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The tectonic framework that controlled the locations of the late Paleozoic Ancestral Rockies was well established in pre-Pennsylvanian time.
The Uncompahgre uplift in southwestern Colorado arose along tectonic lineaments that originated in the late Precambrian. Recurrent movements along the fault system continued through early and middle Paleozoic time and the resulting submarine topography controlled the sedimentation of reservoir facies in the adjacent Paradox basin.
The Front Range and Wet Mountains uplifts of central Colorado were apparently low and inactive prior to Late Devonian time; at least, evidence is lacking that they were source areas during the early Paleozoic. The relation between basement tectonic trends and the location of the Permo-Pennsylvanian uplifts is obscure.
The first demonstrable uplift of the Front Range element occurred in Late Devonian time when coarse clastic material was shed into the Parting sea from the west flank of the uplift and a satellite structure in the northern Sawatch Range. Uplift of these source areas recurred in Early Mississippian time and produced limestone conglomerates in the basal Leadville Formation.
The Wet Mountains lay dormant until Early Mississippian time, and a broad lowland occupied the general region in the Late Devonian. Local deposits of limestone conglomerates in the Leadville Formation attest to the Early Mississippian time of uplift.
Continued detailed petrologic and paleotectonic studies in the 1970s will lead to new petroleum discoveries in the related Paradox and Eagle basins by establishing favorable reservoir facies trends, paleohydrodynamic patterns, and times and paths of petroleum migration.
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