Conjunctive K-Ca and Rb-Sr dating of glauconies

Gopalan, K. (2008) Conjunctive K-Ca and Rb-Sr dating of glauconies Chemical Geology, 247 (1-2). pp. 119-123. ISSN 0009-2541

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The glaucony series (of which glauconitic mica is the K-rich end member) is one of the few widely occurring minerals in the sedimentary record. So their isotopic ages determined mainly by the K-Ar method represent a major database for the geologic time scale. Many K-Ar ages were, however, found to be too young and often also discordant with available corresponding Rb-Sr ages. This discrepancy may reflect the disparate responses of the chemically contrasting daughter elements, Ar and Sr to postdepositional processes, and renders either age equivocal. A potentially promising approach to evaluate the intrinsic potential of glauconies and other K-rich minerals for direct and reliable dating of sediments is the conjunctive use of the chemically very similar K-Ca and Rb-Sr systems. The relationship between K-Ca and Rb-Sr ages may show a coherence or regularity indicative of a geologically meaningful age like in the case of the well known chemically identical dual U-Pb decay systems. As a crucial first step, this report presents the first successful precise K-Ca dating in conjunction with Rb-Sr dating of an Ordovician glauconite using the same sample aliquot, chemical procedure and mass spectrometer.

Item Type:Article
Source:Copyright of this article belongs to Elsevier Science.
Keywords:K-Ca Dating; Rb-Sr Dating; Glaucony; Sedimentary Rocks
ID Code:13581
Deposited On:12 Nov 2010 15:18
Last Modified:01 Jun 2011 11:56

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