Nickolay Rodionov - Academia.edu (original) (raw)

Papers by Nickolay Rodionov

Research paper thumbnail of Палеопротерозойские шошонитовые мафические ассоциаций Иркутного блока (Шарыжалгайский выступ, Юго-Запад Сибирского кратона): u-Pb возраст и условия образования циркона

Geologiya I Geofizika, 2023

Research paper thumbnail of Hydrothermal zircon from Proterozoic carbonatite massif

Research paper thumbnail of Detrital zircons - the unique source of information on tectonics, paleogeography and denudation processes of East Antarctica (subglacial challenge)

Vast (about 7 billions km) almost wholly (98%) covered with ice continental mass of East Antarcti... more Vast (about 7 billions km) almost wholly (98%) covered with ice continental mass of East Antarctica is the central fragment of ancient supercontinents of Rodinia and Gondwana. Any information on its geologic structure is of the greatest importance for solving the problems of formation and amalgamation of lithosphere of ancient continents, processes of intraplate activity, denudation and peneplanation of the earth crust and for geodynamic reconstruction. Geologic structure of central part of the East Antarctica is still absolutely unknown due to the thick (up to 4000 m) ice cover, which is the obstacle even for modern drilling technology to sample directly the underlying rocks. The main goal of the study has been to make an attempt in fill up the hiatus in geologic knowledge on the origin of subglacial continental crust of the Antarctica.

Research paper thumbnail of U–Pb zircon ages from Permian volcanites of the Čierna Hora Mts. (Western Carpathians, Slovakia): Regional tectonic implications

Geologica Carpathica

U-Pb dating of magmatic zircons from the Permian meta-andesites of the Čierna Hora Mts. yielded t... more U-Pb dating of magmatic zircons from the Permian meta-andesites of the Čierna Hora Mts. yielded the Concordia ages of 267.0±1.5 Ma, which correspond to the Guadalupian Epoch in the time span of the Wordian Stage. The sequence was correlated with the Northern Veporic Permian rocks from the Čierťaž Mts. From the geochemical point of view, the studied volcanic rocks belong to a peraluminous calc-alkaline magmatic suite, linked to the post-collisional lithospheric extension. Lithosphere extension and attenuation will promote upwelling of hot asthenosphere. In this context, the calc-alkaline affinity may result through extensive crustal contamination of basaltic magma. Continuous extensional setting, succeeded by overheating is indicated by the newly formed zircon rims of 252.2±3.2 Ma age at the edges of the Wordian zircon grains. The Neoproterozoic (618±8 Ma) and Paleoproterozoic (2080±13 Ma) ages were found within the xenocrystic cores in the studied magmatic zircon grains. The presented xenocrystic zircon ages indicate derivation from the Variscan basement rocks with reworked fragments of Cadomian crust.

Research paper thumbnail of Titanite composite grain as an evidence of alkaline granite evolution

Goldschmidt2021 abstracts

Research paper thumbnail of Geodynamic Emplacement Setting of Late Jurassic Dikes of the Yana–Kolyma Gold Belt, NE Folded Framing of the Siberian Craton: Geochemical, Petrologic, and U–Pb Zircon Data

Minerals

We present the results of geostructural, mineralogic–petrographic, geochemical, and U–Pb geochron... more 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...

Research paper thumbnail of Zircon U–Pb geochronology from Permian rocks of the Tribeč Mts. (Western Carpathians, Slovakia)

Geologica Carpathica

U-Pb dating of magmatic zircons from the Permian basaltic metaandesites/metabasalts of the Tribeč... more U-Pb dating of magmatic zircons from the Permian basaltic metaandesites/metabasalts of the Tribeč Mts. yielded the Concordia ages of 263.1±2.6 Ma, which correspond to the Guadalupian Epoch in the time span of the uppermost Wordian/Capitanian Stages. These magmatic zircon ages clearly document the timing of the Mid-Permian lithospheric extension in the internal zone of the Variscan fragments in the Western Carpathians. The studied volcanic rocks with the associated metasediments belong to the Veporic Unit that overthrusts the Tatric Unit. The considered sequence was correlated with the Northern Veporic Permian rocks from the Čierťaž Mts. From the geochemical point of view, the studied volcanic rocks have a calc-alkaline magmatic trend with an affinity to continental within-plate tectonic setting, linked to the post-orogenic lithospheric extension. The detrital zircon population, obtained from the associated arkosic metagreywackes, displays mainly Tournaisian and Ediacaran zircon ages in the range of 342-367 and 546-631 Ma, respectively. Only a small number of Cambrian/Ordovician (499-466 Ma), Tonian (720-1000 Ma) and Paleoproterozoic/ Neoarchean (~1.9 Ga and ~2.5 Ga) zircon ages were determined. The similar association of zircon ages was found within the xenocrystic cores in the studied volcanic rocks. The presented detrital and xenocrystic zircon ages specify the provenance of the Tribeč Permian deposits from the Western Carpathian Crystalline Basement crust, characteristic of derivation from the Variscan magmatic rocks and reworked fragments of Cadomian crust.

Research paper thumbnail of Exhumation history of the Variscan suture: Constrains on the detrital zircon geochronology from Carboniferous–Permian sandstones (Northern Gemericum; Western Carpathians)

Geologica Carpathica

The Late Paleozoic sedimentary basins in the Northern Gemericum evolved gradually in time and spa... more The Late Paleozoic sedimentary basins in the Northern Gemericum evolved gradually in time and space within the collisional tectonic regime of the Western Carpathian Variscan orogenic belt. The detrital zircon age spectra, obtained from the Mississippian, Pennsylvanian and Permian metasediments, have distinctive age distribution patterns that reflect the tectonic setting of the host sediments. An expressive unimodal zircon distribution, with an age peak at 352 Ma, is shown by the basal Mississippian metasediments. These represent a relic of the convergent trench-slope sedimentary basin fill. In comparison, the Pennsylvanian detrital zircon populations display distinct multimodal distributions, with the main age peaks at 351, 450, 565 Ma and smaller peaks at ~2.0 and ~2.7 Ga. This is consistent with derivation of clastic detritus from the collisional suture into the foreland basin. Similarly, the Permian sedimentary formations exhibit the multimodal distribution of zircon ages, with m...

Research paper thumbnail of Clastic wedge provenance in the Zemplinicum Carboniferous–Permian rocks using the U–Pb zircon age dating (Western Carpathians, Slovakia)

International Journal of Earth Sciences

U-Pb (SHRIMP) detrital zircon ages from the Pennsylvanian-Permian meta-sedimentary rocks of the Z... more U-Pb (SHRIMP) detrital zircon ages from the Pennsylvanian-Permian meta-sedimentary rocks of the Zemplinicum Unit were used to characterise the provenance and the tectono-thermal evolution of the basement. The magmatic zircon ages from the contemporaneous rhyolite pyroclastics, ranging from 308 to 305 Ma, dated the Pennsylvanian sedimentary formations to the Moscovian and Kasimovian Ages. Two brakes in sedimentation within the Pennsylvanian-Permian sequence are presumed, first, flanked by Gzhelian-Asselian and second, intra-Permian. The detrital zircon age spectrum demonstrates two prominent populations: (i) Middle/Late Ordovician (age peak 459 Ma), (ii) Ediacaran-Cryogenian (age peaks 592 and 641 Ma). These, together with minor clusters from ~ 773 to 950 Ma, evidently document the Pan-African multiple magmatic events. The 1.1-1.8 Ga age gap and isolated zircons of Mesoproterozoic ages (1036-1361 Ma) are characteristic. Two populations, 1.8-2.2 Ga and 2.5-2.8 Ga, are presented within the Paleoproterozoic-Neoarchean zircons. The Zemplinicum Neoproterozoic arc crust had been affected by the extensional thermal relaxation and melting during Middle/Late Ordovician. The subsequent reworking had been connected with the Mississippian collision, followed by the Pennsylvanian/Permian extension. The presence of the Neoproterozoic detrital zircon ages including the Tonian ones permit to compare the Zemplinicum basement with the eastern peri-Gondwanan domain, which was situated at the northern margin of the Saharan Metacraton or the Arabian Nubian Shield during Neoproterozoic time.

Research paper thumbnail of Recycling of Paleoproterozoic and Neoproterozoic crust recorded in Lower Paleozoic metasandstones of the Northern Gemericum (Western Carpathians, Slovakia): Evidence from detrital zircons

Geologica Carpathica

U–Pb (SHRIMP) detrital zircon ages from the Early Paleozoic meta-sedimentary rocks of the Norther... more U–Pb (SHRIMP) detrital zircon ages from the Early Paleozoic meta-sedimentary rocks of the Northern Gemericum Unit (the Smrečinka Formation) were used to characterize their provenance. The aim was to compare and reconcile new analyses with previously published data. The detrital zircon age spectrum demonstrates two prominent populations, the first, Late Neoproterozoic (545–640 Ma) and the second, Paleoproterozoic (1.8–2.1 Ga), with a minor Archean population (2.5–3.4 Ga). The documented zircon ages reflect derivation of the studied metasedimentary rocks from the Cadomian arc, which was located along the West African Craton. The acquired data supports close relations of the Northern Gemericum basement with the Armorican terranes during Neoproterozoic and Ordovician times and also a close palinspastic relation with the other crystalline basements of the Central Western Carpathians. In comparison, the detrital zircons from the Southern Gemericum basement and its Permian envelope indicat...

Research paper thumbnail of Detrital zircon U–Pb geochronology of Pennsylvanian–Permian sandstones from the Turnaicum and Meliaticum (Western Carpathians, Slovakia): provenance and tectonic implications

International Journal of Earth Sciences

The blueschist-bearing Bôrka Nappe regarded as a part of the Meliaticum Unit s. l. and the Turnai... more The blueschist-bearing Bôrka Nappe regarded as a part of the Meliaticum Unit s. l. and the Turnaicum Unit in its hanging-wall were thrusted together to the north on the Inner Western Carpathians basement during the orogenic events of the Late Jurassic-Early Cretaceous. A new U-Pb sensitive high-resolution ion microprobe (SHRIMP) magmatic, as well as detrital-zircon ages were used to constrain provenance and paleogeography. The detrital-zircon age spectrum of the studied metasediments contains mainly ages of the Ediacaran-Cryogenian (550-720 Ma) and Tonian-Stenian (0.9-1.1 Ga), which correspond to the Pan-African Belt and Saharan Metacraton. Subordinate Archean ages were likely derived from the Saharan Metacraton of North Gondwana (1.7-2.2 and 2.5-2.7 Ga). The 273 ± 2 Ma zircon age of a metarhyolite, along with the youngest detrital zircon of 265 ± 4 Ma from the associated metasediments, specify the maximum depositional age of the Bučina Fm. from the Bôrka Nappe to the Guadalupian. The rhyolite olistoliths from the Middle/Late Jurassic Meliaticum olistostrome yielded the latest Cambrian/earliest Ordovician (488 ± 6 Ma) and Middle Ordovician (~ 465 Ma) zircon ages. This is consistent with the U-Pb zircon ages from the foot-walling Southern Gemericum basement metavolcanites, which are, therefore, regarded as a potential source. The obtained zircon ages confirm the provenance from the Southern Gemericum basement and its Permian envelope for the Meliaticum-Bôrka Nappe and Turnaicum sedimentary embayment.

Research paper thumbnail of The geological composition of the hidden Wilhelm II Land in East Antarctica: SHRIMP zircon, Nd isotopic and geochemical studies with implications for Proterozoic supercontinent reconstructions

Precambrian Research

ABSTRACT In this paper we present new U − Pb zircon age, Sm–Nd isotopic and chemical composition ... more ABSTRACT In this paper we present new U − Pb zircon age, Sm–Nd isotopic and chemical composition data for rocks cropping out in a few isolated nunataks in Wilhelm II Land in East Antarctica, namely Mirny oasis, Mt Brown and Gaussberg volcano, which contains xenogenic crustal material. These outcrops were subjects of geological investigations during the Soviet Antarctic Expedition of 1956–1957. Our data show that this region is underlain by a uniform crust which experienced a high-grade metamorphic event at ca 980 − 920 Ma, co-eval with the Rayner Orogeny in Kemp Land and the northern Prince Charles Mountains. Extensive indications of a ca 500 Ma event in coastal areas (granitoid intrusions in Mirny oasis and inherited zircons found in Gaussberg volcano), together with the lack of indications of this age in Mt Brown, point to a concentration of ca 500 Ma processes (roughly co-eval with the Prydz Orogeny) in the coastal part of Wilhelm II Land and their attenuation inland. We also determined a ca 1480 Ma age for a mafic magmatic protolith in Mt Brown which may be correlated with roughly co-eval orthogneiss in the Bunger Hills area. These observations suggest the conjugate positions of these crustal blocks in the early Mesoproterozoic and argue against a Cambrian suture running between them. In Gaussberg volcano a range of zircon 206Pb/238U ages of ca 320 Ma, ca 500 Ma, ca 980 Ma, and ca 2000–1800 Ma has been determined. The presence of ca 2000–1800 Ma zircons indicates involvement of mid-Palaeoproterozoic rocks in the structure of Wilhelm II Land. This argues for possible conjugation of this region with other East Antarctic blocks experienced the Palaeoproterozoic tectonic evolution and which have been considered to comprise the Mawson palaeocontinent.

Research paper thumbnail of Archean metabasic rocks at the base of the Riphean of the Bashkirian Meganticlinorium (Southern Urals)

Research paper thumbnail of Refined geological history of the polyphase plutonometamorphic complex in the Thala Hills area (Enderby Land, East Antarctica) from zircon SHRIMP dating and implications for Neoproterozoic amalgamation of Gondwanaland

Geological Society, London, Special Publications

The Thala Hills area occupies a key position in Gondwanaland reconstructions near the India–Sri L... more The Thala Hills area occupies a key position in Gondwanaland reconstructions near the India–Sri Lanka–Antarctica junction. We present U–Pb zircon isotopic age determinations from SHRIMP II obtained on four granite gneiss samples. Three high-temperature tectonomagmatic episodes may be distinguished in the study area at c. 980–970, c. 780–720 and c. 545–530 Ma. The c. 980–970 Ma event corresponds to the Rayner Structural Episode that affected East Antarctica, including the Sør Rondane Mountains to the west and Kemp Land to the east. The c. 780–720 Ma episode included two events at approximately 780 Ma (high-grade anatexis) and 720 Ma (syntectonic granitoid emplacement), and was roughly coeval with tectonomagmatic events in Dronning Maud Land of East Antarctica, as well as in other Gondwanaland regions, such as Madagascar, Sri Lanka and eastern Africa. The c. 780–720 Ma episode may be correlated with the East African Orogeny. These correlations argue for a similar geological evolution ...

Research paper thumbnail of New zircon ages on the Cambrian–Ordovician volcanism of the Southern Gemericum basement (Western Carpathians, Slovakia): SHRIMP dating, geochemistry and provenance

International Journal of Earth Sciences, 2016

The Southern Gemericum basement in the Inner Western Carpathians, composed of low-grade volcano-s... more The Southern Gemericum basement in the Inner Western Carpathians, composed of low-grade volcano-sedimentary rock complexes, constitutes a record of the polyphase Cambrian–Ordovician continental volcanic arc volcanism. These metavolcanic rocks are characterized by the enrichment in K, Rb, Ba, Th and Ce and Sm relative to Ta, Nb, Hf, Zr, Y and Yb that are the characteristic features for volcanic arc magmatites. The new SHRIMP U–Pb zircon data and compilation of previously published and re-evaluated zircon ages, contribute to a new constrain of the timing of the Cambrian–Ordovician volcanism that occurred between 496 and 447 Ma. The following peaks of the volcanic activity of the Southern Gemericum basement have been recognized: (a) mid-late Furongian at 492 Ma; (b) Tremadocian at 481 Ma; (c) Darriwilian at 464 Ma prolonged to 453 Ma within the early Upper Ordovician. The metavolcanic rocks are characterized by a high zircon inheritance, composed of Ediacaran (650–550 Ma), Tonian–Stenian (1.1–0.9 Ma), and, to a lesser extent, Mesoproterozoic (1.3 Ga), Paleoproterozoic (1.9 Ga) and Archaean assemblages (2.6 Ga). Based on the acquired zircon populations, it could be deduced that Cambrian–Ordovician arc crust was generated by a partial melting of Ediacaran basement in the subduction-related setting, into which old crustal fragments were incorporated. The ascertained zircon inheritances with Meso-, Paleoproterozoic and Archaean cores indicate the similarities with the Saharan Metacraton provenance.

Research paper thumbnail of U–Pb zircon ages from Permian volcanic rocks and tonalite of the Northern Veporicum (Western Carpathians)

Journal of Geosciences, 2016

U-Pb dating (SHRIMP) of magmatic zircons from the Northern Veporicum Permian volcanics of the Ľub... more U-Pb dating (SHRIMP) of magmatic zircons from the Northern Veporicum Permian volcanics of the Ľubietová Group yielded concordia ages of 273 ± 6 Ma and 279 ± 4 Ma. Both zircon ages correspond to the Cisuralian Epoch in the time span of Kungurian Stage. The 272 ± 4 Ma U-Pb zircon age, determined on the volcanic dyke cutting the neighbouring crystalline basement, belongs to the same stratigraphic range. The acquired age data support a contemporaneous origin of the Permian sedimentary basin with the volcanic event and the dyke formation in the crystalline basement. Based on the whole-rock geochemical composition, the studied volcanic rocks correspond to weakly alkaline suite (trachyandesite to rhyolite/dacite). They exhibit light rare earth elements enrichment (La N /Yb N = 9.5-17.7) and small negative or absent Eu anomalies (Eu/Eu* = 0.95 and 1.05 for the Permian volcanites and 0.73 for the volcanic dyke). Characteristic of these volcanites is the enrichment in Cs, Rb, Th, U, K and Pb and the depletion in Nb, Ta, Sr and Ti if compared with average primitive mantle composition. All the studied volcanic rocks have low Nb/Ta (0.29-0.38) and Nb/U (4.07 to 5.87) ratios, implying a crustal magmatic source. Based on the incompatible trace elements Ta, Th and Yb, the Permian volcanics as well as the volcanic dyke cutting the crystalline basement fall close to the boundary between active continental margin and the within-plate fields. The 358 ± 4 Ma magmatic zircon concordia age confirmed the Early Mississippian (Tournaisian) intrusion of the metatonalites in the Volchovo Valley, later blastomylonitized and covered by Permian siliciclastics.

Research paper thumbnail of U-Pb SHRIMP-II Baddeleyite and Zircon Dating of the Early Proterozoic Monchegorsk Layered Mafite-Ultramafite Complex (Kola Peninsula): Evidence of Synchronous Magmatism

Acta Geologica Sinica - English Edition, 2016

Research paper thumbnail of Zirconology of ultramafic rocks from the Vostochnotagilskii massif (Middle Urals)

Doklady Earth Sciences, 2014

441 The Vostochnotagilskii massif (VTM; also known as Krasnoural’skii) is one of the largest in t... more 441 The Vostochnotagilskii massif (VTM; also known as Krasnoural’skii) is one of the largest in the Middle and North Urals [1]. This massif occurs in the merid ian direction for >300 km (Fig. 1, the southern part of massif) and controls the Serovsko–Maukskii ophiolite complex separating the Tagil and Magnitogorsk paleo island arc zones. The massif is composed of dunite and harzburgite serpentinized to various degrees. Chrysotile serpentinite prevails in the central part intruded by gabbro diabase and granitoid dykes, whereas antigorite serpentinite predominates in the marginal zones. The exocontact zones of dykes are characterized by bimetasomatic zoning with the for mation of vermiculite, chlorite–actinolite, talc, and talc–carbonate rocks. The freshest rock varieties are preserved in the central part of massif. Poor exposure does not provide unambiguous evidence for relation ships between dunite and harzburgite; according to the composition of chrome spinellids, ultramafic rocks form a continuous series [2]. At the same time, transi tional varieties between dunite and harzburgite were not found in the largest Kutuzovskii mine located at the latitude of Krasnoural’sk.

Research paper thumbnail of SHRIMP-II U-Pb dating of Zircons from Volcanic Ashes with the Early Paleolithic Artifacts (Karakhach locality, Armenia): New Evidence for the Earliest occupation of Eurasia (1.9 Ma)

Research paper thumbnail of New evidence for the early Archean evolution of Aker Peaks, Napier Mountains , Enderby Land (East Antarctica)

Zircons from charnockite-enderbite rocks (Aker Peaks, Napier Mountains), which we have dated by S... more Zircons from charnockite-enderbite rocks (Aker Peaks, Napier Mountains), which we have dated by SHRIMP-II, were analyzed earlier by conventional multigrain U-Pb ID-TIMS methods (Belyatsky et al., 1990) but gave equivocal ages. This study shows that the optimal way to evaluate geologic events in such rocks is local ion-probe analysis of complex zircons with preliminary study of CL, BSE, REE patterns. Due to this approach we have obtained, for the first time, reliable ages of magmatic crystallization for studied charnockite-enderbites (3620 ± 30 Ma) and the age of the primary enderbite’s protolith (3950 – 3970 Ma). Moreover, in all dated zircons a metamorphic event of 2450– 2480 Ma is clearly recorded that is in agreement with the granulite-facies metamorphism described by many authors. These conclusions coincide well with our Sm-Nd isotope data for these enderbite-charnockite gneisses.

Research paper thumbnail of Палеопротерозойские шошонитовые мафические ассоциаций Иркутного блока (Шарыжалгайский выступ, Юго-Запад Сибирского кратона): u-Pb возраст и условия образования циркона

Geologiya I Geofizika, 2023

Research paper thumbnail of Hydrothermal zircon from Proterozoic carbonatite massif

Research paper thumbnail of Detrital zircons - the unique source of information on tectonics, paleogeography and denudation processes of East Antarctica (subglacial challenge)

Vast (about 7 billions km) almost wholly (98%) covered with ice continental mass of East Antarcti... more Vast (about 7 billions km) almost wholly (98%) covered with ice continental mass of East Antarctica is the central fragment of ancient supercontinents of Rodinia and Gondwana. Any information on its geologic structure is of the greatest importance for solving the problems of formation and amalgamation of lithosphere of ancient continents, processes of intraplate activity, denudation and peneplanation of the earth crust and for geodynamic reconstruction. Geologic structure of central part of the East Antarctica is still absolutely unknown due to the thick (up to 4000 m) ice cover, which is the obstacle even for modern drilling technology to sample directly the underlying rocks. The main goal of the study has been to make an attempt in fill up the hiatus in geologic knowledge on the origin of subglacial continental crust of the Antarctica.

Research paper thumbnail of U–Pb zircon ages from Permian volcanites of the Čierna Hora Mts. (Western Carpathians, Slovakia): Regional tectonic implications

Geologica Carpathica

U-Pb dating of magmatic zircons from the Permian meta-andesites of the Čierna Hora Mts. yielded t... more U-Pb dating of magmatic zircons from the Permian meta-andesites of the Čierna Hora Mts. yielded the Concordia ages of 267.0±1.5 Ma, which correspond to the Guadalupian Epoch in the time span of the Wordian Stage. The sequence was correlated with the Northern Veporic Permian rocks from the Čierťaž Mts. From the geochemical point of view, the studied volcanic rocks belong to a peraluminous calc-alkaline magmatic suite, linked to the post-collisional lithospheric extension. Lithosphere extension and attenuation will promote upwelling of hot asthenosphere. In this context, the calc-alkaline affinity may result through extensive crustal contamination of basaltic magma. Continuous extensional setting, succeeded by overheating is indicated by the newly formed zircon rims of 252.2±3.2 Ma age at the edges of the Wordian zircon grains. The Neoproterozoic (618±8 Ma) and Paleoproterozoic (2080±13 Ma) ages were found within the xenocrystic cores in the studied magmatic zircon grains. The presented xenocrystic zircon ages indicate derivation from the Variscan basement rocks with reworked fragments of Cadomian crust.

Research paper thumbnail of Titanite composite grain as an evidence of alkaline granite evolution

Goldschmidt2021 abstracts

Research paper thumbnail of Geodynamic Emplacement Setting of Late Jurassic Dikes of the Yana–Kolyma Gold Belt, NE Folded Framing of the Siberian Craton: Geochemical, Petrologic, and U–Pb Zircon Data

Minerals

We present the results of geostructural, mineralogic–petrographic, geochemical, and U–Pb geochron... more 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...

Research paper thumbnail of Zircon U–Pb geochronology from Permian rocks of the Tribeč Mts. (Western Carpathians, Slovakia)

Geologica Carpathica

U-Pb dating of magmatic zircons from the Permian basaltic metaandesites/metabasalts of the Tribeč... more U-Pb dating of magmatic zircons from the Permian basaltic metaandesites/metabasalts of the Tribeč Mts. yielded the Concordia ages of 263.1±2.6 Ma, which correspond to the Guadalupian Epoch in the time span of the uppermost Wordian/Capitanian Stages. These magmatic zircon ages clearly document the timing of the Mid-Permian lithospheric extension in the internal zone of the Variscan fragments in the Western Carpathians. The studied volcanic rocks with the associated metasediments belong to the Veporic Unit that overthrusts the Tatric Unit. The considered sequence was correlated with the Northern Veporic Permian rocks from the Čierťaž Mts. From the geochemical point of view, the studied volcanic rocks have a calc-alkaline magmatic trend with an affinity to continental within-plate tectonic setting, linked to the post-orogenic lithospheric extension. The detrital zircon population, obtained from the associated arkosic metagreywackes, displays mainly Tournaisian and Ediacaran zircon ages in the range of 342-367 and 546-631 Ma, respectively. Only a small number of Cambrian/Ordovician (499-466 Ma), Tonian (720-1000 Ma) and Paleoproterozoic/ Neoarchean (~1.9 Ga and ~2.5 Ga) zircon ages were determined. The similar association of zircon ages was found within the xenocrystic cores in the studied volcanic rocks. The presented detrital and xenocrystic zircon ages specify the provenance of the Tribeč Permian deposits from the Western Carpathian Crystalline Basement crust, characteristic of derivation from the Variscan magmatic rocks and reworked fragments of Cadomian crust.

Research paper thumbnail of Exhumation history of the Variscan suture: Constrains on the detrital zircon geochronology from Carboniferous–Permian sandstones (Northern Gemericum; Western Carpathians)

Geologica Carpathica

The Late Paleozoic sedimentary basins in the Northern Gemericum evolved gradually in time and spa... more The Late Paleozoic sedimentary basins in the Northern Gemericum evolved gradually in time and space within the collisional tectonic regime of the Western Carpathian Variscan orogenic belt. The detrital zircon age spectra, obtained from the Mississippian, Pennsylvanian and Permian metasediments, have distinctive age distribution patterns that reflect the tectonic setting of the host sediments. An expressive unimodal zircon distribution, with an age peak at 352 Ma, is shown by the basal Mississippian metasediments. These represent a relic of the convergent trench-slope sedimentary basin fill. In comparison, the Pennsylvanian detrital zircon populations display distinct multimodal distributions, with the main age peaks at 351, 450, 565 Ma and smaller peaks at ~2.0 and ~2.7 Ga. This is consistent with derivation of clastic detritus from the collisional suture into the foreland basin. Similarly, the Permian sedimentary formations exhibit the multimodal distribution of zircon ages, with m...

Research paper thumbnail of Clastic wedge provenance in the Zemplinicum Carboniferous–Permian rocks using the U–Pb zircon age dating (Western Carpathians, Slovakia)

International Journal of Earth Sciences

U-Pb (SHRIMP) detrital zircon ages from the Pennsylvanian-Permian meta-sedimentary rocks of the Z... more U-Pb (SHRIMP) detrital zircon ages from the Pennsylvanian-Permian meta-sedimentary rocks of the Zemplinicum Unit were used to characterise the provenance and the tectono-thermal evolution of the basement. The magmatic zircon ages from the contemporaneous rhyolite pyroclastics, ranging from 308 to 305 Ma, dated the Pennsylvanian sedimentary formations to the Moscovian and Kasimovian Ages. Two brakes in sedimentation within the Pennsylvanian-Permian sequence are presumed, first, flanked by Gzhelian-Asselian and second, intra-Permian. The detrital zircon age spectrum demonstrates two prominent populations: (i) Middle/Late Ordovician (age peak 459 Ma), (ii) Ediacaran-Cryogenian (age peaks 592 and 641 Ma). These, together with minor clusters from ~ 773 to 950 Ma, evidently document the Pan-African multiple magmatic events. The 1.1-1.8 Ga age gap and isolated zircons of Mesoproterozoic ages (1036-1361 Ma) are characteristic. Two populations, 1.8-2.2 Ga and 2.5-2.8 Ga, are presented within the Paleoproterozoic-Neoarchean zircons. The Zemplinicum Neoproterozoic arc crust had been affected by the extensional thermal relaxation and melting during Middle/Late Ordovician. The subsequent reworking had been connected with the Mississippian collision, followed by the Pennsylvanian/Permian extension. The presence of the Neoproterozoic detrital zircon ages including the Tonian ones permit to compare the Zemplinicum basement with the eastern peri-Gondwanan domain, which was situated at the northern margin of the Saharan Metacraton or the Arabian Nubian Shield during Neoproterozoic time.

Research paper thumbnail of Recycling of Paleoproterozoic and Neoproterozoic crust recorded in Lower Paleozoic metasandstones of the Northern Gemericum (Western Carpathians, Slovakia): Evidence from detrital zircons

Geologica Carpathica

U–Pb (SHRIMP) detrital zircon ages from the Early Paleozoic meta-sedimentary rocks of the Norther... more U–Pb (SHRIMP) detrital zircon ages from the Early Paleozoic meta-sedimentary rocks of the Northern Gemericum Unit (the Smrečinka Formation) were used to characterize their provenance. The aim was to compare and reconcile new analyses with previously published data. The detrital zircon age spectrum demonstrates two prominent populations, the first, Late Neoproterozoic (545–640 Ma) and the second, Paleoproterozoic (1.8–2.1 Ga), with a minor Archean population (2.5–3.4 Ga). The documented zircon ages reflect derivation of the studied metasedimentary rocks from the Cadomian arc, which was located along the West African Craton. The acquired data supports close relations of the Northern Gemericum basement with the Armorican terranes during Neoproterozoic and Ordovician times and also a close palinspastic relation with the other crystalline basements of the Central Western Carpathians. In comparison, the detrital zircons from the Southern Gemericum basement and its Permian envelope indicat...

Research paper thumbnail of Detrital zircon U–Pb geochronology of Pennsylvanian–Permian sandstones from the Turnaicum and Meliaticum (Western Carpathians, Slovakia): provenance and tectonic implications

International Journal of Earth Sciences

The blueschist-bearing Bôrka Nappe regarded as a part of the Meliaticum Unit s. l. and the Turnai... more The blueschist-bearing Bôrka Nappe regarded as a part of the Meliaticum Unit s. l. and the Turnaicum Unit in its hanging-wall were thrusted together to the north on the Inner Western Carpathians basement during the orogenic events of the Late Jurassic-Early Cretaceous. A new U-Pb sensitive high-resolution ion microprobe (SHRIMP) magmatic, as well as detrital-zircon ages were used to constrain provenance and paleogeography. The detrital-zircon age spectrum of the studied metasediments contains mainly ages of the Ediacaran-Cryogenian (550-720 Ma) and Tonian-Stenian (0.9-1.1 Ga), which correspond to the Pan-African Belt and Saharan Metacraton. Subordinate Archean ages were likely derived from the Saharan Metacraton of North Gondwana (1.7-2.2 and 2.5-2.7 Ga). The 273 ± 2 Ma zircon age of a metarhyolite, along with the youngest detrital zircon of 265 ± 4 Ma from the associated metasediments, specify the maximum depositional age of the Bučina Fm. from the Bôrka Nappe to the Guadalupian. The rhyolite olistoliths from the Middle/Late Jurassic Meliaticum olistostrome yielded the latest Cambrian/earliest Ordovician (488 ± 6 Ma) and Middle Ordovician (~ 465 Ma) zircon ages. This is consistent with the U-Pb zircon ages from the foot-walling Southern Gemericum basement metavolcanites, which are, therefore, regarded as a potential source. The obtained zircon ages confirm the provenance from the Southern Gemericum basement and its Permian envelope for the Meliaticum-Bôrka Nappe and Turnaicum sedimentary embayment.

Research paper thumbnail of The geological composition of the hidden Wilhelm II Land in East Antarctica: SHRIMP zircon, Nd isotopic and geochemical studies with implications for Proterozoic supercontinent reconstructions

Precambrian Research

ABSTRACT In this paper we present new U − Pb zircon age, Sm–Nd isotopic and chemical composition ... more ABSTRACT In this paper we present new U − Pb zircon age, Sm–Nd isotopic and chemical composition data for rocks cropping out in a few isolated nunataks in Wilhelm II Land in East Antarctica, namely Mirny oasis, Mt Brown and Gaussberg volcano, which contains xenogenic crustal material. These outcrops were subjects of geological investigations during the Soviet Antarctic Expedition of 1956–1957. Our data show that this region is underlain by a uniform crust which experienced a high-grade metamorphic event at ca 980 − 920 Ma, co-eval with the Rayner Orogeny in Kemp Land and the northern Prince Charles Mountains. Extensive indications of a ca 500 Ma event in coastal areas (granitoid intrusions in Mirny oasis and inherited zircons found in Gaussberg volcano), together with the lack of indications of this age in Mt Brown, point to a concentration of ca 500 Ma processes (roughly co-eval with the Prydz Orogeny) in the coastal part of Wilhelm II Land and their attenuation inland. We also determined a ca 1480 Ma age for a mafic magmatic protolith in Mt Brown which may be correlated with roughly co-eval orthogneiss in the Bunger Hills area. These observations suggest the conjugate positions of these crustal blocks in the early Mesoproterozoic and argue against a Cambrian suture running between them. In Gaussberg volcano a range of zircon 206Pb/238U ages of ca 320 Ma, ca 500 Ma, ca 980 Ma, and ca 2000–1800 Ma has been determined. The presence of ca 2000–1800 Ma zircons indicates involvement of mid-Palaeoproterozoic rocks in the structure of Wilhelm II Land. This argues for possible conjugation of this region with other East Antarctic blocks experienced the Palaeoproterozoic tectonic evolution and which have been considered to comprise the Mawson palaeocontinent.

Research paper thumbnail of Archean metabasic rocks at the base of the Riphean of the Bashkirian Meganticlinorium (Southern Urals)

Research paper thumbnail of Refined geological history of the polyphase plutonometamorphic complex in the Thala Hills area (Enderby Land, East Antarctica) from zircon SHRIMP dating and implications for Neoproterozoic amalgamation of Gondwanaland

Geological Society, London, Special Publications

The Thala Hills area occupies a key position in Gondwanaland reconstructions near the India–Sri L... more The Thala Hills area occupies a key position in Gondwanaland reconstructions near the India–Sri Lanka–Antarctica junction. We present U–Pb zircon isotopic age determinations from SHRIMP II obtained on four granite gneiss samples. Three high-temperature tectonomagmatic episodes may be distinguished in the study area at c. 980–970, c. 780–720 and c. 545–530 Ma. The c. 980–970 Ma event corresponds to the Rayner Structural Episode that affected East Antarctica, including the Sør Rondane Mountains to the west and Kemp Land to the east. The c. 780–720 Ma episode included two events at approximately 780 Ma (high-grade anatexis) and 720 Ma (syntectonic granitoid emplacement), and was roughly coeval with tectonomagmatic events in Dronning Maud Land of East Antarctica, as well as in other Gondwanaland regions, such as Madagascar, Sri Lanka and eastern Africa. The c. 780–720 Ma episode may be correlated with the East African Orogeny. These correlations argue for a similar geological evolution ...

Research paper thumbnail of New zircon ages on the Cambrian–Ordovician volcanism of the Southern Gemericum basement (Western Carpathians, Slovakia): SHRIMP dating, geochemistry and provenance

International Journal of Earth Sciences, 2016

The Southern Gemericum basement in the Inner Western Carpathians, composed of low-grade volcano-s... more The Southern Gemericum basement in the Inner Western Carpathians, composed of low-grade volcano-sedimentary rock complexes, constitutes a record of the polyphase Cambrian–Ordovician continental volcanic arc volcanism. These metavolcanic rocks are characterized by the enrichment in K, Rb, Ba, Th and Ce and Sm relative to Ta, Nb, Hf, Zr, Y and Yb that are the characteristic features for volcanic arc magmatites. The new SHRIMP U–Pb zircon data and compilation of previously published and re-evaluated zircon ages, contribute to a new constrain of the timing of the Cambrian–Ordovician volcanism that occurred between 496 and 447 Ma. The following peaks of the volcanic activity of the Southern Gemericum basement have been recognized: (a) mid-late Furongian at 492 Ma; (b) Tremadocian at 481 Ma; (c) Darriwilian at 464 Ma prolonged to 453 Ma within the early Upper Ordovician. The metavolcanic rocks are characterized by a high zircon inheritance, composed of Ediacaran (650–550 Ma), Tonian–Stenian (1.1–0.9 Ma), and, to a lesser extent, Mesoproterozoic (1.3 Ga), Paleoproterozoic (1.9 Ga) and Archaean assemblages (2.6 Ga). Based on the acquired zircon populations, it could be deduced that Cambrian–Ordovician arc crust was generated by a partial melting of Ediacaran basement in the subduction-related setting, into which old crustal fragments were incorporated. The ascertained zircon inheritances with Meso-, Paleoproterozoic and Archaean cores indicate the similarities with the Saharan Metacraton provenance.

Research paper thumbnail of U–Pb zircon ages from Permian volcanic rocks and tonalite of the Northern Veporicum (Western Carpathians)

Journal of Geosciences, 2016

U-Pb dating (SHRIMP) of magmatic zircons from the Northern Veporicum Permian volcanics of the Ľub... more U-Pb dating (SHRIMP) of magmatic zircons from the Northern Veporicum Permian volcanics of the Ľubietová Group yielded concordia ages of 273 ± 6 Ma and 279 ± 4 Ma. Both zircon ages correspond to the Cisuralian Epoch in the time span of Kungurian Stage. The 272 ± 4 Ma U-Pb zircon age, determined on the volcanic dyke cutting the neighbouring crystalline basement, belongs to the same stratigraphic range. The acquired age data support a contemporaneous origin of the Permian sedimentary basin with the volcanic event and the dyke formation in the crystalline basement. Based on the whole-rock geochemical composition, the studied volcanic rocks correspond to weakly alkaline suite (trachyandesite to rhyolite/dacite). They exhibit light rare earth elements enrichment (La N /Yb N = 9.5-17.7) and small negative or absent Eu anomalies (Eu/Eu* = 0.95 and 1.05 for the Permian volcanites and 0.73 for the volcanic dyke). Characteristic of these volcanites is the enrichment in Cs, Rb, Th, U, K and Pb and the depletion in Nb, Ta, Sr and Ti if compared with average primitive mantle composition. All the studied volcanic rocks have low Nb/Ta (0.29-0.38) and Nb/U (4.07 to 5.87) ratios, implying a crustal magmatic source. Based on the incompatible trace elements Ta, Th and Yb, the Permian volcanics as well as the volcanic dyke cutting the crystalline basement fall close to the boundary between active continental margin and the within-plate fields. The 358 ± 4 Ma magmatic zircon concordia age confirmed the Early Mississippian (Tournaisian) intrusion of the metatonalites in the Volchovo Valley, later blastomylonitized and covered by Permian siliciclastics.

Research paper thumbnail of U-Pb SHRIMP-II Baddeleyite and Zircon Dating of the Early Proterozoic Monchegorsk Layered Mafite-Ultramafite Complex (Kola Peninsula): Evidence of Synchronous Magmatism

Acta Geologica Sinica - English Edition, 2016

Research paper thumbnail of Zirconology of ultramafic rocks from the Vostochnotagilskii massif (Middle Urals)

Doklady Earth Sciences, 2014

441 The Vostochnotagilskii massif (VTM; also known as Krasnoural’skii) is one of the largest in t... more 441 The Vostochnotagilskii massif (VTM; also known as Krasnoural’skii) is one of the largest in the Middle and North Urals [1]. This massif occurs in the merid ian direction for >300 km (Fig. 1, the southern part of massif) and controls the Serovsko–Maukskii ophiolite complex separating the Tagil and Magnitogorsk paleo island arc zones. The massif is composed of dunite and harzburgite serpentinized to various degrees. Chrysotile serpentinite prevails in the central part intruded by gabbro diabase and granitoid dykes, whereas antigorite serpentinite predominates in the marginal zones. The exocontact zones of dykes are characterized by bimetasomatic zoning with the for mation of vermiculite, chlorite–actinolite, talc, and talc–carbonate rocks. The freshest rock varieties are preserved in the central part of massif. Poor exposure does not provide unambiguous evidence for relation ships between dunite and harzburgite; according to the composition of chrome spinellids, ultramafic rocks form a continuous series [2]. At the same time, transi tional varieties between dunite and harzburgite were not found in the largest Kutuzovskii mine located at the latitude of Krasnoural’sk.

Research paper thumbnail of SHRIMP-II U-Pb dating of Zircons from Volcanic Ashes with the Early Paleolithic Artifacts (Karakhach locality, Armenia): New Evidence for the Earliest occupation of Eurasia (1.9 Ma)

Research paper thumbnail of New evidence for the early Archean evolution of Aker Peaks, Napier Mountains , Enderby Land (East Antarctica)

Zircons from charnockite-enderbite rocks (Aker Peaks, Napier Mountains), which we have dated by S... more Zircons from charnockite-enderbite rocks (Aker Peaks, Napier Mountains), which we have dated by SHRIMP-II, were analyzed earlier by conventional multigrain U-Pb ID-TIMS methods (Belyatsky et al., 1990) but gave equivocal ages. This study shows that the optimal way to evaluate geologic events in such rocks is local ion-probe analysis of complex zircons with preliminary study of CL, BSE, REE patterns. Due to this approach we have obtained, for the first time, reliable ages of magmatic crystallization for studied charnockite-enderbites (3620 ± 30 Ma) and the age of the primary enderbite’s protolith (3950 – 3970 Ma). Moreover, in all dated zircons a metamorphic event of 2450– 2480 Ma is clearly recorded that is in agreement with the granulite-facies metamorphism described by many authors. These conclusions coincide well with our Sm-Nd isotope data for these enderbite-charnockite gneisses.