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Published 1992 | public
Book Section - Chapter

Paleomagnetic results from the Cambrian-Ordovician boundary section at Black Mountain, Georgina Basin, western Queensland, Australia


Zones of alternating magnetic polarity have been identified throughout the Cambrian-Ordovician sequence at Black Mountain, and can be presumed to record geomagnetic field reversals during or immediately after deposition. A strong correlation can be made to polarity zones recognized at Dayangcha, northeastern China, a candidate site for establishment of the Cambrian-Ordovician boundary Global Stratotype Section and Point. Polarity zones associated with the Hispidodontus discretus and Hirsutodontus simplex Assemblage-Zones at Black Mountain are absent at Dayangcha, suggesting hiatuses at these levels in the Dayangcha sequence. Secondary components preserved in the Black Mountain section may provide temporal constraints on Middle Paleozoic diagenetic events in the Burke River Structural Belt.

Additional Information

© 1992 Balkema. The authors gratefully acknowledge J.H. Shergold, R.S. Nicoll, and J. Laurie for their assistance in obtaining samples. P. Pruner and C.T. Klöotwijk are thanked for their help in preparing samples in Canberra. The advice of members of the Cambrian-Ordovician Boundary Working Group has been appreciated, and their efforts acknowledged. We wish also to thank the Bureau of Mineral Resources, Australia, for their logistical and material support. Samples from the upper pan of the Ninmaroo Formation were collected by a BMR field party consisting of J.H. Shergold, R.S. Nicoll, J. Laurie, A.T. Nielsen, B.M. Radke and R.W. Brown. This work was funded in pan by the National Science Foundation (grant EAR-8721391), and by the Atlantic Richfield Corporation. California Institute of Technology contribution #5059.

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August 20, 2023
October 23, 2023