Open AccessMagnetic properties of sediments in a Polish lake: evidence of a relation between the rock‐magnetic record and environmental changes in Late Pleistocene and Holocene sediments
Author(s) -
Jelinowska A.,
Tucholka P.,
Wieckowski K.
Publication year - 1997
Publication title -
geophysical journal international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.302
H-Index - 168
eISSN - 1365-246X
pISSN - 0956-540X
DOI - 10.1111/j.1365-246x.1997.tb04508.x
Subject(s) - geology , diagenesis , greigite , magnetic mineralogy , environmental magnetism , rock magnetism , holocene , sedimentary rock , geochemistry , sediment , authigenic , pleistocene , ferrimagnetism , mineralogy , geomorphology , remanence , paleontology , magnetization , pyrite , physics , quantum mechanics , magnetic field
SUMMARY A study of mineral magnetic parameters was carried out on a Late Pleistocene and Holocene sedimentary sequence (of nearly 18 m) from Lake Bledowo (central Poland). Sediments of Lake Bledowo have already been analysed for bulk sediment mineralogy and biogenic materials. The mineral magnetic stratigraphy confirms the major changes in palaeo‐environmental conditions that have been deduced from other methods. The most important mineral magnetic change results from the authigenetic formation of ferrimagnetic greigite, Fe 3 S 4 , during the beginning of lacustrine conditions (± 12 000 yr BP). Our data also indicate a detrital origin of overlying ferrimagnetic iron oxides. It is suggested that they originate from brown soils developed on the boulder clay constituting the west side of the lake shore. Variations of ferrimagnetic iron oxide size are related to the early diagenetic processes in the sediment. Larger particles are present in periods with early diagenesis of organic matter in anoxic conditions. This indicates the dissolution of fine magnetic particles by iron‐oxide‐reducing bacteria and results in homogeneous magnetic grain sizes, despite their origin from soils, characterized by a multimodal grain‐size distribution.