Aeolian/fluvial interactions and high-resolution sequence stratigraphy of a non-marine lowstand wedge: the Avilé Member of the Argio Formation (Lower Cretaceous), central Neuquén Basin, Argentina

VEIGA, G.D.; SPALLETTI, L. A.; FLINT, S. S.

SEDIMENTOLOGY

Blackwell Publishing

Año: 2002 vol. 49 p. 1001 - 1019

0037-0746

Accumulation within the unconformity-based Hauterivian Avile´ Sandstone ofthe Neuque´n Basin, Argentina, was characterized by a close interaction betweenfluvial and aeolian processes developed after a major relative sea-level drop thatalmost completely desiccated the entire basin and juxtaposed these non-marinedeposits on shallow- and deep-marine facies. Aeolian deposits within the Avile´Member include dune (A1) and sand sheet (A2) units that characterize the lowerpart of the unit. Fluvial deposits comprise distal flood units (F1) interbeddedwith aeolian dune deposits in the middle part of the succession, and low- (F2)and high-sinuosity (F3) channels associated with floodplain deposits (F4)towards the top. The internal characteristics of the aeolian system indicate thatits accumulation was strongly controlled by water-table dynamics, with thedevelopment of multiple horizontal deflation super surfaces that truncate dunedeposits and form the basal boundary of flood deposits and sand sheet units. Along-term wetting-upward trend is recorded throughout the entire unit, with anincrease in fluvial activity towards the top and the development of a morepermanent fluvial system overlying a major erosion surface interpreted as asequence boundary. The upward increase in water-table influence might berelated to relative sea-level rise, which controlled the position of the water tableand allowed the accumulation of tabular aeolian units bounded by horizontaldeflation surfaces. This high-frequency, eustatically driven process actedtogether with a long-term climatic change towards wetter conditions.