Minor and trace element contents of kimberlites of the Front Range, Colorado and Wyoming

Abstract

Since 1960 about 90 separate occurrences of kimberlite have been discovered in the Front Range of northern Colorado and southern Wyoming, and in the Laramie Range, Wyoming (e.g., McCallum, Eggler, and Burns, 1975; McCallum, Eggler, Coopersmith, Smith, and Mabarak, 1977; Smith and others, 1977 and in press). All but two of the known kimberlites occur in the Colorado-Wyoming State Line district or in the Iron Mountain, Wyoming, district (fig. 1). A single kimberlite dike is located at Estes Park, Colo., and a small pipe-like body occurs immediately west of Boulder, Colo. (fig. 1). Continuous research for the purpose of locating and characterizing kimberlite in the Front Range has been conducted from 1960 to the present, primarily by M. E. McCallum, D. H. Eggler, and Colorado State University graduate students. The Boulder kimberlite specifically has been studied by Kridelbaugh and others, 1972; Kridelbaugh and Meyer, 1973; Moyer and Kridelbaugh, 1977; and Boctor and Meyer, 1977. As part of the overall kimberlite project directed by M. E. McCallum, the U.S. Geological Survey has provided the whole-rock minor and trace element analyses reported herein. Although primarily semiquantitative, the analyses show that minor and trace element contents of kimberlites in the Front Range are similar to those of kimberlites elsewhere in the world.