Clay Formation from Basic Volcanic Rocks in a Humid Mediterranean Climate1
- A. Singer and
- J. Navrot2
Clay minerals from soils formed on a variety of basic volcanic rocks in the northern Golan Heights, under humid Mediterranean conditions, have been examined mineralogically. The clay from basalt derived soils, mainly Rhodoxeralfs and Haploxeralfs (Red and Brown Mediterranean Soils) contains kaolinite and dioctahedral vermiculite partially interlayered with Al and Fe hydroxy layers. The presence of some illite and quartz in the upper soil horizons is explained by aeolian accretion. A scoria-derived Rhodoxeralf contains, in addition, some hematite.
The clay fraction from Rhodoxeralfs and Haploxeralfs formed on partly palagonitised tuff-lapilli is composed primarily of b-axis disordered kaolinite and a poorly crystalline, partly expanding, 2:1 clay mineral, presumed to represent a smectite randomly interlayered with chloritic layers. In the lower horizons of these soils the kaolinite is replaced by a hydrated, spheroidal halloysite. No distinctly amorphous clay minerals were identified. A scheme of an alteration sequence of basic pyroclastics under humid Mediterranean conditions is suggested.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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