Final report on Rb-Sr whole rock dating of mudrock suites from the Lake District and Southern Uplands

Evans, J.. 1996 Final report on Rb-Sr whole rock dating of mudrock suites from the Lake District and Southern Uplands. British Geological Survey, 19pp. (NERC Isotope Geosciences Laboratory Report Series, no. 87) (Unpublished)

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Abstract/Summary

Recent work in Wales has shown that mudrocks yield Rb-Sr whole rock ages that are commonly isochrons and which have a precision between 6 and 16 Ma. These ages date the time at which the sediment passed through the smectite-illite transition (Evans 1996). The technique has considerable potential for understanding basin subsidence as the dates mark the time at which the sediments passed though c. 90 C, and could thus be used to map basin subsidence. In areas where thick, unfossiliferous mudrock sequences exist it also provides a simple method of placing a minimum age on sedimentation which, in areas of rapid burial, will be very close to the time of deposition of the sediment. This study was planned to extend the study of British mudrocks by looking at low grade mudrocks from the Lake District and Southern Uplands. Ordovician samples were chosen because there was a significant time difference between deposition and the possible complicating factor of Acadian metamorphism at c 400 Ma. Laterally equivalent samples (two localities within the Clingani Zones) with different burial histories were collected from the Southern Uplands to see if sediments of the same ages gave different burial results. The data is presented in Table 1 and the regression diagrams are given in Fig 1-7.

Item Type:	Publication - Report
Programmes:	BGS Programmes > NERC Isotope Geoscience Laboratory
Funders/Sponsors:	NERC Isotope Geosciences Laboratory
Date made live:	04 Nov 2025 13:53 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/540498

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