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?

Lebedev, Ivan; Тихомиров, П. Л.; Pasenko, A. M.; Eid, B.; Lhuillier, Florian; Павлов, В. Е.

doi:10.1134/s1069351321020014

Cited by 5 publications

(13 citation statements)

References 32 publications

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“…The weighted‐mean age of 87.2 ± 1.65 Ma indicates that the investigated lava flows were emplaced at the termination of CNS (121–84 Ma; Ogg, 2020). These flows, with well‐constrained paleodirections of normal polarity (Figure 2a), were emplaced at paleolatitude of 80.5° ± 4.9°N and are representative of a stable state of the geodynamo (Lebedev et al., 2021).…”

Section: Discussionmentioning

confidence: 98%

“…Therefore, in this paper, due to the complexity of interpolating the available ages, we computed a weighted average age of 87.02 ± 1.65 Ma based on the four U-Pb ages and valid for all studied flows in this area. Paleomagnetic directions, successfully obtained for 74 out of 79 flows, indicate that the flows were emplaced in high polar latitudes (∼81°N; Lebedev et al, 2021). Characteristic remanent magnetization (ChRM) was unambiguously determined by principal component analysis (Kirschvink, 1980) after the removal of a secondary component by heating to 150°C-200°C in most cases.…”

Section: Geology and Samplingmentioning

confidence: 92%

“…(a) Paleomagnetic directions obtained by Lebedev et al. (2021); (b) Day diagram with single‐domain (SD)/multidomain (MD) mixing lines defined by Dunlop (2002). (c, e, g, i) Thermomagnetic curves M S (T) of the saturation magnetization up to 600°C showing heating (red bold lines) and cooling (blue thin lines) branches.…”

Section: Settings and Methodsmentioning

confidence: 99%

“…The area of our research is located in the north‐western part of Chukotka (NE Russia) on the border of the Anadyr and Central Chukotka segments of the OCVB (Figure 1a)—the largest marginal continental magmatic province extending for more than 3,000 km along the Pacific margin of Asia (e.g., Akinin & Miller, 2011; Tikhomirov et al., 2012). To the northeast of the Kupol gold deposit (66.9°N, 170.1°E), in the upper reaches of the Malyi Anyui River, we sampled 79 sites from seven distinct sections during two field campaigns in summers 2019 and 2020 (Lebedev et al., 2021; Tikhomirov et al., 2021). Each site was identified to be an independent basaltic flow with horizontal or subhorizontal occurrence (from 0° to 12°) of volcanogenic covers, usually controlled by paleorelief and elements of compensatory immersion structures.…”

Section: Settings and Methodsmentioning

confidence: 99%

“…To the northeast of the Kupol gold deposit (66. 9°N, 170.1°E), in the upper reaches of the Malyi Anyui River, we sampled 79 sites from seven distinct sections during two field campaigns in summers 2019 and 2020 (Lebedev et al, 2021;Tikhomirov et al, 2021). Each site was identified to be an independent basaltic flow with horizontal or subhorizontal occurrence (from 0° to 12°) of volcanogenic covers, usually controlled by paleorelief and elements of compensatory immersion structures.…”

Section: Geology and Samplingmentioning

confidence: 99%

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High‐Latitude Paleointensities During the Cretaceous Normal Superchron From the Okhotsk–Chukotka Volcanic Belt

et al. 2022

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We conducted an absolute paleointensity survey on 74 lava flows from the Okhotsk–Chukotka Volcanic Belt (NE Russia), emplaced 90–83 Ma toward the end of the Cretaceous Normal Superchron (CNS, 121–84 Ma). Relying on preliminary results, we restricted our analysis to eight lava flows (140 Thellier–Coe experiments), two of which also yielded successful Wilson determinations. A detailed analysis of the magneto‐mineralogy—based on X‐ray structural analysis, reflected‐light microscopy, and thermomagnetic curves—indicates that the determinations from solely two lava flows can be fully trusted, with remanence carriers (a) dominated by low‐titanium titanomagnetite, (b) showing unambiguous traces of high‐temperature oxidation, and (c) yielding partial thermoremanent magnetization (pTRM) tails representative of pseudo‐single‐domain grains. Recalculated in terms of geomagnetic dipole strength, our two successful flow‐mean determinations yield virtual dipole moments of 4.76 ± 0.26 × 1022 Am2 (N = 7) and 9.07 ± 0.84 × 1022 Am2 (N = 8). Using an updated version of the paleointensity database for the Cretaceous epoch, we stress that determinations based on nonglassy whole rocks, submarine basaltic glasses, and single crystals are mutually inconsistent, suggesting a separate analysis of their distributions is more appropriate. Despite statistically indistinguishable estimates of dipole strength before and after the onset of the CNS—in accord with recent studies refuting the existence of a strict correlation between chron duration and dipole moment—we found that the distribution of dipole moments during the CNS is slightly bimodal with a leptokurtic dominant mode, thus more inclined to produce outliers and suggesting distinct geomagnetic field behavior during the CNS.

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Section: Discussionmentioning

confidence: 98%

Section: Geology and Samplingmentioning

confidence: 92%

Section: Settings and Methodsmentioning

confidence: 99%

Section: Settings and Methodsmentioning

confidence: 99%

Section: Geology and Samplingmentioning

confidence: 99%

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High‐Latitude Paleointensities During the Cretaceous Normal Superchron From the Okhotsk–Chukotka Volcanic Belt

et al. 2022

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A Global Paleosecular Variation Database for the Paleogene: Stationary Secular Variation Behavior Since the Triassic?

Engbers,

Thallner,

Bono

et al. 2024

Geochem Geophys Geosyst

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Paleosecular variation analysis is a primary tool for characterizing ancient geomagnetic behavior and its evolution through time. This study presents a new high‐quality directional data set, paleosecular variation of the Paleogene (PSVP), with and without correction for serial correlation, compiled from 1,667 sites from 45 different localities from the Paleogene and late Cretaceous (84–23 Ma). The data set is used to study the variability, structure, and latitude dependence of the geomagnetic field during that period by varying selection criteria and PSV models. Modeled values for the equatorial virtual geomagnetic pole (VGP) dispersion have over‐lapping uncertainty intervals within their uncertainty bounds between 8.3° and 18.6° for the past 250 Ma. We investigate the suitability of two descriptive models of PSV, Model G‐style quadratic fits and covariant Giant Gaussian Process models, and find that both styles of model fail to satisfactorily reproduce the latitude dependent morphology of PSV, but suggest that estimates of the equatorial VGP dispersion may still robustly characterize aspects of Earth's long‐term field morphology. During this time where the PSV behavior has not changed substantially, the reversal frequency has varied widely. The lack of a clear relationship between PSV behavior and reversal frequency is not trivially explained in the context of published findings regarding numerical geodynamo simulations.

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High‐Latitude Geomagnetic Secular Variation at the End of the Cretaceous Normal Superchron Recorded by Volcanic Flows From the Okhotsk‐Chukotka Volcanic Belt

Lhuillier,

Lebedev,

Tikhomirov

et al. 2023

JGR Solid Earth

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The Cretaceous Normal Superchron (CNS, 84–121 Ma) is a singular period of the geodynamo's history, identified by a prolonged absence of polarity reversals. To better characterize the paleosecular variation (PSV) of the geomagnetic field at the end of this interval, we sampled seven continuous sequences of lava flows from the Okhotsk‐Chukotka Volcanic Belt, emplaced 84–89 Ma in the vicinity of the Kupol ore deposit (NE Russia). From a collection of 1,024 paleomagnetic cores out of 82 investigated lava flows, we successfully determined the paleodirections of 78 lava flows, which led to 57 directional groups after removing the serial correlations. The resulting paleomagnetic pole is located at 170.0°E, 76.8°N (A95 = 5.2°, N = 57), in good agreement with previous estimates for north‐eastern Eurasia. Aiming at quantifying PSV at a reconstructed paleolatitude (λ) of ∼80°N, we obtained a virtual geomagnetic pole (VGP) scatter , the value of which was corrected for within‐site dispersion and is little dependent on the choice of the selection criteria. Compared to previous paleodirectional data sets characterizing PSV at various paleolatitudes during the CNS, our Sb estimate confirms a relative latitudinal increase Sb(λ = 90°)/Sb(λ = 0°) on the order of 2–2.5. Focusing on PSV at high paleolatitude within the 70°–90° range, we show that Sb was ∼15% lower at the end of the CNS than during the past 10 Myr, confirming that the singular polarity regime of the geodynamo observed during the CNS is likely accompanied with reduced PSV.

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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?

Cited by 5 publications

References 32 publications

High‐Latitude Paleointensities During the Cretaceous Normal Superchron From the Okhotsk–Chukotka Volcanic Belt

High‐Latitude Paleointensities During the Cretaceous Normal Superchron From the Okhotsk–Chukotka Volcanic Belt

A Global Paleosecular Variation Database for the Paleogene: Stationary Secular Variation Behavior Since the Triassic?

High‐Latitude Geomagnetic Secular Variation at the End of the Cretaceous Normal Superchron Recorded by Volcanic Flows From the Okhotsk‐Chukotka Volcanic Belt

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