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Changes in clay mineral content of tidal flat sediments resulting from dike construction along the Lower Saxony coast of the North Sea, Germany
Author(s) -
Brockamp Olaf,
Zuther Michael
Publication year - 2004
Publication title -
sedimentology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.494
H-Index - 108
eISSN - 1365-3091
pISSN - 0037-0746
DOI - 10.1111/j.1365-3091.2004.00637.x
Subject(s) - illite , geology , chlorite , clay minerals , kaolinite , sediment , geochemistry , mineralogy , mineral , clastic rock , sedimentary rock , geomorphology , quartz , chemistry , paleontology , organic chemistry
The clay mineral content of the < 2 µm fraction in tidal flat sediments in the former Harle Bay on the Lower Saxony coast has changed considerably since the thirteenth century up to the present time. The proportion of smectite has decreased from 29 to 11 wt%, whereas the proportion of illite has increased by about 10 wt% and those of chlorite and kaolinite by about 3 wt% each. The chemical composition of the major clay mineral illite has also changed: Al 2 O 3 has decreased by about 2 wt%, K 2 O by about 1·5 wt% and SiO 2 by about 3 wt%. It can be concluded that the changes in the clay mineral content are mainly influenced by dike construction and sea level rise, modifying flow pattern, submarine morphology, sedimentation and tidal range. These processes cause smectite to settle less rapidly because of its small grain size and low density resulting from interlayer water, so that the sediment becomes impoverished in this mineral.