Litho‐diagenetic implications of the calcium oxalate‐carbonate biogeochemical cycle in semiarid Calcretes, Nazareth, Israel
作者:
EricP. Verrecchia,
期刊:
Geomicrobiology Journal
(Taylor Available online 1990)
卷期:
Volume 8,
issue 2
页码: 87-99
ISSN:0149-0451
年代: 1990
DOI:10.1080/01490459009377882
出版商: Taylor & Francis Group
关键词: Calcium carbonate;calcium oxalate;fungi;calcrete;litho‐diagenesis;Israel
数据来源: Taylor
摘要:
Microscopic observations of calcrete soil samples in semiarid environments from Israel reveal a particular vesicular microfabric. The calcrete horizon is indurated but highly porous and all the pores are coated with a gray layer (quasi‐coating) of secondary calcium carbonate. Two kinds of needles are found inside the pores: thin and regular needles (calcite), and filaments with very sharp spikes that are of fungal origin. Analysis of the proportions of C, O, and Ca were made with an E.D.S. microprobe connected with a scanning electron microscope to distinguish calcite (CaCO3) from calcium oxalate (CaC2O4) and to differentiate inorganic from organic influences. Under biological control, calcium oxalate coexists with calcium carbonate; both contribute to rock diagenesis. In the pores, biological activity promotes a complex cycling of calcium leading to recementation of the matrix and further lithification. Thus, this kind of calcrete is due to geological evolution as much as to biochemical control.
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