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Soil, regolith, and weathered rock: Theoretical concepts and evolution in old-growth temperate forests, Central Europe
Geoderma ( IF 6.1 ) Pub Date : 2020-06-01 , DOI: 10.1016/j.geoderma.2020.114261
Pavel Šamonil , Jonathan Phillips , Pavel Daněk , Vojtěch Beneš , Lukasz Pawlik

Abstract Evolution of weathering profiles (WP) is critical for landscape evolution, soil formation, biogeochemical cycles, and critical zone hydrology and ecology. Weathering profiles often include soil or solum (O, A, E, and B horizons), non-soil regolith (including soil C horizons, saprolite), and weathered rock. Development of these is a function of weathering at the bedrock weathering front to produce weathered rock; weathering at the boundary between regolith and weathered rock to produce saprolite, and pedogenesis to convert non-soil regolith to soil. Relative thicknesses of soil (Ts), non-soil regolith (Tr) and weathered rock (Tw) can provide insight into the relative rates of these processes at some sites with negligible surface removals or deposition. Scenarios of weathering profile development based on these are developed in current study. We investigated these with ground penetrating radar, electrical resistance tomography, and seismic profiling at three old growth forest sites in the Czech Republic, on gneiss, granite, and flysch bedrock. We found that the geophysical methods – which generated thousands of separate measurements of Ts, Tr, Tw – to produce good estimates. The weathered rock layer (sensu lato) was generally the thickest of the weathering profile layers. Mean soil thicknesses were about 0.64–0.75 m at the three sites, with typical maxima around 1.5 m. Non-soil regolith thicknesses averaged about 2.5 m on the gneiss site and 1.2–1.4 at the other sites. Weathered rock had a mean thickness of 7 m at the gneiss site (up to 10.3), 4.6 at the granite site, and 3.4 on flysch. Results indicate that weathering at the bedrock weathering front is more rapid than conversion of weathered rock to regolith, which is in turn more rapid than saprolite-to-soil conversion by pedogenesis on all three bedrock types. No evidence was found of steady-state soil, non-soil regolith, or weathered rock thicknesses or evolution toward steady-state. Steady-state would require that weathering rates at the bedrock and/or regolith weathering fronts decline to negligible rates as profiles thicken, but the relative thicknesses at our study sites do not indicate this is the case.

中文翻译:

土壤、风化层和风化岩:中欧古老温带森林的理论概念和演化

摘要 风化剖面 (WP) 的演变对景观演变、土壤形成、生物地球化学循环以及临界区水文和生态学至关重要。风化剖面通常包括土壤或溶质(O、A、E 和 B 层)、非土壤风化层(包括土壤 C 层、腐泥土)和风化岩石。这些的发展是基岩风化前沿的风化作用产生风化岩;在风化层和风化岩石之间的边界处风化产生腐泥土,以及成土作用将非土壤风化层转化为土壤。土壤 (Ts)、非土壤风化层 (Tr) 和风化岩石 (Tw) 的相对厚度可以提供对这些过程在某些表面去除或沉积可忽略不计的地点的相对速率的洞察。目前的研究开发了基于这些的风化剖面发展情景。我们在捷克共和国三个古老的森林遗址(片麻岩、花岗岩和复理石基岩)上使用探地雷达、电阻层析成像和地震剖面进行了调查。我们发现地球物理方法——产生了数千个 Ts、Tr、Tw 的单独测量——产生了很好的估计。风化岩层(sensu lato)通常是风化剖面层中最厚的。三个地点的平均土壤厚度约为 0.64-0.75 m,典型最大值约为 1.5 m。片麻岩地点的非土壤风化层厚度平均约为 2.5 m,其他地点为 1.2-1.4。风化岩在片麻岩站点的平均厚度为 7 m(高达 10.3),在花岗岩站点为 4.6,在复理石为 3.4。结果表明,基岩风化前沿的风化比风化岩向风化岩的转化更快,而风化岩转化为风化岩的速度又比所有三种基岩类型通过成土作用将腐泥土转化为土壤的速度更快。没有发现稳态土壤、非土壤风化层或风化岩石厚度或向稳态演化的证据。稳态将要求基岩和/或风化层风化前沿的风化速率随着剖面变厚而下降到可以忽略不计的速率,但我们研究地点的相对厚度并未表明情况确实如此。非土壤风化层,或风化岩石厚度或向稳态演化。稳态将要求基岩和/或风化层风化前沿的风化速率随着剖面变厚而下降到可以忽略不计的速率,但我们研究地点的相对厚度并未表明情况确实如此。非土壤风化层,或风化岩石厚度或向稳态演化。稳态将要求基岩和/或风化层风化前沿的风化速率随着剖面变厚而下降到可以忽略不计的速率,但我们研究地点的相对厚度并未表明情况确实如此。
更新日期:2020-06-01
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