DOI: 10.1111/gbi.12191
Scopus记录号: 2-s2.0-84978411828
论文题名: Cryoconite pans on Snowball Earth: supraglacial oases for Cryogenian eukaryotes?
作者: Hoffman P.F.
刊名: Geobiology
ISSN: 1472-4677
EISSN: 1472-4669
出版年: 2016
卷: 14, 期: 6 起始页码: 531
结束页码: 542
语种: 英语
Scopus关键词: alga
; climate modeling
; cold water
; cyanobacterium
; Ediacaran
; eukaryote
; evolution
; fossil record
; fungus
; glaciation
; ice sheet
; metazoan
; organic matter
; protist
; sea ice
; solar radiation
; subglacial environment
; volcanic ash
; Chlorophyta
; Cyanobacteria
; Eukaryota
; Fungi
; Metazoa
; Protista
; dust
; astronomy
; climate
; cyanobacterium
; dust
; ecosystem
; evolution
; ice cover
; physiology
; Biological Evolution
; Climate
; Cyanobacteria
; Dust
; Earth (Planet)
; Ecosystem
; Evolution, Planetary
; Ice Cover
Scopus学科分类: Earth and Planetary Sciences: General Earth and Planetary Sciences
; Environmental Science: General Environmental Science
; Agricultural and Biological Sciences: Ecology, Evolution, Behavior and Systematic
英文摘要: Geochemical, paleomagnetic, and geochronological data increasingly support the Snowball Earth hypothesis for Cryogenian glaciations. Yet, the fossil record reveals no clear-cut evolutionary bottleneck. Climate models and the modern cryobiosphere offer insights on this paradox. Recent modeling implies that Snowball continents never lacked ice-free areas. Wind-blown dust from these areas plus volcanic ash were trapped by snow on ice sheets and sea ice. At a Snowball onset, sea ice was too thin to flow and ablative ice was too cold for dust retention. After a few millenia, sea ice reached 100 s of meters in thickness and began to flow as a ‘sea glacier’ toward an equatorial ablation zone. At first, dust advected to the ablative surface was recycled by winds, but as the surface warmed with rising CO2, dust aka cryoconite began to accumulate. As a sea glacier has no terminus, cryoconite saturated the surface. It absorbed solar radiation, supported cyanobacterial growth, and sank to an equilibrium depth forming holes and decameter-scale pans of meltwater. As meltwater production rose, drainages developed, connecting pans to moulins, where meltwater was flushed into the subglacial ocean. Flushing cleansed the surface, creating a stabilizing feedback. If the dust flux rose, cryoconite was removed; if the dust flux waned, cryoconite accumulated. In addition to cyanobacteria, modern cryoconite holes are inhabited by green algae, fungi, protists, and certain metazoans. On Snowball Earth, cryoconite pans provided stable interconnected habitats for eukaryotes tolerant of fresh to brackish cold water on an ablation surface 60 million km2 in area. Flushing and burial of organic matter was a potential source of atmospheric oxygen. Dominance of green algae among Ediacaran eukaryotic primary producers is a possible legacy of Cryogenian cryoconite pans, but a schizohaline ocean—supraglacial freshwater and subglacial brine—may have exerted selective stress on early metazoans, or impeded their evolution. © 2016 John Wiley & Sons Ltd Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/85090
Appears in Collections: 影响、适应和脆弱性
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作者单位: Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA, United States; School of Earth and Ocean Sciences, University of Victoria, Victoria, BC, Canada
Recommended Citation:
Hoffman P.F.. Cryoconite pans on Snowball Earth: supraglacial oases for Cryogenian eukaryotes?[J]. Geobiology,2016-01-01,14(6)