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首页> 外文期刊>Earth Surface Processes and Landforms: The journal of the British Geomorphological Research Group >Dating floodplain sediments using tree-ring response to burial
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Dating floodplain sediments using tree-ring response to burial

机译：利用树木年轮对埋葬的响应来定洪泛区沉积物

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Floodplain sediments can be dated precisely based on the change in anatomy of tree rings upon burial. When a stem of tamarisk (Tamarix ramosissima) or sandbar willow (Salix exigua) is buried, subsequent annual rings in the buried section resemble the rings of roots: rings become narrower, vessels within the rings become larger, and transitions between rings become less distinct. We combined observations of these changes with tree-ring counts to determine the year of deposition of sedimentary beds exposed in a 150-m-long trench across the floodplain of the Rio Puerco, a rapidly filling arroyo in New Mexico. This method reliably dated most beds thicker than about 30 cm to within a year of deposition. Floodplain aggradation rates varied dramatically through time and space. Sediment deposition was mostly limited to brief overbank flows occurring every few years. The most rapid deposition occurred on channel-margin levees, which migrated laterally during channel narrowing. At the decadal timescale, the cross-section-average sediment deposition rate was steady, but there was a shift in the spatial pattern of deposition in the 1980s. From 1936 to 1986, sediment deposition occurred by channel narrowing, with little change in elevation of the thalweg. After 1986 sediment deposition occurred by vertical aggradation. From 1936 to 2000 about 27 per cent of the arroyo cross-section filled with sediment. The rate of filling from 1962 to 2000 was 0(.)8 vertical m/decade or 85 m(2)/decade. Published in 2005 by John Wiley & Sons, Ltd.
机译：可以根据埋葬时树木年轮的解剖结构精确地确定洪泛区沉积物的年代。将buried柳（Tamarix ramosissima）或沙柳柳（Salix exigua）的茎埋入后，埋藏区中随后的年轮类似于根环：环变窄，环内的血管变大，而环之间的过渡变得不那么明显。我们将对这些变化的观察与树木年轮数相结合，以确定在新墨西哥州快速填充的阿罗约河里约普尔科（Rio Puerco）泛滥平原上150米长的沟渠中露出的沉积床沉积年。该方法可靠地将大多数厚于约30厘米的床层定为沉积的一年之内。洪泛区的聚集速度随时间和空间而变化很大。沉积物沉积主要限于每隔几年发生的短暂的溢流。最快的沉积发生在河道边缘的堤坝上，在河道变窄期间横向迁移。在年代际尺度上，断面平均沉积物沉积速率稳定，但在1980年代沉积物的空间格局发生了变化。从1936年到1986年，沉积物的沉积是通过河道变窄发生的，而海藻的高度变化很小。 1986年以后，垂直沉降使沉积物沉积。从1936年到2000年，阿罗约横截面中约27％充满了沉积物。从1962年到2000年的填充率是0（。）8垂直m /十年或85 m（2）/十年。 John Wiley＆Sons，Ltd.于2005年出版。

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