6533b85bfe1ef96bd12bb2b0

RESEARCH PRODUCT

Environmental geology and geochemistry of lake sediments (Holzmaar, Eifwl, Germany)

subject

description

Quaternary sediments of the lake Holzmaar comprise a well laminated, undisturbed sequence of diatomaceous gyttja, silt, clay laminites and tuff layers. The annually deposited gyttja has been dated by varve chronology yielding a continuous high-resolution time sequence for the Holocene and early Pleistocene. These organic-rich sediments provide an unique paleolimnological record on climatic changes, forest fires, volcanic eruptions, and anthropogenic influences on the sediment composition. Volcanic activity produced thin tephra layers (Laacher See Tephra 11,200±120 radiocarbon yrs BP; Ulmener Maar Tephra 9435±70 radiocarbon yrs BP) in the sedimentary column which possess elevated Ba, Sr, Zr, Y and Nb (±Rb, Ga) values, and heavy metal contents broadly similar to the enclosing gyttja sediments. In contrast, anthropogenic additions of heavy metals occurred in the upper most varvites deposited since the end of the 18th century. These high metal values are interpreted as disturbances of the natural heavy metal cycles due to fossil fuel combustion and processing of geological ores in the industrial and metropolitan areas of central Europe and associated regional anthropogenic metal pollution of the atmosphere.