Rb-Sr glauconite isochron of the Eocene Castle Hayne Limestone, North Carolina

Abstract

Research Article| October 01, 1980 Rb-Sr glauconite isochron of the Eocene Castle Hayne Limestone, North Carolina W. BURLEIGH HARRIS; W. BURLEIGH HARRIS 1Department of Earth Sciences, University of North Carolina at Wilmington, Wilmington, North Carolina 28403 Search for other works by this author on: GSW Google Scholar VICTOR A. ZULLO VICTOR A. ZULLO 1Department of Earth Sciences, University of North Carolina at Wilmington, Wilmington, North Carolina 28403 Search for other works by this author on: GSW Google Scholar Author and Article Information W. BURLEIGH HARRIS 1Department of Earth Sciences, University of North Carolina at Wilmington, Wilmington, North Carolina 28403 VICTOR A. ZULLO 1Department of Earth Sciences, University of North Carolina at Wilmington, Wilmington, North Carolina 28403 Publisher: Geological Society of America First Online: 01 Jun 2017 Online Issn: 1943-2674 Print Issn: 0016-7606 Geological Society of America GSA Bulletin (1980) 91 (10): 587–592. https://doi.org/10.1130/0016-7606(1980)91<587:RGIOTE>2.0.CO;2 Article history First Online: 01 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 W. BURLEIGH HARRIS, VICTOR A. ZULLO; Rb-Sr glauconite isochron of the Eocene Castle Hayne Limestone, North Carolina. GSA Bulletin 1980;; 91 (10): 587–592. doi: https://doi.org/10.1130/0016-7606(1980)91<587:RGIOTE>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 The 11-m-thick lectostratotype of the Castle Hayne Limestone in New Hanover County, North Carolina, consists of lower phosphate pebble biomicrudite; middle bryozoan biosparrudite; and upper bryozoan-sponge biomicrudite. The relative age of the Castle Hayne Limestone is equivocal. The planktic foraminiferal fauna and part of the molluscan fauna suggest that the entire formation should be correlated with the Gulf Coast Claibornian Stage (middle Eocene), whereas calcareous nannofossils, bryozoans, barnacles, and some molluscs indicate that the upper bryozoan-sponge biomicrudite is a Gulf Coast Jacksonian Stage (upper Eocene) equivalent. Because of problems correlating the Castle Hayne Limestone to equivalent Gulf Coast stages, the lectostratotype was dated by application of the Rb-Sr glauconite isochron.Five hand-picked glauconite concentrates analyzed for Rb, Sr, and Sr-isotopic composition yielded an isochron age of 34.8 ± 1 m.y. (λ Rb 87 = 1.42 × 10−11 yr−1) with an initial (Sr87/Sr86)0 ratio of 0.7083 ± 0.0004. The determined initial (Sr87/Sr86)0 ratio is in good agreement with previous estimates of the Sr-isotopic composition of sea water during the Eocene. Although the age is younger than the value of 37 m.y. earlier proposed for the Eocene/Oligocene boundary, it agrees with fission-track and K-Ar ages of tektites and microtektites, and K-Ar ages of bentonites and glauconites in upper Eocene marine and nonmarine units throughout the world. 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.