Patterns of surface downwearing on shore platforms in eastern Canada
Patterns of surface downwearing on shore platforms in eastern Canada
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加拿大东部海岸平台的表面下穿模式
DOI：
10.1002/esp.2018
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发表时间：
2010
影响因子：
3.3
通讯作者：
Jacob I. Kanyaya
中科院分区：
文献类型：
--
作者：
N. J. Porter;A. Trenhaile;Kyle J. Prestanski;Jacob I. Kanyaya
在大约 200 个横向微侵蚀计 (TMEM) 站的岸上平台上测量了 2 至 6 年的磨损率。加拿大东部有七个研究区。对平台进行了测量，并使用施密特岩石试验锤测量岩石硬度。在 3 年的时间里，来自三个研究区域的 1200 多个岩石样本每天都受到浸入和暴露的两个潮汐周期的影响，模拟了中央潮间带。另外 840 个样本在一年的时间内经历了更长时间的暴露和浸泡，分别代表了上潮间带和下潮间带的不同海拔。这些实验表明，潮汐产生的风化和碎片清除是一种有效的侵蚀机制，特别是在最低高潮的高度。在现场，每个研究区域的平均脱衣率范围从 0·24 mm yr−1 到超过 1·5 mm yr−1。比率往往随着田间海拔的升高而增加，在潮间带上部达到最大值。现场的这种趋势不能完全归因于实验室模拟的潮汐引起的风化过程，而必须部分反映波浪、霜、冰和其他机制的影响。结论是，岸上平台不存在强烈的空间下穿模式，潮间带的下穿率是多种具有不同高程功效特征的侵蚀机制的结果。此外，即使一个地区只有一种或两种机制占主导地位，磨损率与海拔之间的任何由此产生的关系也会因岩石化学和物理特性变化的影响而被掩盖或消除。版权所有 © 2010 约翰威利父子有限公司
Downwearing rates were measured on shore platforms at about 200 transverse micro‐erosion meter (TMEM) stations, over periods ranging from 2 to 6 years. There were seven study areas in eastern Canada. The platforms were surveyed and a Schmidt Rock Test Hammer was used to measure rock hardness. More than 1200 rock samples from three of the study areas were also subjected each day, over a 3 year period, to two tidal cycles of immersion and exposure, which simulated the central intertidal zone. A further 840 samples were subjected to longer periods of exposure and immersion, over a 1 year period, which represented different elevations within the upper and lower intertidal zone, respectively. These experiments suggested that tidally generated weathering and debris removal is an effective erosional mechanism, particularly at the elevation of the lowest high tides. In the field, mean rates of downwearing for each study area ranged from 0·24 mm yr−1 to more than 1·5 mm yr−1. Rates tended to increase with elevation in the field, with maxima in the upper intertidal zone. This trend in the field cannot be attributed entirely to the tidally induced weathering processes that were simulated in the laboratory, and must reflect, in part, the effect of waves, frost, ice, and other mechanisms. It is concluded that there are no strong spatial downwearing patterns on shore platforms, and that downwearing rates in the intertidal zone are the result of a number of erosional mechanisms with different elevation‐efficacy characteristics. Furthermore, even if only one or two mechanisms were dominant in an area, any resulting relationship between downwearing rates and elevation would be obscured or eliminated by the effect of variations in the chemical and physical characteristics of the rocks. Copyright © 2010 John Wiley & Sons, Ltd.