2002a, 2002b; Çolak, Lazzarini 2002; Lazzarini et al. 2006; 2012; Brilli 2017 et al.) highlighted the importance of strontium-isotope analysis as a method for provenancing calcite-alabaster/travertine. The present authors propose a new methodology based on a quadruple discriminator combining Sr and Pb data, Ba/Mg/Sr element concentration ratios, and oxygen isotope data. The augmentation of quarry datasets to include Pb isotope data as an additional discriminating tool is expected to refine our ability to identify candidate quarries. This paper reports the results of mineropetrographic and isotopic analyses carried out at the Institut für Geologie at the Universität Bern on a total of 14 quarry samples from four quarries obtained from several sources (J. Harrell: Egypt; J. Herrmann Jr.: North Africa; G. Scardozzi: Hierapolis / Golemezli, Turkey) in addition to those collected by the authors (Italy). The results show that the subsamples were heterogeneous, both isotopically and chemically (one contained practically no lead). In fact, the scale of the hetrogeneity (0.5 cm) confirms that the genetic mechanism that creates alabaster out of calcareous sediments is spatially very irregular and very unpredictable. The analysis suggests that samples from quarries are always likely to present heterogeneous results, and thus overlaps between different quarries will be likely. Mapping out the isotopic and compositional fields of each quarry therefore will require dozens of analyses, rather than a few. Analyzing an artefact will also require multiple subsamples, as the possibility of cm-scale heterogeneities requires establishing a separate field for each artefact.
In 2016, a Stollhof-type copper hoard was found during an excavation in Magyaregres, Hungary. It ... more In 2016, a Stollhof-type copper hoard was found during an excavation in Magyaregres, Hungary. It was placed in a cooking pot, and deposited upside down within the boundaries of an Early Copper Age settlement. Similar hoards dating to the end of the 5 th millennium BCE are well-known from Central Europe, however, this hoard represents the only one so far with thoroughly documented finding circumstances. The hoard contained 681 pieces of copper, 264 pieces of stone and a single Spondylus bead, along with 19 pieces of small tubular spiral copper coils, three spiral copper bracelets, and two large, spectacle spiral copper pendants. Until now, information on the provenance of raw materials and how such copper artefacts were manufactured has not been available. The artefacts were studied under optical microscopes to reveal the manufacturing process. Trace elemental composition (HR-ICP-MS) and lead isotope ratios (MC-ICP-MS) were measured to explore the provenance of raw materials. The ornaments were rolled or folded and coiled from thin sheets of copper using fahlore copper probably originating from the Northwestern Carpathians. A complex archaeological approach was employed to reveal the provenance, distribution and the social roles the ornaments could have played in the life of a Copper Age community. Evidence for local metallurgy was lacking in contemporaneous Transdanubian sites, therefore it is likely that the items of the hoard were manufactured closer to the raw material source, prior to being transported to Transdanubia as finished products. The method of deposition implies that such items were associated with special social contexts, represented exceptional values, and the context of deposition was also highly prescribed. The Magyaregres hoard serves as the first firm piece of evidence for the existence of a typologically independent
D. Matetić Poljak and K. Marasović (eds.) Interdisciplinary Studies on Ancient Stones. Proceedings of the XI ASMOSIA International Conference, Split 2015, 2018
A total of 13 thresholds composed of one or more blocks of alabaster (calcitic onyx alabaster) su... more A total of 13 thresholds composed of one or more blocks of alabaster (calcitic onyx alabaster) survive in situ at Villa A at Oplontis. They decorate the elegantly Second-Style painted rooms, such as atrium (5), triclinium (14), salone (15) and cubiculum (11), as well as (surprisingly) some service areas. The thresholds, which belong to Villa A’s original phase of construction in the middle of the first century BC, arguably represent the most spectacular example of alabaster use to survive from the villas and houses preserved by the eruption on Mt. Vesuvius in AD 79. Visual characteristics – dark beige to light gray with wavy patches and no banding, coarse to very coarse compact crystalline calcite – point to a number of potential sources for the alabaster. Due to the difficulty of positive identification via visual analysis, a total of seven samples from six thresholds have been subjected to laboratory analysis with the aim of determining the source of the stone. This article presents the results of the minero-petrographic (XRD and microscopic study of thin section) and isotopic studies (Sr and Pb isotope analyses by mass spectrometry), conducted by LAMA (Laboratorio di Analisi dei Materiali Antichi) and the Institut für Geologie at the Universität Bern, respectively, that were carried out on the alabaster thresholds of Villa A, Oplontis. While a number of quarry sources can now be ruled out – Egypt, Circeo (province of Latina, Italy), Jano di Montaione (province of Florence, Italy), Castelnuovo dell'Abate (province of Siena, Italy) and Hierapolis (now Pamukkale (province of Denizli in Turkey)) – the actual quarry source still remains uncertain. The results reiterate the need for a thorough investigation and re-examination of the sources of alabaster used in the Roman period in order to provide a comprehensive database of the alabaster quarries that may have been operating during Antiquity.
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