TY - JOUR

T1 - Paleomagnetism of the Taseeva Group (Yenisei Ridge): on the Issue of the Geomagnetic Field Configuration at the Precambrian–Phanerozoic Boundary

AU - Vinogradov, E. V.

AU - Metelkin, D. V.

AU - Abashev, V. V.

AU - Vernikovsky, V. A.

AU - Matushkin, N. Yu

AU - Mikhaltsov, N. E.

N1 - We are grateful to corresponding member of the RAS A.N. Didenko and Professor A.Yu. Kazansky for useful discussion of our materials, valuable remarks and commentary that enabled us to improve the evidence basis for this article. This work was financially supported by the Russian Science Foundation projects 19-17-00091-P (geostructural analysis) and 21-17-00052 (paleomagnetic experiments).

PY - 2023/5

Y1 - 2023/5

N2 - We report results of a detailed study of the paleomagnetic record in the sedimentary rocks of the Taseeva Group of the Yenisei Ridge in three typical sections in the lower courses of the Angara, Taseeva and Irkineeva rivers. Our results confirm that the geomagnetic field was in an anomalous state at the Precambrian–Phanerozoic boundary. It is well known that Ediacaran rocks in general have preserved several different paleomagnetic directions that do not conform to the geocentric axial dipole model. For example, Siberian sections display two equally valid groups of paleopoles that cause many debates over the geometry of the geomagnetic field and whether any of the components correspond to its dipole configuration. The paleomagnetic record we studied is unique in that the rocks of the Chistyakovka and Moshakovka formations have captured both these components, which is factual evidence of a synchronous existence of two sources. To ex-plain these findings, we propose an original hypothesis in which the bipolar component that is widely present in the rocks and corresponds to the Madagascar group of paleomagnetic poles is associated to the field of the geocentric axial dipole. The less widespread monopolar component corresponding to the Australian–Antarctic group of poles is reflective of a stationary anomalous source. The recording of this source became possible due to the abrupt decrease in the strength of the virtual dipole moment that probably was at its lowest during the accumulation of the Chistyakovka and Moshakovka formations. The new paleomagnetic pole calculated for the bipolar component – 39.2°N, 61.1°E – plots on the apparent polar wander path for Siberia and can be considered a key determination for the age ~570 Ma.

AB - We report results of a detailed study of the paleomagnetic record in the sedimentary rocks of the Taseeva Group of the Yenisei Ridge in three typical sections in the lower courses of the Angara, Taseeva and Irkineeva rivers. Our results confirm that the geomagnetic field was in an anomalous state at the Precambrian–Phanerozoic boundary. It is well known that Ediacaran rocks in general have preserved several different paleomagnetic directions that do not conform to the geocentric axial dipole model. For example, Siberian sections display two equally valid groups of paleopoles that cause many debates over the geometry of the geomagnetic field and whether any of the components correspond to its dipole configuration. The paleomagnetic record we studied is unique in that the rocks of the Chistyakovka and Moshakovka formations have captured both these components, which is factual evidence of a synchronous existence of two sources. To ex-plain these findings, we propose an original hypothesis in which the bipolar component that is widely present in the rocks and corresponds to the Madagascar group of paleomagnetic poles is associated to the field of the geocentric axial dipole. The less widespread monopolar component corresponding to the Australian–Antarctic group of poles is reflective of a stationary anomalous source. The recording of this source became possible due to the abrupt decrease in the strength of the virtual dipole moment that probably was at its lowest during the accumulation of the Chistyakovka and Moshakovka formations. The new paleomagnetic pole calculated for the bipolar component – 39.2°N, 61.1°E – plots on the apparent polar wander path for Siberia and can be considered a key determination for the age ~570 Ma.

KW - Ediacaran

KW - Taseeva Group

KW - Yenisei Ridge

KW - anomalous geomagnetic field

KW - geocentric axial dipole model

KW - paleomagnetism

KW - paleopole

UR - https://www.scopus.com/record/display.uri?eid=2-s2.0-85160229580&origin=inward&txGid=119b08df3cba8678ecc6e45dd282554d

UR - https://www.mendeley.com/catalogue/8e89eedd-b263-303f-8164-2d7036dcfcb4/

U2 - 10.2113/RGG20224542

DO - 10.2113/RGG20224542

M3 - Article

VL - 64

SP - 542

EP - 557

JO - Russian Geology and Geophysics

JF - Russian Geology and Geophysics

SN - 1068-7971

IS - 5

ER -