Paleosol
A paleosol ( altgr. παλαιός Palaios, old ' dt, soil ' ) is the word meaning according to an "old ground ". Paleosols are formed under different environmental conditions soils. Fully preserved old soils are very rare. Paleosol as term also includes the remains of a truncated erosive soil. Paleosols are archives of past environmental conditions. Fossil soils in sedimentary sequences provide information about phases of morphodynamic stability ( Sedimentationspausen ) of the Earth's surface and thereby the existing ecological and thus climatic conditions. With the scientific study of paleosols ( pedology ) deals as part of the field of soil science the Paleopedology.
- 3.1 loess - paleosol sequences
- 3.2 tephra - paleosol sequences
Definition
Paleosol is often equated with fossil soil, but does the word meaning only according to "old ground ". In most cases the term is used in buried paleosol ( fossil ) soils which are older than the Holocene. Fossil soils are not affected by extant soil formation. Their formation also subject to environmental conditions that differed from the recent ( Holocene ) ratios. In contrast, soils are relict areas of recent soils that were formed under different environmental conditions. You may be subject of further soil formation - where the substrate of recent soil-forming processes can still be significantly worked up. Paläopedologen dedicated to both fossil soils and relict soils.
Difficulty in defining
The definition of paleosoils is dependent on the definition of the bottom. Chemical weathering alone is not a soil-forming process, so the result is no ground in the pedological sense. If geologists call fossil saprolite example, as paleosol, this is contrary to pedological soil definitions. On the other hand, represents saprolite stability of the land surface progresses in situ weathering, which is an important characteristic of soils and a key feature of paleosols.
Paleosols as environmental archives
With the same starting substrate and comparable relief position climate and time are the main factors of soil formation. With a known time position paleosols information on the climate conditions at the time of their formation may contain. This principle is, among others, in the Quaternary application. Quaternary unconsolidated sediments paleosols have received that show in their physiochemical characteristics of relatively large similarity with recent soils. Paleosols, however, are handed down from almost all phases of Earth's history in sedimentary rocks or even metamorphic rocks. Changes through diagenesis and metamorphism particularly difficult case identification as a paleosol. It is justified by appropriate scientific methods that a layer subject to soil formation prior to fossilization, it can be called a paleosol.
The potential of paleosols for the reconstruction of past environments is thus extended to paleosols trace the relief at the time of their formation. Generally represent paleosols phases of stability of the landscape surface. Stability means change of the starting substrate by weathering and other soil-forming processes take place without erosion, accumulation or migration. As a rule, this vegetation cover is closed.
Paleosols in Quaternary
The Quaternary climate changes are documented in the oxygen isotope curves as changes in average global temperatures over the last 2.6 million years. The regional characteristics of the climate - through the Atmospheric circulation, influenced by the topography - can be studied only in regional archives. For the last 100 ka, there are a number of environmental archives. To understand the relevant environmental changes as a function of Basisoszillation the climate according to the Milankovitch cycles of loess - paleosol sequences are the appropriate archives. Distributed Global Tephra are - paleosol sequences are also studied scientifically.
Loess - paleosol sequences
In sufficiently powerful loess deposits in the temperate latitudes switched paleosols show the climate changes and environmental changes of cold and warm phases phases by the alternation of loess and soil formation. Difficulties arise when erosion or rearrangement events took place. Capped fossil soils are generally still referred to as the paleosol by erosion. For example, resulting from the change from interglacial to glacial period by changing the landscape dynamics large rearrangement events so that in Central Europe are usually obtained from the last interglacial period only the thick Bt horizons of Luvisols, while the easily erodible Ah and Al horizons were removed. The scientific study of loess - paleosol sequences is performed mainly with pedological, geological, mineralogical, paleontological and archaeological and field and laboratory methods.
Tephra - paleosol sequences
Also tephra - paleosol sequences are investigated by Quartärforschern. However, the rhythms of deposition and soil formation are subject to the dynamics of each volcano. But the archives are available in all climate zones and not just restricted to the temperate latitudes.
Credentials
Retallack, GJ: Soils of the Past - an introduction to paleopedology. 2nd ed, Blackwell Science, 2001.