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Taliks, cryopegs, and permafrost dynamics related to channel migration, Colville River Delta, Alaska
Permafrost and Periglacial Processes ( IF 3.0 ) Pub Date : 2020-03-04 , DOI: 10.1002/ppp.2046
Eva Stephani 1 , Jeremiah Drage 2 , Duane Miller 3 , Benjamin M. Jones 1 , Mikhail Kanevskiy 1
Affiliation  

Talik and cryopeg development related to channel migration has been observed in arctic deltas, but our knowledge on the configuration, properties, and rate of freezeback has remained limited. Along a main channel of the Colville River Delta (Alaska), we integrated subsurface data from 79 boreholes with a remote sensing analysis to measure channel changes in 1948–2013. We found that closed taliks occurred under the active channel and extended into intrapermafrost cryopeg layers under the riverbed/riverbar and active floodplain. Cryopegs as isolated small pockets were also identified at depths in older terrain units. In the study corridor, we estimated that the likelihood of talik and cryopeg occurrence was predominantly (42.2% of area) low, yet a high likelihood was also identified (27.0% of area). Permafrost growth occurred at a rapid rate in the land exposed following channel migration, likely due to the low and delayed release of latent heat as the freezing front progresses downward in the coarse‐grained soils of increasing salinity but decreasing temperatures. As the deposits keep cooling, ground ice will continue forming therefore increasing furthermore the salinity of the remaining unfrozen soil pore‐water and likely prevent the complete freezeback of the cryopegs developed in relation to channel migration.

中文翻译:

与河道迁移相关的 Taliks、低温冻土和永久冻土动态,科尔维尔河三角洲,阿拉斯加

在北极三角洲中已经观察到与通道迁移相关的 Talik 和冷冻凝胶开发,但我们对结构、特性和冻结速率的了解仍然有限。沿着科尔维尔河三角洲(阿拉斯加)的一条主要航道,我们将来自 79 个钻孔的地下数据与遥感分析相结合,以测量 1948-2013 年的航道变化。我们发现封闭的 taliks 发生在活动河道下,并延伸到河床/河堤和活动洪泛区下的永久冻土内低温层。在较旧的地形单元的深处也发现了作为孤立小口袋的低温冻存器。在研究走廊中,我们估计 talik 和 cryopeg 发生的可能性主要(面积的 42.2%)较低,但也确定了高可能性(面积的 27.0%)。在通道迁移后暴露的土地中,永久冻土的生长速度很快,这可能是由于在盐度增加但温度降低的粗粒土壤中,随着冻结前沿向下进展,潜热的释放较低且延迟。随着沉积物不断冷却,地面冰将继续形成,从而进一步增加剩余未冻结土壤孔隙水的盐度,并可能阻止与通道迁移相关的低温冰块的完全冻结。
更新日期:2020-03-04
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