The Pinturas Formation (Middle Miocene) includes a sedimentary succession exposed at the Río Pinturas valley, Santa Cruz province, Argentina. It is separated in three members. The lower and the upper ones were dominated by ashfall episodes with paleosol formation during stability times; while the middle member is represented by desert eolian deposits. Mentioned palaeosols bears a moderately diverse ichnofauna. Trace fossils presents are Coprinisphaera murguiai, C. ispp., Loloichnus baqueroensis, Feoichnus challa, Taenidium barretti, Skolithos isp. and an unnamed three-dimensional system of interconnected burrows.
Four ichnofabrics (IF) were defined: the Coprinisphaera, Loloichnus, Skolithos and Boxwork IFs. The Coprinisphaera IF is characterized by scattered Coprinisphaera ispp., and by a low percentage of bioturbation (max. 13%). F. challa is an accessory component which may be locally abundant. The Loloichnus IF shows L. baqueroensis without any regular pattern or spatial disposition. Burrows follow random and tortuous paths, intertwining usually without touching, with each other. Next to soil tops, burrows have a vertical segment. Coprinisphaera ispp., Taenidium barretti and other …show more content…
Such conditions are wet but not flooded soils, with abundant organic matter available. In modern earthworms, different species made different burrow systems; probably these IF could be reflecting that. The Coprinisphaera IF and the Loloichnus IF, which can occur in the same bed, are not coeval as they reflect different environmental conditions to allow its emplacement. Coprinisphaera IF indicates well drained and dry soils with low water table; while the Loloichnus IF suggests wetter soils and a near to surface water table. Its presence suggests changes in water availability conditions, probably reflecting dry-wet climatic
Four ichnofabrics (IF) were defined: the Coprinisphaera, Loloichnus, Skolithos and Boxwork IFs. The Coprinisphaera IF is characterized by scattered Coprinisphaera ispp., and by a low percentage of bioturbation (max. 13%). F. challa is an accessory component which may be locally abundant. The Loloichnus IF shows L. baqueroensis without any regular pattern or spatial disposition. Burrows follow random and tortuous paths, intertwining usually without touching, with each other. Next to soil tops, burrows have a vertical segment. Coprinisphaera ispp., Taenidium barretti and other …show more content…
Such conditions are wet but not flooded soils, with abundant organic matter available. In modern earthworms, different species made different burrow systems; probably these IF could be reflecting that. The Coprinisphaera IF and the Loloichnus IF, which can occur in the same bed, are not coeval as they reflect different environmental conditions to allow its emplacement. Coprinisphaera IF indicates well drained and dry soils with low water table; while the Loloichnus IF suggests wetter soils and a near to surface water table. Its presence suggests changes in water availability conditions, probably reflecting dry-wet climatic