Problems of geological and isotopic age of the Okhotsk-Chukotsk Volcanogenic Belt (OCVB)

Belyi, V. F.

doi:10.1134/s086959380806004x

Cited by 19 publications

(8 citation statements)

References 3 publications

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“…). The correlation of ages derived by stratigraphy and different isotopic systems for the subduction system is still challenging and best summarized in Belyi (). Ages from 77 to 106 Ma are recognized, with an intensive pulse at 87 Ma (Akinin and Miller ).…”

Section: Discussionmentioning

confidence: 99%

“…This discontinuous Andean-type continental volcanic arc spans over 3000 km from the Sea of Okhotsk to the easternmost part of the Chukotka peninsula (e.g., Tikhomirov et al 2012). The correlation of ages derived by stratigraphy and different isotopic systems for the subduction system is still challenging and best summarized in Belyi (2008). Ages from 77 to 106 Ma are recognized, with an intensive pulse at 87 Ma (Akinin and Miller 2011).…”

Section: Is the El'gygytgyn Area Part Of The Okhotsk-chukotka Volcanimentioning

confidence: 99%

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Strontium and neodymium isotope systematics of target rocks and impactites from the El'gygytgyn impact structure: Linking impactites and target rocks

Wegner

Koeberl

2016

Meteorit & Planetary Scien

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The 3.6 Ma El'gygytgyn structure, located in northeastern Russia on the Chukotka Peninsula, is an 18 km diameter complex impact structure. The bedrock is formed by mostly high‐silica volcanic rocks of the ~87 Ma old Okhotsk‐Chukotka Volcanic Belt (OCVB). Volcanic target rocks and impact glasses collected on the surface, as well as drill core samples of bedrock and impact breccias have been investigated by thermal ionization mass spectrometry (TIMS) to obtain new insights into the relationships between these lithologies in terms of Nd and Sr isotope systematics. Major and trace element data for impact glasses are added to compare with the composition of target rocks and drill core samples. Sr isotope data are useful tracers of alteration processes and Nd isotopes reveal characteristics of the magmatic sources of the target rocks, impact breccias, and impact glasses. There are three types of target rocks mapped on the surface: mafic volcanics, dacitic tuff and lava of the Koekvun’ Formation, and dacitic to rhyolitic ignimbrite of the Pykarvaam Formation. The latter represents the main contributor to the impact rocks. The drill core is divided into a suevite and a bedrock section by the Sr isotope data, for which different postimpact alteration regimes have been detected. Impact glasses from the present‐day surface did not suffer postimpact hydrothermal alteration and their data indicate a coherent alteration trend in terms of Sr isotopes with the target rocks from the surface. Surprisingly, the target rocks do not show isotopic coherence with the Central Chukotka segment of the OCVB or with the Berlozhya magmatic assemblage (BMA), a late Jurassic felsic volcanic suite that crops out in the eastern part of the central Chukotka segment of the OCVB. However, concordance for these rocks exists with the Okhotsk segment of the OCVB. This finding argues for variable source magmas having contributed to the build‐up of the OCVB.

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Section: Discussionmentioning

confidence: 99%

Section: Is the El'gygytgyn Area Part Of The Okhotsk-chukotka Volcanimentioning

confidence: 99%

Strontium and neodymium isotope systematics of target rocks and impactites from the El'gygytgyn impact structure: Linking impactites and target rocks

Wegner

Koeberl

2016

Meteorit & Planetary Scien

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“…The upper age limit refers to the upper Cretaceous-Santonian or possibly to the Campanian beginning. The duration of the formation was approximately 25 million years [57][58][59]. According to V.F.…”

Section: Geological Settingmentioning

confidence: 99%

“…The largest one here is the Dukat Au-Ag OFS. The OCVB and the Balygychan-Sugoy trough's detailed structural, geological and metallogenic characteristics have been considered in several works, for example [3,[57][58][59][60][61][62][63][64][65][66][67][68][69][70]. The OCVB tectonic and metallogenic zoning scheme (1-4).…”

Section: Geological Settingmentioning

confidence: 99%

Lithochemical Stream Sediments of the Dukat Gold–Silver Ore-Forming System (North–East of Russia)

2019

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The composition, structure and formation features of the exogenous anomalous geochemical fields (AGFs) identified by lithochemical stream sediments (LSSs) are considered using the examples of the Dukat gold–silver ore-forming system and the deposit with the same name. The research was carried out in the Balygychan–Sugoy trough (Magadan region, north–east of Russia). Areal geochemical surveys on the 1:200,000 and 1:50,000 scales were conducted. Exogenous AGFs of basic element indicators of all known mineralization types were studied. It is shown that the surveys on the 1:200,000 scale are characterized by simplicity, relative depth and the possibility to obtain information operatively about the metallogeny of the area as a whole. At the same time, the anomalies were revealed as a result of surveys often making a relatively poor component composition and low contrast compared with ores. The violation of quantitative and sometimes qualitative relationships can be seen between elements, especially those related to gold–silver mineralization. In this situation, the most informative are surveys of LSSs on the 1:50,000 scale. The AGFs were revealed as a result of their performance to have a richer component composition and high contrast, conforming to different ore types. It is shown that, while prospecting for gold–silver mineralization with LSSs in cryolithogenesis zone conditions, the binding forms study of mineralization element indicators is effective. In watercourse heads, where alluvium is practically absent, mosses are proposed for sampling, as they hold the sandy silt material firmly. The obtained results are recommended for use at all stages of prospecting, not only in the north–east of Russia but also in other similar climatic regions.

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“…Structurally, the deposit is located in the central part of the Okhotsk-Chukotski volcanogenic belt, a major Cretaceous volcano-tectonic structure of superimposed type, formed within a short period of time (Middle Albian-Lower Cenomanian) [17].…”

Section: Geological Settingmentioning

confidence: 99%

Contrasting Surficial Composition of Native Gold from Two Different Types of Gold Ore Deposits

et al. 2017

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Native gold grains sampled at two different gold ore deposits in Eastern Russia have been studied by the techniques of electron spectroscopy (X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES)), electron microprobe analysis (EMPA), and scanning electron microscopy with energy dispersive X-ray spectrometry (SEM-EDX). The high-fineness gold of the deposit hosted by relatively high temperature gold-quartz-sulfide mesothermal ore formation contains no oxidized Au constituents on grain surfaces, whereas the less fine gold of the epithermal Au-Ag deposit contains gold oxidized to the Au (I) state, or higher, in half of the cases. At this deposit the surface of native Au consists of a thin layer (~15 nm) with elevated Ag and S contents and an underlying SiO 2 -containing layer~30-60 nm thick. Such a composite coating can perform a protective function and prevent the gold-silver sulfides in surficial parts of AuAg grains from oxidation. The sulfur-enriched marginal parts of native gold particles do not always correlate with the stoichiometry of well-known binary AuAg-sulfides and have a variable composition. This may be due to the existence of solid solutions, Ag 2−x Au x S, if there is enough S or S adsorption-stabilized cluster agglomerates, Ag n Au m S, under sulfur deficit. The effect of the formation of nano-scale surficial zonality on the surface of native gold is quite common in nature and applicable to geological exploration and technology of gold-ore processing. It can facilitate establishing the geochemical environment and genetic type of Au mineralization.

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Problems of geological and isotopic age of the Okhotsk-Chukotsk Volcanogenic Belt (OCVB)

Cited by 19 publications

References 3 publications

Strontium and neodymium isotope systematics of target rocks and impactites from the El'gygytgyn impact structure: Linking impactites and target rocks

Strontium and neodymium isotope systematics of target rocks and impactites from the El'gygytgyn impact structure: Linking impactites and target rocks

Lithochemical Stream Sediments of the Dukat Gold–Silver Ore-Forming System (North–East of Russia)

Contrasting Surficial Composition of Native Gold from Two Different Types of Gold Ore Deposits

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