Haynesville is the largest of the Arkansas-Louisiana shelf-slope fields which are productive from calcarenites of the upper members of the Late Jurassic Smackover and Buckner Formations. Although associated with closure against a post-Smackover fault, hydrocarbon accumulation in the Haynesville field is stratigraphically controlled. Contrary to widespread belief, the main producing zone is part of the Buckner Formation, rather than Smackover, and is here designated "A₂."

On the shelf slope, Smackover calcarenite bars were formed on turbulent shoals usually localized by contemporaneous structural uplifts, and in the Haynesville area these bars have a northeast trend. In contrast, the overlying Buckner calcarenites suggest a beach environment associated with the actively subsiding seaward edge of the shelf slope, along which was deposited an east-west calcarenite bank up to 600 ft thick. At Haynesville, several transgressive calcarenite units extend updip from this Buckner bank, and one of these, the "A" zone, can be traced regionally and is productive in many shelf-slope fields. The bank contains environmentally controlled facies very similar to those observed in the Smackover, but the most important is a moderate-energy, nonporous, pelletoid, commonly fossiliferous, mixed facies. Higher energy conditions on such positive features as Haynesville led to deposition of a porous reservoir facies in updip areas.

Differences in orientation and configuration between Smackover and Buckner calcarenite zones suggest a period of structural adjustment, but by the beginning of "A₂" deposition, a fairly regular east-west strike had been established. During periods of regression or lack of subsidence, evaporitic mudflats landward of the calcarenite beaches advanced south toward the regional bank. An idealized section from updip to downdip through a typical Buckner cycle would include evaporitic mudstone, shaly transitional limestone, reservoir, mixed, and pellet-mud facies. After final regression and uplift of the continent, Buckner mudstone graded into the overlying nonmarine sandstone of the "P" tongue of the Schuler Formation. Movement contemporaneous with sedimentation began along a larg down-to-north fault after "A" zone deposition, but the greatest displacement occurred during "P" tongue deposition.