Full Title: Geologic Maps of Part of the Spanish Peaks Dike System, South-Central Colorado with Enlarged Maps of Selected Areas Showing Details of Dike Intersections and Segments
Author: Richard P. Smith
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Sheet size = 25" x 27". From abstract: Flow lineations in Spanish Peaks radial dikes show that large amounts of horizontal magma flow occurred in many of the dikes and that dike magma was emplaced upward and outward from the West Peak stock. Projection of flow lineations toward the West Peak suggests that the dikes separated from the stock at or above the Paleozoic-Precambrian unconformity (≤9 km depth). Extrapolation of dike trends toward the West Peak stock shows that there are two intrusion centers, one lying 2 to 3 km east of the West Peak summit (center A) and one lying 0.5 to 1 km northeast of the summit (center B). That the intrusion centers do not coincide with the West Peak stock suggests that there are buried apophyses extending east and northeast from the stock. Crosscutting relationships of radial dikes show that intrusion of a small lamprophyre dike from center B was followed by intrusion of nonlamprophyre dikes from center A and that these, in turn, were followed by intrusion of both lamprophyre and nonlamprophyre dikes from center B. Absolute ages of the radial dikes and stocks range from approximately 20 to 27 m.y.
Published: 5/09/1978
Pages: 2, plus 1 sheet
Product Category: Maps and Charts