ARKANSAS TURBIDITE STUDIES MAY AID OKLAHOMA JACKFORK EXPLORATION

During the past 2 years, more than a dozen successful Pennsylvanian Jackfork gas wells have been drilled in eastern Oklahoma, and the play seems ready for expansion if drilling and completion costs can be contained. To date, wells are thought to produce from fractures in highly quartz-cemented, brittle sandstones. However, there is potential for stratigraphic accumulations of gas. It is generally agreed that Jackfork Group rocks were deposited mainly as turbidites in the deepwater Ouachita basin. A recent suggestion that significant amounts of Jackfork Group rocks are discontinuous and less predictable sandy debris flows has received considerable critical review in the recent literature and at the 1996 American Association of Petroleum Geologists convention. A shallower water origin has also been suggested for some outcrops in eastern Oklahoma. With this in mind, the authors provide a summary of their observations, measurements, and interpretations of upper Jackfork outcrops in southwest-central Arkansas as a guide for interpreting the subsurface Jackfork in eastern Oklahoma.