--> Abstract: Sequence Evolution and Sequence Extinction; Species Level Recognition of Individual Sequences and Parasequence Sets, Lower Permian, West Texas, by Charles A. Ross and June R. P. Ross; #90914(2000)
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Charles A. Ross1, June R. P. Ross1
(1) Western Washington University, Bellingham, WA

Abstract: Previous HitSequenceNext Hit Evolution and Previous HitSequenceNext Hit Extinction; species level recognition of individual Previous HitsequencesNext Hit and parasequence sets, Lower Permian, West Texas

Depositional Previous HitsequencesNext Hit, subsequences, parasequence sets and parasequences are well developed in Lower Permian Wolfcampian and Leonardian strata in the Glass Mountains, West Texas. The depositional Previous HitsequencesNext Hit and some parasequence sets were of sufficient duration that many species of shallow-water carbonate foraminiferans evolved rapidly and were succeeded in the next higher depositional Previous HitsequenceNext Hit by derived younger species. The stratigraphic ranges of many of these species are bounded by hiatuses of non-deposition and are classic examples of the phenomena of evolution within a Previous HitsequenceNext Hit and extinction at the hiatus at the top of the Previous HitsequenceNext Hit. The species identify individual depositional Previous HitsequencesNext Hit.

The lower Nealian (Lower Wolfcampian) includes five major depositional Previous HitsequencesNext Hit that record significant (±20m) sea-level fluctuations. They are defind by species ranges of Leptotriticites, Triticites, Paraschwagerina, Pseudoschwagerina, and Schwagerina. The upper Nealian has fifteen to twenty thinner cycles that represent smaller sea-level fluctuations (±5m) and ranges of species define five or six parasequence sets. The Lenoxian (Upper Wolfcampian) includes five depositional Previous HitsequencesNext Hit; each characterized by a species assemblage.

In the Hessian Stage (Lower Leonardian), seven depositional Previous HitsequencesNext Hit each have distinctive species of fusulinaceans. The higher depositional Previous HitsequencesNext Hit have a progression of increasingly advanced species of primitive Parafusulina.

The Cathedralian Stage (Upper Leonardian) includes at least three depositional Previous HitsequencesNext Hit. A single fusulinacean species, Parafusulina durhami, characterizes the lower two. The top of the upper depositional Previous HitsequenceTop is discontinuously preserved beneath the Mid-Permian event,

AAPG Search and Discovery Article #90914©2000 AAPG Annual Convention, New Orleans, Louisiana