Conclusions and Future Work

The Southern Oklahoma aulacogen represents an understudied large igneous province responsible for over 250,000 km3 of mafic-felsic volcanism. The extent of the aulacogen strikes SE-NW through much of Oklahoma and into parts of northern New Mexico and Southern Colorado. Thanks to oil and gas exploration in the Arbuckle Mountains, Cambrian aged

extrusive mafic-intermediate lavas were found and analyzed as a part of this study. These lavas represent the first evidence of extrusive mafic material in the Arbuckle Mountains. Prior to the extrusive mafic volcanism, only diabase dikes and the intrusive Roosevelt Gabbros of the Wichita Mountains provided evidence of mafic magmatism in the SOA.

These lavas can be defined as subalkaline to transitional tholeiitic basalts-andesites, and are representative of intraplate OIB volcanism. Based on the major element, trace element, and isotope chemistry, the Arbuckle samples are consistent with a substantial contribution of a mantle source enriched in recycled oceanic crust containing pelagic sediment (EMI OIB). Major element, trace element, and Sr and Nd isotope ratios for the SOA samples fall within and around the accepted EMI values. While evidence that the SOA formed from an EMI-type mantle source, it is also likely that some SOA magmas were affected by contamination from the upper

continental crust.

This study argues that the SOA is not only an LIP, but is also representative of flood basalt volcanism. Flood basalts tend to be tholeiitic OIBs. They often erupt in multiple lava packages over a short period of time. Underneath the surface, there is often evidence of massive dike swarms and flood basalt events have been shown to be associated with rifting. The SOA fits each of these qualifications: samples plot as EMI OIB, chemostratigraphy shows the potential of

and while rifting in the SOA is associated with the opening of the Iapetus ocean, it could have been supplemented by the eruption of a flood basalt.

Future studies in the SOA should focus on obtaining isotope analyses on a larger suite of samples as well as obtaining precise dates for the lavas in the Arbuckle Mountains. In particular, samples of similar geochemistry to CB-PAN-20 would be ideal, as this sample is representative of the unaltered, uncontaminated source that formed the mafic-intermediate lavas in the

aulacogen. This means studying low SiO2, high MgO basaltic tholeiites, which fall in and around

present day EMI OIB values. Obtaining precise dates on the lavas would also be beneficial, as this will confirm whether eruptions occurred in a timeframe accepted for flood basalt events, as well as providing a better understanding for the formation of the region in general.

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