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首页> 外文期刊>Geoscience frontiers >Wandering gravel-bed rivers and high-constructive stable channel sandy fluvial systems in the Ross River area, Yukon Territory, Canada
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Wandering gravel-bed rivers and high-constructive stable channel sandy fluvial systems in the Ross River area, Yukon Territory, Canada

机译：加拿大育空地区罗斯河地区的砾石河床和高构造稳定河道沙质河流系统

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Mid-Cretaceous strata within the Tintina Trench, 3?km west of the community of Ross River, contain evidence of deposition in two distinct, alternating, fluvial settings. Coal-bearing, mud-dominated strata are commonly associated with high-constructive sandy channel systems, with extensive overbank, levee and splay deposits. Channels are between 3 and 30?m wide and 0.4–7?m thick. They show repetitive development of side and in-channel bar-forms, as well as up-channel widening of the rivers by selective erosion of associated overbank and levee deposits. Levees extended for several hundred metres away from the channels. In this setting low-angle inclined stratification and epsilon cross stratification may reflect lateral migration of crevasse channels or small streams. The paucity of exposure prevents recognition of the channels as products of multiple channel anastomosed systems or single channel high-constructive systems. Gravel-dominated strata, inter-bedded with, and overlying coal-bearing units, are interpreted as deposits of wandering gravel-bed rivers, with sinuosity approaching 1.4. In most exposures they appear to be dominated by massive and thin planar-bedded granule to small pebble conglomerates, which would traditionally be interpreted as sheet-flood or longitudinal bar deposits of a high-gradient braided stream or alluvial fan. Architectural analysis of exposures in an open-pit shows that the predominance of flat bedding is an artefact of the geometry of the roadside exposures. In the pit the conglomerates are dominated by large scale cross stratification on a scale of 1–5.5?m. These appear to have developed as downstream and lateral accretion elements on side-bars and on in-channel bars in water depths of 2–12?m. Stacking of strata on domed 3rd order surfaces suggests development of longitudinal in-channel bar complexes similar to those observed in parts of the modern Rh?ne River system. Mudstone preserved in some of the channels reflects intervals of channel abandonment or avulsion. Minimum channel width is from 70 to 450?m.
机译：廷斯海沟内的白垩纪中层地层，位于罗斯河群落以西3公里处，包含在两个不同的，交替的河流环境中沉积的证据。含煤，泥浆为主的地层通常与高建设性的沙质河道系统有关，具有大量的堤岸，堤坝和八角形沉积物。通道的宽度在3至30？m之间，厚度在0.4–7？m之间。它们显示了侧向和通道内条形的重复发展，以及由于相关的过高的堤岸和堤坝沉积物的选择性侵蚀而导致的河道向上拓宽。堤坝从通道延伸了数百米。在这种情况下，低角度倾斜分层和ε交叉分层可能反映出裂缝通道或小溪流的横向迁移。暴露的缺乏阻止了将通道识别为多通道吻合系统或单通道高结构系统的产品。砾岩为主的地层，与煤层单元相互夹层并在其上，被解释为砾石床河流的沉积，弯曲度接近1.4。在大多数暴露情况下，它们似乎以块状且薄的平面层状颗粒为主，形成小卵石砾石，传统上将其解释为高梯度辫状流或冲积扇的片状注水或纵向条状沉积物。对露天矿的暴露进行的建筑分析表明，平坦的铺垫占主导地位是路边暴露的几何形状的伪影。在矿坑中，砾岩主要由规模在1–5.5？m的交叉分层构成。这些似乎已发展为水深2–12？m的侧栏和河道栏上的下游和横向增生元件。在三阶穹顶表面上的地层堆积表明，纵向河道内的条形复合体的发展与在现代罗纳河系统的某些部分中观察到的相似。保留在某些河道中的泥岩反映了河道放弃或撕裂的间隔。最小通道宽度为70至450？m。

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