Multiproxy sedimentation patterns of sediment cores from the continental margin off northeast Brazil

Tropical regions have been reported to play a key role in climate dynamics. To date, however, there are uncertainties in the timing and the amplitude of the response of tropical ecosystems to millennial-scale climate change. We present evidence of an asynchrony between terrestrial and marine signals of climate change during Heinrich events preserved in marine sediment cores from the Brazilian continental margin. The inferred time lag of about 1000 to 2000 years is much larger than the ecological response to recent climate change and appears to be related to the nature of hydrological changes.

Chemical and isotopic compositions of sediments and some minerals from the Derugin Basin, Sea of Okhotsk

The paper reports specific mineralogical and geochemical characteristics of deposits from local depressions of the Derugin Basin. They were formed in an environment with periodic changes from oxic to anoxic conditions and show evidence for presence of hydrogen sulfide in bottom waters. Deposits of this type can be considered as a modern model for ancient ore-bearing black shale associations. Compared with typical metalliferous black shale sequences, which are characterized by high contents of organic matter, the sediments described here are depleted in elements of the organophilic association (Mo, Ni, Cu, Zn, V, and U), but have higher Mn contents.

Plant macrofossils from Lac de Fully

We use pollen, stomata and plant-macrofossil records to infer Holocene timberline fluctuations and changes in forest composition at Lac Superieur de Fully (2135 m a.s.l.), a small lake located near the modern regional timberline on a highland plateau in the Central Alps. Our records suggest that during the early Holocene vegetation was rather open on the plateau (eg, heaths of Dryas octopetala, Juniperus nana). The only tree that was able to build major stands was Betula. Other timberline trees (eg, Pinus cembra and Larix) expanded in the catchment of the lake after 8200 cal. BP, when Abies alba expanded at lower elevation. The late appearance of these timberline trees contrasts with previous plant-macrofossil records in the region, which show that the timberline had reached elevations up to at least 2350 m already at 11 000 cal. BP. We suggest that local climatic conditions may have delayed the expansion of closed stands of coniferous trees in the catchment of Lac de Fully until c. 8200 cal. BP, when climate shifted to more humid and less continental conditions. After c. 4600 cal. BP vegetation around the lake primarily responded to human impact, which caused a local lowering of the timberline by at least 150 m.