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| Titel |
Magnetostratigraphy of sediments from Lake El'gygytgyn ICDP Site 5011-1: paleomagnetic age constraints for the longest paleoclimate record from the continental Arctic |
| VerfasserIn |
E. M. Haltia, N. R. Nowaczyk |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1814-9324
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| Digitales Dokument |
URL |
| Erschienen |
In: Climate of the Past ; 10, no. 2 ; Nr. 10, no. 2 (2014-03-26), S.623-642 |
| Datensatznummer |
250116942
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| Publikation (Nr.) |
 copernicus.org/cp-10-623-2014.pdf |
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| Zusammenfassung |
| Paleomagnetic measurements were performed on sediments drilled from ICDP Site
5011-1 in Lake El'gygytgyn (67°30' N, 172°05' E) located
in Far East Russian Arctic. The lake partly fills a crater formed by a
meteorite impact 3.58 ± 0.04 Ma ago. Sediments from three parallel
cores (5011-1A, 5011-1B and 5011-1C), recovered from the middle part of the
lake, yield a total of 355 m of sediment. Sediments are characterized by a
variable lithology, where intervals of homogenous and laminated sediments
alternate, and mass movement deposits occur frequently along the sediment
profile. Mineral magnetic investigation made on sediments enclosed in core
catchers suggests that magnetic carrier in these sediments is partly
maghemitized Ti-rich pseudo-single domain magnetite. Its detrital origin can
be shown by mineral magnetic measurements and SEM-EDS analyses performed on
mini-sized cylindrical rock samples, polished rock sections and creek
sediments. The intensity of the natural remanent magnetization in the
sediments is high with a range from about 1 to 1000 mA m−1. Most of
the sediments carry a stable magnetization interpreted as primary
depositional remanent magnetization. Characteristic inclination data show
alternating intervals of steep positive and negative inclinations that are
used to assign magnetic polarity to the lake sediment profile. This is a
rather straightforward procedure owing to the mainly high quality of data.
The Matuyama/Gauss (M/G) (2.608 Ma) and Brunhes/Matuyama (B/M) (0.780 Ma)
reversals were recognized in the sediments. The Mammoth and Kaena reversed
subchrons were identified during the Gauss chron, and the Olduvai and
Jaramillo normal subchrons as well as the Réunion and Cobb Mountain
cryptochrons were identified during the Matuyama chron. Sediments also
provide a record of the Olduvai precursor and Intra-Jaramillo geomagnetic
excursions. Sediment deposition rate is highest at the base of the sequence
laid down in the early Gauss chron, when the deposition rate is approximately
44 cm kyr−1. Sediment deposition decelerates upcore and it is an order
of magnitude lower during the Brunhes chron in comparison with the early
Gauss chron. Decrease in sediment deposition in the late Pliocene probably
relates to atmospheric and oceanic reorganization heralding the onset of
Quaternary climate change. The high-quality magnetostratigraphy reconstructed
from Lake El'gygytgyn sediments provides 12 first-order tie points to pin
down the age of the longest paleoclimate record from the continental
Arctic. |
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