Anatomy of the tidal scour system at Minas Passage, Bay of Fundy, Canada
Anatomy of the tidal scour system at Minas Passage, Bay of Fundy, Canada
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加拿大芬迪湾米纳斯海峡潮汐冲刷系统的剖析
DOI：
10.1016/j.margeo.2012.07.007
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发表时间：
2012
期刊：
影响因子：
2.9
通讯作者：
Yongsheng Wu
中科院分区：
文献类型：
--
作者：
J. Shaw;B. Todd;Michael Z. Li;Yongsheng Wu
强大的水流侵蚀了厚厚的第四纪沉积物，在加拿大芬迪湾的米纳斯通道形成了一个冲刷槽，这里是地球上最大的潮汐。我们描述了一个更大的系统，包括一系列的元素，即：1）冲刷槽延伸到平均海平面以下的170米被切割成厚的冰海沉积物，并在广泛的地区挖出基岩的背景下，这个槽。侧翼未受侵蚀的地形地势起伏较低，表面被风筛过。2)一组沙旗银行关闭角D 'Or和角Chignecto。3)斯普利特角的一组非典型的旗帜银行，包括苏格兰湾沙丘区及其对应物，一个大型砾石银行被困在米纳斯通道冲刷槽。4)低浮雕银行与沙带和新月形沙丘旁边的一些旗帜银行，并被称为'影子银行'。5)在米纳斯海峡入口处有一个大型（0.8km3）沉积物漂移（无大型底形）。槽和银行的位置可以与潮汐流模式：沟槽位于非常强的双向流的区域;旗帜银行在岬附近的潮汐环流;阴影银行在最大平均海底应力不对称的地区;和沉积物漂移在入口处的米纳斯海峡在一个地区的弱底应力在所有阶段的潮汐。以前的工作认为，冲刷系统形成后340014 Cyrs BP（放射性碳年之前）的障碍系统跨米纳斯通道崩溃。我们推测，冲刷槽系统的形成可能已经释放了大量的沉积物，还没有占在以前的沉积物预算，这释放的沉积物已被隔离在晚全新世盐沼在芬迪湾的头部。
Strong currents have eroded thick Quaternary sediments to create a scour trough at Minas Passage, in the Bay of Fundy, Canada, site of Earth's largest tides. We describe this trough in the context of a larger system that comprises a range of elements, viz: 1) Scour troughs extending 170m below mean sea level are incised into thick glaciomarine sediments and have exhumed bedrock over wide areas. The flanking uneroded terrain has low relief and a winnowed surface. 2) Sets of sand banner banks off Cape D'Or and Cape Chignecto. 3) The atypical set of banner banks at Cape Split, consisting of the Scots Bay dune field and its counterpart, a large gravel bank trapped in the Minas Passage scour trough. 4) Low-relief banks with sand ribbons and barchan dunes alongside some banner banks, and termed ‘shadow banks’. 5) A large (0.8km3) sediment drift at the entrance to Minas Channel (without large bedforms). The location of troughs and banks can be correlated with tidal-current patterns: trenches are located in regions of very strong bi-directional currents; banner banks near headland-sited tidal gyres; shadow banks in areas of maximum mean bottom stress asymmetry; and the sediment drift at the entrance to Minas Channel in an area of weak bottom stress at all stages of the tides. Previous work has argued that the scour system formed after 340014Cyrs BP (radiocarbon years before present) following collapse of a barrier system across Minas Passage. We speculate that formation of the scour trough system may have released vast quantities of sediment that have not been accounted for in previous sediment budgets, and that much of this released sediment has been sequestered in the late-Holocene salt marshes at the head of the Bay of Fundy.