Climate and vegetation history of western Portugal inferred from Albian near-shore deposits (Galé Formation, Lusitanian Basin)

authored by

Ulrich Heimhofer, Peter A. Hochuli, Stefan Burla, Felix Oberli, Thierry Adatte, Jorge L. Dinis, Helmut Weissert

Abstract

The late Early Cretaceous greenhouse climate has been studied intensively based on proxy data derived essentially from open marine archives. In contrast, information on continental climatic conditions and on the accompanying response of vegetation is relatively scarce, most notably owing to the stratigraphic uncertainties associated with many Lower Cretaceous terrestrial deposits. Here, we present a palynological record from Albian near-shore deposits of the Lusitanian Basin of W Portugal, which have been independently dated using Sr-isotope signals derived from low-Mg oyster shell calcite. ⁸⁷Sr/⁸⁶Sr values fluctuate between 0.707373 ± 0.00002 and 0.707456 ± 0.00003; absolute values and the overall stratigraphic trend match well with the global open marine seawater signature during Albian times. Based on the new Sr-isotope data, existing biostratigraphic assignments of the succession are corroborated and partly revised. Spore-pollen data provide information on the vegetation community structure and are flanked by sedimentological and clay mineralogical data used to infer the overall climatic conditions prevailing on the adjacent continent. Variations in the distribution of climate-sensitive pollen and spores indicate distinct changes in moisture availability across the studied succession with a pronounced increase in hygrophilous spores in late Early Albian times. Comparison with time-equivalent palynofloras from the Algarve Basin of southern Portugal shows pronounced differences in the xerophyte/hygrophyte ratio, interpreted to reflect the effect of a broad arid climate belt covering southern and southeastern Iberia during Early Albian times.

Organisation(s)

Institute of Geology

External Organisation(s)

Universität Zürich (UZH)
ETH Zurich
University of Lausanne (UNIL)
University of Coimbra

Type

Review article

Journal

Geological magazine

Volume

149

Pages

1046-1064

No. of pages

19

ISSN

0016-7568

Publication date

11.2012

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/10.1017/S0016756812000118 (Access: Unknown)