DOI: 10.1002/2014GL060477
论文题名: Particle sorting during sediment redistribution processes and the effect on 230Th-normalized mass accumulation rates
作者: Marcantonio F. ; Lyle M. ; Ibrahim R.
刊名: Geophysical Research Letters
ISSN: 0094-9862
EISSN: 1944-9593
出版年: 2014
卷: 41, 期: 15 起始页码: 5547
结束页码: 5554
语种: 英语
英文关键词: Panama Basin
; preferential sorting
; sediment redistribution
; Th-230
Scopus关键词: Screening
; Sediments
; Coarse fractions
; Current velocity
; Fine-grained sediment
; Mass accumulation rates
; Panama Basin
; Sediment redistribution
; Size fractionation
; Th-230
; Bottom current
; Coarse-grained
; Particle sorting
; Sediments
; Screening
; fractionation
; ocean basin
; seafloor
; sediment chemistry
; sediment core
; sediment transport
; sorting
英文摘要: The 230Th method of determining mass accumulation rates (MARs) assumes that little to no fractionation occurs during sediment redistribution processes at the seafloor. We examine 230Th inventories in radiocarbon-dated multicore sediments from paired winnowed and focused sites at Cocos and Carnegie Ridges, Panama Basin. Radiocarbon-derived sand MARs, which likely represent the vertical rain of particles poorly transported by bottom currents, are similar at each of the paired sites but are different using 230Th normalization. 230Th-normalized MARs are about 60% lower at focused sites and likely underestimate vertical MARs, while the reverse is true for winnowed sites. We hypothesize that size fractionation occurs most frequently at lower current velocities, resulting in the coarse fraction being left behind and primarily the fine 230Th-rich grains being transported downslope. 230Th-normalization works well for recording fine-grained (detrital and opal), but not coarse-grained (carbonate), fluxes in regions that have undergone sediment redistribution. Key Points Preferential sorting of 230Th-rich fine particles biases 230Th- normalized MARs Focused sites underestimate MARs while winnowed sites overestimate MARs 230Th-normalized fluxes of fine-grained sediment components are accurate © 2014. American Geophysical Union. All Rights Reserved. URL: https://www.scopus.com/inward/record.uri?eid=2-s2.0-84905290528&doi=10.1002%2f2014GL060477&partnerID=40&md5=1697a4c3d8b7a0e0e8d4b65d7a37d06e
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资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/7126
Appears in Collections: 气候减缓与适应
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作者单位: Department of Geology and Geophysics, Texas A and M University, College Station, TX, United States
Recommended Citation:
Marcantonio F.,Lyle M.,Ibrahim R.. Particle sorting during sediment redistribution processes and the effect on 230Th-normalized mass accumulation rates[J]. Geophysical Research Letters,2014-01-01,41(15).