Search

Your search keyword '"paleomagnetic pole"' showing total 15 results
Start Over Descriptor "paleomagnetic pole" Search Limiters Full Text
15 results on '"paleomagnetic pole"'

1. Paleomagnetic dating of rocks of the Bolshesyrsky magmatic area of the Minusinsky basin

Author

D.V. Kovalenko and M.V. Buzina

Subjects
paleomagnetic pole, plume, magnetization, paleolatitude, magnetic field, Geology, QE1-996.5
Abstract

Paleomagnetic dating of the Bolshesyrsky igneous area, a thick intraplate igneous complex of Khakassia, was carried out. The complex has not been dated due to the peculiarities of the stratigraphy and the lack of suitable rocks for applying the methods of absolute geochronology. The use of the paleomagnetic method has shown that the paleomagnetic pole of the red beds, which are intruded by sills and dikes of the Bolshesyrsky area, is close to the Silurian paleomagnetic poles of Siberia and Tuva and differs sharply from the Ordovician paleomagnetic poles of these areas. That is, red-colored rocks are Silurian, and subvolcanic rocks are post-Silurian. The sharp unconformable overlapping of the red-colored and volcanic strata with the Middle Devonian sedimentary trough without igneous rocks indicates that the age of the Bolshesyrsky complex is limited to the Silurian-Early Devonian interval. The genesis of the rocks of the Bolshesyrsky magmatic area was associated with the activity of the Early Devonian Minusinsk plume.

Published
2024
Full Text
View/download PDF

2. Paleomagnetism of the Permian-Triassic Boundary of the Orenburg Region (East European Platform, Volga-Ural Anteclise)

Author

A. M. Fetisova, R. V. Veselovskiy, and V. K. Golubev

Subjects
paleomagnetism, east european platform, permian, triassic, paleomagnetic pole, orenburg region, Science
Abstract

This article presents the results of a detailed paleomagnetic study of five sections of the Permian-Triassic sedimentary rocks from the southeastern part of the Volga-Ural anteclise in the East European Platform (Orenburg region, Russia): Boevaya Gora, Vyazovka, Sambulak, Krasnogor, and Vozdvizhenka. The magnetic fabric determined by magnetic susceptibility anisotropy indicates that the rocks accumulated under the conditions of intense hydrodynamic activity. This makes it possible to reconstruct a predominantly submeridional transport of detrital material. The rocks of the Boevaya Gora section have a bipolar distribution of the characteristic component of their remanent magnetization, while other sections show a reversed polarity. In the Vyazovka section, the E/I method was used to calculate the inclination shallowing coefficient of the rocks (f = 0.79). The regional fold test yielded positive results, suggesting that the rocks of the studied sections were displaced after the deposition. For each section, paleomagnetic poles were calculated, with the poles of the Boevaya Gora and Vyazovka sections being the most reliable. The mean paleomagnetic pole coordinates of the studied sections, except the Sambulak section, are as follows: slat = 51.7°, slong = 55.8°, n = 4, plat = 48.5°, plong = 173.4°, α95 = 3.4°, paleolat = 23.4°.

Published
2024
Full Text
View/download PDF

3. Paleomagnetism of the Great Dyke of the Kola Peninsula (2.68 Ga): New Evidence of Ultra-Low Paleointensity of the Earth’s Magnetic Field in the Late Archean

Author

V. V. Shcherbakova, R. V. Veselovskiy, G. V. Zhidkov, N. A. Aphinogenova, A. V. Samsonov, A. V. Stepanova, and M. A. Smirnov

Subjects
archean, great dyke of the kola peninsula, paleomagnetic pole, paleointensity, thellier–coe method, Science
Abstract

Giant mafic dykes are the key markers of the Earth’s evolution in the Precambrian and have been the subject of extensive research. This article presents the results of the paleomagnetic, rock-magnetic, and paleointensity Banc studies of the Great Dyke of the Kola Peninsula (2.68 Ga). The mean paleomagnetic direction of the characteristic magnetization component and the paleomagnetic pole of the Murmansk craton were calculated using the data from 5 sites (n = 41 samples): D = 117.6°, I = 77.1°, K = 40.9, α95 = 12.1°, slat = 69.265°, slong = 34.35447°, plat = 51.5°, plong = 70.7°, dp/dm = 21.1°/22.6°, and paleolat = 65°. The rocks under study were thoroughly examined for their thermomagnetic properties, revealing that the main carriers of remanent magnetization are single-domain or small pseudo–single-domain (group A) or multidomain (group B) magnetite. The paleointensity values Banc = (6.16 ± 0.92) μT were obtained for 12 samples from group A by the Thellier–Coe method. The corresponding mean virtual dipole moment VDM2.68Ga = (0.85 ± 0.13)×1022 Am2 was determined. These new findings align with previous results on the Archean and Proterozoic objects, indicating that the Earth’s magnetic field was remarkably weak in the Late Archean.

Published
2024
Full Text
View/download PDF

4. INFLUENCE OF ORIENTATION ERRORS ASSOCIATED WITH THE USE OF A MAGNETIC COMPASS ON THE ACCURACY OF DETERMINING THE POSITION OF THE PALEOMAGNETIC POLE AND THE AMPLITUDE OF PALEOSECULAR VARIATIONS

Author

D. A. Ushakov, I. E. Lebedev, and V. E. Pavlov

Subjects
paleomagnetism, paleomagnetic pole, paleomagnetic samples, magnetic compass, orientation error, geomagnetic field, statistical model, mathematical modeling, paleosecular variations, Science
Abstract

The use of a magnetic compass in paleomagnetic studies of highly magnetic rocks (for instance, basalts) can lead to large errors in the orientation of paleomagnetic samples. On the other hand, alternative methods of orientation are relatively time-consuming, and in the case of using a solar compass, they also require sunny weather – a condition that is rarely met, especially when sampling at high and subpolar latitudes. This often leads to the fact that researchers in their work rely on the results of magnetic compass measurements, while assuming that the resulting errors are of a random nature and, with sufficiently good statistics, are averaged. In this study, numerical modeling is performed, which allows us to verify this assumption and assess how much orientation errors associated with the use of a magnetic compass can affect the final results of paleomagnetic studies, such as determining the position of the paleomagnetic pole and the amplitude of ancient geomagnetic variations. As a result of the work performed , it is shown that: 1) the amplitudes of paleosecular variations and the positions of paleomagnetic poles are weakly sensitive to moderate and even relatively large errors in the orientation of paleomagnetic samples associated with the use of a magnetic compass; 2) very large errors in the orientation of samples lead to a significant increase in the within-site scatter of paleomagnetic directions, which makes it possible to detect and exclude the corresponding sites with a large (for instance >15°) value of the α95; 3) the influence of distortions associated with the use of a magnetic compass on the accuracy of determining the position of the paleomagnetic pole and the amplitude of ancient geomagnetic variations depends on latitude. At near-equatorial latitudes, this effect is maximal, at medium latitudes – minimal.

Published
2024
Full Text
View/download PDF

5. A New 254 Ma Paleomagnetic Pole of the East European Platform: The Moscow Syneclise, the Sukhoborka and Sosnovka Sections.

Author

Fetisova, A. M., Veselovskiy, R. V., and Golubev, V. K.

Subjects
*RED beds, *RIPARIAN areas, *MAGNETIZATION
Abstract

The results of paleomagnetic and rock magnetic studies of the upper Permian red beds from the Sukhoborka and Sosnovka sections of the south-eastern of the Moscow syneclise on the right bank of the Vetluga River in Nizhny Novgorod Region, Russia, are presented. The arguments in favor of the primary nature of the characteristic magnetization component are indicated. The first late Permian (254 Ma) paleomagnetic pole dated precisely for the sedimentary Permian–Triassic complex in the eastern part of the East European Platform is calculated: 56.731° N, 45.748° E, N = 44, plat = 55.3°, plong = 158.1°, dp/dm = 3.5°/5.1°, paleolat = 34.6°. [ABSTRACT FROM AUTHOR]

Published
2023
Full Text
View/download PDF

6. A global apparent polar wander path for the last 320 Ma calculated from site-level paleomagnetic data

Author

Vaes, Bram, van Hinsbergen, Douwe J.J., van de Lagemaat, Suzanna H.A., van der Wiel, Erik, Lom, Nalan, Advokaat, Eldert L., Boschman, Lydian M., Gallo, Leandro C., Greve, Annika, Guilmette, Carl, Li, Shihu, Lippert, Peter C., Montheil, Leny, Qayyum, Abdul, Langereis, Cor G., Vaes, Bram, van Hinsbergen, Douwe J.J., van de Lagemaat, Suzanna H.A., van der Wiel, Erik, Lom, Nalan, Advokaat, Eldert L., Boschman, Lydian M., Gallo, Leandro C., Greve, Annika, Guilmette, Carl, Li, Shihu, Lippert, Peter C., Montheil, Leny, Qayyum, Abdul, and Langereis, Cor G.

Abstract

Apparent polar wander paths (APWPs) calculated from paleomagnetic data describe the motion of tectonic plates relative to the Earth's rotation axis through geological time, providing a quantitative paleogeographic framework for studying the evolution of Earth's interior, surface, and atmosphere. Previous APWPs were typically calculated from collections of paleomagnetic poles, with each pole computed from collections of paleomagnetic sites, and each site representing a spot reading of the paleomagnetic field. It was recently shown that the choice of how sites are distributed over poles strongly determines the confidence region around APWPs and possibly the APWP itself, and that the number of paleomagnetic data used to compute a single paleomagnetic pole varies widely and is essentially arbitrary. Here, we use a recently proposed method to overcome this problem and provide a new global APWP for the last 320 million years that is calculated from simulated site-level paleomagnetic data instead of from paleopoles, in which spatial and temporal uncertainties of the original datasets are incorporated. We provide an updated global paleomagnetic database scrutinized against quantitative, stringent quality criteria, and use an updated global plate motion model. The new global APWP follows the same trend as the most recent pole-based APWP but has smaller uncertainties. This demonstrates that the first-order geometry of the global APWP is robust and reproducible. Moreover, we find that previously identified peaks in APW rate disappear when calculating the APWP from site-level data and correcting for a temporal bias in the underlying data. Finally, we show that a higher-resolution global APWP frame may be determined for time intervals with high data density, but that this is not yet feasible for the entire 320–0 Ma time span. Calculating polar wander from site-level data provides opportunities to significantly improve the quality and resolution of the global APWP by collectin

Published
2023

7. On pole position: new approaches to quantifying polar wander and relative paleomagnetic displacements

Author

Vaes, Bram and Vaes, Bram

Abstract

Paleomagnetism provides the only quantitative tool to reconstruct the position and motion of tectonic plates and continents in deep geological time. These reconstructions often rely on apparent polar wander paths (APWPs), which describe the past position and motion of plates relative to the Earth’s spin axis. In addition to providing a paleomagnetic reference frame for paleogeography, these paths serve to quantify relative tectonic displacements with other lithospheric blocks. A long-discussed problem is that conventional approaches to computing polar wander do not propagate key sources of uncertainty in the underlying data, such as data scatter or age uncertainty, but proposed solutions remained mostly qualitative. Recently, this problem became more urgent: Rowley (2019, Tectonics) showed that as much as 50% of the data that underlie the currently most widely used global APWP are statistically significantly displaced relative to that APWP. This implies that the resolution at which a geologically meaningful statistical difference between a paleomagnetic dataset and an APWP may be determined, is strongly limited, which undermines the current tectonic and paleogeographic applications of paleomagnetism. This thesis aims to examine the causes of dispersion of paleomagnetic data behind APWPs and to build a global APWP in which key data uncertainties are propagated, such that it may be used to determine geologically meaningful relative displacements. We show that the uncertainty of APWPs computed from paleomagnetic poles, which is the current standard, is mostly determined by the arbitrary choice of how many datapoints are used per pole. This thesis then develops a novel approach in which apparent polar wander paths are computed from site-level paleomagnetic data instead of paleomagnetic poles. In this approach, larger weight is assigned to larger datasets and temporal and spatial uncertainties in the paleomagnetic data are incorporated. We present a global apparent polar

Published
2023

8. On Pole Position: Causes of Dispersion of the Paleomagnetic Poles Behind Apparent Polar Wander Paths

Author

Vaes, Bram, Gallo, Leandro C., van Hinsbergen, Douwe J.J., Vaes, Bram, Gallo, Leandro C., and van Hinsbergen, Douwe J.J.

Abstract

Paleomagnetic poles used to compute apparent polar wander paths (APWPs) are strongly dispersed, which was recently shown to cause a large fraction (>50%) of these poles to be statistically distinct from the APWP to which they contributed, suggesting that current statistical approaches overestimate paleomagnetic resolution. Here, we analyze why coeval paleopoles are so dispersed, using the paleopoles behind the most recent global APWP and a compilation of paleomagnetic data obtained from <10 Ma volcanic rocks (PSV10). We find that paleopoles derived from sedimentary rocks, or from data sets underrepresenting paleosecular variation (PSV), are more dispersed and more frequently displaced. We show that paleopoles based on a smaller number of paleomagnetic sites are more dispersed than poles based on larger data sets, revealing that the degree to which PSV is averaged is an important contributor to the pole dispersion. We identify as a fundamental problem, however, that the number of sites used to calculate a paleopole, and thus the dispersion of coeval paleopoles, is essentially arbitrary. We therefore explore a different approach in which reference poles of APWPs are calculated from site-level data instead of paleopoles, thereby assigning larger weight to larger data sets. We introduce a bootstrap-based method for comparing a collection of paleomagnetic data with a reference data set on the same hierarchical level, whereby the uncertainty is weighted against the number of paleomagnetic sites. Finally, our study highlights that demonstrating smaller tectonic displacements requires larger paleomagnetic data sets, and that such data sets can strongly improve future APWPs.

Published
2022

9. Paleomagnetism of the Liassic member of the Zarzaïtine Formation (stable Saharan craton, Illizi basin, Algeria)

Author

B. Bayou, N. Merabet, B. Henry, M. E. M. Derder, and M. Amenna

Subjects
Africa, paleomagnetic pole, liassic, apparent polar wander path, sahara craton, Meteorology. Climatology, QC851-999, Geophysics. Cosmic physics, QC801-809
Abstract

A paleomagnetic study was carried out in the carbonates and marls of the Liassic member of the Zarzaïtine Formation of the Illizi basin (SE Algeria) deposited in a continental environment. Two magnetization components were identified. The first, defined at relatively low blocking temperature, was isolated in five sites, and yields the following paleomagnetic pole (80.8°N, 20.1°E, K = 811 and A 95 = 2.2°). This magnetization is considered an overprint acquired during Cenozoic times. The second component was defined by both normal and reversed polarity. The normal polarity was identified in fourteen sites using both linear regression and great circles. The reversed one was inferred in four sites from the remagnetization circle and demagnetization path analyses. This component is mainly (it could be in part the primary magnetization) a late diagenesis magnetic overprint. It yields a new Liassic pole (71.8°S, 54.9°E, K = 91 and A 95 = 3.9°) for Africa.

Published
2001
Full Text
View/download PDF

10. Study of the pre-cretaceous deformation in the Gastre region, southern north-patagonian massif

Author

Zaffarana, Claudia Beatriz and Somoza, Rubén

Subjects
POLO PALEOMAGNETICO, DEFORMACION DE ROCAS, ENCLAVES, EMPLAZAMIENTO DE GRANITOIDES, ANISOTROPY OF THE MAGNETIC SUSCEPTIBILITY, GRANITOID EMPLACEMENT, PALEOMAGNETIC POLE, ANISOTROPIA DE SUSCEPTIBILIDAD MAGNETICA, ROCK DEFORMATION, GASTRE
Abstract

El objetivo de esta tesis fue conocer el tipo y la edad de la deformación en la zona de Gastre, sector sur del Macizo Norpatagónico, donde se ha sugerido aflora la expresión de un sistema de fallas transcurrentes de escala intercontinental que habría controlado movimientos dextrales de gran magnitud entre el sur de Patagonia y la plataforma estable sudamericana. Se realizó un mapeo detallado de la estructura interna de las rocas intrusivas de la región (conocidas como Batolito de la Patagonia Central) combinando estudios petrográficos, microestructurales, de anisotropía de susceptibilidad magnética (ASM) y de magnetismo de rocas. Se propone que las mismas pueden dividirse en dos asociaciones de granitoides, donde la primera contiene enclaves máficos microgranulares y titanita como mineral accesorio y la segunda es intrusiva en la anterior y posterior al magmatismo máfico de la región. Se mantienen los nombres que les habían otorgado Rapela et al. (1992) (Superunidad Gastre para la unidad más antigua y Superunidad Lipetrén para la más joven), pero el criterio de clasificación de este trabajo es diferente. Asimismo, se caracterizó la mineralogía magnética de cada facies granítica. El mapeo de la estructura interna de las rocas permitió delinear la presencia de un angosto corredor estructuralsubvertical de foliaciones magmáticas de rumbo noroeste-sudeste con lineaciones magnéticas empinadas, someras e intermedias que es común a todas las litologías. Las áreas ubicadas afuera del lineamiento tienen fábrica magnética discordante. Los representantes del magma máfico en la región de Gastre adoptan la forma de enclaves, diques o pequeños stocks debido a la mezcla de magmas de diferente composición en diferentes estadíos de cristalización del magma félsico hospedante. Este proceso permitió también explicar algunas texturas de desequilibrio como oikocristales, xenocristales y cristales corroídos. Se describieron enjambres de enclaves monogénicos hasta ahora no mencionados en la literatura geológica de la zona. Los estudios de ASM en enclaves máficos y su roca hospedante indican que los enclaves constituyen marcadores pasivos de la deformación magmática. Se encontraron diques máficos con fábrica magnética anómala debido a la sobreimposición de deformación tectónica. Se describieron afloramientos de rocas de basamento que registran una foliación metamórfica previa al desarrollo de la foliación tectónica NO-SE subvertical. La deformación tectónica se concentra en afloramientos pequeños dispersos entre granitoides tectónicamente indeformados, y los planos de foliación tectónica y la lineación de estiramiento son altamente heterogéneos entre sí y con respecto al corredor. Se obtuvo un polo paleomagnético a partir de las rocas volcánicas jurásicas de la zona cuya ubicación coincide con la de otros polos de áreas estables de Sudamérica de similar edad, así que se descarta la posibilidad de grandes rotaciones tectónicas en el período Jurásico Temprano-reciente. Se concluye que el Sistema de Fallas de Gastre fue una estructura que controló el emplazamiento diacrónico de algunos cuerpos ígneos tabulares pertenecientes al Batolito de la Patagonia Central, y que también canalizó deformación subsólida post-emplazamiento, pero no fue una zona de movimientos transcurrentes de gran magnitud. Debe recurrirse a otros modelos para reconstruir la paleogeografía jurásica de Gondwana Occidental. The aim of this work was to explain the history of deformation in the Gastre Fault System, Central Patagonia. Some authors had proposed that this was an intercontinental strike-slip system that accommodated important dextral displacements in the Jurassic between the patagonian and the stable South American blocks. A detailed mapping of the internal structure of the granitoids of the region (the Central Patagonian Batholith) was performed combining petrographic, microstructural, anisotropy of the magnetic susceptibility (AMS) and rock magnetic studies. These granitoids can be divided in two groups: an older set of granitoids, which has mafic microgranular enclaves and titanite as an accessory mineral, and an intrusive set of granitoids which postdates the mafic magmatism of the region. The intrusive groups are still called Gastre Superunit and Lipetrén Superunit, because the names formerly given by Rapela et al. (1992) are kept, although the classification scheme of this work is different. The magnetic mineralogy of each granitoid facies was also characterized. The mapping of the internal structure of the magmatic rocks showed the existence of a narrow structural corridor of subvertical NW-SE foliation planes shared by all granitoid facies. Magnetic lineations inside this corridor are of shallow, subvertical and intermediate inclination. The areas outside the lineament have discordant magnetic fabric. The mafic magma in the Gastre region is represented by enclaves, dikes and small stocks; the different morphologies arise from magma mingling at different crystallization stages of the felsic magma host. Magma mingling also explains some disequilibrium textures such as oikocrysts, xenocrysts and crystal corrosion. Undescribed spectacular monogenic enclave swarms were found and described. AMS studies of mafic microgranular enclaves and their host rock showed that enclaves constitute passive markers of magmatic deformation. Anomalous magnetic fabric that can be ascribed to tectonic deformation was found in mafic dikes and felsic veins. Small basement outcrops having metamorphic foliation prior to the development of the NW-SE tectonic foliation were described. Tectonic deformation is constrained to small outcrops scattered among tectonically undeformed granitoids. Foliation planes and stretching lineations are highly heterogeneous. A paleomagnetic pole was calculated from the overlying Jurassic rocks of the region and its position coincides with other paleomagnetic poles of similar age coming from stable areas of South America. Major tectonic rotations did not occur from the Lower Jurassic to recent (only small counterclockwise rotations would be expected). In conclusion, the Gastre Fault System was a structure which controlled the diachronic emplacement of some tabular igneous bodies of the Central Patagonian Batholith, and which also channeled some subsolid post-emplacement deformation, but it was not a major transcurrent fault zone and consequently other tectonic models need to be considered when reconstructing the Jurassic paleogeography of Western Gondwana. Fil: Zaffarana, Claudia Beatriz. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.

Published
2011

11. Paleomagnetism of the Liassic member of the Zarzaïtine Formation (stable Saharan craton, Illizi basin, Algeria)

Author

M. E. M. Derder, M. Amenna, Bernard Henry, B. Bayou, and N. Merabet

Subjects
paleomagnetic pole, geography, Paleomagnetism, geography.geographical_feature_category, Polarity (physics), lcsh:QC801-809, Geophysics, lcsh:QC851-999, Structural basin, Diagenesis, lcsh:Geophysics. Cosmic physics, Magnetization, Craton, Paleontology, Africa, Marl, liassic, lcsh:Meteorology. Climatology, apparent polar wander path, Cenozoic, Geology, sahara craton
Abstract

A paleomagnetic study was carried out in the carbonates and marls of the Liassic member of the Zarzaïtine Formation of the Illizi basin (SE Algeria) deposited in a continental environment. Two magnetization components were identified. The first, defined at relatively low blocking temperature, was isolated in five sites, and yields the following paleomagnetic pole (80.8°N, 20.1°E, K = 811 and A 95 = 2.2°). This magnetization is considered an overprint acquired during Cenozoic times. The second component was defined by both normal and reversed polarity. The normal polarity was identified in fourteen sites using both linear regression and great circles. The reversed one was inferred in four sites from the remagnetization circle and demagnetization path analyses. This component is mainly (it could be in part the primary magnetization) a late diagenesis magnetic overprint. It yields a new Liassic pole (71.8°S, 54.9°E, K = 91 and A 95 = 3.9°) for Africa.

Published
2009
Full Text
View/download PDF

12. Evidence for coeval Late Triassic terrestrial impacts from the Rochechouart (France) meteorite crater

Author

Stuart Gilder, Laurent Carporzen, Institut de Physique du Globe de Paris (IPGP), and Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-IPG PARIS-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Paleomagnetism, 010504 meteorology & atmospheric sciences, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], Paleomagnetic pole, FOS: Physical sciences, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], Apparent polar wander, 010502 geochemistry & geophysics, 01 natural sciences, Geophysics (physics.geo-ph), high temperature, Physics - Geophysics, Paleontology, Tectonics, Geophysics, Impact crater, Meteorite, 13. Climate action, Breccia, General Earth and Planetary Sciences, Geology, meteorite crater, 0105 earth and related environmental sciences
Abstract

High temperature impact melt breccias from the Rochechouart (France) meteorite crater record magnetization component with antipodal, normal and reverse polarities. The corresponding paleomagnetic pole for this component lies between the 220 Ma and 210 Ma reference poles on the Eurasian apparent polar wander path, consistent with the 214 $\pm$ 8 Ma 40Ar/39Ar age of the crater. Late Triassic tectonic reconstructions of the Eurasian and North American plates place this pole within 95% confidence limits of the paleomagnetic pole from the Manicouagan (Canada) meteorite impact crater, which is dated at 214 $\pm$ 1 Ma. Together, these observations reinforce the hypothesis of a Late Triassic, multiple meteorite impact event on Earth.

Published
2007
Full Text
View/download PDF

15. The new Permian–Triassic paleomagnetic pole for the East European Platform corrected for inclination shallowing

Abstract

© 2018, Pleiades Publishing, Ltd. The results of detailed paleomagnetic studies in seven Upper Permian and Lower Triassic reference sections of East Europe (Middle Volga and Orenburg region) and Central Germany are presented. For each section, the coefficient of inclination shallowing f (King, 1955) is estimated by the Elongation–Inclination (E–I) method (Tauxe and Kent, 2004) and is found to vary from 0.4 to 0.9. The paleomagnetic directions, corrected for the inclination shallowing, are used to calculate the new Late Permian–Early Triassic paleomagnetic pole for the East European Platform (N = 7, PLat = 52.1°, PLong = 155.8°, A95 = 6.6°). Based on this pole, the geocentric axial dipole hypothesis close to the Paleozoic/Mesozoic boundary is tested by the single plate method. The absence of the statistically significant distinction between the obtained pole and the average Permian–Triassic (P–Tr) paleomagnetic pole of the Siberian Platform and the coeval pole of the North American Platform corrected for the opening of the Atlantic (Shatsillo et al., 2006) is interpreted by us as evidence that ~250 Ma the configuration of the magnetic field of the Earth was predominantly dipolar; i.e., the contribution of nondipole components was at most 10% of the main magnetic field. In our opinion, the hypothesis of the nondipolity of the geomagnetic field at the P–Tr boundary, which has been repeatedly discussed in recent decades (Van der Voo and Torsvik, 2001; Bazhenov and Shatsillo, 2010; Veselovskiy and Pavlov, 2006), resulted from disregarding the effect of inclination shallowing in the paleomagnetic determinations from sedimentary rocks of “stable” Europe (the East European platform and West European plate).

Catalog

Books, media, physical & digital resources
See catalog results