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Paleoecology of the deposits in the early Mancos Sea of western Colorado and eastern Utah is being studied by palynologic analysis. Seven sections, including 1 from the type area along the Mancos River, have been sampled at 15-20-ft intervals, from the top of the Dakota upward for 100-600 ft. These strata--the Graneros Shale, Greenhorn Limestone, lower Carlile, Juana Lopez, and upper Carlile Members--include most of the Cenomanian and Turonian stages.
The terrestrial microfossil flora includes more than 45 species of spores, about 15 species of gymnospermous pollen and more than 59 species of angiosperms. The microplankton differentiated include more than 30 species of acritarchs and about 40 species of dinoflagellates.
Much of the deposition took place relatively close to the shoreline but some sections were farther from the strand. Variations in the sections also indicate transgressive and regressive stages of the sea and some environmental control over the microplankton. Some stratigraphic zonation seems possible, principally on the terrestrial palynomorphs, and correlation and relative time of deposition of the several sections have been determined tentatively.
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