Print this pageControls over Non-Marine Deposition of the Cutler Group, Paradox Basin
KATTAH, S. S. and W. E. GALLOWAY
The deposition and preservation of non-marine facies of the Cutler Group (Paradox Basin) was controlled by basin tectonics, sediment supply, sea level changes, climate and diffusivity of alluvial and eolian dispersal systems.
Sediment supply rates, though probably not constant, were high throughout the deposition of the Cutler. Large-scale tectono-stratigraphic sequences represent the depositional response to tectonic pulses at the Uncompahgre. High rates of subsidence created space along the Uncompahgre for the two first sequences (Pennsylvanian) restricting progradation into the basin (dominated by evaporite and carbonatic deposition). A decrease in the subsidence rate in the Permian reduced the rate of space creation at proximal areas forcing the maximum progradation of siliciclastic facies into the basin during the third sequence.
Higher-order genetic sequences deposited under the combined influences of climate (proximal areas) and glacio-eustasy (coastal plain and marine settings). Climate and eustasy during the early Permian ice-house to transitional regime were closely related. Glacial periods were marked by low sea level and aridity causing an increase in fluvial diffusivity. Coarse-grained debris were transported to coastal plain and shelf, while erosional surfaces were formed at more proximal areas. During interglacial periods, more favorable climatic conditions and sea level rise favored coastal braidplain and eolian aggradation. Extensive root horizons at the top of eolian facies seems to record the turnaround baselevel fall/rise.
Salt tectonics locally affected alluvial sedimentation by decreasing slopes at proximity of dome uplifts. This must have influenced the style of streams resulting in a more complex stratigraphic record at these areas.