Flood deposits, Bijou Creek, Colorado, JUNE =")(
Flood deposits, Bijou Creek, Colorado, JUNE =")(
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洪水沉积物，Bijou Creek，科罗拉多州，六月 =")(
DOI：
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发表时间：
1967
期刊：
影响因子：
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通讯作者：
H. L. Berryhill
中科院分区：
文献类型：
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作者：
E. D. Mckee;E. Crosby;H. L. Berryhill
一项研究旨在确定科罗拉多州比茹溪沿岸一次大洪水沉积物的特征。这些沉积物由 1965 年 6 月中旬上部流态快速运动期间沉积的沙子组成。它们主要由水平或接近水平的层组成，覆盖河道并向外延伸超出溪流两侧的河岸，通常距离四分之一到半英里或更远。这些沉积物的典型厚度为 2 至 3 英尺，但在 West Bijou Creek 的一处测量到的最大厚度为 12 英尺。据估计，水平地层占所有矿床的 90% 至 95%。洪泛平原的第二个最常见的结构是由主要沿着沉积片的外缘发育的前积物形成的板状平面类型的交错层理。显然，这种结构是在失去部分力量的水沿着倾斜的沉积物前沿沉积沙子时形成的。其他当地发育的结构包括爬升波纹层理和回旋层理，它们是在沉积减弱阶段形成的，显然是远离主洪水路径的相对庇护区域的特征。根据对来自四个研究地点的 137 个样品的力学分析，Bijou Creek 洪水沉积物的主要品位尺寸为中等粒度（0.5-0.25 毫米）；该类有 51 个样本； 37 个主要是细粒度的； 36 是粗粒度的。暴风雨期间沉积的非常大的物体，例如桥梁上的梁和混凝土板，表明水速远高于携带细沙和粗沙所需的速度；沉积物中的颗粒大小可能是由南部几英里的源区可用的沙粒大小决定的。 137 个样本中的大多数样本的排序是公平的；只有七分是好的，十分是差的。有关大规模洪水沉积的砂体的结构、质地和形状的数据应有助于解释在可比环境中形成的古代沉积物。此外，它们还应有助于将可识别的洪水沉积物中的结构类型与洪水沉积的特定阶段或水流状况联系起来，并将河道的沉积物与邻近洪泛平原的沉积物区分开来。
A study was made to determine the character of deposits of a major flood along Bijou Creek, Colorado. These deposits consist of sand that was laid down in mid-June, 1965 during rapid movement of the upper flow regime. They are composed largely of horizontal or nearly horizontal layers that cover the channel and extend outward beyond the banks on each side of the stream commonly for distances of one-quarter to one-half mile or more. Typical thickness of these deposits ranges from two to three feet, but a maximum of 12 feet was measured at one place on West Bijou Creek. Estimates indicate that horizontal strata constitute 90 to 95 percent of all deposits. The second most common structure of the flood plains is a tabular planar type of crossbedding formed of foresets developed mostly along outer margins of depositional sheets. Apparently such structures formed where water that had lost some of its force deposited sand along a sloping sediment front. Other locally developed structures include climbing ripple laminae and convolute bedding, which formed during waning stages of deposition and which apparently are characteristic of relatively sheltered areas away from the path of the main flood. The dominant grade size represented by sand of the Bijou Creek flood deposits, based on mechanical analyses of 137 samples from the four localities studied, is medium grained (0.5-0.25 mm); 51 samples were in this class; 37 were dominantly fine grained; and 36 dominantly coarse grained. The very large objects, such as beams and concrete slabs from bridges, that were deposited during the storm indicate a velocity of water well above that necessary to carry fine to coarse sand; grain size in the deposits probably was determined by the size of sand particles available in the source area a few miles to the south. Sorting was fair in most of the 137 samples; it was good in only seven and poor in ten. Data on the structure, texture, and shape of the sand bodies deposited by floods of major proportions should be useful in interpreting ancient deposits formed in a comparable environment. Also, they should help in relating the types of structures in a recognizable flood deposit to the specific stage of flood deposition, or stream regime, and in distinguishing the deposits of a river channel from those of adjacent flood plains.