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Radio-echo sounding and waveform modeling reveal abundant marine ice in former rifts and basal crevasses within Crary Ice Rise, Antarctica
Journal of Glaciology ( IF 3.4 ) Pub Date : 2021-03-04 , DOI: 10.1017/jog.2021.17
Trevor R. Hillebrand , Howard Conway , Michelle Koutnik , Carlos Martín , John Paden , J. Paul Winberry

Crary Ice Rise formed after the Ross Ice Shelf re-grounded ~1 kyr BP. We present new ice-penetrating radar data from two systems operating at center frequencies of 7 and 750 MHz that confirm the ice rise is composed of a former ice shelf buried by subsequent accumulation. Stacks of englacial diffraction hyperbolas are present almost everywhere across the central ice rise and extend up to ~350 m above the bed. In many cases, bed reflections beneath the diffraction hyperbolas are obscured for distances up to 1 km. Waveform modeling indicates that the diffraction hyperbolas are likely caused by marine ice deposits in former basal crevasses and rifts. The in-filling of rifts and basal crevasses may have strengthened the connection between the ice rise and the surrounding ice shelf, which could have influenced local and regional ice dynamics. Three internal reflection horizons mark the upper limit of disturbed ice and diffraction hyperbolas in different sections of the ice rise, indicating at least three stages of flow stabilization across the ice rise. A surface lineation visible in MODIS imagery corresponds spatially to deepening and strong deformation of these layers, consistent with the characteristics of former grounding lines observed elsewhere in Antarctica.

中文翻译:

无线电回波探测和波形建模揭示了南极洲克拉里冰隆内以前的裂谷和基底裂缝中有丰富的海冰

在罗斯冰架重新接地〜1 kyr BP后形成了Crary Ice Rise。我们展示了来自两个以 7 和 750 MHz 的中心频率运行的系统的新的破冰雷达数据,这些数据证实了冰层上升是由一个被后续堆积掩埋的前冰架组成的。在中央冰隆处几乎到处都存在成堆的冰期衍射双曲线,并延伸至海床上方约 350 m。在许多情况下,衍射双曲线下方的床层反射在长达 1 公里的距离内会被遮挡。波形模型表明,衍射双曲线可能是由前基底裂缝和裂谷中的海冰沉积引起的。裂谷和基底裂缝的填充可能加强了冰隆与周围冰架之间的联系,这可能影响了当地和区域的冰动态。三个内反射视界标志着冰隆不同部分的扰动冰和衍射双曲线的上限,表明冰隆上至少有三个流动稳定阶段。MODIS 图像中可见的表面线在空间上对应于这些层的加深和强烈变形,这与在南极洲其他地方观察到的前接地线的特征一致。
更新日期:2021-03-04
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