Hostname: page-component-cd9895bd7-gbm5v Total loading time: 0 Render date: 2024-12-24T01:40:33.200Z Has data issue: false hasContentIssue false
  • English
  • Français

Radiometric age of the Monograptus cyphus graptolite zone in Southeastern Alaska — an estimate of the age of the Ordovician—Silurian boundary

Published online by Cambridge University Press:  01 May 2009

M. A. Lanphere ,
M. Churkin Jr  and
G. D. Eberlein
M. A. Lanphere
Affiliation:
U.S. Geological Survey, Menlo Park, California 94025, U.S.A.
M. Churkin Jr
Affiliation:
U.S. Geological Survey, Menlo Park, California 94025, U.S.A.
G. D. Eberlein
Affiliation:
U.S. Geological Survey, Menlo Park, California 94025, U.S.A.
Get access Rights & Permissions [Opens in a new window]

Summary

K—Ar age measurements on Esquibel Island, southeastern Alaska yield a minimum age of about 433±3 Ma for the Zone of Monograptus cyphus of the Lower Silurian. An age of approximately 435—437 Ma is estimated for the Ordovician—Silurian boundary.

Type
Articles
Information
Geological Magazine , Volume 114 , Issue 1 , January 1977 , pp. 15 - 24
Copyright
Copyright © Cambridge University Press 1977

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Adams, J. A. S., Osmond, J. K., Edwards, G. & Henle, W. 1960. Absolute dating of the Middle Ordovician. Nature, Lond. 188, 636–8.CrossRefGoogle Scholar
Aldrich, L. T., Wetherill, G. W., Tilton, G. R. & Davis, G. L. 1956. Half-life of Rb87. Phys. Rev. 103 1045–7.CrossRefGoogle Scholar
Beckinsale, R. D. & Gale, N. H. 1969. A reappraisal of the decay constants and branching ratio of 40K. Earth Planet. Sci. Lett. 6, 289–94.Google Scholar
Bofinger, V. M., Compston, W. & Gulson, B. L. 1970. A Rb—Sr study of the Lower Silurian State Circle Shale, Canberra, Australia. Geochim. cosmochim. Acta 34, 433–45.CrossRefGoogle Scholar
Bottino, M. L. & Fullagar, P. D. 1966. Whole-rock rubidium—strontium age of the Silurian—Devonian boundary in north-eastern North America. Bull. geol. Soc. Am. 77, 1167–76.Google Scholar
Byström-Asklund, A. M., Baadsgaard, H. & Folinsbee, R. E. 1961. K/Ar age of biotite, sanidine, and illite from Middle Ordovician bentonies at Kinnekulle, Sweden. Geol. För. Stockh. Förh. 83, 92–6.CrossRefGoogle Scholar
Churkin, M. Jr, 1974. Paleozoic marginal ocean basin-volcanic arc systems in the Cordilleran foldbelt. In Dott, R. H. Jr., & Shaver, R. H. (eds): Modern and ancient geosynclinal sedimentation. Spec. Pub. Soc. Econ. Paleontol. Mineral. 19, 174–92.Google Scholar
Churkin, M. Jr, Carter, C. & Eberlein, G. D. 1971. Graptolite succession across the Ordovician—Silurian boundary in south-eastern Alaska. Q. Jl. geol. Soc. Lond. 126, 319–30.CrossRefGoogle Scholar
Dallmeyer, R. D. & Williams, H. 1975. 40Ar/39Ar ages from the Bay of Islands metamorphic aureole: their bearing on the timing of Ordovician ophiolite obduction. Can. J. Earth Sci. 12, 1685–90.Google Scholar
Dalrymple, G. B. & Lanphere, M. A. 1971. 40Ar/39Ar technique of K—Ar dating: A comparison with the conventioanl technique. Earth Planet. Sci Lett. 12, 300–8.CrossRefGoogle Scholar
De Laeter, J. R., Vernon, M. J. & Compston, W. 1973. Revision of lunar Rb—Sr ages. Geochim. cosmochin. Acta 37, 700–2.CrossRefGoogle Scholar
Eberlein, G. D. & Churkin, M. Jr, 1970. Paleozoic formations in the northwest coastal area of Prince of Wales Island, southeastern Alaska. Bull. U.S. geol. Survey 1284, 67.Google Scholar
Fullagar, P. D. & Bottino, M. L. 1968. Rb—Sr whole-rock ages of Silurian—Devonian volcanics from eastern Maine. Trans. Am. Geophys. Un. 49, 346.Google Scholar
Harland, W. B., Smith, A. G. & Wilcock, B. (Eds.) 1964. The Phanerozoic time-scale. Q. Jl. geol. Soc. London 120s, 458.Google Scholar
Harris, P. M., Farrar, E., Macintyre, R. M., York, D. & Miller, J. A. 1965. Potassium— argon age measurements on two igneous rocks from the Ordovician system of Scotland. Nature, Lond. 205, 352–3.CrossRefGoogle Scholar
Holmes, A. 1959. A revised geological time-scale. Trans. Edin. geol. Soc. 17, 183–216.CrossRefGoogle Scholar
Jaffey, A. H., Flynn, K. F., Glendenin, L. E., Bentley, W. C. & Essling, A. M. 1971. Precision measurements of half-lives and specific activities of 235U and 238U. Phys. Rev. C. 4, 1889–1906.Google Scholar
Kulp, J. L. 1961. Geologic time scale. Science 133, 1105–1114.Google Scholar
Lambert, R. St. J. 1971. The pre-Pleistocene Phanerozoic time-scale — a review: In Part I of The Phanerozoic Time-scale — a supplement, Spec. Publ. geol. Soc. no. 5, pp. 9–31. London.Google Scholar
Lanphere, M. A. & Dalrymple, G. B. 1976. K—Ar ages of basalt from Holes 315A (Line Islands) and 317A (Manihiki Plateau), Leg 33 of the Deep Sea Drilling Project. Init. Rep. Deep Sea Drilling Project, 33, 649—53.Google Scholar
Mattinson, J. M. 1975. Early Paleozoic ophiolite complexes of Newfoundland: Isotopic ages of zircons. Geology, 3, 181–3.Google Scholar
Öpik, A. A. 1958. The geology of the Canberra City District. Bull. Aust. Bur. Min. Res. 32, 99.Google Scholar
Owen, M., Gardner, D. E., Wyborn, D., Saltet, J. & Shackelton, M. S. 1975. Geology of the Tantangara 1:100,000 sheet area, Australian Capital Territory and New South Wales. Rec. Bur. Min. Res. Aust. 1974/176. 394 pp.Google Scholar
Stevens, R. K. 1970. Cambro-Ordovician flysch sedimentation and tectonics in west Newfoundland and their possible bearing on a proto-Atlantic Ocean. Spec. Pap. geol. Assoc. of Can. 7, 165–77.Google Scholar
Toghill, P. 1968(a). The stratigraphical relationships of the earliest monograptidae and the dimorphograptidae. Geol. Mag. 105, 46–51.Google Scholar
Toghill, P. 1968(b). The graptolite assemblages and zones of the Birkhill Shales (Lower Silurian) at Dobbs Linn. Paleontology 11, 654–68.Google Scholar
Whittington, H. B. & Williams, A. 1964. In Harland, W. B., Smith, A. G. & Wilcock, B. (Eds): The Phanerozoic time-scale, pp. 241–54. Q. Jl. geol. Soc. Lond. 120s, 458.Google Scholar
Williams, H. 1975. Early Paleozoic ophiolite complexes of Newfoundland: isotopic ages of zircons: comment. Geology 3, 479.2.0.CO;2>CrossRefGoogle Scholar
Williams, I. S., Compston, W., Chappell, B. W. & Shirahase, T. 1975. Rubidium- strontium age determinations on micas from a geologically controlled composite batholith. Jl. geol. Soc. Aust. 22, 497–506.CrossRefGoogle Scholar
Winterer, E. L., Reidel, W. R., Moberly, R. M. Jr., Resig, J. M., Kroenke, L. W., Gealy, E. L., Heath, G. R., Bronniman, P., Martini, E. & Worsley, T. R., 1971. Init. Rep. Deep Sea Drilling Project, 7, Washington (U.S. Government Printing Office), 841 pp.Google Scholar