Comparative Lithology of The Barnett Shale, Central Texas and
Age-Equivalent Caney Shale in Southern Oklahoma
Puckette, Jim1,
Darwin Boardman1, Bill Coffey2, Eric Gerding1,
Patrick Kamman2, Naranjan Aryal1,
Manish Singh1, Andy Rihn1, Stan Paxton3 (1)
Oklahoma State University, Stillwater, OK (2) Devon Energy Corporation,
Oklahoma City, OK, (3) United States Geological Survey, Oklahoma City, OK
Gas production from Upper Mississippian siliciclastic mudrock reservoirs
in Texas and the southern Midcontinent region is generating intense interest in the
Barnett Shale and age-equivalent Caney Shale. The Barnett Shale at the type Chappel locality near San Saba, Texas consists of 39.4 feet
(12 m) of gray to black phosphatic shales that contain thin lenticular
carbonates. Six prominent, shale to carbonate, depositional cycles are evident.
Biostratigraphic analyses indicate that the upper Meramecian and entire Chesterian
Stages are represented at this locality. Caney Shale outcrops were examined on
the Arbuckle and Lawrence uplifts, near Ardmore and Ada, Oklahoma, respectively. Total
measured thickness of the Caney exceeds 325 feet (99 m) on the south flank of
the Arbuckle uplift and 280 feet (85 m) feet along partially exposed sections
near Ada. The Caney consists of three
lithologically distinct members: the Ahloso, Delaware Creek and Sand Branch. The Ahloso Member is coarser-grained and primarily dark grey to
brown silstones and silty
shale. Faunal evidence places the Osagian-Meramecian
boundary near the base. The Delaware Creek Member consists of dark grey to
olive shales that contain prominent carbonate
concretions (bullion). Faunal evidence places the Meramecian-Chesterian
boundary in the upper part of the Delaware Creek. The Sand Branch is black to
dark gray phosphatic shale with sparse carbonate
concretions. Ammonoid and conodont
faunas, place the Sand Branch as upper Chesterian.
Caney lithologies reflect high frequency depositional
cycles and a generalized upward increasing water depth during deposition from
lowest in the Ahloso to maximal in the Sand Branch.