Evidence for abrupt climate changes in annually laminated marine sediments

Alan E. S. Kemp

Abstract

Annually laminated sediments from marine or lacustrine settings represent valuable high–resolution archives of climate change that record variation due to changing precipitation and run–off from land or variation in biological productivity and flux in the water column. Because of their annual resolution such sediments may capture abrupt changes of interannual to decadal scales rivaling corals and ice cores in resolution. Laminated sediments often occur intermittently in the sediment column, and the onset and cessation of laminae commonly record the abrupt crossing of thresholds related to climate change, for example, in the degree of oxygenation of bottom waters. Such records from marginal basins and continental margins have been pivotal in demonstrating that abrupt changes hitherto documented only in high–latitude ice cores are synchronous with climatic change at low latitudes. These insights into global teleconnections have improved our understanding of the mechanisms of rapid climate change. In deep–sea settings, the discovery of the episodic occurrence of laminated diatom–rich sediments in the Equatorial Pacific and Southern Ocean provides evidence for massive climate–related biogeochemical excursions tied to abrupt changes in the input, distribution and availability of nutrients in the oceans.

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