Summary of Subsurface Geology of Northeast Texas
Authors: Nichols P. H. , Peterson G. E. , Wuestner C. E. 
Published: May 2021

Abstract
Northeast Texas, more commonly known as East Texas, is one of the major oil- and gas- producing provinces in North America. Production has been found throughout most of the sedimentary section of Northeast Texas, which ranges from Upper Jurassic into the Tertiary.
Sparse control indicates that basement is a complex of folded and faulted Paleozoic rocks (Ordovician-Lower Pennsylvanian). All the overlying rocks that have been definitely dated are 'Mesozoic and Cenozoic in age, the oldest strata known to be Mesozoic being the Upper Jurassic Werner Formation; between this and basement is a redbed sequence that has been penetrated locally, and has been assigned to the Eagle Mills Formation. Oil and gas production has been established in the Smackover, Bossier, and Schuler formations of the Jurassic.
The Lower Cretaceous Comanche Series contains oil and gas accumulations in the Trinity Group (Travis Peak Formation, Glen Rose subgroup, Massive Anhydrite [“Bacon Lime”], upper Glen Rose, and Paluxy Formations); the Edwards Limestone of the Fredericksburg Group; limestones of the Georgetown subgroup; and the Buda Limestone of the Washita Group. The Upper Cretaceous Gulf Series includes the Woodbine Group—one of the most prolific hydrocarbon reservoirs in the United States, and production has been established in the Eagle Ford, Austin (Tokio Formation), Taylor (Wolfe City Formation), and Navarro (Nacatoch Sandstone) Groups.
The Tertiary of Northeast Texas comprises the Paleocene Series (Midway Group) and Eocene Series (Wilcox and Claiborne Groups). Scattered hydrocarbon production has been established in the Wilcox Group and from the base of the Claiborne Group.
Mesozoic sedimentation began with a transgression of the base-leveled complex of deformed Paleozoic rocks constituting the Ouachita fold belt; this transgression was originated by the ancestral Gulf of Mexico. The close of the Jurassic Period and the Comanche and Gulf Epochs were marked by major regression; initiation of each succeeding epoch was marked by major transgression. Regressions and transgressions of lesser extent punctuated the history of each of the epochs.
In general, Mesozoic and Cenozoic strata dip and thicken toward the center of the Northeast Texas area, which may be divided into five tectonic provinces: (1) Updip belt, (2) Mexia-Talco fault zone, (3) Downdip belt, (4) Northeast Texas basin, and (S) Sabine uplift.
Minor accumulation of hydrocarbons have been established on some anticlinal structures in grabens of the Mexia-Talco fault zone, and major accumulations have been trapped against faults in this zone. In the downdip belt and in the Northeast Texas basin, major accumulations have been established on many structures generated by salt movement. On the Sabine uplift, accumulations in structural-stratigraphic traps are common, including the East Texas field.
Data from widely scattered wells in Northeast Texas indicate that igneous activity—intrusions, lava flows, and ash falls—occurred in post-Paleozoic and pre-Early Cretaceous time. There is a little evidence to indicate pre-Late Jurassic igneous activity.