Improved time control on Cretaceous coastal deposits

New results from Sr isotope measurements using laser ablation

authored by

Stefan Burla, Felix Oberli, Ulrich Heimhofer, Uwe Wiechert, Helmut Weissert

Abstract

Sr-isotope measurements of unaltered oyster shell calcite using laser-ablation multi-collector ICPMS techniques represent a powerful tool capable of establishing a chronostratigraphic framework for fossil near-shore deposits. This approach is tested on two shoal-water successions from the Portuguese Algarve and Lusitanian basins covering Late Barremian to Albian strata. ⁸⁷Sr/⁸⁶Sr values derived from low-Mg calcite of oyster shells fluctuate between 0.70717 ± 0.00001 and 0.70746 ± 0.00002; absolute values as well as stratigraphic trends match well with the global open-marine seawater signal. The new Sr-isotope results in combination with existing bio- and chemostratigraphic records allow for identification of an Early Aptian biocalcification crisis at both studied localities and show that this event has severely affected coastal environments along the evolving Atlantic. Siliciclastic intervals in the Algarve section are interpreted as near-shore equivalents of enhanced detrital shedding into shelf and deep-sea environments as a consequence of increased chemical weathering rates during humid climate episodes.

External Organisation(s)

ETH Zurich
Ruhr-Universität Bochum
Freie Universität Berlin (FU Berlin)

Type

Article

Journal

TERRA NOVA

Volume

21

Pages

401-409

No. of pages

9

ISSN

0954-4879

Publication date

10.2009

Publication status

Published

Peer reviewed

Yes

ASJC Scopus subject areas

Geology

Sustainable Development Goals

SDG 13 - Climate Action, SDG 14 - Life Below Water

Electronic version(s)

https://doi.org/10.1111/j.1365-3121.2009.00897.x (Access: Unknown)