New Mexico Geological Society Annual Spring Meeting — Abstracts

The Tucumcari, Estancia, Carrizozo, and Vaughn Basins are located in northeast and central New Mexico. These basins began to form during the Atokan (Early Pennsylvanian) and saw continued tectonic development through the Wolfcampian (Early Permian). They are tectonic elements of the southern Ancestral Rocky Mountains and were formed along the flanks of the late Paleozoic Sierra Grande and Pedernal uplifts in a strike-slip setting. During the late Paleozoic, the Precambrian cores of these uplifts were exposed and were the source of sediments deposited in the adjoining basins.

The Tucumcari, Estancia, Carrizozo, and Vaughn Basin areas were dominated by shallow-shelf deposition. Along the boundaries of the adjoining uplifts, however, these basins have component elevator basins. Elevator basins are long, narrow, and structurally deep troughs bounded by high-angle faults. They are either elongate parallel to the axes of the adjoining uplifts and separate the uplifts from areas of shelf deposition or they cut into the flanks of these uplifts. The bounding faults, of Early Pennsylvanian to Early Permian age, have vertical offsets that can exceed 5,000 ft. Basin width can range from 5 to 15 miles and basin length can range from 20 to 50 miles. Early to Late Pennsylvanian strata in these elevator basins contain mature petroleum source rocks. Deposition was dominated by shales and sandstones derived from erosion of Precambrian rocks exposed on the adjacent uplifts. Total organic carbon (TOC) can exceed 9 percent in darkgray to black shales. Kerogens range from gas-prone woody types to oil-prone amorphous types. Greater depth of burial in the elevator basins as compared to the adjoining uplifts and shelf areas has resulted in increased levels of thermal maturation within the basins. Shales within many of these elevator basins are within the oil window and shales on the adjoining shelves are less mature. Hydrocarbons generated within the basins may be trapped within basinal sandstones but may have also migrated upward along the bounding faults and into strata on the adjacent shelves
and uplifts.