Paleoclimate and paleoelevation of the Oligocene Pitch-Pinnacle flora, Sawatch Range, Colorado

Abstract

Research Article| May 01, 1996 Paleoclimate and paleoelevation of the Oligocene Pitch-Pinnacle flora, Sawatch Range, Colorado Kathryn M. Gregory; Kathryn M. Gregory 1Lamont-Doherty Earth Observatory of Columbia University, Palisades, New York 10964-8000 Search for other works by this author on: GSW Google Scholar W. C. McIntosh W. C. McIntosh 2New Mexico Bureau of Mines and Mineral Resources, Socorro, New Mexico 87801 Search for other works by this author on: GSW Google Scholar GSA Bulletin (1996) 108 (5): 545–561. https://doi.org/10.1130/0016-7606(1996)108<0545:PAPOTO>2.3.CO;2 Article history first online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share MailTo Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation Kathryn M. Gregory, W. C. McIntosh; Paleoclimate and paleoelevation of the Oligocene Pitch-Pinnacle flora, Sawatch Range, Colorado. GSA Bulletin 1996;; 108 (5): 545–561. doi: https://doi.org/10.1130/0016-7606(1996)108<0545:PAPOTO>2.3.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 Angiosperm leaves from the Oligocene Pitch-Pinnacle flora, which grew between 32.9 and 29 Ma, are described for the first time. This flora is especially interesting because it grew in a tectonically active region around the time of the precipitous Oligocene temperature drop and thus provides important constraints on paleoclimate and paleoelevation. New multiple regression models are developed from the modern vegetation leaf physiognomy data set of J. A. Wolfe and, when applied to the Pitch-Pinnacle flora, suggest a mean annual temperature (MAT) of 12.7 ± 1.5°C, with cold month and warm month means of 4.5 ± 2.2°C and 20.4 ± 2.5°C, respectively, and a mean annual range of temperature of 18.5 ± 3.8°C. Growing season precipitation is estimated to have been 101 ± 16 cm, with this rain falling mostly during the nongrowing season. When the MAT estimate for the Pitch-Pinnacle flora is combined with MAT estimates for coeval floras from the coast, the implied elevation is either 2–3 km if the flora is pre-Oligocene deterioration, or around 1 km if post-deterioration. Paleodrainage reconstructions suggest the former, but more data are needed to resolve this issue. 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.