Age of emplacement of Riley County, Kansas, kimberlites and a possible minimum age for the Dakota Sandstone
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Abstract
Field evidence suggests that the kimberlites of Riley County, Kansas, were emplaced into Lower Permian rocks in post-Dakota Sandstone time. The Dakota Sandstone in Kansas is thought to be earliest Late Cretaceous in age; thus the maximum age of emplacement of the kimberlites is approximately 100 ± 20 m.y. K-Ar dates on chloritized biotite and phlogopites from the kimberlites range from 112 ± 6 m.y. to 380 ± 40 m.y.; the dates earlier than 100 m.y. (6 of 7 samples) are attributed to either the xenocrystalline nature of the chlorites and/or excess Ar and low temperature of intrusion. Fission track dates from two apatites from granite xenoliths are 115 ± 12 m.y. and 123 ± 12 m.y.; these dates reflect cooling at about 120 m.y. ago, which may place a maximum age of emplacement on the kimberlites.
Suggested Citation
Brookins, D.G., and Naeser, C.W., 1971, Age of emplacement of Riley County, Kansas, kimberlites and a possible minimum age for the Dakota Sandstone: Bulletin of the Geological Society of America, v. 82, no. 6, p. 1723-1725, https://doi.org/10.1130/0016-7606(1971)82[1723:AOEORC]2.0.CO;2.
Study Area
| Publication type | Article |
|---|---|
| Publication Subtype | Journal Article |
| Title | Age of emplacement of Riley County, Kansas, kimberlites and a possible minimum age for the Dakota Sandstone |
| Series title | Bulletin of the Geological Society of America |
| DOI | 10.1130/0016-7606(1971)82[1723:AOEORC]2.0.CO;2 |
| Volume | 82 |
| Issue | 6 |
| Year Published | 1971 |
| Language | English |
| Publisher | Geological Society of America |
| Description | 3 p. |
| First page | 1723 |
| Last page | 1725 |
| Country | United States |
| State | Kansas |
| County | Riley County |