A Revised 87Sr/86Sr Curve for the Silurian: Implications for Global Ocean Chemistry and the Silurian Timescale

Cramer, Bradley D., Munnecke, Axel, Schofield, David I., Haase, Karsten M. and Haase-Schramm, Alexandra (2011) A Revised 87Sr/86Sr Curve for the Silurian: Implications for Global Ocean Chemistry and the Silurian Timescale Journal of Geology, 119 (4). pp. 335-349. DOI 10.1086/660117.

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Abstract

Recent recalibration of the Silurian timescale and improved global chronostratigraphic correlation of Silurian strata significantly altered the Silurian (87)Sr/(86)Sr curve and the temporal extent of available data. Whereas previous Silurian (87)Sr/(86)Sr composites showed a generally monotonic increase throughout the Silurian, revisions to the Silurian timescale now require a major increase in the rate of change in (87)Sr/(86)Sr at or near the onset of the Gorstian Age of the Ludlow Epoch. Similarly, improved chronostratigraphic correlations between Silurian outcrops on Anticosti Island, Canada, and Gotland, Sweden, indicate that the middle part of the Telychian Age, which is roughly 10%-15% of the total duration of the Silurian period, is undersampled and underrepresented in Silurian (87)Sr/(86)Sr composites. A revised Silurian (87)Sr/(86)Sr curve based on 241 new and published analyses confirms the significant increase in the rate of change of (87)Sr/(86)Sr toward more radiogenic values near the base of the Ludlow Series. On the basis of these data, we propose that the rapid trend toward more radiogenic (87)Sr/(86)Sr values is indicative of increased weathering of old sialic crust exposed during the Silurian uplift of portions of Baltica, Laurentia, and Avalonia. Importantly, however, the actual rate of change of (87)Sr/(86)Sr will remain equivocal until the durations of Silurian epochs and ages are better constrained.

Document Type: Article
Keywords: Meeresgeologie; STRONTIUM ISOTOPE STRATIGRAPHY; ALASKA ALEXANDER TERRANE; PHANEROZOIC TIME-SCALE; OLD RED SANDSTONE; PB ZIRCON AGES; HIGH-RESOLUTION; SEAWATER SR-87/SR-86; INTEGRATED BIOSTRATIGRAPHY; NORTHERN APPALACHIANS; TECTONIC IMPLICATIONS
Research affiliation: OceanRep > GEOMAR > FB2 Marine Biogeochemistry > FB2-MG Marine Geosystems
Refereed: Yes
DOI etc.: 10.1086/660117
ISSN: 0022-1376
Date Deposited: 11 Jan 2012 13:12
Last Modified: 05 Dec 2016 11:12
URI: http://eprints.uni-kiel.de/id/eprint/13389

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