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We report new estimates of the intensity of the geomagnetic field strength for the Permian–Triassic boundary. Amid predominantly low virtual dipole moment values for that time in the Global Paleointensity Database, episodes of increased VDM up to 8.9 × 1022 Am2 were recorded in the sections of the trap formation of the Kuznetsk depression, which do not conform to the Mesozoic Dipole Low concept. Analysis of data on changes in the value of the virtual dipole moment during the formation of the Siberian Large Igneous Province within the framework of modern magnetostratigraphic correlations indicates a persistently weak geomagnetic field only at the initial stage, when most of its Norilsk area was formed. A change in the geomagnetic mode is noted after ~800 thousand years at the level of subchron LT1n.1r (251.2–251.1 Ma) of the General Magnetostratigraphic Scale and was recorded in the basaltic andesite lava sheets of the Kuznetsk area. Low virtual dipole moment values from this time correspond to episodes of reversals, while the overall intensity was on average only slightly lower than today. Thus, the drop in paleointensity at the very beginning of the Triassic period was not caused by a major long-term change in the geodynamo, but was short-term and related to plume activity. [ABSTRACT FROM AUTHOR]

Data on the absolute value of the geomagnetic field intensity at the beginning of the Cretaceous Normal Superchron (C34n) was obtained from basalts of Hooker Island of the Franz Josef Land archipelago (FJL). These basalts are considered as one of the manifestations of the High Arctic Large Igneous Province. The record of the ancient geomagnetic field in the studied Early Cretaceous basalts was preserved well due to the presence of pseudo-single domain grains of primary magmatic titanomagnetite. The paleointensity, obtained by the Thellier–Coe method, satisfies the generally accepted reliability criteria, taking into consideration other necessary evidence. This information indicates that 125 Ma, during the formation of the FJL traps, the intensity of the geomagnetic field was four times lower than today. Our estimates show that the mean value of the virtual dipole moment was 1.7 × 1022 Am2. These results support the views about the low paleointensity at the Barremian–Aptian boundary and indicate a correlation between the intensity of the geomagnetic field, the frequency of reversals, and the formation of mantle plumes. [ABSTRACT FROM AUTHOR]

Here we present reconstructions indicating the stationary position and paleogeography of the Iceland plume, as well as its direct connection to the Mesozoic–Cenozoic large igneous provinces of the northern Atlantic and the Arctic. The main evidence for the stationary position of the Iceland hotspot comes from paleomagnetic data for the trap formation of the Franz Josef Land archipelago. Our reconstructions show that the Barents Sea magmatic province included in these traps belongs to the trace of the Iceland plume and formed as part of the High Arctic Large Igneous Province during a single relatively brief event ca. 125 Ma. Older pulses of basaltic magmatism inferred previously for the Franz Josef Land archipelago for the Early and Middle Jurassic period do not have known analogs in adjacent territories of the present-day Arctic. [ABSTRACT FROM AUTHOR]

The paper presents new 40Ar/39Ar age determination of basalts from the Franz Josef Land archipelago. The obtained set of dates confirms the predominance of products only of Early Cretaceous age, which is also confirmed by results of paleomagnetic studies. Analysis of the entire set of geochronological data, taking into account information on their magnetic polarity, indicates that the interval of active magmatism occurred at the latest Barremian–Aptian and corresponds to the beginning of the Cretaceous Normal Superchron (C34n) at about 125 Ma. Significantly older age estimates are not related to the time of formation of the FJL basalts as a part of the High Arctic Large Igneous Province. [ABSTRACT FROM AUTHOR]

The work presents the first results on the anisotropy of magnetic susceptibility in Hooker Island basaltoids; this anisotropy is related to the direction of motion of the melt, the location of eruption centers, and the morphology of igneous bodies. The peculiarities of the primary magnetic fabric revealed correspond to a trap mechanism of formation of the Franz Josef Land igneous province and reflect the simultaneous effect of multiple small eruption centers. Earlier conclusions about the long-term (during the Early Jurassic–Early Cretaceous) multistage magmatism history have not been supported. [ABSTRACT FROM AUTHOR]