Depositional environments and sediment transport directions of the Itarare Group rocks from the state of Sao Paulo, Brazil

The Itarare Group sedimentary rocks were deposited in the Parana Basin of South America during the Late Paleozoic Ice Age (LPIA) and were collected throughout the state of Sao Paulo, Brazil, for a paleomagnetic, anisotropy of magnetic susceptibility (AMS), and rock magnetic study. These rocks have been interpreted to be overprinted by secondary magnetizations acquired during the widespread Cretaceous magmatic events associated with the opening of the South Atlantic, however, the rock-magnetic experiments demonstrate that the AMS fabrics are dominantly carried by the paramagnetic fraction and are therefore largely immune from the secondary overprints. AMS fabrics are analyzed in terms of their shape and orientation, and according to the relationship between their magnetic lineation/foliation (q-value) and imbrication () on a q- diagram. Using multiple lines of evidence, we demonstrate that AMS records primary sedimentary fabrics that reflect the periglacial depositional environments and paleo-current conditions in which the rocks were deposited. The magnetic fabrics consistently record SE-NW paleocurrent orientations, with a prevalent direction of transport to the NW, in agreement with ice-flow and sediment transport directions reported from sedimentary structures and ice-kinematic indicators. Moreover, the depositional regimes determined from the q- diagram agree remarkably well with the depositional environments interpreted from facies analyses, confirming the validity of AMS in obtaining transport directions from rocks that are largely void of sedimentary structures and interpreting their environments of deposition.