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Abstract

It is disputed whether Terrae Rossae form mainly out of the bedrock residue, from allochthonous material like aerosols, or by isovolumetric replacement. Furthermore, whether they are mainly relic soils or are still forming is subject to debate. These questions were addressed by comparing the geochemistry of several limestone and basalt based Red Mediterranean Soils with Lithosols on sandstone and limestone in Jordan. The bedrock residue was included at all test sites. Paleosols and initial soils on the limestone Regolith of historic ruins delivered insights into the possible time frame of soil development. A major reduction of elements in the soils compared to bedrock could be observed for CaO in carbonaceous, SiO2 in arenaceous, and Fe2O3 and MgO in basaltic rocks. All Terrae Rossae, however, are characterised by a significant increase of SiO2, Al2O3, TiO2, Fe2O3, K2O, and a range of mainly metallic minor elements that cannot be derived from the bedrock. A reasonable explanation could be input via aeolian transfer of minerals, with clay minerals as the major carrier plus quartz. This input probably originates in Egypt and Sudan and has remained largely unchanged over long periods. Growing aridity during the Holocene has apparently increased the share of silt while clay deposition and soil development has been reduced. At some sites, metasomatic processes have contributed to soil development and might help to explain the depth of some profiles. However, formation of red soils during the Holocene seems very limited, and the Red Mediterranean Soils may represent remains of a paleolandscape.