Rhythmic Growth of pacific Ferromanganese Nodules and their Milankovitch Climatic Origin

Han, X., Xianglong, J., Shufeng, Y., Fietzke, Jan and Eisenhauer, Anton (2003) Rhythmic Growth of pacific Ferromanganese Nodules and their Milankovitch Climatic Origin Earth and Planetary Science Letters, 211 (1-2). pp. 143-157. DOI 10.1016/S0012-821X(03)00169-9.

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Abstract

The internal microstructure of a ferromanganese nodule (#2392, from 154°37.52′W, 9°37.56′N, at water depth 5194 m) was examined in detail on polished sections, and radiometrically dated (230Thex/232Th) along a high-resolution (0.1 mm) depth profile (0–1.3 mm), spanning approximately 271 ka. The fabric shows typical stromatolithic structure and exhibits four orders of basic cyclic growth pattern, namely laminae bands, laminae zones, laminae groups and laminae pairs having average thicknesses of 402–454, 185–206, 58–67 and 15–18 μm, respectively. A profile from the depth of 200–2661 μm was selected to obtain the geochemical series using line-scanning electron microprobe analyses, which provide a record of paleoceanographic oscillations during the growth period. Power spectral analysis of the geochemical series for Al, Mn, Fe and Fe/Mn from the depth of 200–1220 μm, where no obvious discontinuity could be observed, display conspicuous cyclicities. The cycles of laminae zones, laminae groups and laminae pairs are reflected in the spectral patterns as well. The significant spectral peaks are located at 186, 108, 66 μm. Together with the cycle of laminae bands, the ratios of these cyclicities are close to those of Milankovitch orbital cycles. Through tuning to orbital cycles, a net growth rate of 4.5 mm/Ma is derived for the profile, which is in perfect agreement with the growth rate of 4.6 mm/Ma determined by 230Thex/232Th dating. Therefore, the rhythmic growth of ferromanganese nodules appears definitely associated with Milankovitch cycles, and the growth cyclicities may offer a new tool for estimating growth rates of ferromanganese nodules and paleoenvironmental reconstruction at substage resolution when supported by radiometric dating.

Document Type: Article
Keywords: Rhythmic growth; Milankovitch cycles; 230Thex/232Th dating; growth rate; Ferromanganese nodules; Pacific Ocean
Research affiliation: OceanRep > GEOMAR > FB2 Marine Biogeochemistry > FB2-MG Marine Geosystems
OceanRep > SFB 574
OceanRep > SFB 574 > B4
Refereed: Yes
DOI etc.: 10.1016/S0012-821X(03)00169-9
ISSN: 0012-821X
Projects: SFB574
Contribution Number:
ProjectNumber
SFB 57420
Date Deposited: 07 Apr 2010 11:48
Last Modified: 15 Nov 2016 11:14
URI: http://eprints.uni-kiel.de/id/eprint/7982

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