The results of a laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) U–Pb dating and a Hf isotope study of zircon crystals separated from small eclogite xenoliths found in Devonian kimberlites within the Prypyat horst, Ukraine, have been reported. The studied area is located in the junction zone between the Sarmatian and Fennoscandian segments of the East European Platform. Four laser ablation sites on two zircon grains yielded Paleoproterozoic U–Pb ages between 1954 ± 24 and 1735 ± 54 Ma. In contrast, three of four Hf sites revealed negative εHf values and Paleoarchean to Mesoarchean model ages, excluding the possibility that the eclogite xenoliths represented segments of a juvenile Paleoproterozoic subducted slab or younger mafic melts crystallized in the subcontinental lithospheric mantle. A single laser ablation Hf spot yielded a positive εHf value (+3) and a Paleoproterozoic model age. Two models for eclogite origin can be proposed. The first foresees the extension of the Archean lower-crustal or lithospheric roots beneath the Sarmatia–Fennoscandia junction zone for over 200 km from the nearest known outcrop of Archean rocks in the Ukrainian Shield. The second model is that the Central Belarus Suture Zone represents a rifted-out fragment of the Kola–Karelian craton that was accreted to Sarmatia before the actual collision of these two segments of Baltica.
The article presents the results of prospecting of diamond boring within the Kuhotsko-Bilska area, which is located on the north-western slope of the Ukrainian Shield.The data of the researches of 1995–2013 made it possible to form a new view on regional and local criteria and signs of diamond-bearing area of work, including a detailed study of the material composition of breccia, to distinguish among them explosive, to discover a new type of potentially diamond- bearing structures.According to all available geological and geophysical information, specific recommendations are given for direct searches for kimberlite or lamproite bodies within promising structures and breccia occurrence.
We used LA-ICP-MS U-Pb data for detrital zircon to constrain the Maximum Depositional Age (MDA) and provenance of clastic sedimentary rocks of the Volyn-Orsha sedimentary basin, which filled an elongated (~625 × 250 km) depression in SW Baltica and attained ~900 m in thickness. Eighty-six zircons out of one hundred and three yielded concordant dates, with most of them (86%) falling in the time interval between 1655 ± 3 and 1044 ± 16 Ma and clustering in two peaks at ca. 1630 and 1230 Ma. The remaining zircons yielded dates older than 1800 Ma. The MDA is defined by a tight group of three zircons with a weighted mean age of 1079 ± 8 Ma. This age corresponds to the time of a ~90° clockwise rotation of Baltica and the formation of the Grenvillian—Sveconorwegian—Sunsas orogenic belts. Subsidence was facilitated by the presence of eclogites derived from subducted oceanic crust. The sediments of the Orsha sub-basin in the northeastern part of the basin were derived from the local crystalline basement, whereas the sediments in the Volyn sub-basin, extending to the margin of Baltica, were transported from the orogen between Laurentia, Baltica and Amazonia.
We used LA-ICP-MS U-Pb data for detrital zircon to constrain the Maximum Depositional Age (MDA) and provenance of clastic sedimentary rocks of the Volyn-Orsha sedimentary basin, which filled an elongated (~625×250 km) depression in SW Baltica and attained ~900 m in thickness. Eighty-six zircons out of one hundred and three yielded concordant dates, with most of them (86 %) falling in the time interval between 1655 ± 3 and 1044 ± 16 Ma and clustering in two peaks at ca. 1630 and 1230 Ma. The remaining zircons yielded dates older than 1800 Ma. The MDA is defined by a tight group of three zircons with a weighted average age of 1079 ± 8 Ma. This age corresponds to the time of a clockwise ~90° rotation of Baltica and the formation of the Grenvillian – Sveconorwegian – Sunsas orogenic belts. Subsidence was facilitated by the presence of eclogites derived from subducted oceanic crust. The sediments of the Orsha sub-basin in the northeastern part of the basin were derived from the local crystalline basement, whereas the sediments in the Volyn sub-basin, extending to the margin of Baltica, were transported from the orogen between Laurentia, Baltica, and Amazonia.
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