UNDERSTANDING SABINIA - A MULTIDISCIPLINARY 'BIG SCIENCE' EFFORT?

The nature, margins and history of the microcontinental block underlying the Sabine Uplift - "Sabinia" - is perhaps the single most important enigma in the northern Gulf Coast. Current knowledge of the pre-Jurassic in this large area of East Texas and Louisiana is based on one gravity profile and a half-dozen or so deep well penetrations. From the gravity profile (Mickus and Keller, 1992), Sabinia is a crustal block 35-40 km thick with a density structure identical to continental crust found to the north, and separated from it by a thin 'oceanic' crust underlying a thick sedimentary basin (both Ouachita and Eagle Mills). Is this block a Paleozoic arc, as was originally suggested? Or is it a piece of continental crust, and if so, is it Laurentian or Gondwanan in affinity? Then, why is there a thin 'oceanic' pre-Mesozoic crust in the Texarkana area?

We need to develop a 3D gravity model of the entire region; we don't even have a good shape for this block that isn't dependent on assumptions about Mesozoic rifting! How extensive are thin-crust basins, and are they really Paleozoic? The effects of salt movement and post-salt sedimentation on the gravity picture will need to be evaluated. Deep seismic reflection/refraction (an onshore GUMBO) would also allow a better understanding. Well samples are old and limited, but newer work may be performed here also. Understanding of top-basement structures has been much improved by Haynesville-Bossier exploration. Eventually, deep drilling could be piggybacked on Cotton Valley or Haynesville producing wells.