Universität zu Köln

Just, J., Sagnotti, L., Nowaczyk, N. R., Francke, A. and Wagner, B. (2019). Recordings of Fast Paleomagnetic Reversals in a 1.2 Ma Greigite-Rich Sediment Archive From Lake Ohrid, Balkans. J. Geophys. Res.-Solid Earth, 124 (12). S. 12445 - 12465. WASHINGTON: AMER GEOPHYSICAL UNION. ISSN 2169-9356

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Abstract

State-of-the-art paleoclimate research strongly depends on the availability of time-equivalent markers as chronological control to disentangle interrelationships in the climate system from regional to global scale. Geomagnetic reversals are regarded as excellent age constraints because they are global events and independent from climatic conditions. However, spatial variations of timing and internal dynamics of reversals may limit their precision. Our 1.2 Ma high-resolution (similar to 25 cm/kyr) sediment record from Lake Ohrid is promising to precisely depict the Matuyama-Brunhes (MB) reversal and the Jaramillo subchron. Two generations of diagenetic ferrimagnetic minerals are present in glacial intervals of the Lake Ohrid record. Early diagenetic greigite acquired a quasi synsedimentary chemical magnetization, while a late diagenetic greigite formation, triggered by the upward diffusion of H2S-rich waters, obscures the polarity record at the top of the Jaramillo. Interglacial intervals are unaffected by greigite formation, likely due to low iron concentrations. Based on an orbitally tuned age model with tephrostratigraphic markers, the base of Jaramillo can be precisely dated to 1072.4 ka, and the MB reversal to 778.5 ka. Both polarity reversals occurred very rapidly in our record, lasting 2.3 and 1 kyr, respectively. Our results reveal that the dipole component of the Earth's magnetic field fell below the nondipole components only for a short duration in the Mediterranean region. The comparison of the timing of the MB boundary across different archives implies that the onset of the reversal provides a more synchronous age marker compared to often used midpoint ages.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Just, J. UNSPECIFIED UNSPECIFIED UNSPECIFIED Sagnotti, L. UNSPECIFIED UNSPECIFIED UNSPECIFIED Nowaczyk, N. R. UNSPECIFIED UNSPECIFIED UNSPECIFIED Francke, A. UNSPECIFIED UNSPECIFIED UNSPECIFIED Wagner, B. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-125065
DOI:	10.1029/2019JB018297
Journal or Publication Title:	J. Geophys. Res.-Solid Earth
Volume:	124
Number:	12
Page Range:	S. 12445 - 12465
Date:	2019
Publisher:	AMER GEOPHYSICAL UNION
Place of Publication:	WASHINGTON
ISSN:	2169-9356
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language BRUNHES GEOMAGNETIC REVERSAL; NATURAL REMANENT MAGNETIZATION; PALEOSECULAR VARIATION RECORD; NEOGENE MARINE-SEDIMENTS; LATE DIAGENETIC GROWTH; POLARITY TRANSITIONS; LOWER JARAMILLO; RELATIVE PALEOINTENSITY; FIELD EVOLUTION; MATUYAMA CHRON Multiple languages Geochemistry & Geophysics Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/12506