Intra‐ice and intra‐sediment cryopeg brine occurrence in permafrost near Utqiaġvik (Barrow)
Intra‐ice and intra‐sediment cryopeg brine occurrence in permafrost near Utqiaġvik (Barrow)
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乌特恰维克（巴罗）附近永久冻土中冰内和沉积物内冷冻盐水的出现
DOI：
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发表时间：
2021
影响因子：
5
通讯作者：
H. Eicken
中科院分区：
文献类型：
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作者：
G. Iwahana;Zachary S Cooper;S. Carpenter;J. Deming;H. Eicken
低温冻土层是永久冻土层内的一层，由于溶解的盐，含有大量的低温未冻结水。为了探索在Utqiahovik附近发现的低温层和相关盐水的起源和发展，我们在巴罗永久冻土隧道内进行了广泛的采样。我们根据其独特的位置发现了两种类型的低温卤水：（a）冰内卤水（IIB），完全由大量的地面冰包围，以前在北方半球没有观察到;和（B）沉积物内卤水（IsB），如预期的那样在永久冻土内的未冻结沉积物中发现。所遇到的IIB位于大约大气压力下的巨大冰层内的小椭圆形或更复杂形状的口袋中。放射性碳年代测定表明，IIB最早在大约11 ka BP的时候从巨大冰层下的含IsB的低温层中分离出来。根据地球化学分析，IsB透镜体被解释为是通过泻湖环境中海水的重复蒸发和低温浓缩而形成的，然后当周围沉积物冻结并被大约40 ka BP或更早的上部沉积物单元覆盖时被分离。IIB的发现和这两种盐水类型的起源方案的发展验证了高分辨率采样的重要性，这是由永久冻土隧道的独特设施实现的。
Cryopeg is a layer within permafrost containing a significant amount of cryotic unfrozen water due to dissolved salts. To explore the origin and development of cryopeg and associated brines found near Utqiaġvik, we sampled extensively within the Barrow Permafrost Tunnel. We found two types of cryopeg brines based on their distinctive locations: (a) intra‐ice brine (IiB), entirely bounded by massive ground ice, and not previously observed in the Northern Hemisphere; and (b) intra‐sediment brine (IsB), found as expected in unfrozen sediments within permafrost. The encountered IiBs were situated in small ellipsoidal or more complex shaped pockets within the massive ice at roughly atmospheric pressure. Radiocarbon dating suggests that the IiB segregated from IsB‐bearing cryopeg beneath the massive ice at about 11 ka BP, at the earliest. From geochemical analyses, IsB lenses were interpreted as having developed through repeated evaporation and cryoconcentration of seawater in a lagoonal environment, then isolated when the surrounding sediment froze and became covered by an upper sediment unit around 40 ka BP or earlier. The discovery of IiB and development of origin scenarios for both brine types validate the importance of high‐resolution sampling as enabled by the unique facility of a permafrost tunnel.