Thickness, Compositional and Textural Variability, and Genesis of El-Lajjun Oil Shale, Central Jordan H Alnawafleh 1, D Large 2 & B Spiro 3 1 Department of Mining Engineering, Al-Hussein Bin Talal University, Ma an, an, PO Box 20, Jordan hanialnawafleh@ahu.edu.jo 2 School of Chemical, Environmental & Mining Engineering, Nottingham University, Nottingham, NG7 2RD, UK. 3 Department of Mineralogy, Natural History Museum, London, SW7 5BD, UK 1
Aim Understand the geological characteristics of El-Lajjun oil shale deposit (Central Jordan) and its genesis Objectives Study the compositional and textural variability Understand the dominant processes and the depositional environment Determine the source and type of organic matter and the controls on its accumulation and preservation Construct a simplified depositional model of oil shale in El-Lajjun Basin 2
Distribution & Reserve Wide spread, subsurface Up to 50 billon tons in central Jordan Unlimited in the north 3
Geological History Bituminous calcareous rocks (limestone, chalk and marl) Deposited in Maastrichtian-Danian during the tectonic evolution of Syrian Arc System Shallow continental shelf of Tethys Ocean Latitude ~ 30 o N Deep water to N and NE of Jordan, shallow coastal regions to S, Nubian-Arabian Shield Source: Rosenthal et al., 2000 with minor modification 4
Why El-Lajjun Oil Shale Deposit? Great importance of El-Lajjun oil shale deposit for future mining and utilization Easily accessible Oil shale sampling from surface outcrop Extensive drilling activities and availability of core samples 5
El-Lajjun: Structure & Stratigraphy Synclinal basin bordered on the E and W by two parallel faults (tectonic-related), limbs are gently dipping Folding is pre-rifting rifting Oil shale is in the core,, no unconformity surfaces Variable in thickness (between( 1.4 to 86.5 m) Epoch Paleocene (Danian)- Maastrichtian Maastrichtian- Campanian Santonian- Coniacian Unit Bender (1974) Chalk-Marl [oil shale in the bottom] Phosphorite Silicified Limestone 6
Oil Shale in Central Jordan El Lajjun Open Pit in El-Lajjun Top soil & Gravel Marl Upper Chalk Lower Chalk Oil Shale Wadi Sediments Wadi Sediments Phosphorite is not exposed 7
Organic Matter & Its Relation to Other Rock Components Rapid transition form organic rich to organic poor Concretionary layers, phosphate and chalk are depleted in OM Data for BH LC98011, El-Lajjun 8
One Oil Shale Succession Top soil & Gravel Marl Upper Chalk Lower Chalk Oil Shale Oil Shale Succession Conc Lst Datum Wadi Sediments 9
Mineralogical & Textural Change Laminated Oil Shale Silicified oncretionary Lst (Dolomitic) 10
Organic Matter Mineralization - Authigenic Carbon 0.2 mm Organic Poor Horizon: Dolomite cement Calcite overgrowth Benthic forams Clay-bearing Low pyrite content Bioturbation? 0.2 mm 11
Organic Rich Acid Conditions - Carbonate Dissolution 0.2 mm Gyp OM Dol Organic Rich Horizon: More laminated Productivity derived and authigenic components Carbonate shell: compaction and dissolution Low pyrite content Benthic foraminifera decrease More phosphatic particles and detrital grains 500 µm 12
Productivity, Anoxia & Sea Level 13
Oxic vs. Anoxic Conditions Sharp decrease in Pr/Ph ratio = Change from oxidizing conditions to more anoxic conditions 14
Type of Source Organic Matter 15
Type of Source Organic Matter & Depositional Environment Regular Sterane biomarkers 16
Simplified Depositional Model of Oil Shale in El-Lajjun Basin 17
Simplified Depositional Model of Oil Shale in El-Lajjun Basin 18
Conclusions El-Lajjun oil shale in central Jordan is carbonate rich and shows compositional variability Organic rich horizons (oil shale) deposited during periods of high primary productivity under suboxic to anoxic conditions probably during relatively high stand of sea level Organic poor horizons were formed when conditions changed to oxic conditions and decreased primary productivity The OM is primarily of marine origin with contribution from terrestrial sources from the continental parts in the S and SE. 19
Acknowledgments Dr J Mackquaker, The University of Manchester, UK Prof H Khoury,, The University of Jordan, Amman, Jordan Dr J Alali,, The NRA, Amman, Jordan Staff of the Laboratories of SEM Microscopy, The NHM, London NATO Science Programme 20