Oceanographic variability on the West Antarctic Peninsula during the Holocene and the influence of upper circumpolar deep water
Oceanographic variability on the West Antarctic Peninsula during the Holocene and the influence of upper circumpolar deep water
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DOI：
10.1016/j.quascirev.2015.04.002
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发表时间：
2015-07
影响因子：
4
通讯作者：
V. Peck;C. Allen;S. Kender;E. McClymont;D. Hodgson
中科院分区：
文献类型：
--
作者：
V. Peck;C. Allen;S. Kender;E. McClymont;D. Hodgson
最近，由风引起的上绕极深水上升的加剧与西南极冰架和冰川的加速融化有关。为了更好地评估UCDW上升流与西南极冰盖稳定性之间的长期关系，我们提出了一种全新世以来西南极半岛玛格丽特湾(WAP)表层和底层水状况的多指标重建。首次将沉积学、硅藻和有孔虫记录结合在一起，推断玛格丽特湾的UCDW影响在全新世早至中期减弱，并在晚全新世以旋回强迫为主。广泛的冰川融化、有限的海冰和9.7至7.0年间初级生产力的提高被认为与UCDW通过玛格丽特海槽的持续入侵最为一致。从7.0ka BP开始，海冰季节增多，生产力下降，表明UCDW对玛格丽特湾的影响减弱，与南半球西风(SWW)向赤道迁移相一致。UCDW的影响持续到全新世中期，到公元前4.2年，玛格丽特海湾持续了漫长的海冰季节。晚全新世海冰的间歇性融化和重塑可能预示着UCDW在这一时期对玛格丽特湾的周期性入侵。晚全新世期间玛格丽特湾内海洋学的周期性变化与对ENSO强迫的敏感性增强一致，而不是似乎主导了全新世早至中期的SWW强迫。目前对WAP大陆架的海洋学测量表明，该系统现在已恢复到这里报道的类似于全新世早期的海洋配置，在这两种情况下，这两种情况都与快速冰川消融有关。
Recent intensification of wind-driven upwelling of warm upper circumpolar deep water (UCDW) has been linked to accelerated melting of West Antarctic ice shelves and glaciers. To better assess the long term relationship between UCDW upwelling and the stability of the West Antarctic Ice Sheet, we present a multi-proxy reconstruction of surface and bottom water conditions in Marguerite Bay, West Antarctic Peninsula (WAP), through the Holocene. A combination of sedimentological, diatom and foraminiferal records are, for the first time, presented together to infer a decline in UCDW influence within Marguerite Bay through the early to mid Holocene and the dominance of cyclic forcing in the late Holocene. Extensive glacial melt, limited sea ice and enhanced primary productivity between 9.7 and 7.0 ka BP is considered to be most consistent with persistent incursions of UCDW through Marguerite Trough. From 7.0 ka BP sea ice seasons increased and productivity decreased, suggesting that UCDW influence within Marguerite Bay waned, coincident with the equatorward migration of the Southern Hemisphere Westerly Winds (SWW). UCDW influence continued through the mid Holocene, and by 4.2 ka BP lengthy sea ice seasons persisted within Marguerite Bay. Intermittent melting and reforming of this sea ice within the late Holocene may be indicative of episodic incursions of UCDW into Marguerite Bay during this period. The cyclical changes in the oceanography within Marguerite Bay during the late Holocene is consistent with enhanced sensitively to ENSO forcing as opposed to the SWW-forcing that appears to have dominated the early to mid Holocene. Current measurements of the oceanography of the WAP continental shelf suggest that the system has now returned to the early Holocene-like oceanographic configuration reported here, which in both cases has been associated with rapid deglaciation.