| Full text | |
| Author(s): |
Bilardello, Dario
[1]
Total Authors: 1
|
| Affiliation: | [1] Univ Minnesota, Inst Rock Magnetism, Minneapolis, MN 55455 - USA
Total Affiliations: 1
|
| Document type: | Journal article |
| Source: | EARTH AND SPACE SCIENCE; v. 8, n. 7 JUL 2021. |
| Web of Science Citations: | 0 |
| Abstract | |
Sedimentary rocks of the Itarare Group, deposited during the Late Paleozoic Ice Age in the Parana Basin of South America, were collected throughout the state of Sao Paulo, Brazil, for an anisotropy of magnetic susceptibility (AMS) and rock-magnetic study. A recent paleomagnetic study conducted on the same samples had determined that these rocks were largely remagnetized during the Cretaceous; however, rock-magnetic experiments demonstrate that the AMS is dominantly carried by paramagnetic minerals and therefore is unaffected by the secondary magnetic overprints. AMS data are analyzed in terms of their shape and orientation, and according to the relationship between the q-value (magnetic lineation/foliation) and the imbrication angle (beta) of the minimum susceptibility axes with respect to bedding (q-beta diagram). Using multiple lines of evidence, we demonstrate that AMS records primary sedimentary fabrics that reflect the depositional environments and paleocurrent conditions in which these rocks were deposited. The magnetic fabrics consistently record a SE-NW paleocurrent orientation, with dominant direction of transport to the NW throughout the entire state of Sao Paulo, in agreement with ice flow and sediment transport directions reported from limited numbers of sites possessing sedimentary structures and ice-kinematic indicators. (AU) | |