MagNetZ With Andres Cukjati (2023/11/29) - Geodynamic or geomagnetic complexities in the Edicaran
Channel: MagNetZ
Date: 2023-11-29

New paleomagnetic data from the sedimentary cover of the Tandilia System: Further geodynamic or geomagnetic complexities in the Late Edicaran.

The video is also available for download at: https://earthref.org/ERDA/2727/
and can be referenced with the doi: 10.7288/V4/ERDA/2727

Title:New paleomagnetic data from the sedimentary cover of the Tandilia System: Further geodynamic or geomagnetic complexities in the Late Edicaran.
Author: Andres Cukjati from Universidad de Buenos Aires, Argentina

Paleomagnetic, magnetic fabric and rock magnetic studies were carried out in the Avellaneda Formation (~570-560 Ma) from two bore cores of the Alicia quarry in the Olavarría area of the Tandilia System, in the Río de la Plata craton. Anisotropy of magnetic susceptibility (AMS) studies were carried out indicating a pre-tectonic origin for the magnetic fabric of this Formation. The rock magnetic studies performed in one of the bore cores suggest the presence of magnetite and hematite in different proportions as the main ferromagnetic minerals carrying the remanence. After stepwise thermal demagnetization, two different characteristic remanence directions were obtained, one corresponding to the marls (“b1”) of the lower section of the Avellaneda Formation, and the other from the claystones (“b2”) of the upper section of this unit. These results were combined with the remanence directions obtained by Franceschinis et al. (2022) for the same unit in the La Cabañita quarry, located at 10 km away. This procedure allows the calculation of two paleomagnetic poles for the Avellaneda Formation. The AV1 pole was obtained from the lower marly section and is located at: 2.0° S, 311.1° E, A95: 5.0°, N: 58 while the AV2 pole correspond to the upper mudstone section and is at: 3.3° N, 348.9° E, A95: 11.7°, N: 7. These results suggest changes in the Late Ediacaran apparent polar wander path (APWP) of the Río de la Plata Craton which implies extremely fast movements in very short periods of time if the GAD hypothesis can be held valid for that period. Assuming this, the results can be interpreted as evidence of two inertial interchange true polar wander (IITPW) events in the Ediacaran. An alternative possibility could suppose a non-actualistic behaviour of the Earth Magnetic Field, switching from axial to equatorial positions, with an intermediate stable position between them.


-----------------------------------------------------------

00:00 - Intro
01:18 - Presentation
25:15 - Questions
34:01 - Announcements