Factores de control sobre los tipos de cementos en areniscas carboníferas de la Cuenca Paganzo, noroeste de Argentina

petrographic sandstone analysis of 192 thin sections belonging to the lower section of the paganzo group (upper carboniferous; lagares, malanzán, loma larga, guan-dacol, tupe, punta del agua and río del pe？ón formations) cropping out in the paganzo basin (figs. 1, 2) was carried out in order to define cementation styles (primmer et al., 1997) and reveal the main controlling factors, such as clast composition, matrix content, sedimentary environments and burial depth. the lower sedimentary section of the paganzo group (200 to 1200 m thick) was deposited in alluvial fan, glacial, deltaic, marine shoreline, marine shelf and fluvial environments (fig. 3). three distinct structural and paleogeographical areas of the basin were distinguished and sampled: a) the eastern area (olta and malanzán valleys, las mellizas mine and bum bum localities, fig. 1), corresponds to the stable foreland sector of the basin, dominated by thick fluvial deposits whose provenance region is the plutonic-metamorphic basement of the sierras pampeanas located to the east, and only registering a short marine event from the west. this region records minimum relative burial depths. b) the central area (cuesta de huaco and cerro guandacol localities, fig. 1), is composed of thick continental deposits from the sierras pampeanas that alternate with two main marine episodes flooding the basin from the west; the latter carries fragments of fine marine sedimentary and volcanic rocks from the precordillera. burial depths in this area are intermediate. c) the western area (punta del agua locality, fig. 1), transitional to the río blanco basin, is composed of a thick conglomeratic and volcanic sequence followed by marine and deltaic sediments from the precordillera but also including some fluvial deposits from the sierras pampeanas area. maximum thickness of the postcar-boniferous sedimentary pile in this area accounts for maximum relative burial depths. these sandstones exhibit large textural and composition