Age of Emplacement of Riley County, Kansas, Kimberlites and a Possible Minimum Age for the Dakota Sandstone

Research Article| June 01, 1971 Age of Emplacement of Riley County, Kansas, Kimberlites and a Possible Minimum Age for the Dakota Sandstone DOUGLAS G BROOKINS; DOUGLAS G BROOKINS Department of Geology, Kansas State University, Manhattan, Kansas 66502 Search for other works by this author on: GSW Google Scholar CHARLES W NAESER CHARLES W NAESER U.S. Geological Survey, Menlo Park, California 94025 Search for other works by this author on: GSW Google Scholar Author and Article Information DOUGLAS G BROOKINS Department of Geology, Kansas State University, Manhattan, Kansas 66502 CHARLES W NAESER U.S. Geological Survey, Menlo Park, California 94025 Publisher: Geological Society of America Received: 15 Jan 1971 First Online: 02 Mar 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Copyright © 1971, The Geological Society of America, Inc. Copyright is not claimed on any material prepared by U.S. government employees within the scope of their employment. GSA Bulletin (1971) 82 (6): 1723–1726. https://doi.org/10.1130/0016-7606(1971)82[1723:AOEORC]2.0.CO;2 Article history Received: 15 Jan 1971 First Online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation DOUGLAS G BROOKINS, CHARLES W NAESER; Age of Emplacement of Riley County, Kansas, Kimberlites and a Possible Minimum Age for the Dakota Sandstone. GSA Bulletin 1971;; 82 (6): 1723–1726. doi: https://doi.org/10.1130/0016-7606(1971)82[1723:AOEORC]2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search 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. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.