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Hanson et al. 2012 3D Projection of the Southern Mid-Continent Basement-Rock Surface Washita Valley Fault and Overthrust Penetrations Western Arbuckle Mountains 42 overthrust drilling penetrations Accessible samples from 21 wells 26.6 km of uncorrelated igneous section Puckett et al., 2014 Oklahoma Geological Survey Guidebook 38 2014 34 km Non-Correlated Cross Section Mafic Rock Photomicrographs Mafic Rock Geochemistry Characterized as broadly transitional tholeiitic basalts to andesites from multiple overlapping eruptive systems. Similar to OIB and other continental flood basalts originating from an enriched mantle source. Pan Am Newberry Pan Am Williams Pan Am Jarman Sec. 13-T1N-R3W Sec. 20-T1N-R2W Sec. 19-T1N-R2W Modified from Brueseke et al. 2014 Rhyolite Photomicrographs Rhyolite Geochemistry Dominantly rhyolites and peralkaline rhyolites Highly fractionated – Depleted Sr, P, Ti - Typical A-type signature Typical within Plate, A-type, consistent with emplacement in alaucogen type setting Outcrop-Based Generalized Cooling Unit Diagram Surface Exposures of the Carlton Rhyolite in the Wichita Mountains From Puckett et al. 2011 Rhyolite Cooling Unit Pan American Oil Co. Moore #1-A Sec.20 T1N-R2W Rhyolite Glassy Flow Margin Kaiser Francis/Westheimer-Neustadt Chapman #1 Sec.9-T2S-R2E Rhyolite glassy flow margin (Dark Brown cuttings) Flow interior 40 m below glassy margin sample above Gamma Ray, Induction Log, and Lithologic Log COHO Resources Story #4 Sec. 18-T1N-R2W W e l Phreatomagmatic Interval – Magma in Contact With Ground Water Pan American Oil Co. Whyte #1 Sec. 21-T1N-R1W 1.14 km 426 m Clastic Section Pan Am Jar man #1 Sec. 19-T1N-R2W Washita Valley Fault and Overthrust Penetrations Western Arbuckle Mountains 42 overthrust drilling penetrations Accessible samples from 21 wells 26.6 km of uncorrelated igneous section Puckett et al., 2014 1.2 km Cumulative Volcaniclastic Interval Intercalated with Rhyolite Frankfort Oil Co. Sparks Ranch #1 Sec. 32-T1S-R1W Post Volcanic Sedimentation close to the Rift Axis Frankfort Oil Co. Sparks Ranch Sec. 32-T1S-R1W Reagan Islands • Positive relief features that resisted inundation until Latest Cambrian/Early Ordovician • Identifiable by the absence of Reagan Sandstone resulting in Arbuckle Group carbonates unconformably overlying the Early Cambrian volcanic rocks. • Also found in the Wichita Mountains at Balley Mountain and the Slick Hills Modified from Campbell and Weber 2006 2.48 km beneath surface SOHIO Traub #1-3 Sec. 3-T6N-R14W 6.8 km NNE of Bally Mountain 415 m thick basalt interval with 35 m rhyolite dike/sill 104 m thick basalt interval 229 m thick basalt interval POSSIBLE FAULT FAULT 6.19 km beneath surface Helmerich & Payne McNutt Unit #1 Sec. 23-T9N-R26W Surface 2.91 km of Permian and Pennsylvanian sedimentary rocks including Granite Wash 4.9 km (minimum) Normal fault 2.49 km 2.91 km 1.44 km of Diabase, Diorite, and Granite 4.35 km 850 m of Gabbro 280 m of metamorphic rocks 3 m core of amphibolite and quartzo-feldspathic gneiss Poss. Fault indicated on Caliper log 5.48 km Total Depth 5,436.5 m 5,467.8 m Photo by OGS Core Facility Staff Penetratively folded tonalitic gneiss Hornblende Biotite Sericitized plagioclase Light green areas on hornblende represent partial retrogression to actinolite. PPL Field width 5mm Amphibolite with migmatitic quartz-feldspar patch. Summary The Southern Oklahoma Aulacogen contains a minimum emplaced volume of 250,000 km3. Igneous activity was voluminous, strongly bimodal, and intercalated. Coeval mafic and felsic volcanism phases overlap. Felsic magmas were A-type, mafic magmas have an EMI-OIB signature. Eruption products are lava-dominated - Rhyolitic pyroclastic deposits are limited to thin beds between flows - Basalt pyroclastic deposits seem to be primarily sourced from phreatomagmatic eruptions. Cratonic-sourced sedimentation into the rift was active during volcanism and defines a negative topographic profile after volcanism ceased. Intercalated rhyolites and basalts are present in the subsurface throughout the aulacogen.