High-resolution clay mineral assemblages in the inner shelf mud wedge of the East China Sea during the Holocene: Implications for the East Asian Monsoon evolution

Provenance changes in fine detrital quartz in the inner shelf sediments of the East China Sea associated with shifts in the East Asian summer monsoon front during the last 6 kyrs

“…On the ESR signal intensity versus CI diagram, most of the fine silt fraction samples from the MD06-3040 core plotted within the area of the fine silt fraction of riverbed sediments from the entire Yangtze River drainage, suggesting that they can be explained by mixing of the sediments from the four major source areas in the modern Yangtze River drainage classified by Saito et al (2017). Notably, this result is consistent with the idea that the Yangtze River has been a predominant source of fine-silt-sized sediments on the inner shelf of ECS over the last 6 kyrs (Zheng et al 2010;Wang et al 2014;Yang et al 2015;Fang et al 2018).…”

“…The proportion of clay, fine silt, and coarse silt fraction in the bulk samples of the MD06-3040 core during the period 6.0-0 kyr on average is 17.3%, 64.5%, and 18.1%, respectively. The geochemical compositions and clay mineral assemblages of MD06-3040 core sediments suggests that most of the terrigenous sediments originated from the Yangtze River (Zheng et al 2010;Yang et al 2015;Bi et al 2017), with minor contribution from Taiwan island during the entire Holocene (Fang et al 2018). However, sediments deposited at the MD06-3040 site during the period from 7.5 to 6 kyr BP occasionally show quasi-bimodal grain size distributions, which is similar to that of typical modern sediments from the inner margin of the mud belt (Liu et al 2006).…”

“…Thus, we infer that the quartz in the fine silt fraction (4-16 μm) of the sediments deposited during this interval is a mixture of quartz derived from the southeastern and northeastern tributaries of the Yangtze River and the upper Jinshajiang with a possible rare contribution from the Qiantang and/or Ou rivers. Fang et al (2018) examined the clay mineralogy of the MD06-3040 core and tentatively concluded that kaolinite content (%) represented the contribution of the Fujian-derived source, illite content (%) was a contribution from the Taiwanese source, and the contribution from the Yangtze River was the sum of its smectite proportion (%) and illite content (%). They also suggested that most fine-grained (< 2 μm) terrigenous sediments originated from the Yangtze River, with a minor contribution from Taiwan island and the nearby Zhejiang and Fujian provinces during the entire Holocene (Fang et al 2018).…”

“…Fang et al (2018) examined the clay mineralogy of the MD06-3040 core and tentatively concluded that kaolinite content (%) represented the contribution of the Fujian-derived source, illite content (%) was a contribution from the Taiwanese source, and the contribution from the Yangtze River was the sum of its smectite proportion (%) and illite content (%). They also suggested that most fine-grained (< 2 μm) terrigenous sediments originated from the Yangtze River, with a minor contribution from Taiwan island and the nearby Zhejiang and Fujian provinces during the entire Holocene (Fang et al 2018). However, using clay mineral analyses of sediments from the MZ02 core retrieved from the mud belt area of the inner ECS, Liu et al (2014) suggested that the increased strength of the TWC might have played an important role in sediment Fig.…”

“…The provenance of sediment as well as paleoenvironmental changes on the inner shelf of the ECS have been well studied (Zheng et al 2010;Wang et al 2014;Liu et al 2014;Yang et al 2015;Bi et al 2017;Fang et al 2018;Liu et al 2018). In this study, we conducted provenance discrimination using the electron spin resonance (ESR) signal intensity and crystallinity index (CI) of quartz, which has been successfully applied to modern surface samples to trace eolian dusts from various deserts in western China (Sun et al 2007(Sun et al , 2013, to core sediment recovered from the Japan Sea to trace dust provenance changes in association with the southward-northward shifts of the Westerly Jet (WJ) (Nagashima et al 2007(Nagashima et al , 2011(Nagashima et al , 2012(Nagashima et al , 2013 and to characterize suspended particulate matter (SPM) collected from various segments of the Yangtze River drainage (Saito et al 2017).…”