Here the soil regolith and rock configuration is more complex with Cenozoic
duricrusts (variably cemented palaeo-Shoalhaven River alluvium) forming resistant crestal landforms overlying deeply weathered, bedded and fractured metasedimentary rock.
As in
duricrust, secondary shapes are mostly micro-sized spherules, but bigger automorphic crystals or irregular aggregates can develop, probably because the B-horizon of these soils is seasonally saturated.
The doleritic regolith samples (Zh-d) form the
duricrust and friable zone of lateritic bauxite profiles.
Laterisation refers to the in-situ formation of an Fe-rich
duricrust capping a deep weathering profile (Tardy 1992).
Outcrop in the area occurs mostly as laterite
duricrust or lateritised outcrops; a total of 278 sample analyses have now been received from the rock chip (ASX releases of 6 May 2010 and 11 June 2010).
The soil of this work was formed by colluvial materials containing hematite-rich
duricrust fragments (nodules).
Atlhopheng JR, Ekosse GE (2007) Mineralogical appraisal of sediments of
duricrust suites and pans around Jwaneng Area, Botswana.
Outcrop in the area occurs mostly as laterite
duricrust or lateritised outcrops; a total of 278 sample analyses have now been received (including those announced in the ASX release of 6 May 2010).
This mantle is known as the lateritic profile and consists, when complete, of partially weathered material, the saprolite, overlying the fresh rock, overlain by the completely weathered pallid zone, which is in turn overlain by the transitional mottled zone, then the iron oxide rich
duricrust, and finally the sandy soil layer (McArthur 1991).
When intact, this profile consists of fresh rock immediately overlaid by partially weathered material, the saprolite, then overlaid by the completely weathered pallid zone, which is in turn overlaid by the transitional mottled zone, then the iron oxide rich
duricrust, and finally the sandy soil layer (McArthur 1991).
The area of the
duricrust occurrences is the depression of Oriola, in the Alentejo region, south of the town of Evora, about 150 km east of Lisbon (Fig.
Plinthite, once it has irreversibly cemented as a result of cycles of humidity and dryness, is known as petroplinthite (comparable to the terms "ferruginous crusts" used by French soil scientists and "
duricrusts" used by Australian ones).
