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Abstract: The upper portion of the Pedra Pintada Alloformation includes about 100 m of mostly eolian deposits. This paper emphasizes the vertical succession and lateral association of sedimentary facies, based on analysis of outcrop data and aerial photographs, as well as the hierarchy and origin of bounding surfaces. It aims to propose a high-resolution stratigraphic and depositional model that may be useful to exploitation of eolian reservoirs. The succession has been preserved due to basin subsidence, and is described in terms of four facies associations that constitute three dominantly eolian units. These units are sharply bounded by major flooding surfaces (super surfaces) that, in turn, are overlain by 1 to 2 m thick, dominantly water-laid facies (lacustrine, fluvial, deltaic and eolian). Both their internal organization and boundaries were controlled by changes in the base level rise rate. The basal Eolian Unit is composed of crescentic eolian dunes and damp interdune deposits ascribed to a wet eolian system. On the other hand, eolian units II and III, also characterized by crescentic eolian dunes (simple and compound) deposits, were related to dry eolian systems, since they comprise dry (eventually wet) interdune facies. Eolian Unit III is truncated by basinwide unconformity, which is then overlain by the ephemeral fluvial deposits (Varzinha Alloformation). This second type of super surface is related to climate-induced wind erosion (deflation) down to the water table level (regional Stokes surface) followed by fluvial incision linked to tectonic activity. [Copyright &y& Elsevier]

Tunnel valleys are subglacial incisions formed mainly by meltwater erosion on soft sediment overridden by glaciers. Despite being common in the Pleistocene and Ordovician glacial record, where their fills constitute excellent aquifers and hydrocarbon traps, tunnel valleys are poorly recognized in late Paleozoic strata. Other types of glacial and non-glacial valleys, on the other hand, have been widely reported from Carboniferous and Permian glacial successions, most cut into the basement or older sedimentary rocks and interpreted as glacial valleys eroded by outlet glaciers draining high-relief settings. The degree of glacial influence on the formation of these valleys has strong implications for the volume of ice during late Paleozoic glaciations. In this paper, we report the Lapa sandstone, an exhumed valley-fill succession encased in Pennsylvanian glacial rocks of eastern Paraná Basin, southern Brazil, and its subsurface counterparts. The Lapa sandstone forms a slightly sinuous ribbon several tens of kilometers long, 1500 m wide and 100 m thick composed essentially of glaciofluvial facies. By comparing the external geometry and the sediment fill of the valley with several types of erosive-based, elongated sediment bodies, we conclude that the Lapa formed as the infilling of a tunnel valley cut beneath an ice margin that advanced to the north onto poorly consolidated, mud-rich sediments. Valley fills previously mapped in the subsurface area to the west are considered to have been formed by the same mechanism and during the same glaciation event. The Lapa tunnel valley and its subsurface counterparts are the first example reported from the late Paleozoic glacial record in South America, but similar features are also expected in any formerly glaciated basin, and their recognition may help in estimating the extent of glaciation across the region and guiding exploration for hydrocarbon traps. • The first tunnel valleys in the late Paleozoic record of South America are documented. • The Lapa sandstone in eastern Paraná Basin is the exhumed fill of a subglacial tunnel valley. • Time-equivalent, deeply buried tunnel-valley fills constitute hydrocarbon reservoirs. • An ice margin several hundreds of kilometers wide advanced northward into the Paraná Basin around 300 Ma ago. [ABSTRACT FROM AUTHOR]