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The provenance of serpentinite tools in the Corded Ware culture of Moravia (Czech Republic)

Frýbová P., Gadas P., Přichystal A., Všianský D., Hadacz R., Hlavsa P.

Geological Quarterly

2018

Vol. 62, No. 3

563--578

This paper constrains the provenance of polished tools used in the Corded Ware culture (CWC) in Moravia. Based on optical microscopy, Přichystal and Šebela (1992) suggested the source for the CWC battle-axes would be the Gogołów-Jordanów Massif in Lower Silesia (Poland). The present study examines 14 serpentinite tools from archaeological sites of Central Moravia. We have located the origin of the tools' raw material by applying detailed petrographic, geochemical and petrophysical methods, as well as comparisons with data from probable serpentinite sources. Possible sources are adjacent to the Sowie Góry Block (mainly the Gogołów-Jordanów Massif) and within other areas in Central Europe (Penninic Bernstein Window, Western Lugicum and the eastern part of the Moldanubicum). Its most probable source is the Gogołów-Jordanów Massif, which is a part of the Ślęża ophiolite. The tools resemble the raw material source in several ways: firstly in magnetic susceptibility, with an average value of~40 x 10-3 SI; secondly, in the light yellowish-green patched patinated surface and very strong serpentinisation with almost no primary mineral relics; and lastly, in the occurrence of pseudomorphs filled with opaque minerals, and also parts with magnesite aggregates, which are quite rare. The main common feature is the presence of large primary zoned spinels, with Cr- and Al-rich cores and Fe-rich rims. The conclusions are supported by the results of bulk-rock chemical analysis, both the raw material from Lower Silesia and the tools being Mg-rich. In addition, the shape of some Moravian battle-axes (from Prusinovice) corresponds to the Ślęża type that is believed to be characteristic of Lower Silesia. The estimated distance of transport from the source area in Gogołów-Jordanów Massif to the archaeological sites in Central Moravia is >260 km.

Origin of serpentinite-related nephrites from Gogołów-Jordanów Massif, Poland

Gil G., Barnes J. D., Boschi Ch., Gunia P., Szakmány G., Bendő Z., Raczyński P., Péterdi B.

Geological Quarterly

2015

Vol. 59, No. 3

457--472

The Gogołów-Jordanów Massif (GJM) in the Fore-Sudetic Block, SW Poland, hosts nephrites traditionally interpreted as serpentinite-related (ortho-nephrite). This contribution confirms the serpentinite-related origin of the nephrites on the basis of mineralogy, bulk-rock chemistry, and O and H isotopes. Rock-forming amphiboles from nephrites of the GJM have 7.73–7.99 Si apfu, comparable to 7.76–8.03 Si apfu of serpentinite-related Crooks Mountain nephrite amphibole (Granite Mountains, Wyoming, USA). The GJM amphiboles also have Mg/(Mg + Fe2+) values ranging from 0.82 to 0.94, similar to serpentinite-related Crooks Mountain and New Zealand nephrites amphiboles with Mg/(Mg + Fe2+) values of 0.86–0.90 and 0.91 to 0.92, respectively. The GJM nephrite amphiboles differ from the Val Malenco dolomite-related nephrite (Italy) amphibole, e.g., Val Malenco has a higher Si content (~8.0 Si apfu), although it overlaps with some of the GJM nephrite samples, and ~1.0 Mg/(Mg + Fe2+), also higher than the GJM samples. Also, apatite in the nephrite studied from the GJM has a slightly higher Ca content than apatite from dolomite-related nephrite. Chlorites found in the Jordanów nephrite have similar compositions to that of chlorites in the serpentinite-related nephrites and also to chlorites associated with serpentinisation/rodingitisation. The bulk-rock FeO vs. Fe/(Fe + Mg), Cr, Ni, and Co are also typical of the serpentinite-related nephrites. The d18O values range from +6.1 to +6.7‰ (±0.1‰), and the average dD values = –61‰, corresponding with the serpentinite-related nephrites range. Based on petrographic observations, we suggest four crystallisation stages (including rodingitisation prior to nephrite formation): 1 – leucogranite rodingitisation and black-wall formation; 2 – tremolite formation at the expense of rodingite diopside and black-wall chlorite (nephritisation) and garnet break-down, with spinel and chlorite formation (chlorite can be a product of garnet break-down or spinel with serpentine reaction); 3 – prehnite vein formation; 4 – tremolite formation at the expense of prehnite veins and actinolite veins formation. Spinels composed of 0.29–1.96 wt.% MgO, 24.87–29.67 wt.% FeO, 8.72–22.82 wt.% Fe2O3, 3.11–4.36 wt.% Al2O3, and 39.07–54.46 wt.% Cr2O3 suggest nephritisation in the greenschist to lower-amphibolite-facies conditions.