ANALYSIS OF CARBONIFEROUS DIAMICTS OF THE ITARARÈ SUBGROUP IN WITMARSUM, PARANA STATE, BRAZIL

Glaciogenic diamicts of the Carboniferous Itararè Subgroup in the Parana Basin, Southern Brazil were deposited during the advance and retreat cycles of the Parana and Sao Paulo lobes. Newly exposed glacial deposits located on a road cut in rural Witmarsum, Parana State were mapped, described and analyzed to determine depositional environment. These glacial deposits consist of a boulder diamict and a dropstone unit positioned atop a laminated to massive clay. These facies have not previously been recognized within the Witmarsum region.

Depositional environment and province of the boulder diamict and dropstones were determined using field and laboratory analysis. Field analysis centered on boulder lithologies and the contact between the clay and diamict unit, which consists of bowed laminations. Laboratory methods including grain counts and palynology were used to analyze both the diamict and dropstones determining depositional age and trace lithologies. These laminations suggest an abrupt deposition of the dropstone and diamict within a low energy environment. The contact between the clay and diamict unit is indicative of an ice proximal environment near the glacial grounding line. Preliminary results suggest the depositional environment to be that of a rainout diamict and debris flow from an ice shelf.

Research for this study was funded by a grant from the N.S.F.-R.E.U Program (NSF-EAR-1262945).