About This Item
- Full TextFull Text(subscription required)
- Pay-Per-View PurchasePay-Per-View
Purchase Options Explain
Share This Item
About 13,000 feet of Pennsylvanian strata (of upper Pottsville and lower Allegheny age) are present in the southern part of the Arkansas coal field. The strata thin northward at such a rapid rate that they are only about half as thick at the north side of the coal field as equivalent strata at the south side. The sediments in the Pottsville portion of the section consist dominantly of shale, sandy shale, and sandstone, and the overlying strata of Allegheny age consist of these lithologic types together with a number of coal beds. The major source of the sediments appears to have been farther south, in and south of the Quachita Mountains, but some sediments in the lower part of the section probably came from the east.
Deposition of the Pennsylvanian sediments took place in a basin: (1) that was progressively warped downward and whose north margin migrated northward across the area but lay across the central part of the coal field during most of early Atoka time; (2) that underwent minor deformation by lateral pressure from the south during the deposition of the sediments; (3) that stood close to sea-level throughout the greater part of the time of deposition of the sediments; (4) that received no invasion of marine waters of sufficient depth or duration to leave a perceptible record in the stratigraphic column; and (5) that received the bulk of the sediments under fluviatile conditions. In consequence of these and other conditions the Arkansas coal field is characterized by (1) northward thinning o the strata, part of which is due to progressive northward overlap at the base of the Atoka formation and part to northward thinning of individual beds; (2) a sharp change in the structural pattern along an east-west line which probably marks the zone of greatest change in thickness of the coal-basin strata; (3) limited lateral extent of lithologic units; and (4) no apparent symmetry of recurrence of lithologic types in the stratigraphic column.
Pay-Per-View Purchase Options
The article is available through a document delivery service. Explain these Purchase Options.
|Watermarked PDF Document: $14
|Open PDF Document: $24
Members of AAPG receive access to the full AAPG Bulletin Archives as part of their membership. For more information, contact the AAPG Membership Department at [email protected].