Biostratigrafía y litoestratigrafía del Paleógieno del área de Sierra Espuña (Cordillera Bética oriental, SE de España)

Abstract

From new biostratigraphic and lithostratigraphic data, a revision is made of the Paleogene of the Malaguide Complex of Sierra Espuña, located in the Interna1 Zone (Internal-Externa1 Zone Boundary) of the Betic Cordillera. The Paleogene deposits are characterized according to formations and integrated into depositional sequences and sedimentary cycles. The biostratigraphic data are based on larger forarninifers, planktonic foraminifers, and calcareous nannoplankton. The results are integrated into a lithostratigraphic synthesis and correlated to a chronostratigraphic chart proposed by Sena-Kiel et al. (1998). The Paleogene of Sierra Espuña is suhdivided into two main sedimentary cycles hounded by regional unconformities: a preorogenic Lower Sedimentary Cycle and a synorogenic Upper Sedimentary Cycle:

1) The Malaguide Tertiary Lower Sedimentary Cycle ranges from the Paleocene to the Lower Oligocene, and is suhdivided into four depositional sequences: The Paleocene Depositional Sequence is represented by the Mula Formation and compnses a lower part dated as Danian, a middle part dated as Selandian, and an upper part dated as Thanetian. The Cuisian-early Lutetian Depositional Sequence is represented by the laterally related Espuña and Valdelaparra formations, which have heen dated as SBZ10-SBZ13(early Cuisian-early Lutetian). The Middle Lutetian-Pnabonian Depositional Sequence is represented by the laterally related Malvariche and Cánovas formations, and has been dated as SBZ14 (middle Lutetian) at the base and NP18-NP20 and P 15 (late Bartonian-Pnahonian) at the top. The Lower Oligocene Depositional Sequence is represented by the As Formation. Our results show that some Lower Oligocene species occur together with reworked Eocene foraminifers in this formation. This age is highly important in determining the true timing of the test events of the upper units of the Malaguide Complex.

2) The synorogenic, Malaguide Tertiary Upper Sedimentary Cycle ranges from the late Lower Oligocene to the Aquitanian. It is represented by the laterally related Bosque and Río Pliego Forrnations. The base was dated as NP23 and the upper part as NN 1. This cycle is followed by an also synorogenic, but not malaguide cycle: the Early Burdigalian Sedimentary Cycle represented by the El Niño Formation, which can be correlated with the Viñuela Group.