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. Sr-87/Sr-86
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.