A review on late Paleozoic ice related erosional landforms in the Parana Basin origin and paleogeographical implications
Manuscript ID: 20160050. Received in: 03/30/2016. Approved in: 05/15/2016 ABSTRACT: The Late Paleozoic Ice Age is recorded in the Parana Basin as glacial deposits, deformational features and ice related erosional landforms of the Itarare Group. Erosional landforms are often employed to build paleogeographic models that depict the location of ice masses and paleo ice flow directions. This paper provides a review of the literature and new data on microto meso scale ice related, erosional landforms of the Parana Basin. Examined landforms can be placed into four broad categories based on their mode of origin. Subglacial landforms on rigid substrates occur on the Precambrian basement or on older units in the Parana Basin. They include streamlined landforms and striated pavements formed by abrasion and/or plucking beneath advancing glaciers. Subglacial landforms on soft beds are intraformational surfaces generated by erosion and deformation of unconsolidated deposits when overridden by glaciers. Ice keel scour marks are soft sediment striated/grooved landforms developed by the scouring of free floating ice masses on underlying sediments. Striated clast pavements are horizons containing aligned clasts that are abraded subglacially due to the advance of glaciers on unconsolidated deposits. Only those erosional landforms formed subglacially can be used as reliable paleo ice flow indicators. Based on these data, the paleogeography of the Parana Basin during the Late Paleozoic Ice Age fits into a model of several glacial lobes derived from topographically controlled ice spreading centers located around the basin instead of a single continental ice sheet.