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首页> 外文期刊>Quaternary geochronology >Differences in Be-10 concentrations between river sand, gravel and pebbles along the western side of the central Andes
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Differences in Be-10 concentrations between river sand, gravel and pebbles along the western side of the central Andes

机译：安第斯山脉中部西侧河砂，砾石和卵石之间Be-10浓度的差异

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Cosmogenic nuclides in river sediment have been used to quantify catchment-mean erosion rates. Nevertheless, variable differences in Be-10 concentrations according to grain size have been reported. We analyzed these differences in eleven catchments on the western side of the Andes, covering contrasting climates and slopes. The data include eight sand (0.5-1 mm) and gravel (1-3 cm) pairs and twelve sand (0.5-1 mm) and pebble (5-10 cm) pairs. The difference observed in three pairs can be explained by a difference in the provenance of the sand and coarser sediment. The other sand pebble pairs show a lower Be-10 concentration in the pebbles, except for one pair that shows similar concentrations. Two sand-gravel pairs show a lower Be-10 concentration in the gravel and the other five pairs show a higher Be-10 concentration in the gravel. Differences in climate do not reveal a particular influence on the Be-10 concentration between pairs. The analysis supports a model where pebbles and gravel are mainly derived from catchment areas that are eroding at a faster rate. The five gravel samples with high Be-10 concentrations probably contain gravel that were derived from the abrasion of cobbles exhumed at high elevations. In order to validate this model, further work should test if pebbles are preferentially exhumed from high erosion rate areas, and if the difference between pebbles with high Be-10 concentrations and sand decreases when the erosion rate tends to be homogeneous within a catchment. (C) 2014 Elsevier B.V. All rights reserved.
机译：河流沉积物中的宇宙成因核素已用于量化流域平均侵蚀率。然而，据报道Be-10浓度随晶粒大小而变化。我们分析了安第斯山脉西侧的11个流域的这些差异，涵盖了形成对比的气候和斜坡。数据包括八对沙子（0.5-1毫米）和砾石（1-3厘米）和十二对沙子（0.5-1毫米）和卵石（5-10厘米）。三对中观察到的差异可以用砂和较粗的沉积物的出处不同来解释。其他一对卵石在卵石中的Be-10浓度较低，除了一对卵石的浓度相似。两对砂砾石在砾石中的Be-10浓度较低，其他五对砾石中的Be-10浓度较高。气候差异并未显示出两对之间Be-10浓度的特殊影响。该分析支持一个模型，其中卵石和砾石主要来自以更快速度侵蚀的集水区。五个Be-10浓度高的砾石样品中可能含有砾石，这些砾石是从高海拔挖掘出的鹅卵石的磨损中得到的。为了验证该模型，应进一步进行工作，以测试是否优先从高侵蚀率地区挖出卵石，以及当流域内的侵蚀率趋于均匀时，Be-10浓度高的卵石与沙子之间的差异是否会减小。 （C）2014 Elsevier B.V.保留所有权利。

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