A stratigraphic investigation of the Celtic Sea megaridges based on seismic and core data from the Irish-UK sectors
A stratigraphic investigation of the Celtic Sea megaridges based on seismic and core data from the Irish-UK sectors
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基于爱尔兰-英国部门的地震和核心数据对凯尔特海巨脊进行地层调查
DOI：
10.1016/j.quascirev.2018.08.029
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发表时间：
2018
影响因子：
4
通讯作者：
Lockhart E
中科院分区：
文献类型：
--
作者：
Lockhart E
凯尔特海拥有世界上最大的大陆架沉积脊。这些巨脊最初被解释为冰后期海侵形成的潮汐特征，但从它们的侧翼已经恢复了冰川沉积物。我们使用新的分米制分辨率地球物理数据相关的沉积物岩心测试假设的潮汐与冰川的形成模式，研究地层的巨脊。巨脊由三个主要单元组成：1）在不整合面上方延伸的横跨大陆架的浅表向上变细披覆;在这种褶皱的下面是2），梅尔维尔组（MFm），它包括巨脊的上部，有时显示出倾斜的内部声波反射，由中粗砂和贝壳碎片组成;特征与潮汐或冰川冲积成因一致。MFm不整合地覆盖在3）上小鞋底组（ULSFm）之上，以前解释为上新世晚期至更新世早期，但这里显示与形成前兆地形的晚更新世冰川沉积物相关。表层披盖被解释为一个产品的长期波能量的潮流减少在冰后期海侵的最后阶段。我们认为，地层学限制的年龄之间的MFm 24.3和14万年BP，根据公布的日期，与冰消期和模拟期的大潮汐条件在冰后期海侵。从地层学和沉积学角度来看，巨脊可以代表保存的冰川冲积特征，但我们认为，它们包括冰后期潮汐沉积（MFm）覆盖部分侵蚀的冰川地形（ULSFm）。观察到的地层学表明，冰延伸到大陆架边缘。
The Celtic Sea contains the world's largest continental shelf sediment ridges. These megaridges were initially interpreted as tidal features formed during post-glacial marine transgression, but glacigenic sediments have been recovered from their flanks. We examine the stratigraphy of the megaridges using new decimetric-resolution geophysical data correlated to sediment cores to test hypothetical tidal vs glacial modes of formation. The megaridges comprise three main units, 1) a superficial fining-upward drape that extends across the shelf above an unconformity. Underlying this drape is 2), the Melville Formation (MFm) which comprises the upper bulk of the megaridges, sometimes displaying dipping internal acoustic reflections and consisting of medium to coarse sand and shell fragments; characteristics consistent with either a tidal or glacifluvial origin. The MFm unconformably overlies 3), the Upper Little Sole Formation (ULSFm), previously interpreted to be of late Pliocene to early Pleistocene age, but here shown to correlate to Late Pleistocene glacigenic sediments forming a precursor topography. The superficial drape is interpreted as a product of prolonged wave energy as tidal currents diminished during the final stages of post-glacial marine transgression. We argue that the stratigraphy constrains the age of the MFm to between 24.3 and 14 ka BP, based on published dates, coeval with deglaciation and a modelled period of megatidal conditions during post-glacial marine transgression. Stratigraphically and sedimentologically, the megaridges could represent preserved glacifluvial features, but we suggest that they comprise post-glacial tidal deposits (MFm) mantling a partially-eroded glacial topography (ULSFm). The observed stratigraphy suggests that ice extended to the continental shelf-edge.
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DOI：
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期刊：
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DOI：
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发表时间：
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