Aeolian wet system in the sedimentary intertraps successions of Mosquito Formation, Jurassic of the Parnaiba Province, Brazil

Prior to the tectonic events related to the opening of the Central Atlantic, the Mosquito Formation of Jurassic age in the Parnaiba Sedimentary Basin was deposited as a succession of interbedded basaltic flows and sedimentary packets. The sedimentary successions deposits accumulated in topographic depressions with erosional contacts at both their base and top. Their contacts with the basalts are marked by eolian supersurfaces. The thickest intertrapp unit in the formation, the Macapa Member, found in the Mosquito river valley, is made up of sandstones comprising three facies associations: 1) eolian dune fields with interdune pond deposits, 2) sand sheets with ephemeral fluvial deposits and 3) siliciclastic sabkha. Relative water level, which controlled sediment availability and the accumulation surface and varied as a function of climate and probably subsidence rate, was the most important factor affecting intertrapp sedimentation in the Mosquito Formation.