Print this pageAAPG GEO 2010 Middle East
Geoscience Conference & Exhibition
Innovative Geoscience Solutions – Meeting Hydrocarbon Demand in Changing Times
March 7-10, 2010 – Manama, Bahrain
Biogenic Silica Particles in Permo-Carboniferous Rocks and Their Significance as Biostratigraphic Indicators
(1) EXPEC Advanced Research Center, Saudi Arabian Oil Company, Dhahran, Saudi Arabia;
(2).. TNO Built Environment and Geosciences, Utrecht, Netherlands.
Late Carboniferous to Early Permian clastic rocks of the Unayzah resting on the Hercynian Unconformity surface in Saudi Arabia, are of great economic significance, bearing significant quantities of gas and oil. The Unayzah reservoir sequences are often barren of fauna and flora which limits independent biostratigraphic control and well correlation. The presence of newly discovered siliceous microfossils may provide a tool for subdividing and correlating these rock successions. These siliceous microfossils may constitute phytoliths, microscopic silica bodies of various shape and size that form in the cells of roots, stems and leaves of plants. As major plant groups like gymnosperms, lycopods and ferns already existed by the end of the Devonian, one might expect that these early land plants also formed phytoliths in their tissues. Following decay of the plant, the silica bodies may become part of the sedimentary record. In order to test this hypothesis Permo-Carboniferous rocks from 12 wells, distributed over a large geographic area in Saudi Arabia, were studied. Biogenic silica particles (BSPs) were found in all studied wells and lithostratigraphic units. A total of 14 BSPs with some significant morphological differences were identified and described. BSP assemblages are currently being studied to determine whether they can provide information on facies, paleoclimate or stratigraphy. The fact that almost all BSP species were found in all lithostratigraphic units studied suggests that subdivision of the sedimentary sequences based on conventional first and last occurrence datums of BSPs, is not promising. On the other hand, BSPs show distinct abundance patterns that may be of stratigraphic importance. The sample collection from the Unayzah succession has recently been extended in order to enlarge the areal and stratigraphic coverage. If the outlined studies are successful, BSPs may provide a new tool for subdividing and correlating terrestrial rock sequences that are often barren of microfossils, including palynomorphs.