--> Abstract: Late Carboniferous Mixed Carbonate-Siliciclastic Shelf Sequences, Paradox Basin, Utah: Controls and Sequence Attributes, by G. L. Gianniny and J. A. T. Simo; #90956 (1995).
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Abstract: Late Carboniferous Mixed Carbonate-Siliciclastic Shelf Previous HitSequencesNext Hit, Paradox Basin, Utah: Controls and Previous HitSequenceNext Hit Attributes

Gary L. Gianniny, J. A. Toni Simo

The Lower Desmoinesian (Late Carboniferous) Barker Creek and Akah productive intervals exposed in the incised meanders of the San Juan river illustrate that cyclicity, facies and geometries of a mixed system vary by the interaction of sea level history, relative position on the shelf, syndepositional topography, sedimentary processes, siliciclastic influx, and differential compaction and erosion. All of these parameters combine to change, from Previous HitsequenceNext Hit to Previous HitsequenceNext Hit, facies successions in both dip and strike sections.

The 165 m thick section comprises 31 exposure-bounded Previous HitsequencesNext Hit grouped into 3 Previous HitsequenceNext Hit sets. Previous HitSequenceNext Hit sets are bounded by fluvial incision, or very coarse non marine sandstones. The partially exposed basal Previous HitsequenceNext Hit set is characterized by 9, thin, subtidal and subtidal-intertidal Previous HitsequencesNext Hit with peloidal and skeletal limestone facies. Previous HitSequenceNext Hit set two consists of 16 Previous HitsequencesNext Hit, and Previous HitsequenceNext Hit set three contains six subtidal Previous HitsequencesNext Hit. Previous HitSequenceNext Hit thickness in Previous HitsequenceNext Hit sets two and three vary from 27 to 1 meters. These Previous HitsequencesNext Hit form thinning and thickening bundles. Beginning and end of the bundles change from section to section (e.g. in an updip column a bundle commonly starts one Previous HitsequenceNext Hit earlier than a downdip column). These changes in bundling reflect the effects of progradation and shin ling, position on the shelf, and topography and compaction around carbonate buildups. Previous HitSequenceNext Hit thickness and facies diversity are positively correlated. Thick Previous HitsequencesNext Hit show a more complete succession with a lower onlaping wedge of siliciclastic sandstone, an up-dip transgressive open-marine carbonate, an early highstand prograding mixed carbonate-siliciclastic sandstone and siltstone, and a late highstand succession of carbonate buildups, oolitic shoals and stromatolites. Quartz-rich sandstones in both the low-and highstand are volumetrically important in thick Previous HitsequencesNext Hit. Thinner Previous HitsequencesTop lack of highstand carbonate buildups and mixed carbonate-siliciclastic sandstones, and peloidal and skeletal limestone, and algal laminates dominate.

AAPG Search and Discovery Article #90956©1995 AAPG International Convention and Exposition Meeting, Nice, France