A review on late Paleozoic ice-related erosional landforms in the Paraná Basin: origin and paleogeographical implications

Eduardo Luiz Menozzo Da Rosa,Almério Barros França,Fernando Farias Vesely

doi:10.1590/2317-4889201620160050

Eduardo Luiz Menozzo Da Rosa, Almério Barros França + Show 1 more

Open Access

https://doi.org/10.1590/2317-4889201620160050

Copy DOI

Abstract

ABSTRACT: The Late Paleozoic Ice Age is recorded in the Paraná Basin as glacial deposits, deformational features and ice-related erosional landforms of the Itararé 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 micro- to meso-scale ice-related, erosional landforms of the Paraná 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 Paraná 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 Paraná 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.

Highlights

The Late Paleozoic Ice Age (LPIA) was a period in Earth history during which global temperatures were relatively low and the Gondwana supercontinent was situated in high latitudes of the Southern Hemisphere
The traditional one assumes that the LPIA lasted for about 100 Ma as a long, single glacial period dominated by large ice sheets derived from a huge polar ice mass centered over Antarctica (Veevers & Powell 1987, Frakes et al 1992, Scotese et al 1999, Scotese 2014)
We present a review and a critical reassessment of ice-related erosional landforms of the LPIA reported in the Paraná Basin

Summary

INTRODUCTION

The Late Paleozoic Ice Age (LPIA) was a period in Earth history during which global temperatures were relatively low and the Gondwana supercontinent was situated in high latitudes of the Southern Hemisphere. Equivalent striated pavements can be found in other localities of eastern Santa Catarina, as, for instance, the occurrence noticed by Puigdomenech et al (2014) in Vidal Ramos, where thin striations occur at the bottom and at the sidewall of an elongated groove about 1 m deep carved onto low-grade metamorphic rocks (their Figure 3B) These authors did not provide kinematic indicators for paleo ice-flow, new field observations at the same surface found non-striated steps perpendicular to the main striations (Fig. 5A), which allow to interpret that the ice slid on the bed towards the northwest. Directional trends measured by Vesely & Assine (2014) from 19 striated surfaces in this area show a deviation of up to 40o from the regional paleo-ice flow indicated by subglacial landforms on the underlying Furnas Formation These characteristics and the fact that the surfaces are not associated with poorly sorted glaciogenic deposits support an origin related to iceberg scouring instead of subglacial erosion (cf Woodworth-Lynas & Dowdeswell 1994). In the Paraná Basin, two striated clast pavements were documented by Rocha-Campos et al (1968) and

Pre-scouring Original bottom morphology

CONCLUSIONS