LATE QUATERNARY ICE-SURFACE FLUCTUATIONS OF BEARDMORE GLACIER, TRANSANTARCTIC MOUNTAINS
LATE QUATERNARY ICE-SURFACE FLUCTUATIONS OF BEARDMORE GLACIER, TRANSANTARCTIC MOUNTAINS
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DOI：
10.1016/0033-5894(89)90005-7
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发表时间：
1989-03-01
影响因子：
2.3
通讯作者：
LEIDE, JE
中科院分区：
文献类型：
--
作者：
DENTON, GH;BOCKHEIM, JG;LEIDE, JE
Beardmore冰川是横贯南极山脉的一个出口，它的前纵剖面限制了南极洲中心附近的极地高原海拔和罗斯湾南部的冰架。三个晚第四纪砾石漂移席出现在比尔德摩尔冰川旁边。最年轻的冰碛物与现今冰面平行，高出现今冰面7-30米。Beardmore冰碛物的上限位于极地高原附近现今冰面的35-40 m范围内，而在冰川口附近的现今冰面之上约1100 m。最古老的Meyer漂移的上限与Beardmore漂移平行，并在Beardmore漂移上方30-50 m。从相关的数值测年漂移更远的北方，我们分配一个全新世早期的年龄Plunket漂移，晚威斯康星州年龄Beardmore漂移，和海洋同位素阶段6迈耶漂移的年龄。根据我们的年龄模型，在以Beardmore和Meyer漂移为代表的最后两次全球冰川作用期间，Beardmore冰川上游的海拔接近于目前的海拔，而在其中下游则显著增厚。最有可能的是，罗斯湾南部的接地冰导致了比尔德摩尔冰川的增厚，几乎达到了极地高原。伴随而来的降水量下降是由附近的自治领山脉的冰帽退缩所暗示的，这与上比尔德摩尔冰川的微小变化是一致的。冰架搁浅最有可能是由于海平面下降和/或基底融化。低于现在的降水量可能是由更冷的气温和更远的开放水域造成的。Plunket剖面记录了全新世冰面降低，增加表面消融，减少冰流，或接地线衰退。
Former longitudinal profiles of Beardmore Glacier, an outlet through the Transantarctic Mountains, constrain polar plateau elevations near the center of Antarctica and ice-shelf grouding in the southern Ross Embayment. Three gravel drift sheets of late Quaternary age occur alongside Beardmore Glacier. Plunket drift, the youngest, is parallel to and 7–30 m above the present ice surface. The upper limit of Beardmore drift, intermediate in age, is within 35–40 m of the present ice surface near the polar plateau but about 1100 m above the present ice surface near the glacier mouth. The upper limit of Meyer drift, the oldest, is parallel to and 30–50 m above Beardmore drift. From correlation with numerically dated drifts farther north, we assign an early Holocene age to Plunket drift, a late Wisconsin age to Beardmore drift, and an age of marine isotope Stage 6 to Meyer drift. By our age model, Beardmore Glacier was close to current elevations in its upper reaches and thickened considerably in its middle and lower reaches during the last two global glaciations represented by Beardmore and Meyer drifts. Most likely, grounded ice in the southern Ross Embayment caused such thickening of Beardmore Glacier almost to the polar plateau. A concomitant decline in precipitation is implied by ice-cap retreat on the nearby Dominion Range and is consistent with little change of upper Beardmore Glacier. Ice-shelf grounding most likely resulted from lowered sea level and/or basal melting. Lower than present precipitation was probably caused by colder air temperatures and more-distant open water. The Plunket profile records Holocene ice-surface lowering from increased surface ablation, decreased ice flow, or grounding-line recession.