Iverson Nels A, Lieb-Lappen Ross, Dunbar Nelia W, Obbard Rachel, Kim Ellen, Golden Ellyn
Department of Earth and Environmental Sciences, New Mexico Tech, Socorro, NM, USA.
Vermont Technical College, Randolph, VT, USA.
Sci Rep. 2017 Sep 13;7(1):11457. doi: 10.1038/s41598-017-11515-3.
The West Antarctic ice sheet (WAIS) is highly vulnerable to collapsing because of increased ocean and surface temperatures. New evidence from ice core tephra shows that subglacial volcanism can breach the surface of the ice sheet and may pose a great threat to WAIS stability. Micro-CT analyses on englacial ice core tephra along with detailed shard morphology characterization and geochemical analysis suggest that two tephra layers were derived from subglacial to emergent volcanism that erupted through the WAIS. These tephra were erupted though the center of the ice sheet, deposited near WAIS Divide and preserved in the WDC06A ice core. The sources of these tephra layers were likely to be nearby subglacial volcanoes, Mt. Resnik, Mt. Thiel, and/or Mt. Casertz. A widespread increase in ice loss from WAIS could trigger positive feedback by decreasing ice mass and increasing decompression melting under the WAIS, increasing volcanism. Both tephra were erupted during the last glacial period and a widespread increase in subglacial volcanism in the future could have a considerable effect on the stability of the WAIS and resulting sea level rise.
由于海洋温度和地表温度升高，西南极冰盖（WAIS）极易坍塌。冰芯火山灰的新证据表明，冰下火山活动可能会冲破冰盖表面，对西南极冰盖的稳定性构成巨大威胁。对冰内冰芯火山灰进行的显微CT分析，以及详细的碎片形态特征描述和地球化学分析表明，两层火山灰源自通过西南极冰盖喷发的从冰下到喷发至地表的火山活动。这些火山灰是通过冰盖中心喷发出来的，沉积在西南极冰盖分水岭附近，并保存在WDC06A冰芯中。这些火山灰层的来源可能是附近的冰下火山，雷斯尼克山、蒂尔山和/或卡塞尔茨山。西南极冰盖冰损失的普遍增加可能会通过减少冰量和增加西南极冰盖下的减压融化来引发正反馈，从而增加火山活动。这两层火山灰都是在上一个冰川期喷发的，未来冰下火山活动的普遍增加可能会对西南极冰盖的稳定性以及由此导致的海平面上升产生重大影响。
