Soil-forming rates and processes on Quaternary moraines near Lago Buenos Aires, Argentina
Soil-forming rates and processes on Quaternary moraines near Lago Buenos Aires, Argentina
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阿根廷布宜诺斯艾利斯湖附近第四纪冰碛的成土速率和过程
DOI：
10.1016/j.yqres.2005.08.027
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发表时间：
2006
影响因子：
2.3
通讯作者：
Bockheim, James G.
中科院分区：
文献类型：
--
作者：
Douglass, Daniel C.;Bockheim, James G.
在阿根廷的圣克鲁斯省，使用了四个冰碛群上的34个冰碛土，研究了冰碛土发育的机制和速率。所有土壤均为粗壤质、中质、典型的单钙土或钙质单旱生土，发生在半干旱气候的矮草灌丛草原下。主要的成土过程是有机质、碳酸盐和粘土颗粒的积累。有机碳在这些土壤中迅速积累，但在最古老的两个冰碛群中，有机碳含量明显较高，这可能是土壤形成环境或放牧方式略有差异的结果。碳酸盐和粘土的积累率随着年龄的增长而下降，这表明在记录的最早部分减少流入量或达到流入量和损失之间的平衡。土壤红色没有变化，最古老的土壤中保存着耐候矿物，表明在这种环境中几乎没有化学风化。测得的粉尘输入解释了粘土和碳酸盐的积累。我们提出了一个碳酸盐循环模型，描述了在这种环境中的潜在来源和钙的流动性。土壤形成率的校准创建了一个强大的相关性工具，比较其他冰川沉积物在阿根廷的布宜诺斯艾利斯湖的日期明确的冰碛。
Thirty-four pedons on four moraine groups spanning the last 1 myr are used to investigate mechanisms and rates of soil development in Santa Cruz province, Argentina. All soils are coarse-loamy, mesic, Typic Haplocalcids or Calcic Haploxerolls occurring under short grass-shrub steppe, in a semi-arid climate. The dominant soil-forming processes are the accumulation of organic matter, carbonate, and clay-sized particles. Organic carbon accumulates rapidly in these soils, but significantly higher amounts in the oldest two moraine groups are likely the result of slight differences in soil-forming environment or grazing practices. Accumulation rates of carbonate and clay decrease with age, suggesting either decreased influx in the earliest part of the record or attainment of equilibrium between influx and loss. There are no changes in soil redness, and preservation of weatherable minerals in the oldest soils indicates there is little chemical weathering in this environment. Measured dust input explains the accumulation of both clay and carbonate. We present a carbonate cycling model that describes potential sources and calcium mobility in this environment. Calibration of rates of soil formation creates a powerful correlation tool for comparing other glacial deposits in Argentina to the well-dated moraines at Lago Buenos Aires.