Nikolay Y Matushkin

We present the results of geostructural, mineralogic–petrographic, geochemical, and U–Pb geochronological investigations of mafic, intermediate, and felsic igneous rocks from dikes in the Yana–Kolyma gold belt of the Verkhoyansk–Kolyma folded area (northeastern Asia). The dikes of the Vyun deposit and the Shumniy occurrence intruding Mesozoic terrigenous rocks of the Kular–Nera and Polousniy–Debin terranes were examined in detail. The dikes had diverse mineralogical and petrographic compositions including trachybasalts, andesites, trachyandesites, dacites, and granodiorites. The rocks showed significant similarities in distributions of REE, and their concentrations of most HFSEs were close to the intermediate ones between ocean islands basalts and enriched middle ocean ridge basalts. We propose that the subduction that was ongoing during the collision of the Kolyma–Omolon superterrane with Siberia led to melting in the asthenospheric wedge and in the lithosphere, which formed a mixe...

—We document the evolution of A-type granitoid magmatism during the Cryogenian tectonic transformation of the Yenisei Ridge from a postcollisional mode to the early stage of development of an active continental margin. We illustrate the A-type granitoid magmatism evolution in a model for the emplacement and cooling of the intrusions of the Strelka pluton, reflecting the final stage of magmatism during the formation of the postcollisional Glushikha complex (719–702 Ma). These processes took place at the same time as the formation of mantle, mantle-crustal and crustal rocks of the Tatarka complex (711–683 Ma), including the Yagodka pluton A-type granites (711–705 Ma) during the early stage of active continental margin development. During this period of tectonic transition, both convergent events involved the continuous formation of felsic intrusions corresponding to oxidized A-type granites.

We present new structural, petrographic, geochemical and geochronological data for the late Paleozoic–early Mesozoic granites and associated igneous rocks of the Taimyr Peninsula. It is demonstrated that large volumes of granites were formed due to the oblique collision of the Kara microcontinent and the Siberian paleocontinent. Based on U-Th-Pb isotope data for zircons, we identify syncollisional (315–282 Ma) and postcollisional (264–248 Ma) varieties, which differ not only in age but also in petrochemical and geochemical features. It is also shown that as the postcollisional magmatism was coming to an end, Siberian plume magmatism manifested in the Kara orogen and was represented by basalts and dolerites of the trap formation (251–249 Ma), but also by differentiated and individual intrusions of monzonites, quartz monzonites and syenites (Early–Middle Triassic) with a mixed crustal-mantle source. We present a geodynamic model for the formation of the Kara orogen and discuss the rel...

We present the first comprehensive data for the early Ediacaran stage of evolution of the western active continental margin of the Siberian Craton (Yenisei Ridge). U-Pb (SHRIMP-II SIMS) data for zircons from dikes of picrodolerites, quartz diorites, and leucocratic granites show that they were emplaced at 625 ± 5, 623 ± 8, and 626 ± 5 Ma, respectively, which indicates a narrow time window of Ediacaran magmatic events. The mafic tholeiitic rocks have OIB and E-MORB mantle components in their magmatic sources. Mineralogical and geochemical observations showed that the mantle-sourced mafic melts assimilated some crustal material, forming Th-enriched dikes of intermediate composition and K- and Rb-enriched felsic rocks. The possible geodynamic conditions for the formation of these early Ediacaran dikes are shown and a geodynamic model is presented for the development of the Yenisei Ridge orogen from the late Cryogenian to the late Ediacaran.

The geodynamic development of the north–western (Arctic) margin of the Siberian craton is comprehensively analyzed for the first time based on our database as well as on the analysis of published material, from Precambrian-Paleozoic and Mesozoic folded structures to the formation of the Mesozoic-Cenozoic Yenisei-Khatanga sedimentary basin. We identify the main stages of the region’s tectonic evolution related to collision and accretion processes, mainly subduction and rifting. It is demonstrated that the prototype of the Yenisei-Khatanga basin was a wide late Paleozoic foreland basin that extended from Southern Taimyr to the Tunguska syneclise and deepened towards Taimyr. The formation of the Yenisei-Khatanga basin, as well as of the West-Siberian basin, was due to continental rifting in the Permian-Triassic. The study describes the main oil and gas generating deposits of the basin, which are mainly Jurassic and Lower Cretaceous mudstones. It is shown that the Lower Cretaceous depos...

During computational modeling of cooling intrusions thermal regimes in collisional orogens, which are regions with thickened continental crust and heightened radioactive heat sources concentration, the main factors are the morphology and sizes of igneous bodies, emplacement depths, heat conductivity of igneous and host rocks and the heat flow in the crust. The purpose of this modeling is to reconstruct the thermal history of the events caused by successive intrusion of igneous rock masses in the Tatarka-Ishimba suture zone. This zone was emplaced in the Neoproterozoic during the formation of the Yenisey Ridge orogen (western framing of the Siberian craton). In the thermal models we imposed a heat flow of up to 0.05 W/m2 which is higher than the average for the Yenisey Ridge (0.03 W/m2). The intrusion of collisional granitoid plutons at 760-720 Ma led to additional heating of the crust in the Tatarka-Ishimba suture zone (1). Our calculations for the zone showed that in the middle par...

ABSTRACT This paper is a summary of the geological and geophysical information available today on the tectonics of the Arctic continental structures in the Late Precambrian–Paleozoic. We propose a new outlook on the history of Arctida – a continental mass that combined sialic blocks of the current Eurasian shelf of the Arctic Ocean. Based on new materials including paleomagnetic data we present a series of paleotectonic reconstructions that reflect the main evolutionary stages and mechanisms of the structure of Arctida from the Early Neoproterozoic to the Mesozoic. We demonstrate the role of the continental blocks of the Arctic in the global drift of lithospheric plates from the breakup of Rodinia to the assembly of Pangea. From the presented model we propose the existence of two (!) Arctic subcontinents in the Neoproterozoic–Paleozoic history of the Earth. Arctida-I was a collage of ancient blocks of Arctic sialic crust within Rodinia in the junction zone between the Laurentia, Siberia and Baltica cratons. During the breakup of Rodinia this subcontinent was destroyed with the formation of a series of small continental plates such as Kara, Svalbard and, probably, the New Siberian Islands (NSI), which is usually regarded as part of the Chukchi-Alaska composite terrane. By the time of its breakup Arctida-I was in a subequatorial position. The post-rifting tectonics of the newly formed small plates was closely associated with strike-slips that played a defining role both at the stages of opening and closure of the Paleozoic oceans. The rebirth of Arctida was due to the assembly of Pangea at the Paleozoic-Mesozoic limit. We consider Arctida-II a newly formed subcontinent that composed the shelf margin of Pangea in the temperate latitudes of the northern hemisphere, and again connected the margins of Laurentia, Baltica and Siberia.

ABSTRACT The Yenisey Ridge is an ancient orogen of the collisional-accretionary type, located in the south-western framing of the Siberian platform. It is roughly N-S trending along the Yenisey River for 650 km, while being 50-180 km wide. Its formation took place during the collision of the Central Angara terrane with the Siberian craton (760-720 Ma) and the subsequent accretion of terranes (700-630 Ma) from the west, composing the Yenisey island arc and ophiolite belt. In the Late Neoproterozoic during the orogen formation the emplacement of syn-collisional 760-750 Ma Ayakhta granites took place, and following them 750-720 Ma - the emplacement of the multiple plutons of the post-collisional Glushikha granites. The Ayakhta granites are confided to the Tatarka-Ishimba suture zone, which frames the Central Angara terrane from the east and consists of upthrows and thrusts fault systems, while the Glushikha granites are widely distributed in the western part of the terrane. We show the particularities of the formation of the granitoids on the post-collisional stage on the example of the Strelka pluton leucogranites. They were formed on the closing stage of the Central Angara terrane - Siberian craton collision, which took place 719-718 Ma according to zircon geochronological data. These rocks are geochemically classified as oxidized A-type leucogranites, whose magmatic source was mainly continental crustal. We observed schlieren-like structures in the leucogranites and consider them as products of early magmatic differentiates of the Strelka pluton. Their structural characteristics (morphology and orientation) indicate the direction of magma movement at the moment of emplacement. Our thermochronological model for the post-collisional leucogranites of the Yenisey Ridge [Vernikovskaya et al., 2009] that uses a combination of methods for the modelling of heat transfer and of the behaviour of the K-Ar isotopic system shows that the cooling of the pluton took place ~710 Ma. The last tectonic-thermal events for the pluton, registered in Ar-Ar data took place 687 Ma and were due to the accretion of the Yenisey island arc system from the western margin of the craton. The endocontact of the pluton intruding deformed sedimentary host rocks is vertical and submeridional as are the schlieren structures, which indicates that the pluton did not change its vertical position. This makes it a favourable object of paleomagnetic investigations. Magnetite is the main magnetization carrier in the leucogranites and their endo- and exocontact zones, while pyrrhotine is the one in the host limestones as well as in the farthest parts of the exocontact zones. The paleomagnetic pole calculated for the Strelka pluton is in good accordance with the apparent polar wander path for Siberia proposed to this day [Metelkin et al., 2007]. It is located between the paleomagnetic pole of the Nersa complex of the Prisayan basin (741 Ma) and the pole of the Yenisey island arc complex of the Yenisey Ridge (637 Ma). Therefore we can affirm that when the Strelka pluton was emplaced the Central Angara terrane was already a part of the Siberian craton.

The particularities of the current tectonic structure of the Russian part of the Arctic region are discussed with the division into the Barents–Kara and Laptev–Chukchi continental margins. We demonstrate new geological data for the key structures of the Arctic, which are analyzed with consideration of new geophysical data (gravitational and magnetic), including first seismic tomography models for the Arctic. Special attention is given to the New Siberian Islands block, which includes the De Long Islands, where field work took place in 2011. Based on the analysis of the tectonic structure of key units, of new geological and geophysical information and our paleomagnetic data for these units, we considered a series of paleogeodynamic reconstructions for the arctic structures from Late Precambrian to Late Paleozoic. This paper develops the ideas of L.P. Zonenshain and L.M. Natapov on the Precambrian Arctida paleocontinent. We consider its evolution during the Late Precambrian and the en...

Results of complex geological, petrological, geochemical, and isotope-geochronological studies of Neoproterozoic postcollisional A-type granites of the Glushikha complex, Yenisei Ridge, are presented, as well as results of mathematical modeling. The localization, sizes, and depths of formation of magmatic bodies and the physicochemical conditions of the formation of granite intrusions and their magmatic sources are considered. The research is focused on the modeling of the thermal history of the formation and subsequent cooling of granites in the collision orogen. The modeling of heat transfer during the acid-magma intrusion was performed by the example of the Lendakha and Glushikha leucogranite plutons. With the combined methods of the modeling of heat transfer and the behavior of K/Ar isotopic system, the models for leucogranite pluton cooling have been verified for the first time. The time of formation and cooling of granite bodies is estimated, and a generalized geodynamic model...

... Original Russian Text © VA Vernikovsky, AE Vernikovskaya, EB Sal'nikova, NG Berezhnaya, AN Larionov, AB Kotov, VP Kovach, IV Vernikovskaya, N.Yu. ... The U–Pb isotopic parameters of titanite were mea-sured on a Finnigan MAT-261 multichannel mass spec-trometer. ...