Analysis of Pleistocene paleodrainage evolution in the Po Basin (Italy) by multivariate statistical techniques

In order to obtain a high-resolution Pleistocene stratigraphy, eleven continuously cored boreholes, 100 to 220m deep were drilled in the northern part of the Po Plain by Regione Lombardia in the last five years. Quantitative provenance analysis (QPA, Weltje and von Eynatten, 2004) of Pleistocene sands was carried out by using multivariate statistical analysis (principal component analysis, PCA, and similarity analysis) on an integrated data set, including high-resolution bulk petrography and heavy-mineral analyses on Pleistocene sands and of 250 major and minor modern rivers draining the southern flank of the Alps from West to East (Garzanti et al, 2004; 2006). Prior to the onset of major Alpine glaciations, metamorphic and quartzofeldspathic detritus from the Western and Central Alps was carried from the axial belt to the Po basin longitudinally parallel to the SouthAlpine belt by a trunk river (Vezzoli and Garzanti, 2008). This scenario rapidly changed during the marine isotope stage 22 (0.87 Ma), with the onset of the first major Pleistocene glaciation in the Alps (Muttoni et al, 2003). PCA and similarity analysis from core samples show that the longitudinal trunk river at this time was shifted southward by the rapid southward and westward progradation of transverse alluvial river systems fed from the Central and Southern Alps. Sediments were transported southward by braided river systems as well as glacial sediments transported by Alpine valley glaciers invaded the alluvial plain. Kew words: Detrital modes; Modern sands; Provenance; Principal Components Analysis; Similarity, Canberra Distance; palaeodrainage

Distributions and phylogeographic data of rheophilic freshwater fishes provide evidences on the geographic extension of a central-brazilian amazonian palaeoplateau in the area of the present day Pantanal Wetland

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Sucessão estratigráfica do Andar Alagoas na Serra do Tonã, Bacia do Tucano (BA)

STRATIGRAPHIC SUCCESSION OF ALAGOAS STAGE ON SERRA DO TONÃ, TUCANO BASIN (BAHIA). Located in northeast of Bahia, serra do Tonã is a NS elongated plateau that standsout in the flattened relief of Tucano Basin. The stratigraphic succession belongs to the Aptian post-rift sequence of this basin. Based on facies analysis, vertical stratigraphic profiles and satelite images interpretation, three stacked stratigraphic units were recognized: (1) lower carbonate unit, composed by laminated limestones and breccias, 5 m thick, correlated with Camadas Batateira of Arripe Basin; (2) intermediate siliciclastic unit, 100m thick and made of sandstones exhibiting finning upward cycles, overlaid by mudstones and sandstones wich sedimentary structures suggest action of tidal currents and (3) upper carbonate unit, composed by laminated limestones, 2-10 m thick, related with Santana Formation, that record lacustrine environment with possible marine influence. Paleocurrent analysis indicates proviniance from north and paleoflows towards south, similar to the Aptian fluvial facies of Araripe Basin, showing that both basins integrated the same continental paleodrainage