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在卡普瓦尔克拉通早太古到早元古的泥质岩和火山岩中,含Al_2O_3高于20％的岩石广泛分布。这些岩石的富铝性质归因于分解作用,当原始物质含Al_2O_3量达60％时,它从源岩滤掉并移入溶液中。这些岩石很大部分也显示含K_2O达10％的成岩环境,许多情况下,分解作用反应影响没有打乱细微构造的原岩,如在火山玻璃颗粒中的去玻璃化珍珠裂纹口。这些岩石大多数的成因可归因于地面风化时的分解作用,它们代表古土壤。对其它产状而言,在地层上下关系上排除作为古土壤的解释,这种岩石类型的成因归因于熔岩或凝灰岩在热液喷气作用下所产生的水下分解。已经表明,在绿片岩带中富铝的岩石几乎无例外的都是水下形成的,而更年轻的产地都是风化成因的,地质构造的不同引起与此相反的解释。从加拿大地盾、津巴布韦、西澳大利亚、印度和波罗的地盾所记载的相同化学成分的岩石来看,它们显示出这些岩石的保存潜力是很强的,只有进行地层关系的研究,才能作出是否一个特殊产状是风化产物还是水下分解作用产物的结论。
In the early Archean argillaceous and volcanic rocks of the Capupercraton, rocks containing more than 20% Al 2 O 3 were widely distributed. The aluminum-rich nature of these rocks is attributed to decomposition, which is filtered off of the source rock and moved into solution when the starting material contains 60% Al 2 O 3. Most of these rocks also show a diagenetic environment containing up to 10% K_2O, and in many cases the decomposition reaction did not disrupt the finely structured protoliths, such as de vitrified pearl cracks in volcanic glass particles. The genesis of most of these rocks can be attributed to the decomposition of the ground during weathering, which represents paleosol. For other occurrences, the exclusion of paleo-soil from stratigraphic correlations is attributed to the origin of this type of rock due to sub-surface decomposition of lava or tuff under hydrothermal jet. It has been shown that almost all of the aluminum-rich rocks in the greenschist zone are formed underwater, whereas the younger areas are all weathering. The differences in geological structures give the opposite explanation. From the rocks of the same chemical composition recorded by the Shield of Canada, Zimbabwe, Western Australia, India and the Baltic Shield, they show that the preservation potential of these rocks is very strong and can only be made after studying the stratigraphic relationship Whether or not a particular occurrence is a weathered product or an underwater decomposition product results.