Origin and significance of calcium carbonate in soils of southwestern Patagonia
Origin and significance of calcium carbonate in soils of southwestern Patagonia
复制标题
巴塔哥尼亚西南部土壤中碳酸钙的起源和意义
DOI：
10.1016/j.geoderma.2006.05.013
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发表时间：
2006
期刊：
影响因子：
6.1
通讯作者：
Douglass, Daniel C.
中科院分区：
文献类型：
--
作者：
Bockheim, James G.;Douglass, Daniel C.
一个跨越过去0.76-1.0 Ma的土壤年代序列表明，碳酸钙的逐渐增加，基于（1）Bk+BCK层的厚度，（2）最大碳酸盐阶段，（3）剖面积累的成壤碳酸盐，和（4）从地球化学质量平衡的Ca的质量通量。我们倾向于碳酸盐的粉尘来源，因为（1）冰碛物母质含有少量的CaCO 3，（2）土壤中含钙矿物风化的证据很少，（3）剖面中CaCO 3的量远远超过风化释放的量，（4）从研究区域收集的粉尘富含CaCO 3，（5）确定了碳酸盐岩的源区。尽管第四纪期间灰尘沉积速率可能发生了变化，我们的计算表明，0.18 g CaCO 3 m − 2 yr − 1的当前沉积速率与0.16 g CaCO 3 m − 2 yr −1.230Th/U的长期剖面累积速率相当，碳酸盐垂悬物的不平衡年龄与宇宙成因表面一致-暴露年龄表明，这种方法有可能在巴塔哥尼亚其他地貌表面的约会。低温过程影响了许多冰脚，特别是在最后一次盛冰期。
A soil chronosequence spanning the last 0.76–1.0 Ma shows a progressive increase in calcium carbonates based on (1) thickness of the Bk+BCk horizons, (2) maximum carbonate stage, (3) profile accumulation of pedogenic carbonates, and (4) mass flux of Ca from a geochemical mass balance. We favor a dust origin of the carbonates because (1) the till parent materials contain low amounts of CaCO3, (2) there is minimal evidence for weathering of Ca-bearing minerals in the soil, (3) the amount of CaCO3in the profile is far in excess of what could be released by weathering, (4) dust collected from the study area is enriched in CaCO3, and (5) a source area for the carbonates was identified. Although there likely were changes in dust deposition rates during the Quaternary, our calculations suggest that the current deposition rate of 0.18 g CaCO3m−2yr−1is comparable to the long-term profile accumulation rate of 0.16 g CaCO3m−2yr−1.230Th/U disequilibrium ages of carbonate pendants are consistent with cosmogenic surface-exposure ages indicating that this method has potential for dating other geomorphic surfaces in Patagonia. Cryogenic processes have affected many of the pedons, particularly during the last glacial maximum.