Major controls on carbonate deposition during the evolution of a continental basin: Pliocene-Pleistocene of the Guadix Basin (Betic Cordillera, southern Spain).

Abstract

The Fonelas P-1 large-mammal site is located stratigraphically in the youngest unit (Late Pliocene–Pleistocene) of the endorheic fill of the Guadix Basin (Betic Cordillera). At the site location this unit is represented by fluvial sediments of the basin's axial drainage system. The general succession of the site consists of stacked fining-upward cycles, basically beginning with gravel and/or sand filling a meandering channel and concluding with floodplain mud and carbonate. Each of the cycles is made up of four facies associations determined by sedimentological analysis of the sections measured in the paleontological excavation of the site. These associations correspond to sedimentation in definite areas of the fluvial system: (A) filling of a sinuous channel at maximum activity, (B) levee deposits, (C) abandoned channel and (D) floodplain. In the cycle in which the site is located there is a fifth association (E), where the main fossil concentration is found (Fonelas P-1). This is a facies bioturbated by mammals moving over sediments of the abandoned channel association (C). By space–time reconstruction of the fluvial environments, we can infer that the morphological depression caused by a meander abandonment due to chute cut-off was used as a hyena den. The animal settlement ended when overflow from the laterally migrating active channel began to bury the abandoned meander with floodplain sediments.