1. New insights into the Early Cambrian igneous and sedimentary history of the Southern Oklahoma Aulacogen from basement well penetrations
Robert E. Puckett Jr., Richard E. Hanson, G. Randy Keller, Matthew E. Brueseke, Casey L. Bulen, Amy M. Eschberger, Stanley A. Mertzman

2. Hanson et al. 2012

4. 3D Projection of the Southern Mid-Continent Basement-Rock Surface

5. 35 km 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
35 km
Puckett et al., 2014

6. Oklahoma Geological Survey
Guidebook 38
2014

7. 34 km Non-Correlated Cross Section

8. Mafic Rock Photomicrographs

9. 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 Sec. 13-T1N-R3W
Pan Am Williams Sec. 20-T1N-R2W
Pan Am Jarman Sec. 19-T1N-R2W
Modified from Brueseke et al. 2014

10. Rhyolite Photomicrographs

11. Rhyolite Geochemistry
Dominantly rhyolites and peralkaline rhyolites
Typical within Plate, A-type, consistent with
emplacement in alaucogen type setting
Highly fractionated – Depleted Sr, P, Ti - Typical A-type signature

12. Outcrop-Based Generalized Cooling Unit Diagram
Surface Exposures of the Carlton Rhyolite in the Wichita Mountains
From Puckett et al. 2011

13. Pan American Oil Co. Moore #1-A Sec.20 T1N-R2W
Rhyolite Cooling Unit
Pan American Oil Co. Moore #1-A Sec.20 T1N-R2W

14. 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

15. Gamma Ray, Induction Log, and Lithologic Log
COHO Resources Story #4 Sec. 18-T1N-R2W
Well log interval from the COHO Resources Story #4 (18-1N-2W), showing gamma ray and induction logs and corresponding lithologic log.

16. Phreatomagmatic Interval – Magma in Contact With Ground Water
Pan American Oil Co. Whyte #1 Sec. 21-T1N-R1W

17. Clastic Section
Pan Am Jar man #1
Sec. 19-T1N-R2W
426 m
1.14 km

18. 35 km 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
35 km
Puckett et al., 2014

19. 1.2 km Cumulative Volcaniclastic Interval Intercalated with Rhyolite
Frankfort Oil Co. Sparks Ranch #1 Sec. 32-T1S-R1W

20. Post Volcanic Sedimentation close to the Rift Axis
Frankfort Oil Co. Sparks Ranch Sec. 32-T1S-R1W

21. 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

24. Modified from Campbell and Weber 2006

25. SOHIO Traub #1-3 Sec. 3-T6N-R14W 6.8 km NNE of Bally Mountain
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
6.19 km beneath surface

26. 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
Poss. Fault indicated on Caliper log
3 m core of amphibolite and quartzo-feldspathic gneiss
5.48 km Total Depth

27. 5,436.5 m
5,467.8 m
Photo by OGS Core Facility Staff

28. 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.

29. 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.