Paleomagnetism of the Late Cretaceous ignimbrite from the Okhotsk-Chukotka Volcanic Belt, Kolyma-Omolon Composite Terrane: Tectonic implications

New species Sequoia ochotica Yudova et Golovn. (Pinopsida, Cupressaceae) from the Turonian-Coniacian deposits of the Arman and Chingandzha Formations of the Okhotsk-Chukotka volcanic belt is described based at morphological features of leaves and shoots. Two other Late Cretaceous species of this genus: S. minuta Sveshn. from the Vilyui River basin of Eastern Siberia and S. tenuifolia (Schmalh.) Sveshn. et Budants. from the New Siberian Islands have comparable shoot morphology, but these species were described based at epidermal features.

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New Paleomagnetic Data on Late Cretaceous Chukotka Volcanics: the Chukotka Block Probably Underwent Displacements Relative to the North American and Eurasian Plates after the Formation of the Okhotsk-Chukotka Volcanic Belt?

Izvestiya Physics of the Solid Earth ◽

10.1134/s1069351321020014 ◽

2021 ◽

Vol 57 (2) ◽

pp. 232-246

Author(s):

I. E. Lebedev ◽

P. L. Tikhomirov ◽

A. M. Pasenko ◽

B. Eid ◽

F. Lhuillier ◽

...

Keyword(s):

Late Cretaceous ◽

North American ◽

Volcanic Belt ◽

Paleomagnetic Data ◽

The North ◽

Chukotka Volcanic Belt

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Amplitude of paleosecular variations during the Cretaceous superchron: Okhotsk-Chukotka Volcanic Belt, high latitudes

10.5194/egusphere-egu21-13171 ◽

2021 ◽

Author(s):

Elizaveta Bobrovnikova ◽

Ivan Lebedev

Keyword(s):

Late Cretaceous ◽

Geomagnetic Field ◽

Volcanic Belt ◽

Time Interval ◽

High Latitudes ◽

Magnetic Minerals ◽

Geological Time ◽

Russian Science ◽

Virtual Geomagnetic Pole ◽

Chukotka Volcanic Belt

Studying of paleosecular variations (PSV) over geological time allows us to characterize not only the behavior and evolution of the geomagnetic field, but also to estimate the rate of formation of large igneous provinces (LIP). In order to use this paleomagnetic tool, the amplitude of paleosecular variations during the corresponding time interval has to be known, but for the end of the Cretaceous superchron, in particular for high latitudes, such the data sets are extremely small. Our study is aimed at obtaining a limit on the PSV amplitude for Late Cretaceous in order to use these data to estimate the rate of formation of the Okhotsk-Chukotka Volcanic Belt.The formation of a paleomagnetic record in volcanic flows occurs by acquiring a thermal remanent magnetization (TRM) during their cooling below the Curie temperature of the magnetic minerals. Direction of this TRM can be used for calculation of the virtual geomagnetic pole (VGP), which characterizes the direction of the geomagnetic field at a given time and place. The angular dispersion of virtual geomagnetic poles (VGP scatter, Sb) is generally accepted as a measure of the paleosecular variations and uses to assess the duration of volcanic section formation. If the volcanic section was formed for a long time (more than 10 000 years), then the amplitude of the recorded geomagnetic variations will correspond to the expected dispersion for a given latitude. In the case of significantly higher eruption rates, the amplitude of the recorded PSV will be lower than it is predicted by the model for a given latitude.During the 2019-2020 field seasons paleomagnetic studies were carried out on a number of Late Cretaceous volcanic sections of the Okhotsk-Chukotka Volcanic Belt located in the Bilibinsky District of the Chukotka Region. VGPs and their scatter were calculated for 79 flows of the Kupol object. Preliminary results show that the amplitude of PVS in the Cretaceous for high latitudes of the northern hemisphere was close to that for the last 5 million years (Sb=21.4, [19.0; 23.9]).The work is supported by the Russian Science Foundation grant N 19-47-04110.

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The Chingandzha flora of the Okhotsk-Chukotka volcanic belt

Palaeobotany ◽

10.31111/palaeobotany/2019.10.13 ◽

2019 ◽

Vol 10 ◽

pp. 13-179

Author(s):

L. B. Golovneva

Keyword(s):

River Basin ◽

Volcanic Belt ◽

Flowering Plants ◽

Sedimentary Deposits ◽

North East ◽

The North ◽

Magadan Region ◽

Chukotka Volcanic Belt ◽

Systematic Composition ◽

Coastal Lowlands

The Chingandzha flora comes from the volcanic-sedimentary deposits of the Chingandzha Formation (the Okhotsk-Chukotka volcanic belt, North-East of Russia). The main localities of the Chingandzha flora are situated in the Omsukchan district of the Magadan Region: on the Tap River (basin of the middle course of the Viliga River), on the Kananyga River, near the mouth of the Rond Creek, and in the middle reaches of the Chingandzha River (basin of the Tumany River). The Chingandzha flora includes 23 genera and 33 species. Two new species (Taxodium viligense Golovn. and Cupressinocladus shelikhovii Golovn.) are described, and two new combinations (Arctopteris ochotica (Samyl.) Golovn. and Dalembia kryshtofovichii (Samyl.) Golovn.) are created. The Chingandzha flora consists of liverworts, horsetails, ferns, seed ferns, ginkgoaleans, conifers, and angiosperms. The main genera are Arctop teris, Osmunda, Coniopteris, Cladophlebis, Ginkgo, Sagenoptepis, Sequoia, Taxodium, Metasequoia, Cupressinocladus, Protophyllocladus, Pseudoprotophyllum, Trochodendroides, Dalembia, Menispermites, Araliaephyllum, Quereuxia. The Chingandzha flora is distinct from other floras of the Okhotsk-Chukotka volcanic belt (OCVB) in predominance of flowering plants and in absence of the Early Cretaceous relicts such as Podozamites, Phoenicopsis and cycadophytes. According to its systematic composition and palaeoecological features, the Chingandzha flora is similar to the Coniacian Kaivayam and Tylpegyrgynay floras of the North-East of Russia, which were distributed at coastal lowlands east of the mountain ridges of the OCVB. Therefore, the age of the Chingandzha flora is determined as the Coniacian. This flora is assigned to the Kaivayam phase of the flora evolution and to the Anadyr Province of the Siberian-Canadian floristic realm. The Chingandzha flora is correlated with the Coniacian Aleeky flora from the Viliga-Tumany interfluve area and with other Coniacian floras of the OCVB: the Chaun flora of the Central Chukotka, the Kholchan flora of the Magadan Region and the Ul’ya flora of the Ul’ya Depression.

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Mineralogy of the Svetloye epithermal district, Okhotsk-Chukotka volcanic belt, and its insights for exploration

Ore Geology Reviews ◽

10.1016/j.oregeorev.2021.104257 ◽

2021 ◽

pp. 104257

Author(s):

Tamara Yu. Yakich ◽

Yury S. Ananyev ◽

Alexey S. Ruban ◽

Roman Yu. Gavrilov ◽

Dmitry V. Lesnyak ◽

...

Keyword(s):

Volcanic Belt ◽

Chukotka Volcanic Belt

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Золотая минерализация штокового рудного поля (Магаданская область)

Bulletin of the North-East Science Center ◽

10.34078/1814-0998-2021-1-13-29 ◽

2021 ◽

pp. 13-29

Author(s):

A. N. Glukhov ◽

◽

M. I. Fomina ◽

E. E. Kolova ◽

◽

...

Keyword(s):

Volcanic Belt ◽

Rare Metal ◽

Geological Structure ◽

Physicochemical Conditions ◽

Epithermal Mineralization ◽

Ore Bodies ◽

Mineral Associations ◽

Rare Metal Mineralization ◽

Chukotka Volcanic Belt ◽

Formation Conditions

The authors briefly characterize the geology and structure of the Shtokovoye ore field attached to the area where the Khurchan-Orotukan zone of tectonic-magmatic activation overlays the structures of the Yana-Kolyma ore-bearing belt. Studied are mineral associations and physicochemical conditions of gold ore bodies, located both in granites and in hornfelsed sedimentary masses. By the main features of its geological structure, ore composition, and physicochemical formation conditions, the Shtokovoye ore field mineralization corresponds to the "depth" group of the gold-rare-metal formation, analogous to the Butarnoye, Basugunyinskiye, Dubach, and Nadezhda occurrences. Its ores are peculiar in the late epithermal mineralization, which is associated with the Okhotsk-Chukotka volcanic belt and overlays the sinaccretional gold-rare-metal mineralization.

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Tracking compositional changes within the High Arctic Large Igneous Province using zircon Hf isotopes from altered volcanic ash layers of the Sverdrup Basin, Canada

10.5194/egusphere-egu21-15074 ◽

2021 ◽

Author(s):

Michael Pointon ◽

Michael Flowerdew ◽

Peter Hülse ◽

Simon Schneider ◽

Ian Millar ◽

...

Keyword(s):

Late Cretaceous ◽

Volcanic Ash ◽

Volcanic Belt ◽

High Arctic ◽

Ellesmere Island ◽

Hf Isotope ◽

Large Igneous Province ◽

Volcanic Material ◽

Igneous Province ◽

Sverdrup Basin

During Late Cretaceous times the Sverdrup Basin, Arctic Canada, received considerable air-fall volcanic material. This is manifested as numerous centimetre- to decimetre-thick diagenetically altered volcanic ash layers (bentonites) that occur interbedded with mudstones of the Kanguk Formation. Previous research on bentonite samples from an outcrop section in the east of the basin (Sawtooth Range, Ellesmere Island) revealed two distinct volcanic sources for the bentonites: most of the bentonites analysed (n=9) are relatively thick (0.1 to 5 m), were originally alkaline felsic ashes, and were likely sourced from local volcanic centres on northern Ellesmere Island or the Alpha Ridge that were associated with the High Arctic Large Igneous Province (HALIP). Two thinner (<5 cm) bentonites with contrasting subalkaline geochemistry were also identified. These were inferred to have been derived from further afield, from volcanic centres within the Okhotsk-Chukotka Volcanic Belt, Russia.To better understand volcanism within the vicinity of the Sverdrup Basin during Late Cretaceous times, and further test the above interpretations, a larger suite of bentonite samples was investigated, drawing on samples from outcrop sections in the central and eastern Sverdrup Basin. Whole-rock geochemical analyses and combined zircon U-Pb age and Hf isotope analyses were undertaken. The vast majority of bentonites analysed to date have alkaline geochemistry and were likely sourced from proximal volcanic centres related to the HALIP. The combined U-Pb and Hf isotope data from these bentonites show a progression from evolved (-2 to 0) to moderately juvenile (+9 to +10) &#949;Hf(t) values between late Cenomanian and early Campanian times (c. 97&#8211;81 Ma). This is interpreted to record compositional change through time within the local HALIP magmatic system.

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