![Early to middle Holocene changes in Laptev Sea water masses deduced from diatom and aquatic palynomorph assemblages [An article from: Global and Planetary Change]](https://www.ebooknetworking.net/books/B00/0RR/bigB000RR6HDK.jpg)
Early to middle Holocene changes in Laptev Sea water masses deduced from diatom and aquatic palynomorph assemblages [An article from: Global and Planetary Change]
Description
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Description:
On the basis of diatom and aquatic palynomorph assemblages in sediment cores obtained from the eastern Laptev Sea shelf, major phases of environmental change associated with the last postglacial global sea-level rise can be recognized for the time since 11.3 calendar years BP (cal. ka). Until 11 cal. ka, the outer Laptev Sea shelf (>=51 m paleodepth) was inundated and paleoenvironmental conditions were characterized by increased precipitation of river-loaded matter, primarily diatom plankton, in a river-proximal environment where reconstructed surface water salinities, using freshwater diatoms as proxy, remained below 9. The time interval 10.7-9.2 cal. ka was marked by a predominance of the dinoflagellate cyst Operculodinium centrocarpum as well as by the appearance of relatively warm-water indicative species in the outer Laptev Sea, probably due to enhanced influence of Atlantic Water at the continental margin. Because a continuously rising sea level resulted in an increasing distance between the investigated site and the southward retreating coastline, surface-water salinities on the outer shelf approached modern values of about 15-16 around 8.6 cal. ka. On the inner Laptev Sea shelf, modern-like environmental conditions were reached about 1 to 1.5 ky later, around 7.4 cal. ka, emphasizing the overwhelming influence of the global transgression on the Holocene evolution of Arctic shelf water masses.
Description:
On the basis of diatom and aquatic palynomorph assemblages in sediment cores obtained from the eastern Laptev Sea shelf, major phases of environmental change associated with the last postglacial global sea-level rise can be recognized for the time since 11.3 calendar years BP (cal. ka). Until 11 cal. ka, the outer Laptev Sea shelf (>=51 m paleodepth) was inundated and paleoenvironmental conditions were characterized by increased precipitation of river-loaded matter, primarily diatom plankton, in a river-proximal environment where reconstructed surface water salinities, using freshwater diatoms as proxy, remained below 9. The time interval 10.7-9.2 cal. ka was marked by a predominance of the dinoflagellate cyst Operculodinium centrocarpum as well as by the appearance of relatively warm-water indicative species in the outer Laptev Sea, probably due to enhanced influence of Atlantic Water at the continental margin. Because a continuously rising sea level resulted in an increasing distance between the investigated site and the southward retreating coastline, surface-water salinities on the outer shelf approached modern values of about 15-16 around 8.6 cal. ka. On the inner Laptev Sea shelf, modern-like environmental conditions were reached about 1 to 1.5 ky later, around 7.4 cal. ka, emphasizing the overwhelming influence of the global transgression on the Holocene evolution of Arctic shelf water masses.
