High-resolution chronostratigraphy of the terrestrial Cretaceous-Paleogene transition and recovery interval in the Hell Creek region, Montana

Research Article| March 01, 2015 High-resolution chronostratigraphy of the terrestrial Cretaceous-Paleogene transition and recovery interval in the Hell Creek region, Montana Courtney J. Sprain; Courtney J. Sprain † 1Department of Earth and Planetary Science, University of California, Berkeley, California 94720, USA †E-mail: spra0111@berkeley.edu Search for other works by this author on: GSW Google Scholar Paul R. Renne; Paul R. Renne 1Department of Earth and Planetary Science, University of California, Berkeley, California 94720, USA2Berkeley Geochronology Center, 2455 Ridge Road, Berkeley, California 94720, USA Search for other works by this author on: GSW Google Scholar Gregory P. Wilson; Gregory P. Wilson 3Department of Biology, and Burke Museum of Natural History and Culture, University of Washington, Seattle, Washington 98195, USA Search for other works by this author on: GSW Google Scholar William A. Clemens William A. Clemens 4Department of Integrative Biology, University of California, Berkeley, California 94720, USA5Museum of Paleontology, University of California, Berkeley, California 94720, USA Search for other works by this author on: GSW Google Scholar GSA Bulletin (2015) 127 (3-4): 393–409. https://doi.org/10.1130/B31076.1 Article history received: 02 Feb 2014 rev-recd: 24 Jun 2014 accepted: 12 Aug 2014 first online: 08 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Courtney J. Sprain, Paul R. Renne, Gregory P. Wilson, William A. Clemens; High-resolution chronostratigraphy of the terrestrial Cretaceous-Paleogene transition and recovery interval in the Hell Creek region, Montana. GSA Bulletin 2015;; 127 (3-4): 393–409. doi: https://doi.org/10.1130/B31076.1 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 Detailed understanding of ecosystem decline and recovery attending the Cretaceous-Paleogene boundary (KPB) mass extinctions is hindered by limited constraints on the pace and tempo of environmental events near the boundary. To mitigate this shortcoming, high-resolution 40Ar/39Ar geochronology was performed on tephras intercalated between fossiliferous terrestrial sediments of the upper Hell Creek and lower Fort Union Formations in the western Williston Basin of northeastern Montana (USA). Tephra samples were collected from 10 stratigraphic sections spanning an area of ∼5000 km2. Several distinctive tephras can be correlated between sections separated spatially by as much as ∼60 km. The tephras are thin distal deposits generally preserved only in lignite beds, which are interbedded with clastic deposits yielding vertebrate faunas of Lancian (late Maastrichtian) to Torrejonian (early Danian) North American Land Mammal Ages. Sanidine from 15 tephra samples was analyzed in 1649 total fusion experiments (1597 on single crystals) and 12 incremental heating analyses of multigrain aliquots. Ages were determined for 13 distinct tephras, ranging from 66.289 ± 0.051 to 64.866 ± 0.023 Ma, including only analytical uncertainties. This level of precision is sufficient to resolve the ages of all of the coal beds that have served as a basis for a regional stratigraphic framework. The data confirm that the Hell Creek–Fort Union formational contact is diachronous, and further support the age of the KPB impact layer at 66.043 ± 0.010 Ma (or ± 0.043 Ma considering systematic uncertainties). Application of the new results to previous magnetostratigraphic data indicates an appreciably compressed time interval between the base of chron C29r and the top of chron C28r, with a maximum duration estimate of 1.421 ± 0.066 Ma. Most notable is the implied brevity of chron C29r, with a maximum estimate of 457 ± 54 ka, and possibly as brief as 345 ± 38 ka, compared to the 710 ka estimate from the Geologic Time Scale 2012 (GTS2012). Further, application of new results to terrestrial biostratigraphy adds higher precision to the timing and tempo of biotic change before and after the KPB. Our results indicate that the timing of pre-KPB ecological decline is constrained to the last ∼200 ka of the Cretaceous, adding further support to the press-pulse extinction hypothesis. Additionally, the duration of the depauperate basal Paleogene Puercan 1 disaster fauna is confined to a 70 ka interval. Faunal recovery in this region, indicated by the appearance of primitive members of the placental mammal radiation and the restoration of taxonomic richness and evenness, occurred within ∼900 ka after the KPB. These results show that biotic recovery after the mass extinction in the terrestrial realm was more rapid than in the marine. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.