Carbonate rocks occur in Brazil under diverse climatic and environmental conditions, and therefore are of great importance for pedological studies. The northwest region of the State of Rio de Janeiro, Brazil, is composed of calc-silicate rocks and marbles that occur under tropical climate with a long period of water deficit, which provides conditions for peculiar pedogenesis. The objective of this study was to characterize the attributes of soils formed from carbonate materials and to understand the role of the main factors and processes in pedogenesis, as well as to provide information to the WRB (World Reference Base for Soil Resources) to improve carbonate soils classification. A toposequence was selected in the municipality of Italva, RJ, Brazil, with six profiles being described and sampled. All profiles presented median CaCO₃ equivalent contents, high base saturation with the predominance of Ca⁺² and Mg⁺², and high activity clay. The absence of effervescence and low CaO/MgO ratio obtained by acid digestion suggest the dolomitic nature of the carbonates. Pedogenic carbonates were amorphous, since no XRD peaks were found. The high Mg⁺² concentration provided by the parent material increases the dispersion of clays and favors clay illuviation, which is manifested in the micromorphology through a large amount of clay infillings and coatings. Four profiles on the highest part of the landscape were classified as Kastanozems (Mollisols), the footslope profile as Fluvisol (Inceptisol), and the toeslope profile as Vertisol. The mineralogy of the Vertisol's clay fraction was predominantly composed of kaolinite interstratified with 2:1 phyllosilicates, mainly illite. Acid digestion can complete the analysis of the CaCO3 equivalent content by quantifying CaO and MgO concentration in fine earth samples, presenting the potential to distinguish the Dolomitic/Calcaric qualifiers. The recognition of Dolomitic/Calcaric qualifiers for the Kastanozem reference soil groups is suggested, considering that the carbonate present in the calcic horizon may be diverse.

碳酸盐岩在巴西存在于不同的气候和环境条件下，因此对土壤学研究具有重要意义。巴西里约热内卢州的西北地区是由钙硅酸盐岩石和大理石组成的，这些钙硅酸盐岩石和大理石在热带气候下长期缺水，这为特殊的成岩作用提供了条件。这项研究的目的是表征由碳酸盐材料形成的土壤的特性，并了解成岩作用的主要因素和过程的作用，并向WRB（世界土壤资源参考基地）提供信息以改善碳酸盐土壤分类。在巴西RJ I​​talva市选择了一个toposequequ，并描述和采样了六个轮廓。所有资料均显示了中位数CaCO₃当量含量，以Ca ⁺²和Mg ⁺²为主的高碱饱和度和高活性粘土。通过酸消化没有起泡和低的CaO / MgO比表明碳酸盐的白云性。由于没有发现XRD峰，因此成岩碳酸盐是无定形的。高镁⁺²母体材料提供的高浓度会增加粘土的分散性，并有利于粘土的光化，这通过大量的粘土填充物和涂料在微观形态上得以体现。地势最高处的四个剖面被分类为Kastanozems（Mollisols），山坡剖面被分类为Fluvisol（Inceptisol），而趾坡剖面被分类为Vertisol。Vertisol粘土级分的矿物学主要由高岭石与2：1层状硅酸盐层积而成，主要是伊利石。酸消解可以通过量化细土样品中CaO和MgO的浓度来完成CaCO3当量含量的分析，从而有可能区分Dolomitic / Calcaric定性剂。建议识别Kastanozem参考土壤组的白云岩/方钙质限定词，