Composition and origin of clay minerals in Holocene sediments from the south‐eastern North Sea

Abstract

The distribution of clay minerals varies systematically in sediments from Holocene core material taken along a profile from the East Frisian coast to the Doggerbank. The proportion of illite increases with distance from the coast at the expense of kaolinite, whereas slight variations are seen in smectite and chlorite abundances. The chemical composition changes, and the K/Rb ratio and K‐Ar isotopic age of illite increase seawards. This trend results from progressive mixing processes of riverine detritus with Pleistocene fluvioglacial material reworked during the Holocene transgression. However, the clay fluvial flux only became dominant during the decreasing rate of sea‐level rise in the Late Holocene, especially near the shore. For example, modern sediments in tidal flats contain 75% of river‐borne Holocene‐supplied clay detritus, whereas this amount is only 10% in modern marine sediments at the Doggerbank.

Changes in clay mineral content of tidal flat sediments resulting from dike construction along the Lower Saxony coast of the North Sea, Germany

“…The d ‐values and the sequence of peak intensities in the diffractograms indicate clinochlore. Comparable chlorite types have already been reported for recently deposited tidal‐flat sediments along the German North Sea coast (Zuther et al ., 2000). Absorption bands in the IR spectrum between 3570 and 3560 cm −1 are a further indication of the clinochlore group.…”

“…The mineral composition of a ‘Lauenburg Clay’ sample was calculated from the combined XRD (peak area), IR (kaolinite content) and XRF (chemical composition) data, keeping the chemical composition of kaolinite, smectite and chlorite constant. The different steps in this complex calculation are detailed by Zuther et al . (2000).…”

“…The samples were prepared for X‐ray diffractometry (XRD), infrared spectrometry (IR) and X‐ray fluorescence (XRF) analysis. The following methods for the calculation of mineral content and illite composition were used (Zuther et al ., 2000).…”

Tunnel valley deposits from the southern North Sea – material provenance and depositional processes

“…Nevertheless, the obtained Caledonian K‐Ar age is in line with the age of the Scandinavian and Baltic sourced sediments as revealed by the K‐Ar dating of Elsterian deposits of such origin recovered from the eastern SNS (Zuther et al . ; Brockamp & Clauer ). This suggests that the Fennoscandian and Baltic shields were active sources of sediment in the Early Pleistocene deposits of the study area.…”

The mineralogy of suspended matter, fresh and Cenozoic sediments in the fluvio-deltaic Rhine–Meuse–Scheldt–Ems area, the Netherlands: An overview and review

“…With the exception of the studies by Zuther et al (2000), Pache et al (2008), Zeelmaekers (2011), Koenen & Griffioen (2013) and Adriaens (2014), who state that their results are quantitative or at least semi-quantitative, all the other studies cited below qualify their data at best as semi-quantitative. To understand the distribution of the clay assemblages in the North Sea, it is now generally agreed that clays in seawater are transported in flocs with a size of about 40 µm (e.g.…”