Magnetic characteristics and its environmental implications of core YSJD-86GC sediments from the southern South China Sea

Abstract

Sediments of core YSJD-86GC (referred to as 86GC) collected from the southern South China Sea were selected for environmental magnetic studies. Combined with the published chronological framework, sediment magnetic properties were revealed for the study area since the MIS3 stage. The rock magnetic results indicate that low-coercivity magnetite is the main magnetic mineral within the sediments. Also, a certain amounts of hematite are present. The King plot and Day plot, which reflect the magnetic particle size, show that fine-grained pseudo-single-domain phase magnetic particles dominate the magnetic minerals in the sediments. Comparison of magnetic parameters and geochemical indicators show that magnetic properties of core 86GC sediments reflect a terrigenous input. Simultaneously, magnetic characteristics of the studied sediment are influenced by the quantity of terrigenous sediment input, oxidation-reduction conditions of the provenance area, and the transportation environment and distance. Sea level fluctuation caused by global climate change was the main factor for variation in concentration of magnetic minerals and magnetic particle size of the studied core sediments. Thus, variation of sediment magnetic properties in the study area can be used as an indirect indicator of sea level fluctuation.

Sensitivity of Sediment Magnetic Records to Climate Change during Holocene for the Northern South China Sea

“…As the previous published research for the core PC24 (Ouyang et al, 2014a) suggested that both detrital (mainly pseudo single domain, PSD) and biogenic (mainly single domain, SD) magnetite were coexisted within core PC24 sediments. κ-T curves, hysteresis loops, IRM acquisition and backfield demagnetization curves, gradient acquisition plot of IRM acquisition curves from CLG analysis are illustrated at Figure 3 for representative samples.…”

“…This correlation implies that total content of all magnetic particles is affected by a common factor. Total concentration of magnetic minerals within marine sediments was proved to be related to variation of temperature despite that sediment magnetic response to climate change differed from different regions within the SCS (Hou et al, 1996;Tang et al, 2003;Zhang et al, 2010;Ouyang et al, 2014a). Variation of χ lf , χ ARM and SIRM for the studied core PC24 was coincident with variation of χ lf for a previous reported core DSH-1C from the northern SCS before 6 cal.…”

“…As discussed within the previous article (Ouyang et al, 2014a), granularity of magnetic minerals reflected by Day-plot, King-plot and FORC diagrams suggested both detrital pseudo-single domain (PSD) and biogenic single domain (SD) magnetite particles (DM and BM, respectively) were concurrence within the studied sediments. As shown in the previous published article (Ouyang et al, 2014a), both noninteracting biogenic magnetite and a detrital magnetite were identified from the FORC diagrams (not shown here) of all sediments from the whole core PC24.…”

“…Many magnetic results of the SCS sediments were reported since the past decade. However, previous research indicated that sediment magnetic response to climate change varied much among different regions within the South China Sea (SCS) (Wang et al, 1993;Hou et al, 1996;Kissel et al, 2003;Yim et al, 2004;Yang et al, 2007;Ouyang et al, 2014a). Zhang et al (2010) compared many cores within the SCS and pointed out that the SCS could be divided into at least two regions according to variation characteristics of magnetic susceptibility.…”

Paleoenvironmental reconstruction of the radial sand ridge field in the South Yellow Sea (east China) since 45ka using the sediment magnetic properties and granulometry

“…Magnetic measurements provide a means of characterizing the mineralogy, concentration, and grain size of magnetic minerals contained in sediments in a rapid, economical and non-destructive way (Thompson and Oldfield, 1986). Therefore, the environmental magnetic method has been widely applied to characterize sediments and extract information regarding sediment provenance (Bloemendal et al, 1992;Jenkins et al, 2002;Liu et al, 2003;Booth et al, 2005;Wang et al, 2009;Ouyang et al, 2014), sedimentary dynamics (Rosenbaum et al, 1996;Yamazaki and Ioka, 1997;Watkins et al, 2007;) and post-depositional diagenesis (Demory et al, 2005;Karlin and Levi., 1983;Liu et al, 2004;Rowan et al, 2009;Chen et al, 2015).…”