Architecture and seismic expression of Miocene carbonate barrier-lagoon systems (Ermenek platform, Turkey and Zhujiang platform, South China Sea).

摘要

Increasing volume and data content of subsurface data sets have progressively eclipsed outcrop as a source of geological input to solve problems. However, outcrop studies remain the only provider of almost continuous linked scales of observations. They are not only useful for calibrating the subsurface data but also provide guidance in integrating the different subsurface data sets with their different spatial and temporal resolution. The Ermenek platform is a well-exposed Miocene carbonate depositional system, which allows reconstruction of its architecture in detail and in 3 dimensions. The exceptionally well preserved depositional geometries of the barrier-lagoon system permit direct comparison and calibration of equivalent systems in subsurface. It also allows extrapolating facies distribution from the outcrop to the subsurface data where only geometrical informations can be studied.; The Ermenek Platform margin architecture is a barrier margin with slump features and redeposited sediment. The seaward side of a steep platform margin consists of massive slumps, finer-grained redeposited sediment and meters scale blocks that rolled-down the steep-slope. Large-scale margin collapse has similar geometries in both outcrop and on an equivalent Miocene platform margin on seismic sections. Detachment planes produce characteristic unconformities and juxtaposition of seismic facies. Such large margin collapses produce detached rotated blocks of folded sediment or attached massive contorted bed packages imaged as a chaotic seismic facies in subsurface; The 3-dimensional platform architecture is a combined result of sediment production and accommodation changes, which vary in time and space. The physiography of the shelf, the hydrology, the climate evolution and clastic input strongly influence the carbonate production and therefore the depositional geometries. The actual topography of the platform system is influencing the water circulation that in turn controls reefal build-up development, which influences the shape of the clinoform geometries.; Detailed stratigraphic architecture of an intra-platform prograding margin provides calibration of various seismic attributes using forward seismic modeling. Detailed stratigraphic reconstruction from outcrop documents heterogeneities beyond the conventional seismic resolution. Improvement of horizontal resolution significantly increases the recognition of the stratigraphy on the seismic profiles. Single attribute analysis has some level of ambiguity, which may be diminished by integrating several seismic attributes.