PALEOCLIMATIC SIGNIFICANCE OF THE LACUSTRINE CARBONIFEROUS DEPOSITS IN NORTHWEST ARGENTINA

LIMARINO, C.O.; CESARI, S.N.

PALAEOGEOGRAPHY PALAEOCLIMATOLOGY PALAEOECOLOGY

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 1988

0031-0182

The origin and probable paleoclimatic significance of Carboniferous lacustrine deposits in northwest Argentina arediscussed. These rocks are developed extensively throughout northwestern Argentina, but are described in thepresent paper only from the region of the Sistema del Famatina.Five lithofacies have been identified: (A) laminated siltstones and claystones; (B) thinly interbedded mudstones andsandstones; (C) interlayered mudstones and sandstones with sole structures (flute marks and tool marks); (D)conglomerates and fine sandstones; (E) sandstones and diamictites. These lithofacies are interpreted as lacustrinedeposits formed during the final episode of the Carboniferous glaciation. Lithofacies A originated as a suspension-loaddeposit in the central and intermediate parts of the lake; the presence of dropstones in this lithofacies suggests coevalice-rafting processes. Underflow currents probably formed lithofacies B, and lacustrine turbidites lithofacies C.Lithofacies D and E were deposited in marginal environments and represent in some cases shoreline bars and smalldeltas.The age of the lacustrine episode is deduced from paleobotanical information. Both palynological and megafloristicdata suggest that these deposits were formed during the middle Carboniferous. A palynological assemblage dominatedby Cristatisporites.like spores characterizes these sediments.