Decoding the dipstick: Thickness of Siple Dome, West Antarctica, at the Last Glacial Maximum
Decoding the dipstick: Thickness of Siple Dome, West Antarctica, at the Last Glacial Maximum
复制标题
解码量油尺：南极洲西部末次盛冰期 Siple Dome 的厚度
作者：
E. Waddington;H. Conway;E. Steig;R. Alley;E. Brook;K. Taylor;J. White
南极洲西部末次冰盛期（LGM）的冰厚是了解冰流和解释冰芯的关键信息，但知之甚少。虽然修剪线，冰碛的限制，并确保年龄测年提供的地质约束，冰厚度附近的跨南极山脉和玛丽伯德土地，缺乏暴露的基岩阻碍传统的地质方法在中央，;2 3 10 6 km 2的区域。在这里，我们推断冰盖厚度的变化，在中部罗斯海海湾使用瞬态冰流模型，以找到组合的积累率和冰盖厚度的历史，匹配的深度-年龄关系和测得的层厚度模式的Siple圆顶冰芯。在我们拒绝不合理的积累率的历史，剩余的历史对表明减薄200-400米，因为末次冰期。我们的估计是低于以前的重建所限制的地质证据从跨南极山脉和海洋数据从罗斯海底，这表明，接地冰盖延伸到大陆架边缘在末次冰期。在末次冰期期间，罗斯海中央海湾的低表面海拔并不排除沿其边界沿着有较厚的冰。然而，如果像通常假设的那样，这个接地的冰盖来自西南极洲内部1000公里以上，那么它的表面坡度非常低，需要非常光滑的床。或者，罗斯海的冰可能是从横贯南极山脉和西部的玛丽伯德地流过来的。
Ice thickness in West Antarctica at the Last Glacial Maximum (LGM) is poorly known, yet is key information for understanding ice streams and interpreting ice cores. Although trim lines, moraine limits, and exposure-age dating provide geologic constraints on ice thickness near the Transantarctic Mountains and in Marie Byrd Land, lack of exposed bedrock hampers traditional geologic methods in a central, ;2 3 10 6 km 2 region. Here we infer ice-sheet thickness changes in the central Ross Sea Embayment by using a tran- sient ice-flow model to find combinations of accumulation-rate and ice-sheet thickness histories that match the depth-age relationship and the measured layer-thickness pattern in the Siple Dome ice core. After we reject unreasonable accumulation-rate histories, the remaining history pairs indicate thinning of 200-400 m since the LGM. Our estimate is lower than previous reconstructions that were constrained by geologic evidence from the Transantarctic Mountains and by marine data from the Ross Sea floor, which indicate that a grounded ice sheet extended to the continental shelf margin during the last glacial period. Low surface elevations in the central Ross Sea Embayment during the LGM do not preclude thicker ice along its boundaries. However, if this grounded ice sheet came over 1000 km from interior West Antarctica, as is usually assumed, then it had very low surface slope, requiring a very slippery bed. Alternatively, the grounded Ross Sea ice might have flowed from the Transantarctic Mountains and western Marie Byrd Land.