New Pb-Pb single zircon age constraints on the timing of neoproterozoic glaciation and continental break-up in Namibia.
Journal Article
1996
Permanent link to this Item
Authors
Journal Title
Journal of Geology
Link to Journal
Journal ISSN
Volume Title
Publisher
University of Chicago Press
Publisher
University of Cape Town
Series
Abstract
Dating of single zircons from low-grade metamorphosed rhyolites in the Rosh Pinah Formation of the Gariep Belt
in southwestern Namibia, using the Pb evaporation technique, yielded a primary crystallization age of 741 ± 6 Ma.
Both the stratigraphic position and the geochemistry of the volcanic rocks indicate an early continental rift environ-
ment. The new data not only provide an age for the massive Zn-Pb-Cu sulfide mineralization associated with these
volcanic rocks, but they also set a maximum age limit for Neoproterozoic continental break-up in southern Namibia.
This age is statistically indistinguishable from a recently reported age of 748 + 3 Ma for stratigraphically equivalent
volcanic rocks in the northern rift of the Damara Belt, suggesting that the onset of the formation of the N-S-trending
Adamastor ocean and of the NE-trending Khomas ocean in central and northern Namibia occurred at the same time.
The volcanic unit directly overlies, in both rift grabens, a diamictite horizon with glaciogenic features. Our new
results further constrain the age of this glacial epoch, which may be correlated with the Sturtian glaciation, to around
750 Ma
Description
Reference:
Frimmel, H. E., Klötzli, U. S., & Siegfried, P. R. (1996). New Pb-Pb single zircon age constraints on the timing of Neoproterozoic glaciation and continental break-up in Namibia. The Journal of Geology, 459-469.