--> --> ABSTRACT: Reference Sections and Sequence Stratigraphic Model: Albian to Turonian Strata of Northeast New Mexico and Oklahoma Panhandle, by Robyn Wright Dunbar, Spencer G. Lucas, John M. Holbrook; #91002 (1990).

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ABSTRACT: Reference Sections and Sequence Stratigraphic Model: Albian to Turonian Strata of Northeast New Mexico and Oklahoma Panhandle

Robyn Wright Dunbar, Spencer G. Lucas, John M. Holbrook

Cretaceous strata in the Dalhart and Tucumcari basins span late Albian (Lytle Sandstone) to early Turonian (Greenhorn Formation), and include Kiowa-Skull Creek and Greenhorn cyclothems. Reference sections for this interval are presented and a preliminary sequence stratigraphic working model proposed to include the Lytle through Graneros. Tucumcari and Dalhart basins responded differently to Cretaceous relative sea-level changes, resulting in contrasting development of sequence stratigraphic units. Stratal relationships in the Dalhart basin correspond with those of southern Colorado, except that late Albian Mowry deposits did not extend into New Mexico. The basal Kiowa-Skull Creek lowstand/transgressive systems tract is marked by: (1) estuarine backfilling of channels cut nto Cretaceous Lytle and/or Jurassic Morrison sandstones, (2) coastal ravinement, and (3) deposition of marine Glencairn and Tucumcari sandstones and shales. Distinction between transgressive and highstand systems tracts within the marine units is currently under study. Mesa Rica Sandstone fluvial channels incised the Dalhart basin to produce an unconformity correlative with the Muddy surface from Colorado to Wyoming, but synchronously fed the late Albian (lowstand) Mesa Rica delta in the deeper Tucumcari basin. Backfilled Mesa Rica estuaries and marine-submergent delta plain (lower Pajarito Formation) apparently recorded rising Mowry (earliest Greenhorn) base level. The overlying fluvial Pajarito best fits within a highstand systems tract presumably capped by a third (yet unrecognized) equence boundary near the formation top. Romeroville (= marine Dakota) sandstones and Graneros shales sharply overlay the Pajarito define ravinement and onset of a new transgressive systems tract in both Tucumcari and Dalhart basins.

AAPG Search and Discovery Article #91002©1990 AAPG Rocky Mountain Section Meeting, Denver, Colorado, September 16-19, 1990