Pedogenic Silica Accumulation in Chronosequence Soils, Southern California
Pedogenic Silica Accumulation in Chronosequence Soils, Southern California
复制标题
南加州年代土壤中成土二氧化硅的积累
DOI：
10.2136/sssaj2004.1295
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发表时间：
2004
影响因子：
2.9
通讯作者：
R. Graham
中科院分区：
文献类型：
--
作者：
K. Kendrick;R. Graham
土壤性质的时序分析已被证明是一个有价值的方法，估计年龄的地貌表面没有独立的年龄控制存在。在这项研究中，我们研究成壤二氧化硅作为土壤和地貌表面的相对年龄的指标，并评估潜在的二氧化硅来源。在加州南部的两个不同的年代序列中，一个在圣巴斯蒂奥荒地，一个在卡洪山口，用铁试剂（4，5-二羟基-1，3-苯二磺酸[二钠盐]，C 6 H 4 Na 2 O 8 S 2）提取pedons，对成土乳白色二氧化硅进行定量。这两个年代序列的土壤都发育在长石沉积物中，时间跨度为11.5 ~ 500 ka。成土硅的量随着成土作用持续时间的增加而增加，最大硅积累的深度通常与粘土层的最大表达相一致。成土硅积累在所有的土壤中，范围从1.2%的铁离子可提取的硅（Si m）在最年轻的土壤中的4.6%，在最古老的。原生硅随着风化时间的增加而减少，特别是在风化条件最强烈的上层。Si的损失与Na和K的损失相一致，暗示长石的风化可能是Si损失的来源。硅在上层的流失量足以解释成土硅在底土中的积累。成土二氧化硅作为这些土壤相对土壤年龄的指标与成土铁氧化物同样有效。
Chronosequential analysis of soil properties has proven to be a valuable approach for estimating ages of geomorphic surfaces where no independent age control exists. In this study we examined pedogenic silica as an indicator of relative ages of soils and geomorphic surfaces, and assessed potential sources of the silica. Pedogenic opaline silica was quantified by tiron (4,5-dihydroxy-1,3-benzene-disulfonic acid [disodium salt], C 6 H 4 Na 2 O 8 S 2 ) extraction for pedons in two different chronosequences in southern California, one in the San Timoteo Badlands and one in Cajon Pass. The soils of both of these chronosequences are developed in arkosic sediments and span 11.5 to 500 ka. The amount of pedogenic silica increases with increasing duration of pedogenesis, and the depth of the maximum silica accumulation generally coincides with the maximum expression of the argillic horizon. Pedogenic silica has accumulated in all of the soils, ranging from 1.2% tiron-extractable Si (Si m ) in the youngest soil to 4.6% in the oldest. Primary Si decreases with increasing duration of weathering, particularly in the upper horizons, where weathering conditions are most intense. The loss of Si coincides with the loss of Na and K, implicating the weathering of feldspars as the likely source of Si loss. The quantity of Si lost in the upper horizons is adequate to account for the pedogenic silica accumulation in the subsoil. Pedogenic silica was equally effective as pedogenic Fe oxides as an indicator of relative soil age in these soils.