The Experts below are selected from a list of 111 Experts worldwide ranked by ideXlab platform
Paul K. Link - One of the best experts on this subject based on the ideXlab platform.
-
Pennsylvanian and Permian Paleogeography of South-Central Idaho: the Wood River Basin
AAPG Bulletin, 1991Co-Authors: J.b. Mahoney, Bradford R. Burton, J. P. O’brien, Paul K. LinkAbstract:The Sun Valley Assemblage (Wood River, Dollarhide, and Grand Prize formations) was deposited in the Wood Rover basin in what is now south-central Idaho, north of the Snake River Plain, from the Atokan to Wolfcampian and Leonardian( ). Atokan and Des Moinesian deposition occurred in braided deltas and overlying clear water carbonate shoals. The rocks of this depositional system vary in thickness from tens to several hundreds of meters reflecting irregularities in the erosional surface on the underlying foundered Antler highland. This basal unconformity has been sheared during Mesozoic and Paleogene deformation. Significant regional subsidence of the Wood River basin began in the Des Moinesian, was most rapid in the Virgilian, and slowed in the Wolfcampian, resulting in total thickness of over 2,000 m for each of the three formations. In the central part of the basin (Wood River Formation) a sub-wave-base ramp system with southeastern paleoslope was fed by turbidite flows of mixed carbonate-siliciclastic fine-grained sediment that had been thoroughly mixed on a shelf area to the north and east. The carbonate fraction may have been derived from the Snaky Canyon Formation carbonate platform to the east. To the north, a siliciclastic fan or ramp system (Grand Prize Formation)more » was present. Virgilian and Wolfcampian strata represent highstand systems tracts and a lowstand tract is present in strata deposited near the Virgilian-Wolfcampian boundary.« less
Spencer G. Lucas - One of the best experts on this subject based on the ideXlab platform.
-
Vertebrate biostratigraphy and biochronology of the upper Paleozoic Dunkard Group, Pennsylvania–West Virginia–Ohio, USA
International Journal of Coal Geology, 2013Co-Authors: Spencer G. LucasAbstract:Abstract The Dunkard Group is ~ 343 m of mostly clastic rocks exposed in Pennsylvania, Ohio and West Virginia, USA. Correlation of the Dunkard Group to the Pennsylvanian–Permian boundary has long been debated. Fossil vertebrates from the Dunkard Group include paleoniscoids, dipnoans, a rhipidistian crossopterygian, selachians, lepospondyl and temnospondyl amphibians, diadectomorphs, primitive amniotes, eureptiles and eupelycosaurs. These vertebrates represent two biostratigraphically distinct assemblages, one from the Waynesburg and Washington formations and the other from the overlying Greene Formation. Comparison of the Dunkard vertebrate biostratigraphy to a vertebrate biostratigraphy and biochronology developed in New Mexico–Texas allows correlation to the Coyotean (= latest Virgilian–middle Wolfcampian) and Seymouran (late Wolfcampian–early Leonardian) land-vertebrate faunachrons. Tetrapod taxa from the Waynesburg and Washington formations include Edops and Protorothyris , Coyotean index taxa, as well as the characteristic Coyotean taxa Trimerorhachis , Diadectes , Edaphosaurus and Dimetrodon . Significantly, these Dunkard taxa are best known from the Archer City Formation in Texas, which is late Coyotean (= middle Wolfcampian). The Greene Formation contains the eupelycosaur Ctenospondylus , an index taxon of the Seymouran land-vertebrate faunachron. Dunkard xenacanth selachians support the tetrapod-based correlations. Vertebrate biochronology thus indicates that the Waynesburg and Washington formations are late Coyotean, whereas the Greene Formation is Seymouran. Therefore, vertebrate biostratigraphy and biochronology indicate that the entire Dunkard Group is Early Permian and likely straddles the Wolfcampian–Leonardian boundary.
-
FACIES, MICROFOSSILS (SMALLER FORAMINIFERS, CALCAREOUS ALGAE) AND BIOSTRATIGRAPHY OF THE HUECO GROUP, DOÑA ANA MOUNTAINS, SOUTHERN NEW MEXICO, USA
Rivista Italiana Di Paleontologia E Stratigrafia, 2009Co-Authors: Karl Krainer, Daniel Vachard, Spencer G. LucasAbstract:The Lower Permian Hueco Group of the Dona Ana Mountains (south-central New Mexico, USA) is studied in three sections (A, B, C) located east of Leasburg, Dona Ana County. Regionally, the Hueco Group has been subdivided into four formations termed Shalem Colony, Community Pit, Robledo Mountains and Apache Dam formations; the lower three are exposed in the Dona Ana Mountains. The succession shows a shallowing upward trend from dominantly shallow, open marine conditions (Shalem Colony Fm) to increasingly restricted marine environments (Community Pit Fm) and siliciclastic influx (Robledo Mountains Formation). Sedimentation, particularly siliciclastic influx, was mainly controlled by reactivation of basement uplifts during the last pulses of the Ancestral Rocky Mountains deformation. The microfossils and microfacies of the two first formations are studied in detail here. The Shalem Colony Formation can be divided into a lower biozone with Triticites pinguis , which is Newwellian (latest Pennsylvanian, early Wolfcampian) in age, and an upper division characterized by the first occurrence of Geinitzina , and lower-middle Asselian (late early Wolfcampian) in age. By comparison with the subdivisions of the Carnic Alps (Austria), the Community Pit Formation is characterized as Sakmarian (middle Wolfcampian) in age due to the first occurrence of the genus Pseudovermiporella , and its probable complete phylogeny from Hedraites . The late Asselian is restricted to the uppermost part of the Shalem Colony and lowermost part of the Community Pit Formation. Due to the occurrence of Pseudoreichelina the Robledo Mountains Formation is dated as Artinskian (late Wolfcampian). Some bioconstructions of Archaeolithophyllum are emphasized, as well as some species of foraminifers-globivalvulinids, Miliolata and Nodosariata.
J.b. Mahoney - One of the best experts on this subject based on the ideXlab platform.
-
Pennsylvanian and Permian Paleogeography of South-Central Idaho: the Wood River Basin
AAPG Bulletin, 1991Co-Authors: J.b. Mahoney, Bradford R. Burton, J. P. O’brien, Paul K. LinkAbstract:The Sun Valley Assemblage (Wood River, Dollarhide, and Grand Prize formations) was deposited in the Wood Rover basin in what is now south-central Idaho, north of the Snake River Plain, from the Atokan to Wolfcampian and Leonardian( ). Atokan and Des Moinesian deposition occurred in braided deltas and overlying clear water carbonate shoals. The rocks of this depositional system vary in thickness from tens to several hundreds of meters reflecting irregularities in the erosional surface on the underlying foundered Antler highland. This basal unconformity has been sheared during Mesozoic and Paleogene deformation. Significant regional subsidence of the Wood River basin began in the Des Moinesian, was most rapid in the Virgilian, and slowed in the Wolfcampian, resulting in total thickness of over 2,000 m for each of the three formations. In the central part of the basin (Wood River Formation) a sub-wave-base ramp system with southeastern paleoslope was fed by turbidite flows of mixed carbonate-siliciclastic fine-grained sediment that had been thoroughly mixed on a shelf area to the north and east. The carbonate fraction may have been derived from the Snaky Canyon Formation carbonate platform to the east. To the north, a siliciclastic fan or ramp system (Grand Prize Formation)more » was present. Virgilian and Wolfcampian strata represent highstand systems tracts and a lowstand tract is present in strata deposited near the Virgilian-Wolfcampian boundary.« less
Timothy R. Carr - One of the best experts on this subject based on the ideXlab platform.
-
ABSTRACT: Subsurface Structure and Sequence Stratigraphy of the Western Margin of the Hugoton Embayment, Morton County, Kansas
AAPG Bulletin, 1999Co-Authors: John F. Hopkins, Timothy R. CarrAbstract:In low-relief basins mapping the subtle structural and stratigraphic features required for effective exploration and production of hydrocarbons can be difficult. The Hugoton Embayment, containing the giant Hugoton and Panoma gas fields, is an example of such a basin. We have used digital wireline logs and a new approach, termed pseudoseismic, to map subtle structural and stratigraphic features on the western edge of the Hugoton Embayment in Morton County, Kansas. Mapped were four previously poorly constrained faults and low-relief structural noses plunging into basin. Eight Wolfcampian sequences also were defined and mapped. The extreme landward position of these sequences has influenced their geometries and results in a modified sequence-stratigraphic model for the Wolfcampian rocks of southwestern Kansas. The sequence model places nonmarine-dominated strata in the latehighstand systems tract. Pinchouts of marine-dominated reservoir-prone lithologies within the Wolfcampian sequences, coupled with structural features, seem to be controlling factors on production from the Hugoton and Panoma gas fields. These stratigraphic and structure problems are not unique to the Hugoton Embayment. The approaches and results could have widespread application in other basins and mature exploration provinces.
J.f. Sarg - One of the best experts on this subject based on the ideXlab platform.
-
Wolfcampian sequence stratigraphy of eastern Central Basin platform, Texas
AAPG Bulletin, 1992Co-Authors: M.p. Candelaria, D.j. Entzminger, F.h. Behnken, Midland Gas Co., J.f. Sarg, G.l. WildeAbstract:Integrated study of well logs, cores, high-resolution seismic data, and biostratigraphy has established the sequence framework of the Atokan (Early Pennsylvanian)-Wolfcampian (Early Permian) stratigraphic section along the eastern margin of the Central Basin platform in the Permian basin. Sequence interpretation of high-resolution, high-fold seismic data through this stratigraphic interval has revealed a complex progradational/retrogradational evolution of the platform margin that has demonstrated overall progradation of at least 12 km during early-middle Wolfcampian. Sequence stratigraphic study of the Wolfcamp interval has revealed details of the internal architecture and morphologic evolution of the contemporaneous platform margin. Two generalized seismic facies assemblages are recognized in the Wolfcampian. Platform interior facies are characterized by high-amplitude, laterally continuous parallel reflections; platform margin facies consist of progradational sigmoidal to oblique clinoforms and are characterized by discontinuous, low-amplitude reflections. Sequence interpretation of carbonate platform-to-basin strata geometries helps in predicting subtle stratigraphic trapping relationships and potential reservoir facies distribution. Moreover, this interpretive method assists in describing complex reservoir heterogeneities that can contribute to significant reserve additions from within existing fields.
-
Tectonics, Eustasy, and Sequence Stratigraphy -- The Middle Pennsylvanian-Wolfcampian of the Permian basin
AAPG Bulletin, 1992Co-Authors: J.f. SargAbstract:The depositional patterns of sedimentary rocks are controlled by the interaction of tectonics, eustasy, and sediment supply. Tectonics and eustasy combine to cause relative changes of sea level that control the accommodation space for sediments. Sediment supply controls how much of the accommodation space is filled. Tectonics has the greatest effect on accommodation. Long-term basin fill histories are interpreted as first-order tectonic events. Second-order tectonic events are initiated by increase in the rate of subsidence that progressively decay and may culminate in a period of uplift or structural growth. Three second-order tectonic events characterize the middle-late Paleozoic history of the Permian basin. These events occur over tens of millions of years and are (1) Givetian-Meramecian, (2) Chesterian-Desmoinesian, and (3) Missourian-Guadalupian. Sediment response to these tectonic events include initial backstepping carbonate platform deposition, followed by deepening and starvation of the basin areas resulting in black shale deposition. Eustasy controls the rate of relative sea level change and is the major controlling factor on the timing of stratigraphic discontinuities. The discontinuities bound sequences and subdivide them into systems tracts. The Middle Pennsylvanian-Wolfcampian of the Permian basin can be subdivided into 19-21 third-order sequences (1-5-m.y. duration) and include six Desmoinesian, four Missourian, fivemore » to six Virgilian, and four to five Wolfcampian cycles. The cyclothems of the mid-continent represent higher order depositional sequences that stack in an orderly fashion to comprise the systems tracts of the third-order sequences.« less
