Open AccessPalaeomagnetism of the Jurassic Asphaltkalk deposits, Holzen, northern Germany
Author(s) -
Katz Bodo,
Elmore R. D.,
Engel M. H.,
Leythaeuser D.
Publication year - 1996
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.1996.tb04721.x
Subject(s) - remanence , geology , natural remanent magnetization , apparent polar wander , paleomagnetism , authigenic , rock magnetism , magnetic mineralogy , magnetization , syncline , magnetite , polar wander , geochemistry , geophysics , paleontology , mineralogy , diagenesis , magnetic field , tectonics , physics , quantum mechanics
SUMMARY Palaeomagnetic and rock magnetic studies on the Kimmeridgian‐Portlandian Asphaltkalk deposits of the Hils Syncline near Holzen in northern Germany suggest a connection between bitumen impregnation and magnetization in the limestones. A stable remanent magnetization is only found in the Asphaltkalk deposits, not in non‐bitumen‐impregnated limestones of the same age. The stable remanence was acquired after folding in this region, as revealed by a palaeomagnetic fold test. The timing of remanence acquisition is Late Cretaceous‐early Tertiary, as derived from a comparison of the mean pole of the magnetic component with the European apparent polar wander path (APWP). The decay pattern of the natural remanent magnetization (NRM) during alternating field (AF) and thermal demagnetizaton indicates that the magnetization is carried by magnetite. Isothermal remanent magnetization (IRM) acquisition and thermal decay measurements, as well as hysteresis parameters, are consistent with this interpretation. This study suggests that the creation of authigenic magnetite during the lower Tertiary in the Asphaltkalk deposits might coincide with the timing of hydrocarbon migration into the unit.