The deposit of 134 metal socketed arrowheads from the Late Bronze Age settlement in Wrocław-Widaw... more The deposit of 134 metal socketed arrowheads from the Late Bronze Age settlement in Wrocław-Widawa in SW Poland was subject of multi-faceted analyses. The composition and structure of the metal (XRF, SEM, EDS) was examined in samples from 15 objects, while the whole collection underwent macro-and micro-observations of production traces and use-wear. The bulk metal XRF analyses demonstrated that the arrowheads were made of tin bronze (Sn 3.0-11.6% wt). In terms of composition and structure, the samples represented four basic structural types: (1) homogeneous, (2) diffuse dendritic with two phases, (3) well-defined cored dendritic with phases, but with subordinate volume of eutectoid tin-rich phase and (4) well-defined cored dendritic with three phases with significant volume of eutectoid tin-rich phase. The dendritic structure of the metal in the sockets is crystallographically driven while in the cutting edges it is recrystallized, homogenised or plastically deformed. The manufacturing process of such a vast and homogenous collection required efficient casting methods, as well as skilled metalworker(s). The current dating methods do not allow to precisely state if the deposit represents one casting event or was collected over weeks or decades. The traces on the arrowheads included production traces (casting seams, casting jets), casting defects (sprue remnants and openings in the sockets), inward bending of the socket (probably due to core stabilization while casting) impact on the tips and barbs. The cast arrowheads were worked to obtain the desired shape and edge qualities: the sockets and the heads were ground, while the edges were hammered and sharpened. The arrowheads bear traces of being prepared for further use: they were hammered, ground and sharpened. Fractured or bent tips and bent barbs indicate that most of them were collected after use, removed from their shafts and deposited in a ceramic container within the settlement site.
Three metal sickles from the late Bronze Age (ca. 1000/900-750 BC, HB1-HB3 period) scrap deposit ... more Three metal sickles from the late Bronze Age (ca. 1000/900-750 BC, HB1-HB3 period) scrap deposit (34 objects, 3443 g in total) from Paszowice in SW Poland were sampled to analyse their chemical composition and metal structure. They are made of low-tin bronze (Sn 2.6-4 wt. %) and such property is usually interpreted as making them more malleable, flexible and easy to sharpen. One of the sickles bears no macroscopic traces of processing after the casting and its dendritic structure also indicates that the molten metal was cooled without any deformation. The metal structure reorganisation due to hammering is well visible in SEM images and suggests that the two other sickles were subject to treatment after heating. The traces of that kind of treatment are not visible in the macroscopic study. We show, therefore, that a precise identification of manufacturing techniques is impossible by macroscopic surface observations only.
Petrographic observations as well as new and published mineral major and trace element compositio... more Petrographic observations as well as new and published mineral major and trace element compositions, in part complemented by electron backscatter diffraction, evidence that representative mantle xenolith suites from several Cenozoic basalt locations in the European Variscan orogen can be grouped into three main types. Each type is derived from parts of the sub-continental lithospheric mantle which have experienced a different geological history. The oldest type, referred to as orogenic mantle, is dominated by strongly depleted harzburgites, which represent a fossil Variscan mantle wedge with slices of mantle of continental and oceanic plates attached to it during collision. This mantle lithosphere has been overprinted by Cenozoic carbonated alkali basalt melts, and clinopyroxene, if present, is LREE-enriched and reintroduced. This type of mantle is exemplified by xenoliths from Lower Silesia (Poland) and the northern Massif Central (France). The second type of lithospheric mantle lies beneath parts of the Variscan orogen which experienced Cenozoic rifting. This mantle is dominated by harzburgites and lherzolites formed by multiple episodes of reactive percolation of basaltic melts generated at various stages of continental rifting. The clinopyroxene REE patterns range from flat to LREE-enriched. The xeno-liths from Vogelsberg (Germany) are an example of such a lithospheric mantle. The third mantle type consists of lherzolites which originated by refertilization of a harzburgitic protolith by melts derived from upwelled as-thenosphere. Lherzolites contain primary clinopyroxene characterized by LREE-depleted-patterns. The xenoliths from south Massif Central (France) are an example of that third type. The xenoliths in Cenozoic basalts considered so far show that the mantle root of the Variscan orogen in Central Europe consists of various domains which in part conserve their characteristics from the time of the Variscan collision , and in part are overprinted by metasomatism caused by late-orogenic asthenosphere upwelling or by Ce-nozoic rifting. The metasomatically affected domains are decoupled from the Variscan structure of the orogen.
The deposit of 134 metal socketed arrowheads from the Late Bronze Age settlement in Wrocław-Widaw... more The deposit of 134 metal socketed arrowheads from the Late Bronze Age settlement in Wrocław-Widawa in SW Poland was subject of multi-faceted analyses. The composition and structure of the metal (XRF, SEM, EDS) was examined in samples from 15 objects, while the whole collection underwent macro-and micro-observations of production traces and use-wear. The bulk metal XRF analyses demonstrated that the arrowheads were made of tin bronze (Sn 3.0-11.6% wt). In terms of composition and structure, the samples represented four basic structural types: (1) homogeneous, (2) diffuse dendritic with two phases, (3) well-defined cored dendritic with phases, but with subordinate volume of eutectoid tin-rich phase and (4) well-defined cored dendritic with three phases with significant volume of eutectoid tin-rich phase. The dendritic structure of the metal in the sockets is crystallographically driven while in the cutting edges it is recrystallized, homogenised or plastically deformed. The manufacturing process of such a vast and homogenous collection required efficient casting methods, as well as skilled metalworker(s). The current dating methods do not allow to precisely state if the deposit represents one casting event or was collected over weeks or decades. The traces on the arrowheads included production traces (casting seams, casting jets), casting defects (sprue remnants and openings in the sockets), inward bending of the socket (probably due to core stabilization while casting) impact on the tips and barbs. The cast arrowheads were worked to obtain the desired shape and edge qualities: the sockets and the heads were ground, while the edges were hammered and sharpened. The arrowheads bear traces of being prepared for further use: they were hammered, ground and sharpened. Fractured or bent tips and bent barbs indicate that most of them were collected after use, removed from their shafts and deposited in a ceramic container within the settlement site.
Three metal sickles from the late Bronze Age (ca. 1000/900-750 BC, HB1-HB3 period) scrap deposit ... more Three metal sickles from the late Bronze Age (ca. 1000/900-750 BC, HB1-HB3 period) scrap deposit (34 objects, 3443 g in total) from Paszowice in SW Poland were sampled to analyse their chemical composition and metal structure. They are made of low-tin bronze (Sn 2.6-4 wt. %) and such property is usually interpreted as making them more malleable, flexible and easy to sharpen. One of the sickles bears no macroscopic traces of processing after the casting and its dendritic structure also indicates that the molten metal was cooled without any deformation. The metal structure reorganisation due to hammering is well visible in SEM images and suggests that the two other sickles were subject to treatment after heating. The traces of that kind of treatment are not visible in the macroscopic study. We show, therefore, that a precise identification of manufacturing techniques is impossible by macroscopic surface observations only.
Petrographic observations as well as new and published mineral major and trace element compositio... more Petrographic observations as well as new and published mineral major and trace element compositions, in part complemented by electron backscatter diffraction, evidence that representative mantle xenolith suites from several Cenozoic basalt locations in the European Variscan orogen can be grouped into three main types. Each type is derived from parts of the sub-continental lithospheric mantle which have experienced a different geological history. The oldest type, referred to as orogenic mantle, is dominated by strongly depleted harzburgites, which represent a fossil Variscan mantle wedge with slices of mantle of continental and oceanic plates attached to it during collision. This mantle lithosphere has been overprinted by Cenozoic carbonated alkali basalt melts, and clinopyroxene, if present, is LREE-enriched and reintroduced. This type of mantle is exemplified by xenoliths from Lower Silesia (Poland) and the northern Massif Central (France). The second type of lithospheric mantle lies beneath parts of the Variscan orogen which experienced Cenozoic rifting. This mantle is dominated by harzburgites and lherzolites formed by multiple episodes of reactive percolation of basaltic melts generated at various stages of continental rifting. The clinopyroxene REE patterns range from flat to LREE-enriched. The xeno-liths from Vogelsberg (Germany) are an example of such a lithospheric mantle. The third mantle type consists of lherzolites which originated by refertilization of a harzburgitic protolith by melts derived from upwelled as-thenosphere. Lherzolites contain primary clinopyroxene characterized by LREE-depleted-patterns. The xenoliths from south Massif Central (France) are an example of that third type. The xenoliths in Cenozoic basalts considered so far show that the mantle root of the Variscan orogen in Central Europe consists of various domains which in part conserve their characteristics from the time of the Variscan collision , and in part are overprinted by metasomatism caused by late-orogenic asthenosphere upwelling or by Ce-nozoic rifting. The metasomatically affected domains are decoupled from the Variscan structure of the orogen.
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