CALCIFIED FILAMENTS IN QUATERNARY CALCRETES - ORGANOMINERAL INTERACTIONS IN THE SUBAERIAL VADOSE ENVIRONMENT

A petrographic study of calcretes from coastal regions of the W Mediterranean reveals that calcified filaments are abundant and characteristic structures in these terrestrial deposits. From their sizes, shapes and arrangements, these structures are interpreted as calcified organic filaments of soil fungi, algae, actinomycetes and root hairs of vascular land plants. The mineralogy of the calcified filaments is generally low Mg calcite. The fabric of this calcite consists of micronsized needles, rhombs, or plates. The recognition of calcified organic filaments in calcretes indicates the former existence of organic activity and, moreover, indicates that these deposits functioned as biological soils. -from Author