Environmental mechanism of magnetic susceptibility changes of lacustrine sediments from Lake Hulun, China

Citation
Sy. Hu et al., Environmental mechanism of magnetic susceptibility changes of lacustrine sediments from Lake Hulun, China, SCI CHINA D, 43(5), 2000, pp. 534-540
Citations number
19
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Earth Sciences
Journal title
SCIENCE IN CHINA SERIES D-EARTH SCIENCES
ISSN journal
1006-9313 → ACNP
Volume
43
Issue
5
Year of publication
2000
Pages
534 - 540
Database
ISI
SICI code
1006-9313(200010)43:5<534:EMOMSC>2.0.ZU;2-V
Abstract
The changes of magnetic susceptibility (kappa) are correlated with those of corresponding sedimentological, geochemical, mineralogical and biological results, which verifies that kappa can be taken as one of the environmental proxies. However, usually the exact origin of magnetic signal is poorly un derstood, and is difficult to relate with the environmental evolution. Magn etic properties of material derived from the catchment and sedimentary envi ronment may affect the accumulation, preservation, or authigenesis and diag enesis of magnetic minerals. In the Lake Hulun region in inner Mongolia, it is found that muddy sediments, deposited during high water level period (c orresponding to humid climate), have comparatively high kappa values. In co ntrast, the sandy sediments, deposited during low water level period (corre sponding to arid climate), have low kappa values. Detailed rock magnetic in vestigation confirms that detrital magnetite derived from volcanic rocks in the catchment exists in both muddy and sandy sediments. During high water level period, secondary ferrimagnetic iron sulphide was produced in muddy s ediments under relatively reductive conditions. Ferrimagnetic iron sulphide , coexisting with detrital magnetite, predominates the magnetic properties of muddy sediments, resulting in increasing kappa: This paper reveals the s ignificance of authigenic ferrimagnetic iron sulphide produced after sedime nt deposition.