Paleogeographic and tectonic implications of the first paleomagnetic results from the Middle-Late Cambrian Meson Group: NW Argentina

摘要

The first paleomagnetic data from autochthonous Cambrian rocks in NW Argentina is reported to constrain the apparent polar wander path (APWP) of Gondwana during the Early Paleozoic. The paleomagnetic pole (Lat 4.5°S; Long 359.0°E; dp = 5.5; dm = 8.8; n = 26) was obtained from the red to purple sandstones of the Campanario Formation. These rocks present a characteristic remanence carried by fine-grained hematite. The pole indicates that during the Late Cambrian, rocks now exposed in the Eastern Cordillera of NW Argentina were deposited at relatively low latitudes (≈26°S), consistent with intense chemical alteration during wet and warm climates, as indicated from petrography of apparent first-cycle quarzites of the Meson Group. However, the pole position is anomalous with respect to the most accepted apparent polar wander paths for Gondwana, suggesting that the study area (22°50′S, 65°00′W) underwent clockwise rotation of 38° ± 8°, likely related to the Cenozoic central Andes rotation pattern characteristic of the region.