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Study of the magmatics in the Nakyn kimberlite field, with consideration of the isotope dating results, allowed us to establish a sequence of their formation. First, 368.5–374.4 Ma ago intrusions of the Vilyui–Markha dike belt formed. Then (363–364 Ma) intrusion of kimberlites took place. In the Early Carboniferous (338.2–345.6 Ma), alkaline basaltic magma intruded through faults controlling the kimberlites. The magmatic activity finished 331–324.9 Ma ago with the formation of explosive breccias. It has been found that the Nyurba kimberlite pipe consists of two bodies: their kimberlite melts have successively intruded through independent channels. 相似文献
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Konstantinov K. M. Tomshin M. D. Konstantinov I. K. Yakovlev A. A. 《Doklady Earth Sciences》2019,486(2):695-698
Doklady Earth Sciences - The eastern boundary of the Siberian Craton was formed as a result of rifting that split the continent late in the Middle Paleozoic. The paleomagnetic data derived from the... 相似文献
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Prokopiev A. V. Polyansky O. P. Koroleva O. V. Vasiliev D. A. Tomshin M. D. Reverdatto V. V. Novikova S. A. 《Doklady Earth Sciences》2020,490(1):4-7
Doklady Earth Sciences - The paper presents the results from the first 40Ar/39Ar isotope dating of eleven mafic sills recovered by deep boreholes in the eastern Siberian Platform. Most of the dates... 相似文献
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This article reports the first joint paleomagnetic and U-Pb geochronologic study of Precambrian diabase dikes in the Anabar Shield and adjacent Riphean cover of Siberia. It was undertaken to allow comparison with similar published studies in Laurentia and to test Proterozoic reconstructions of Siberia and Laurentia. An east-trending Kuonamka dike yielded a provisional U-Pb baddeleyite emplacement age of 1503+/-5 Ma and a virtual geomagnetic pole at 16 degrees S, 221 degrees E (dm=17&j0;, dp=10&j0;). A paleomagnetic pole at 6 degrees N, 234 degrees E (dm=28&j0;, dp=14&j0;) was obtained from five Kuonamka dikes. An east-southeast-trending Chieress dike yielded a U-Pb baddeleyite emplacement age of 1384+/-2 Ma and a virtual geomagnetic pole at 4 degrees N, 258 degrees E (dm=9&j0;, dp=5&j0;). Kuonamka and Chieress poles are interpreted to be primary but do not average out secular variation. Assuming that the Siberian Plate has remained intact since the Mesoproterozoic, except for mid-Paleozoic opening of the Viljuy Rift, then the above results indicate that the Siberian Plate was in low latitudes at ca. 1503 and 1384 Ma, broadly similar to low latitudes determined for Laurentia from well-dated paleopoles at 1460-1420, 1320-1290, and 1267 Ma. This would allow Laurentia and Siberia to have been attached in the Mesoproterozoic, as suggested in several recent studies based on geological criteria. However, because paleomagnetic results from the Anabar Shield region do not average out secular variation and the ages of poles from Siberia and Laurentia are not well matched, it is not yet possible to distinguish between these reconstructions or to rule out other configurations that also maintain the two cratons at low paleolatitudes. 相似文献
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M.D. Tomshin A.G. Kopylova K.M. Konstantinov S.S. Gogoleva 《Russian Geology and Geophysics》2018,59(10):1204-1216
We present results of study of the basites of the Vilyui paleorift. Their 40Ar/39Ar isotopic ages were used to establish the sequence of their intrusion, which lasted ~ 18 Myr. Dolerite sills of the Kontai-Dzherba zone were the first crystallizing phase (378.0-380.7 Ma), which was followed by the intrusion of dikes of the Vilyui-Markha zone (372-373 Ma). Dikes of the Chara-Sinsk zone were the last crystalizing phase (362-364 Ma). The prolonged plume-lithosphere interaction resulted in the successive enrichment of basaltic melt with titanium, phosphorus, REE, HSFE, and LILE. Accumulation of the melt and formation of a magmatic lens at the crust-mantle boundary led to early crystallization of the melt at a depth of 35-40 km from the paleosurface under reducing conditions at a temperature of 1450-1470 °C. We assume that the inception and sequent opening of the Vilyui paleorift were associated with the relative rotation of 22° of the Angara-Anabar block with respect to the Aldan block in Early Famennian time. The Euler pole of rotation was located in the southern part of the paleorift, and a melting zone was directly beneath it. 相似文献
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O.P. Polyansky A.V. Prokopiev O.V. Koroleva M.D. Tomshin V.V. Reverdatto A.V. Babichev V.G. Sverdlova D.A. Vasiliev 《Russian Geology and Geophysics》2018,59(10):1217-1236
Possible mechanisms of rifting and the thermal regime of the lithosphere beneath the rift zone of the Vilyui sedimentary basin are considered based on the available isotopic ages of dike swarms, rates of sedimentation, and results of numerical modeling. Temporal correlations between the intrusion of mafic magma and a sharp increase in the rate of subsidence and sedimentation in the rift basin prove the contribution of both plate-tectonic and magmatic factors to the formation of the Vilyui rift. The results show a relationship between the rapid extension of the lithosphere and the formation of mafic dike swarms in the Yakutsk-Vilyui Large Igneous Province of the Siberian Platform at the Frasnian-Famennian boundary, with a peak at ~ 374.1 Ma, and at the end of the Late Devonian, with a peak at ~ 363.4 Ma. There were two pulses of dike formation during rapid subsidence of the basin basement in the period 380-360 Ma, with a sedimentation rate of 100-130 m/Myr, at a background rate of 10-20 m/Myr. Analysis of numerical thermomechanical models revealed that the best-fit model is that combining the mechanisms of intraplate extension (passive rifting) and the ascent of a mantle magmatic diapir (active rifting). A conclusion about the nature of the heat source of trap magmatism has been drawn: The plume-driven regime of the lithosphere can better explain the dynamics of extension during rifting than the decompression melting mechanism. 相似文献
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