Revista Mexicana de Ciencias Geológicas,Soil memory: v. 21, núm.Types 1, of 2004, record, p. carriers,1-8 hierarchy and diversity 1 Soil memory: Types of record, carriers, hierarchy and diversity Victor O. Targulian* and Sergey V. Goryachkin Institute of Geography, Russian Academy of Sciences, Staromonetny per.29, Moscow, 119029, Russia. * [email protected] ABSTRACT The concept of palimpsest-wise soil memory and record is generally characterized in comparison with the book-wise memory and record of sedimentary rocks. Soil systems have a capacity for storing information about environmental factors and pedogenic processes that have been acting for a period of pedogenesis. The main mechanisms of soil memory and record formation are those sets of pedogenic processes that generate the solid phase products and features within the multiphase soil system. The main types of solid-phase carriers of soil memory and their spatial/temporal hierarchy within the soil system are briefly described. The phenomena of isomorphism and polymorphism of soil record carriers in regard to the pedogenic processes should be realized when we try to decode and understand the information stored in soil memory. Each specific type of climate could not be imprinted in only one type of pedon. When reading the record in the soil system under one type of climate, it is obligatory to account for the diversity of solid phase soil horizons and pedons induced by the diversity of parent materials (lithodiversity), topography (topodiversity), biota (biodiversity) and duration of pedogenesis (chronodiversity). Key words: soil memory, solid phase carriers, isomorphism, polymorphism. RESUMEN El concepto de registro y memoria palimpséstica en suelos es generalmente caracterizado en comparación con la memoria y registro en forma de libro presente en rocas sedimentarias. Los sistemas de suelos tienen capacidad para almacenar información sobre los factores ambientales y los procesos que han estado actuando durante un periodo de pedogénesis. Los principales mecanismos de memoria del suelo y formación de registro son aquellos conjuntos de procesos pedogenéticos que generan los productos de fase sólida y los rasgos dentro del sistema de suelo multifásico. Se describen brevemente los principales tipos de portadores en fase sólida de la memoria del suelo y su jerarquía espacio-temporal. Los fenómenos de isomorfismo y polimorfismo de los portadores del registro del suelo, en relación con los procesos pedogenéticos, deben ser considerados cuando tratamos de descifrar y entender la información almacenada en la memoria del suelo. Cada tipo específico de clima podría no estar marcado o grabado en un solo tipo de pedón. Cuando se lee el registro en el sistema de suelo bajo un tipo de clima, es obligatorio tener en cuenta la diversidad de los horizontes de suelo de fase sólida y los pedones inducida por la diversidad de materiales parentales (litodiversidad), topografía (topodiversidad), biota (biodiversidad) y duración de la pedogénesis (cronodiversidad). Palabras clave: memoria del suelo, portadores de fase sólida, isomorfismo, polimorfismo. 2 Targulian and Goryachkin TYPES OF ENVIRONMENT RECORDING IN interactions of soil-forming factors in time. Solid carriers EARTH LAND SURFACE SYSTEMS of soil memory can be developed from any kind of solid parent materials: igneous or sedimentary, natural or Soil memory is both: (i) a capacity of the complex anthropogenic. Soil records are forming in situ within the multiphase soil system to record environmental phenomena body of parent material due to its gradual transformation through pedogenic processes acting in situ in each point of by the interacting climatic, biotic, hydrological vertical and the land surface of the Earth, and (ii) a record itself of this lateral fluxes and cycles (including the anthropogenic ones). environmental and process information on the resistant soil Parent material changes, that resulted in new composition solid-phase carriers in situ. and/or arrangement of substances, could be perceived There are three main fundamentally different simultaneously as soil formation and as the soil recording pathways of recording of environmental and process of environment. information on the time-resistant and long-living solid Due to in-situ formation of soil memory, in each carriers. The first one is a very specific way of recording in ‘point’ of land surface it records very local, even ‘point’, glaciers where the individual ice layers record regional and combinations of environmental factors and pedogenic global climatic conditions, as well as chemical and dust processes at the levels of small-area ecosystems, variations composition of the atmosphere (Petit et al., 1990). Records of microclimate, microrelief, parent rocks mosaics, etc. in glaciers have very high temporal resolution and follow Therefore, soil memory has much more exact space exactly the seasonal and annual snow precipitation. But this resolution than sedimentary memory. On the other hand, way of recording is realized only in several very cold regions soil record is forming usually in one volume and thickness of the Earth (Antarctic, Arctic, and high-mountain glaciers). of the parent materials and rocks having been penetrated in The second pathway (Figure 1) is a well-known situ by atmo-hydro-biogenic forces, fluxes, and cycles. When recording by the Earth sedimentary systems, both these factors are changing in time, their records in soil are continental and marine. These systems reflect a much more changing thereafter and are superimposing on the previous complex set of environmental factors and processes: records in the same volume. Such superimposing can lead climatically, biologically and geologically controlled to different and complex combinations of older and newer mobilization of solid particles and solutions from records in the same soil volume and thickness: addition, watersheds, their mechanical and geochemical transfer, and juxtaposition, plexus, or obliteration of the features of each sedimentation, diagenesis and epigenesis of sediments record. (Strachov, 1963). Sedimentary records are very diverse: they Such sophistication of soil records leads, in the case could be biogenic (fossil plants, animal bones, phytoliths, of environmental evolution in time, to less exact time spores and pollen, coal, humus, etc.), lithogenic (mineral resolution of soil memory compared with sedimentary grains, rock debris), or geochemical (salts, carbonates, Fe, memory. In contrast with book-wise sedimentary memory Al, Si oxides precipitation). Sedimentary records are always and record, the soil memory and record could be called formed in individual lithological layers stacked up in vertical palimpsest-wise, which is a the term proposed for the sedimentary sequence, which reflects the temporal changes geomorphic systems (Allaby and Allaby, 1990). in environment and lithogenesis. Therefore, this type of Sedimentary and soil records are the two main record has high and exact time resolution and resembles a complementary ways of environmental records within the book-wise memory. At the same time, the sedimentary record upper part of the land lithosphere. The first one occurrs always accumulates the environmental and process both in terrestrial and marine environments, but only in areas information of the specific catchment area (or an area of of accretion; land areas without accretion do not have eolian transfer) and therefore memorizes the environment sedimentary memory. In such land areas, the main systems and geomorphic processes of some territory, but not of an recording the interaction of climate and biota with individual site. So, sedimentary records have usually low lithosphere are the soil and weathering systems developing space resolution because they are not on-site specific. They in situ (Martini and Chesworth, 1992). Moreover, soil summarize the results of bioclimatic and geomorphic records can be formed within the sedimentary rocks, being processes and factors, which are acting on some territory superimposed on the sedimentary memory as the memory not only in situ but also laterally, along the land surface. of the latest existing environment events (epilithogenic In contrast with sedimentary memory and record, soils pedogenesis). In several cases, the rates of slow terrestrial and weathering mantles* have a quite different type of sedimentation are comparable to the rates of soil formation, memory and record, which was proposed to be called soil and so called synlithogenic pedogenesis takes place. In such memory (Targulian and Sokolov, 1978; Targulian and cases the processes of solid particle deposition are closely Goryachkin, 2001). Soil memory and soil record (Figure 1) combined with the humification, weathering, leaching, and are forming in situ, in each specific place of on site other pedogenic processes within the forming soil body (many alluvial soils, Fluvisols, and volcanic-ash soils, * We consider the weathering mantle of all kinds of rocks as well as the Andosols). More often in areas of terrestrial sedimentation, soil to represent in-situ formed exogenic records on the land surface. the stratigraphic lacunae are imprinted by soil and/or Soil memory: Types of record, carriers, hierarchy and diversity 3 Figure 1. Formation of sedimentary (book-wise) and soil (palimsest-wise) memory. weathering profiles that record the environment conditions pedogenesis. Later, in the 1970s, Targulian and Sokolov, during the break of sedimentation (loess-soil, tephra-soil