Tectonic Controls on Oligocene Carbonate Platform-Basin Deposition, Costa Blanca, Southeast Spain
Published:January 01, 2008
Michelle Stoklosa, J.A. (Toni) Simo, 2008. "Tectonic Controls on Oligocene Carbonate Platform-Basin Deposition, Costa Blanca, Southeast Spain", Controls on Carbonate Platform and Reef Development, Jeff Lukasik, J.A. (Toni) Simo
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A thick Oligocene succession of shallow-water carbonates exposed in southeast Spain provides an opportunity for studying the controls on platform and off-platform morphology and arrangement of facies successions, including compositional trends. The Oligocene platform of the Costa Blanca progressively onlaps a topographic high. It includes four high-frequency sequences that, together, show an overall upward-deepening trend and a vertical transition from cyclical inner-platform strata at the base to open-marine coralline algalmounded morphologies at the top. The margin is interpreted to have been a steep-sided and possibly faulted margin that shed coarsegrained platformal and older material into the basin. The five defined facies associations (restricted inner shelf, open-marine inner shelf, open-marine middle shelf, open-marine mounded outer shelf, and basin) consist chiefly of heterozoan biotic assemblages (red algae, benthic foraminifera, bryozoans, mollusks) that are in contrast to most other coral-dominated Oligocene strata of the Tethys.
Deposition of the Oligocene platform and basin strata occurred contemporaneously with the opening of the Valencia Trough, and postdated and predated contractional events that folded the area. Faulting and increased subsidence associated with this extensional tectonic setting governed the overall platform morphology, deepening-upward trend, and slope-basin sedimentary wedges. The tectonic setting allowed the accumulation of a thick stratigraphic succession and subsequent drowning; it also overprinted the effects of global sea-level fall. The opening of the Valencia Trough may have brought deeper, cooler, and possibly nutrient-rich waters onto the shelf, controlling the heterozoan biotic assemblage. The tectonic setting, biotic assemblages, and deepening-upward characteristics of this Tethyan platform make it a good analog for Cenozoic carbonates of Southeast Asia.
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Controls on Carbonate Platform and Reef Development
Carbonate platforms and reefs emerge, grow and die in response to intrinsic and extrinsic mechanisms forced primarily by tectonics, oceanography, climate, ecology and eustasy. These mechanisms, or controls, create the physical, biological and chemical signals accountable for the myriad of carbonate depositional responses that, together, form the complex depositional systems present in the modern and ancient settings. If we are to fully comprehend these systems, it is critical to ascertain which controls ultimately govern the “life cycle” of carbonate platforms and reefs and understand how these signals are recorded and preserved. Deciphering which signals produce a dominant sedimentological response from the plethora of physical and biological information generated from superimposed regional to global-scale controls is critical to achieving this goal. With this understanding, it may be possible to extract common time- and space-independent depositional responses to specific mechanisms that may, ultimately, be used in a productive sense. Extensive research on a wide variety of carbonate platform and reefal systems in the past few decades has provided the foundation and understanding necessary to take carbonate research to a new level. With assistance from rapidly advancing computer software and an increasing use of cross-disciplinary integration, carbonate research is shifting from description and morphological analysis towards a science that is more focused on the assessment of process and genetic relationships. The aim of this special publication is to present a cross section of recent research that shows this evolution from a variety of perspectives and scales using examples distributed throughout the Phanerozoic.