Distribution of Iron and Manganese in Terra Rossa from Istria and its Genetic Implications

Abstract

Haematite and goethite are the predominant pedogenic mineral phases in terra rossa from Istria. Limited variation of selected Fe oxide characteristics in analysed samples indicates the specific pedogenic environment in which terra rossa is formed. The mean value of the Fed/Fet ratio, taken as an index of weathering is 0.7 and reflects quite a high degree of weathering of Fe-containing primary silicates. Relatively uniform Fed/clay ratios clearly indicate a predominance of co-illuviation of clay and Fe oxides. Low values of Feo point to the low content of poorly crystalline Fe oxides in analysed terra rossa. Feo/Fed ratios in the analysed profiles vary. In the upper part of the Pomer, Porec and Novigrad profiles Feo/Fed ratios are higher than in the lower part of those profiles which may be explained as a result of different pedogenic environments and/or additions of external materials in the upper part of those profiles. The lack of positive correlation between Mnd and clay and Mnd and Fed is a consequence of remobilization of manganese due to hydromorphic processes which post-dated co-illuviation of clay and Fe oxides. During the Late Tertiary and Quaternary the pedogenic environment on hard carbonate rocks of the Jurassic-Cretaceous-Palaeogene carbonate plain of southern and western Istria generally remained suitable for rubification. However, (Neo)tectonic activity and the input of external material, as well as various climatic fluctuations might have significantly effected terra rossa through the processes of erosion, colluviation, yellowing and secondary hydromorphy.

Analisis Perkembangan Tanah Metode Pelarutan Selektif Dengan Ekstraksi Ditionit Sitrat Bikarbonat, Ammonium Oksalat, Dan Pirofosfat Pada Andisol Puncak Gunung Sumbing Kabupaten Magelang

“…Nisbah Fek/ Fe total sebesar 0,17 %. Durn et. al., (2001) menggunakan nilai ratarata nisbah Fek/ Sit sebagai indeks pelapukan tanah yang berasal dari mineral silikat dengan angka 0,7.…”

Effect of Sedimentary Environment in Iron and Manganese Crystallization Index of some Soil of Anbar Government

“…Soil weathering leads to the crystallization of iron and manganese, released from primary minerals, resulting in the formation of new secondary minerals in dry climatic conditions [13]. The Crystallization Index (CI) is considered a genetic standard for classifying iron and manganese crystallization in the soil [14]. The development of iron and manganese crystallization increases as a result of soil-forming factors obtained from the parent material, which is influenced by varying conditions of drought and moisture in the soil [15].…”