Contrasting models of temperate carbonate sedimentation in a small Mediterranean embayment: the Pliocene Carboneras Basin, SE Spain

Abstract

Temperate carbonates consisting of bioclastic (bryozoan–bivalve–coralline algal) packstones to rudstones formed in the Carboneras Basin, a small embayment of the Mediterranean Sea in SE Spain, during the early Pliocene. Transgressive systems tract carbonate deposits exhibit three distinct sedimentary styles, with contrasting lithofacies patterns and stratal-geometry arrangements. Palaeotopography and local hydrodynamic conditions were the major factors controlling sedimentation. On the steep northern margin, affected by southeasterly wind-driven storms, a prograding platform (distally steepened ramp) with well-marked, platform-slope clinoforms developed. Bivalves extensively colonized the outer platform, and rhodolith pavements covered its edge. Coarse-grained, bioclastic sediments were frequently removed from the platform by storms and redeposited on the platform slope. On the southern margin of the basin, longshore currents driven by southeasterly winds hydrodynamically accumulated carbonate particles to form a spit-platform, on top of which some shoals developed. These shoals were dismantled from time to time by the northern storms, and the sediment was redeposited on the lee-side slope of the spit-platform. On the gentle and protected western margin, oyster banks and rhodolith pavements colonized the inner-ramp environment whereas coralline algal–bryozoan–bivalve bioconstructions formed on the outer ramp. This example shows that several sedimentary styles of temperate carbonate deposition can coexist in a single basin.