Dinosaurs, spherules, and the “magic” layer: A new K-T boundary clay site in Wyoming

Abstract

Research Article| October 01, 1987 Dinosaurs, spherules, and the "magic" layer: A new K-T boundary clay site in Wyoming Bruce F. Bohor; Bruce F. Bohor 1U.S. Geological Survey, Box 25046, Denver, Colorado 80225 Search for other works by this author on: GSW Google Scholar Don M. Triplehorn; Don M. Triplehorn 1U.S. Geological Survey, Box 25046, Denver, Colorado 80225 Search for other works by this author on: GSW Google Scholar Douglas J. Nichols; Douglas J. Nichols 1U.S. Geological Survey, Box 25046, Denver, Colorado 80225 Search for other works by this author on: GSW Google Scholar Hugh T. Millard, Jr. Hugh T. Millard, Jr. 1U.S. Geological Survey, Box 25046, Denver, Colorado 80225 Search for other works by this author on: GSW Google Scholar Geology (1987) 15 (10): 896–899. https://doi.org/10.1130/0091-7613(1987)15<896:DSATML>2.0.CO;2 Article history first online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Bruce F. Bohor, Don M. Triplehorn, Douglas J. Nichols, Hugh T. Millard; Dinosaurs, spherules, and the "magic" layer: A new K-T boundary clay site in Wyoming. Geology 1987;; 15 (10): 896–899. doi: https://doi.org/10.1130/0091-7613(1987)15<896:DSATML>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 SocietyGeology Search Advanced Search Abstract A new Cretaceous-Tertiary (K-T) boundary clay site has been found along Dogie Creek in Wyoming in the drainage of Lance Creek—the type area of the Lance Formation of latest Cretaceous age. The boundary clay was discovered in the uppermost part of the Lance Formation, 4–7 cm beneath the lowest lignite in the Paleocene Fort Union Formation and approximately 1 m above a fragmented dinosaur bone.The boundary clay consists of a basal kaolinitic claystone layer as much as 3 cm thick containing hollow goyazite spherules, overlain by a 2–3 mm smectitic layer (the "magic" layer) containing both shock-metamorphosed minerals and an iridium anomaly of 21 ppb. A palynological break coincides with the base of the claystone layer; numerous Late Cretaceous palynomorph species terminate at this boundary.The paleontological significance of this new boundary site lies in its close association with the well-studied assemblage of dinosaurs and other vertebrates and flora within the type area of the Lance Formation. The spherules at the Dogie Creek site are extremely well preserved by virtue of their replacement by the mineral goyazite. This preservation should facilitate the resolution of the origin of the spherules and of their host layer. 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.