Sedimentary features of a Weichselian glaciolacustrine delta |
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| Authors: | LARS B CLEMMENSEN MICHAEL HOUMARK-NIELSEN |
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| Institution: | Institut for almen Geologi, øster Voldgade 10, DK-1350 København K, Denmark;23rd April, 1980 |
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| Abstract: | Inclined beds of sand, granules, pebbles and cobbles resembling a glacio-tectonically tilted sequence were shown by sedimentological studies to constitute the 10–12 m thick foreset beds of a glaciolacustrine Gilbert-type delta in Kyndby, North Sjælland, Denmark. The foreset beds are slightly curved, dip 10–28 SE, and display a bundlewise structure with alternating coarse-grained cobble-rich and fine-grained sandy units. The occurrence of ascending megaripple cross-bedding and climbing ripple cross-lamination in the sandy foresets can be ascribed to strong backflow currents formed by the lee-side vortice. The foreset beds are underlain by flat-lying fine-grained sand, silt and clay (bottomset beds), and are overlain transitionally or erosively by 2–3 m of flat-lying sand, pebbles and cobbles (topset beds). In the transition zone between foreset beds and topset beds, various delta distributary channel units occur. The delta probably formed in a partly ice-dammed lake in connection with the general retreat of a Weichselian advance from the north ('Norwegian ice') |
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