Depositional sequences and correlation of middle(?) to late Miocene carbonate complexes, Las Negras and Nijar areas, southeastern Spain

Abstract

During Serravallian through Messinian time, marine carbonates flanked topographic highs that rimmed Neogene basins in the Western Mediterranean. Middle to upper Miocene carbonate strata in the Las Negras and Nijar areas (southeastern Spain) are 50‐150 m thick and display 50‐200 m of shelf‐to‐basin relief over 1‐2 km. Detailed studies in those areas document the effects of relative sea‐level change on sedimentation, biotic composition, and reef development. We identify three previously unrecognized, regionally correlatable depositional sequences (DS1, DS2, DS3) that occur between the underlying basement and the overlying Terminal Carbonate Complex. The lower depositional sequences (DS1, DS2) are mostly normal marine shelf (ramp) carbonates deposited on the flanks of basement highs. The basal part of DS2 locally contains some megabreccia reef blocks composed of Tarbellastraea and Porites. These blocks are the first evidence of reef growth in the area and represent a previously unrecognized period of reef development prior to the fringing reef development. The reef blocks probably formed as upslope patch reefs that were eroded and transported to distal slope locations. The upper sequence (DS3) is characterized by clinoform strata of a Porites‐dominated fringing reef complex that prograded basinward in a downstepping style with successively younger reefs forming in a topographically lower and more basinward position as a result of a net sea‐level drop. Regional correlation of Miocene shallow‐marine strata between basins in Spain and elsewhere in the western Mediterranean is complicated because basins were semi‐isolated from adjacent basins making physical correlation impossible. In addition, age‐definitive biostratigraphic markers are poorly preserved in most of the Miocene shallow‐water strata; basinal sediments that are more easily dated by microfossils do not typically interfinger with the shallow‐marine strata in outcrop. Even where datable microfossils are found, resolution of dating is poor. Our studies in the Las Negras and Nijar areas illustrate the usefulness of integrating sedimentological, geometric and biotic data with locally derived relative sea‐level (accommodation space) curves for correlation. The relative sea‐level curves for each area show remarkable similarities in shape and magnitude of sea‐level changes. These curves indicate several relative sea‐level fluctuations during Miocene carbonate deposition prior to the major sea‐level drop at the end of DS3 deposition that culminated in the exposure of the basin margin deposits and the deposition of evaporites in basinal areas during the Messinian. The depositional sequences in the Las Negras and Nijar areas may correlate with depositional sequences of similar age throughout the southern Cabo de Gata area, in Mallorca some 600 km to the northeast, and possibly in other Mediterranean locations. The widespread occurrence and possible correlation of the depositional sequences suggest regional processes such as eustacy or tectonism for their form...

Effects of antecedent topography on reefal carbonate deposition: Early-Middle Miocene of the Adana Basin, S Turkey

“…Miocene shallow marine sediments are widely distributed around the Mediterranean, such as in Italy (Vecsei and Sanders, 1999), Spain (Franseen and Mankiewicz, 1991;Pomar, 1991;Pomar et al, 2004) and Southern Turkey (Fig. 1).…”

Sedimentary facies during early stages of flooding in an extensional basin: the Br�che Rouge de Carboneras (Late Miocene, Almer�a/SE Spain)

“…Subsequently, many additional outcrops of BRC have been found to the southwest of Carboneras in the areas of Mesa Roldµn, Ricardillo and Agua Amarga Hultzsch 1999;Brachert et al 2001). Earlier works by Melendez et al (1964), Saavedra (1966), FustØr et al (1967), Zeck and Soediono (1970), Franseen and Mankiewicz (1991) and Serrano (1992) have documented neptunian dikes and volcaniclastic breccia/conglomerate attributable to the BRC from various areas of the Níjar-Carboneras Basin, which suggest an original distribution much more widespread than originally perceived, and which calls into question the original olistostrome model. Second, Franseen et al (1993) have shown that some concentric and polygonal cracks within the volcanic substrate are related to subaerial weathering.…”

“…Rotations in the orientation of stresses caused the NE-SW fault systems to change from dominantly reverse displacements (Tortonian and late Pliocene to Holocene) to sinistral wrench displacements (late Tortonian-early Pliocene; de la Chapelle 1988; Montenat et al 1990). The distribution of local depocenters within the Carboneras subbasin, such as in the areas of Agua Amarga (Martin et al 1996) or Las Negras (Franseen and Mankiewicz 1991), corresponds with uplifted and subsided blocks defined by an array of faults which strike NW-SE and NE-SW ( Fig. 1; Brachert et al 2002).…”

Non-seagrass meadow sedimentary facies of the Pontinian Islands, Tyrrhenian Sea: A modern example of mixed carbonate–siliciclastic sedimentation

“…Beach and shoals facies show the same compositional and textural characteristics of the silicilastic skeletal F5b and terrigenous sand (F5a) of the Pontian shelf. Franseen and Mankiewicz (1991) illustrated Upper Miocene siliciclastic-carbonate deposits from Las Negras and Nijar (Southeastern Spain). The facies model presented by these authors show a general increase basinward in finegrained wackestone/packstones and a shelfward increase in red algae-rich packstone and coarse-grained packstone/ grainstone with a discrete increase of terrigenous (siliciclastic and vulcanoclastic sediment) material in the near-shore environment.…”