Skip to main content
    • Aa
    • Aa

Geochronology of the Cambrian: a precise Middle Cambrian U–Pb zircon date from the German margin of West Gondwana


A volcanic tuff 1.0 m above the base of the Triebenreuth Formation in the Franconian Forest provides the first precise and biostratigraphically bracketed date within the traditional Middle Cambrian. The first illustration of fossils from the Triebenreuth Formation in this report and their discussion allow a more highly refined correlation within the Middle Cambrian. A weighted mean 206Pb–238U date of 503.14±0.13/0.25/0.59 Ma on zircons from this subaerial pyroclastic tuff was determined by U–Pb chemical abrasion isotope dilution mass spectrometry (CA-TIMS) techniques. At c. 6.0–7.0 Ma younger than the base of the traditional Middle Cambrian in Avalonia, the new West Gondwanan date from east-central Germany suggests that estimates of 500 Ma for the base of the traditional Upper Cambrian and 497 Ma on the base of the Furongian Series may prove to be too ‘old’. Biostratigraphically well-bracketed dates through most of the Middle Cambrian/Series 3 and below the upper Upper Cambrian/upper Furongian Series do not exist. An earlier determined 494.4±3.8 Ma date from the Southwell Group of Tasmania may actually prove to be a reasonable estimate for the age of the base of the traditional Upper Cambrian. Until high precision dates are determined on the base of the traditional Upper Cambrian and base of the Furongian Series, the rates of biotic replacements and geological developments and the durations of biotic zones in the Middle/Series 3 and Upper Cambrian/Furongian Series remain as ‘best guesses’.

Corresponding author
Author for correspondence:
Hide All
J. J. Álvaro , J. M. Rouchy , T. Bechstädt , A. Boucot , F. Boyer , F. Debrenne , E. Moreno-Eiris , A. Perejón & E. Vennin 2000. Evaporitic constraints on the southward drifting of the western Gondwana margin during Early Cambrian times. Palaeogeography, Palaeoclimatology, Palaeoecology 160, 105–22.

B. M. Crowe & R. V. Fisher 1973. Sedimentary structures in base-surge deposits with special reference to cross-bedding, Ubehebe Craters, Death Valley, California. Geological Society of America Bulletin 84, 663–82.

K. Davidek , E. Landing , S. S. Bowring , S. R. Westrop , A. W. A. Rushton , R. A. Fortey & Adrain . 1998. New uppermost Cambrian U-Pb date from Avalonian Wales and age of the Cambrian–Ordovician boundary. Geological Magazine 135, 305–9.

J. Encarnación , A. J. Rowell & A. M. Grunow 1999. A U-Pb age for the Cambrian Taylor Formation, Antarctica: implications for the Cambrian time scale. Journal of Geology 107, 497504.

G. Geyer 2005. The base of a revised Middle Cambrian: are suitable concepts for a series boundary in reach. Geosciences Journal 9, 8199.

G. Geyer & O. Elicki 1995. The Lower Cambrian trilobites from the Görlitz Synclinorium (Germany) – review and new results. Paläontologische Zeitschrift 69, 87119.

T. H. P. Harvey , M. Williams , D. J. Condon , P. R. Wilby , D. J. Siveter , A. W. A. Rushton , M. J. Leng & S. E. Gabbott 2011. A refined chronology for the Cambrian succession of southern Britain. Journal of the Geological Society, London 168, 705–16.

C. E. Isachsen , S. A. Bowring , E. Landing & S. D. Samson 1994. New constraint on the division of Cambrian time. Geology 22, 496–8.

J. B. Jago , K. O. Reid , P. G. Quilty , G. R. Green & B. Daily 1972. Fossiliferous Cambrian limestone from within the Mount Read volcanics, Mt Lyell Mine area, Tasmania. Journal of the Geological Society of Australia 19, 370–82.

E. Landing , K. Davidek , S. R. Westrop , G. Geyer & W. Heldmaier 1998. Duration of the Early Cambrian: U-Pb ages of volcanic ashes from Avalon and Gondwana. Canadian Journal of Earth Sciences 35, 329–38.

J. M. Mattinson 2005. Zircon U/Pb chemical abrasion CA-TIMS method; combined annealing and multi-step dissolution analysis for improved precision and accuracy of zircon ages. Chemical Geology 220, 4766.

N. M. McLean , J. F. Bowring & S. A. Bowring 2011. An algorithm for U-Pb isotope dilution data reduction and uncertainty propagation. Geochemistry, Geophysics, Geosystems 12, QOAA18, doi: 10.1029/2010GC663478.

C. Perkins & J. L. Walshe 1993. Chronology of the Mount Read Volcanics, Tasmania, Australia. Economic Geology 88, 1176–97.

K. Sdzuy 2000. Das Kambrium des Frankenwaldes. 3. Die Lippertsgrüner Schichten und ihre Fauna. Senckenbergiana Lethaea 79, 301–27.

M. F. Sheridan 1979. Emplacement of pyroclastic flows: a review. In Ash-Flow Tuffs (eds C. E. Chapin & W. G. Elston ), pp. 125–36. Geological Society of America, Special Paper 180.

Recommend this journal

Email your librarian or administrator to recommend adding this journal to your organisation's collection.

Geological Magazine
  • ISSN: 0016-7568
  • EISSN: 1469-5081
  • URL: /core/journals/geological-magazine
Please enter your name
Please enter a valid email address
Who would you like to send this to? *



Full text views

Total number of HTML views: 2
Total number of PDF views: 16 *
Loading metrics...

Abstract views

Total abstract views: 116 *
Loading metrics...

* Views captured on Cambridge Core between September 2016 - 18th October 2017. This data will be updated every 24 hours.