DOI: 10.1016/j.epsl.2019.116012
论文题名: Post-depositional manganese mobilization during the last glacial period in sediments of the eastern Clarion-Clipperton Zone, Pacific Ocean
作者: Volz J.B. ; Liu B. ; Köster M. ; Henkel S. ; Koschinsky A. ; Kasten S.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2020
卷: 532 语种: 英语
中文关键词: CCZ
; last glacial period
; manganese
; ocean oxygenation
; polymetallic nodules
; redox zonation
英文关键词: Carbon dioxide
; Chemical industry
; Conservation
; Digital storage
; Glacial geology
; Iron compounds
; Leaching
; Manganese
; Manganese nodules
; Manganese removal (water treatment)
; Oceanography
; Organic carbon
; Oxygenation
; Salinity measurement
; Sedimentology
; Surficial sediments
; Biogeochemical process
; Carbon dioxide storage
; Clarion-Clipperton zone
; Last glacial period
; Last glacial terminations
; Organic carbon burial rates
; Redox zonation
; Steady-state transport
; Oxic sediments
英文摘要: Numerous studies have provided compelling evidence that the Pacific Ocean has experienced substantial glacial/interglacial changes in bottom-water oxygenation associated with enhanced carbon dioxide storage in the glacial deep ocean. Under postulated low glacial bottom-water oxygen concentrations (O2 bw), redox zonation, biogeochemical processes and element fluxes in the sediments must have been distinctively different during the last glacial period (LGP) compared to current well-oxygenated conditions. In this study, we have investigated six sites situated in various European contract areas for the exploration of polymetallic nodules within the Clarion-Clipperton Zone (CCZ) in the NE Pacific and one site located in a protected Area of Particular Environmental Interest (APEI3) north of the CCZ. We found bulk sediment Mn maxima of up to 1 wt% in the upper oxic 10 cm of the sediments at all sites except for the APEI3 site. The application of a combined leaching protocol for the extraction of sedimentary Mn and Fe minerals revealed that mobilizable Mn(IV) represents the dominant Mn(oxyhydr)oxide phase with more than 70% of bulk solid-phase Mn. Steady state transport-reaction modeling showed that at postulated glacial O2 bw of 35 μM, the oxic zone in the sediments was much more compressed than today where upward diffusing pore-water Mn2+ was oxidized and precipitated as authigenic Mn(IV) at the oxic-suboxic redox boundary in the upper 5 cm of the sediments. Transient transport-reaction modeling demonstrated that with increasing O2 bw during the last glacial termination to current levels of ∼ 150 μM, (1) the oxic-suboxic redox boundary migrated deeper into the sediments and (2) the authigenic Mn(IV) peak was continuously mixed into subsequently deposited sediments by bioturbation causing the observed mobilizable Mn(IV) enrichment in the surface sediments. Such a distinct mobilizable Mn(IV) maximum was not found in the surface sediments of the APEI3 site, which indicates that the oxic zone was not as condensed during the LGP at this site due to two- to threefold lower organic carbon burial rates. Leaching data for sedimentary Fe minerals suggest that Fe(III) has not been diagenetically redistributed during the LGP at any of the investigated sites. Our results demonstrate that the basin-wide deoxygenation in the NE Pacific during the LGP was associated with (1) a much more compressed oxic zone at sites with carbon burial fluxes higher than 1.5 mg Corg m−2 d−1, (2) the authigenic formation of a sub-surface mobilizable Mn(IV) maximum in the upper 5 cm of the sediments and (3) a possibly intensified suboxic-diagenetic growth of polymetallic nodules. As our study provides evidence that authigenic Mn(IV) precipitated in the surface sediments under postulated low glacial O2 bw, it contributes to resolving a long-standing controversy concerning the origin of widely observed Mn-rich layers in glacial/deglacial deep-sea sediments. © 2019 The Authors Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/165329
Appears in Collections: 气候变化与战略
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作者单位: Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany; Jacobs University Bremen, Department of Physics and Earth Sciences, Bremen, Germany; University of Bremen, Faculty of Geosciences, Klagenfurter Strasse, Bremen, Germany
Recommended Citation:
Volz J.B.,Liu B.,Köster M.,et al. Post-depositional manganese mobilization during the last glacial period in sediments of the eastern Clarion-Clipperton Zone, Pacific Ocean[J]. Earth and Planetary Science Letters,2020-01-01,532