Annual lamination and its sedimentary implications in the Yangtze River delta inferred from High-resolution biogenic silica and sensitive grain-size records

作者：Fan, Dejiang^*; Qi, Hongyan; Sun, Xiaoxia; Liu, Yong; Yang, Zuosheng

来源：Continental Shelf Research, 2011, 31(2): 129-137.

DOI：10.1016/j.csr.2010.12.001

• The Yangtze River delta
• Seasonal variation
• Annual lamination
• Biogenic silica
• Sensitive grain-size fraction
• Sedimentary rate

Annual sedimentary layers in core A from the Yangtze River (Changjiang) subaqueous delta were identified based on high-resolution biogenic silica (BSi) and grain-size records. The contents of BSi, the sediment grain-size and the sensitive grain-size fractions of <13.14 mu m and 13.14-250 mu m illustrated steady coincident fluctuations with the depth profile of core A These fluctuations were inferred to reflect seasonal changes in physical and biological processes. For example, variations in the content of BSi likely represent changes in primary production in flood versus dry seasons. It in flood seasons was several times higher than that in dry seasons. The amounts of <13.14 and 13.14-250 pm fractions were complimentary to each other and co-varied with the BSi amount. Therefore, the BSi, grain-size and sensitive fractions can be used as proxies for the annual sedimentation. From 1992 to 2005, the estimated sedimentary rate based on the annual layer varied from 1.0 to 3.5 cm/a (mean of 2.07 cm/a), and these values varies with the annual sediment discharge from the Yangtze River to the sea. The significant seasonal variations in the water discharge, sediment load, ocean hydrodynamics and primary production, which are common in the area affected by the East Asian monsoon, are likely responsible for the formation of the annual sedimentary lamination.

• 出版日期2011-2-15
• 单位中国海洋大学