We present palaeo- A nd rock magnetic results from a well-dated, 21 m-thick, Late Pleistocene continental sedimentary section located in southern Germany. Rock magnetic measurements reveal a complex magnetic mineralogy dominated by low coercivity minerals likely related to single domain biogenic magnetite and biogenic or early diagenetic greigite. In the lower part of the section also detrital haematite is present. The stable remanence shows predominantly normal polarity with two marked deviations at ∼1280-1200 cm and at 886 cm profile depth. Whereas the lower excursion is well established by several samples and documented also by detrital haematite, the upper one is only represented by a single sample and revealed by magnetite and greigite. Using the radiocarbon-based age model for the section, the lower excursion yields an age of 42.8-41.3 ka cal BP and is interpreted to represent the Laschamps geomagnetic excursion. The increased abundance of greigite in the upper part of the section, especially in the sample responsible for the upper anomalous direction, renders the interpretation of an actual excursion problematic due to the reducing environment necessary for the greigite formation.

The Laschamps geomagnetic excursion recorded in continental sediments from southern Germany / U. Kirscher, E. Dallanave, V. Weissbrodt, P. Stojakowits, M. Grau, V. Bachtadse, C. Mayr. - In: GEOPHYSICAL JOURNAL INTERNATIONAL. - ISSN 0956-540X. - 227:2(2021 Nov), pp. 1354-1365. [10.1093/gji/ggab276]

The Laschamps geomagnetic excursion recorded in continental sediments from southern Germany

E. Dallanave
Secondo
;
2021

Abstract

We present palaeo- A nd rock magnetic results from a well-dated, 21 m-thick, Late Pleistocene continental sedimentary section located in southern Germany. Rock magnetic measurements reveal a complex magnetic mineralogy dominated by low coercivity minerals likely related to single domain biogenic magnetite and biogenic or early diagenetic greigite. In the lower part of the section also detrital haematite is present. The stable remanence shows predominantly normal polarity with two marked deviations at ∼1280-1200 cm and at 886 cm profile depth. Whereas the lower excursion is well established by several samples and documented also by detrital haematite, the upper one is only represented by a single sample and revealed by magnetite and greigite. Using the radiocarbon-based age model for the section, the lower excursion yields an age of 42.8-41.3 ka cal BP and is interpreted to represent the Laschamps geomagnetic excursion. The increased abundance of greigite in the upper part of the section, especially in the sample responsible for the upper anomalous direction, renders the interpretation of an actual excursion problematic due to the reducing environment necessary for the greigite formation.
palaeomagnetism; Europe; geomagnetic excursions; rock and mineral magnetism
Settore GEOS-02/B - Geologia stratigrafica e sedimentologia
nov-2021
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/1122228
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