THE OUACHITA OROGENIC BELT: SOME NEW RESULTS AND THOUGHTS ON ITS STRUCTURE, AND EVOLUTION

The structure and evolution of the Ouachita Orogenic Belt remains a mystery in many respects because it is mostly buried, deep drilling results are scarce, and deep geophysical results are sparse. Some new 3-D seismic reflection data have been released for analysis, and the results show interesting new details about the relationships between Paleozoic and Pre-Cambrian structures. Specifically, the complexity of the triple junction between the Southern Oklahoma Aulacogen and the Cambrian margin of North America, as well as, its effects on the Ouachita Orogenic Belt has been refined. Another result is that new seismic results northeast of the Llano uplift show that gravity anomalies along the Ouachita Orogenic Belt that have been attributed to Late Paleozoic basins overthrusted during the Ouachita Orogeny are at least partly due to deeper sources that probably include sediments associated with Cambrian rifting and felsic intrusions. In both cases, we have integrated these results into a broader context. Our analysis also shows that the Llano uplift itself is probably a distinct crustal fragment.