HIGH-RESOLUTION MAPPING OF KARST FEATURES WITHIN THE MESOZOIC AND CENOZOIC OF THE PERSIAN GULF

Karst features within the Mesozoic and Cenozoic of offshore Iran were mapped and classified using a 2D seismic dataset, in order to understand potential periods of sea-level lowstand, sub-aerial exposure of the carbonate platform and the impact on related petroleum systems. This work will produce insights into the development of karst surfaces and provide information on sea-level changes within the Persian Gulf. There is little published literature on seismic interpretation and visualization of paleokarst topographies, thus this project represents a new use of this type of data.

The sedimentary sequence within the Persian Gulf is composed of alternating clastic and carbonate deposits. This sequence has been previously investigated using 2D data from the Persian Carpet 2000 survey, and preliminary maps of stratigraphic surfaces have been created. Erosional, possibly karstic features have been identified at the top of several of the ancient (>60 Ma) carbonate sequences, thus defining periods of sea-level lowstand, and sub-aerial exposure and erosion of the carbonate platform.

The aim of the present work is, firstly, to continue mapping the karst surfaces and improve the accuracy of the existing seismic interpretation on these horizons. The second aim of this project is to classify the karstic features based on their morphology, size in map view and vertical extent of possible caves, sinkholes and lateral fracture features. The seismic stratigraphy of potential karst features will also be investigated, as infill of collapsed material is indicative of paleokarst.

The project will result in the development of a high-resolution map of paleokarst features within the dataset, and an increased accuracy of current seismic interpretations, with implications for hydrocarbon exploration in the region. In addition, the development of a karst surface is expected to represent a period of sub-aerial exposure, and this may be caused by a reduction in sea level or deformation-induced elevation of the crust. Therefore, results from this mapping will be compared to previous work on the geologic history of the region. Thus, a more detailed geologic history of the region and potential sea level change will be presented, forming an important contribution to understanding the geologic history of this economically important region.