Geochemical compositional changes at the Pliocene-Pleistocene transition in fluviodeltaic deposits in the Tegelen-Reuver area (southeastern Netherlands)
At the Pliocene-Pleistocene transition, major changes occurred in the Rhine system: Climatic cooling, extension of the drainage area into the Alps and a marine regression. We studied the geochemistry, clay mineralogy and micromorphology of several sections with Pliocene and Early Pleistocene Rhine d...
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Published in | International journal of earth sciences : Geologische Rundschau Vol. 89; no. 1; pp. 154 - 169 |
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Main Authors | , , , |
Format | Journal Article |
Language | English |
Published |
Berlin
Springer Nature B.V
01.06.2000
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Subjects | |
Online Access | Get full text |
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Summary: | At the Pliocene-Pleistocene transition, major changes occurred in the Rhine system: Climatic cooling, extension of the drainage area into the Alps and a marine regression. We studied the geochemistry, clay mineralogy and micromorphology of several sections with Pliocene and Early Pleistocene Rhine deposits to determine the effects of this change on the bulk geochemical record. We found a general increase in Na sub(2)O contents, which can be attributed to the Alpine source supplying fresh, sodic plagioclase-rich material instead of the local, strongly weathered sediments. Increasing K sub(2)O/Al sub(2)O sub(3) can be attributed to a similar decrease in degree of weathering. However, this trend is disturbed by the loss of K from clay minerals during weathering in organic-rich layers. Local high TiO sub(2) anomalies, caused by preferential sorting and concentration, are found in most Pliocene sections, but they are absent in the Upper Pliocene and Lower Pleistocene Alpine-derived deposits. This change is probably due to a change in the energy of the fluvial system. Finally, (pyrite-) S contents drop (siderite-) Fe contents rise. Micromorphological observations indicate that the Pliocene pyrite was formed when freshwater deposits were flooded with seawater during short-term events. The decrease in S, and the increase in siderite-Fe, can be attributed to decreasing marine influence, as a result of the marine regression at the Pliocene-Pleistocene transition. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 ObjectType-Article-2 ObjectType-Feature-1 |
ISSN: | 1437-3254 1437-3262 1437-3262 |
DOI: | 10.1007/s005310050323 |