 |
| Titel |
Rock magnetic properties, magnetic susceptibility, and organic geochemistry comparison in core LZ1029-7 Lake El'gygytgyn, Russia Far East |
| VerfasserIn |
K. J. Murdock, K. Wilkie, L. L. Brown |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1814-9324
|
| Digitales Dokument |
URL |
| Erschienen |
In: Climate of the Past ; 9, no. 1 ; Nr. 9, no. 1 (2013-02-28), S.467-479 |
| Datensatznummer |
250017998
|
| Publikation (Nr.) |
 copernicus.org/cp-9-467-2013.pdf |
|
|
|
|
|
| Zusammenfassung |
| Susceptibility measurements performed on initial short (~ 16 m)
cores PG1351 taken from Lake El'gygytgyn exhibited a large range in values.
This observation led to the suggestion of widespread magnetite dissolution
within the sediments due to anoxic conditions within the lake. Rock magnetic
properties and their comparison with magnetic susceptibility, total organic
carbon (TOC), and bulk δ13Corg proxies in core LZ1029-7,
taken from the same site as the previously drilled PG1351, provide an
insight into the character of the magnetic minerals present within the lake
and can further the understanding of processes that may be present in the
newer long core sediments. Susceptibility measurements (χ) of discrete
samples corroborate the two order of magnitude difference seen in previous
continuous susceptibility measurements (κ), correlating high values
with interglacial periods and low values with glacial intervals. Hysteresis
parameters indicate that the majority of the magnetic material to be
magnetite of PSD size. TOC values increase while δ13Corg values decrease in one section of LZ1029-7, which is defined
as the Last Glacial Maximum (LGM), and help confine the age of the core to
approximately 62 ka. Increases in TOC during the most recent glacial
interval suggest increased preservation of organic carbon during this
period. High TOC and low magnetic susceptibility during the LGM support the
theory of perennial ice cover during glacial periods, which would lead to
lake stratification and therefore anoxic bottom water conditions. Low
temperature magnetic measurements confirmed the presence of magnetite, but
also indicated titanomagnetite and possibly siderite, rhodochrosite, and/or
vivianite were present. The latter three minerals are found only in anoxic
environments, and further support the notion of magnetite dissolution. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|