Abstract This seismic line, as interpreted, illustrates salt "rollers" or "anticlines" as they appear on the west flank of the East Texas salt basin. The rollers occur in a belt approximately 32 km (20 mi) wide parallel to structural and depositional contours. Downdip (east) of the zone of salt rollers is a zone of piercement salt domes, which represent the maximum original thickness of salt in the basin. The piercement salt domes are described on a seismic line edited by Engleman and Kemmer (this volume); the line continues eastward from the east end of this line. Updip (northwest) the salt thins to a feather edge within 64 km (40 mi) of the northwestern end of this line. Salt deformation in this zone is restricted to a few low relief pillows. An extensional fault system, the Mexia-Talco Fault Zone, is located approximately 9.5 km (6 mi) northwest of the northwestern end of this line. This fault system is believed to represent a regional pull-apart, from which salt moved downslope (east) following deposition of the Jurassic carbonates. This movement, in addition to overburden loading is thought to have been largely responsible for the anticlinal forms seen here. Timing of salt movement is complex, and appears to be episodic in some areas and continuous in others. Salt can be observed to have withdrawn almost completely on both flanks of the roller at shot point 425, as well as on the eastern flank of the roller at shot point 625. The up-turn of the Jurassic carbonates at the extreme eastern end of this line may represent the west flank of a "turtle" structure. Hydrocarbon production is associated with many of the rollers, where it is obtained principally from Jurassic carbonates. The well at shot point 425 produces from a structure in the Smackover Limestone overlying a well-developed roller. Structures over rollers may persist high in the stratigraphic section, as exemplified by the well at shot point 620 which produces from Lower Cretaceous carbonates.

Abstract The seismic line depicting the salt anticline is located in Van Zandt County, Texas (Figure 1). The line is oriented in a northwest to southeast direction and is approximately 18.1 km (11.25 mi) long. The structural deformation of Mesozoic and Tertiary sediments in the East Texas basin is caused by movement of the underlying Middle Jurassic salt. The East Texas basin is one of several grabens which developed in response to the Triassic rifting of the Gulf of Mexico (Kreitler, 1980; Jackson, 1981). The boundary of the East Texas basin is delineated by the Mexia-Talco Fault System to the north and west, by the Sabine Uplift to the east, and the Angelina-Caldwell flexure to the south which separates the embayment from the Gulf Coast basin (Figure 1; Collins et al, 1981; Wood and Guevara, 1981). Initially the East Texas basin was partly restricted allowing the deposition of up to 2 km (1.2 mi) of salt (Kreitler, 1980). Subsequent subsidence of the basin combined with the rapid deposition of clastics in the Early Cretaceous (Seni and Kreitler, 1981) provided the differential loading required for salt movement (Trusheim, 1960). Consequently, both salt anticlines and salt domes were formed from the lateral and vertical migration of salt. Regionally the salt anticlines are found mainly on the outer edges of the basin while salt domes are located toward the middle of the basin where both the overburden and salt may have been the thickest (Wood, 1981). Turtle-shaped anticlines are regionally found among salt domes and salt anticlines. The formation of these structures is summarized here from descriptions by Wood (1981) and Wood and Guevara (1981). Initially salt migrates away from an area of maximum deposition causing the formation of a withdrawal basin in the overlying sediments. Complete withdrawal of salt first occurs at the basin's center where the sediments are the thickest and then progresses outward. Once the salt is completely withdrawn from beneath the basin the thickest sediments form the core and the collapsed flanks of the withdrawal basin form the limbs of the turtle-shaped anticline.