Paleomagnetic evidence for modern plate motion velocities at 3.2 Ga
Abstract
The mode and rates of tectonic processes and lithospheric growth during the Archean Eon (4.0-2.5 Ga) are subjects of considerable debate. Paleomagnetic methods may contribute to the discussion by quantifying past plate velocities. Here we report a new paleomagnetic pole for the ~3180 Ma Honeyeater Basalt of the Pilbara craton, Western Australia. Several lines of evidence support a primary origin for the observed high-temperature component of magnetization. It robustly passes a fold test within the Soanesville Syncline, a ~2930 Ma structure. Our inferred moderate paleolatitude of the Honeyeater Basalt, when compared with the previously reported equatorial paleolatitude from the ~3350 Ma Euro Basalt, requires that the average latitudinal drift rate of the East Pilbara Terrane was at least 2.5 cm/y during the ~170 My interval before 3180 Ma, making its velocity comparable with those of modern plates. Assuming this motion is due primarily to plate motion instead of true polar wander, the result is consistent with uniformitarian tectonic processes in place by the Mesoarchean (3.2 Ga).
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.V31G0134B
- Keywords:
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- 1020 Composition of the continental crust;
- GEOCHEMISTRY;
- 3660 Metamorphic petrology;
- MINERALOGY AND PETROLOGY;
- 8110 Continental tectonics: general;
- TECTONOPHYSICS;
- 8178 Tectonics and magmatism;
- TECTONOPHYSICS