carbonates are among the most common soil constituents in arid and semiarid zones. they exhibit many significant differences in their chemical and mineralogical, suite, origin, physical and micromorphological properties and consequently in their activities in soil. the differences cause different properties of calcareous soils. six profiles of aridisols and inceptisols with carbonate accumulati...

[1] To understand the aqueous history of Mars, it is critical to constrain the alteration mineralogy of the Martian surface. Previously published analyses of thermal infrared (l = 6–25 mm) remote sensing data of Mars suggest that dark regions have 15–20% clay minerals. However, near-infrared (l = 1–3 mm) spectral results generally do not identify widespread clay minerals. Thermal infrared detec...

We have detected a concentration of boron in martian clay far in excess of that in any previously reported extra-terrestrial object. This enrichment indicates that the chemistry necessary for the formation of ribose, a key component of RNA, could have existed on Mars since the formation of early clay deposits, contemporary to the emergence of life on Earth. Given the greater similarity of Earth...

We show that 85% of variation in total organic carbon can be explained by mineral surface area in a black shale deposit from two locations in the late Cretaceous Western Interior Seaway, United States. This relation suggests that, as in modern marine sediments, adsorption of carbon compounds onto clay mineral surfaces played a fundamental role in the burial and preservation of organic carbon. O...

Soil biotic and abiotic factors strongly influence nitrogen (N) availability and increases in nitrification rates associated with the application of manure. In this study, we examine the effects of edaphic properties and a dairy (Bos taurus) slurry amendment on N availability, nitrification rates and nitrifier communities. Soils of variable texture and clay mineralogy were collected from six US...

Cryogenian cap carbonates that overlie Sturtian glacial deposits were formed during a post-glacial transgression. Here, we describe microfossils from the Kakontwe Formation of Zambia and the Taishir Formation of Mongolia-both Cryogenian age, post-Sturtian cap carbonates-and investigate processes involved in their formation and preservation. We compare microfossils from these two localities to a...

The mineral calcium sulphate transforms from anhydrite through bassanite to gypsum and then can convert back to bassanite and anhydrite. This transformation of calcium sulphate causes volume change that adds to the potential hazards with indigenous soils containing expansive clay minerals. Heave and settlement are the most important geotechnical problems associated with many argillaceous soils ...

The Main Glauconite Bed (MGB) is a pelleted greensand located at Stone City Bluff on the south bank of the Brazos River in Burleson County, Texas. It was deposited during the Middle Eocene regional transgression on the Texas Gulf Coastal Plain. Stratigraphically it lies in the upper Stone City Member, Crockett Formation, Claiborne Group. Its mineralogy and geochemistry were examined in detail, ...

abstract geomorphology and soil genesis and its development are closely related. besides, soil-landscape studies provide a better understanding of soil forming processes. the objectives of the present research include soil genesis studies, micromorphology and clay mineralogy of soils related to geomorphic surfaces in jiroft area. soil temperature and moisture regimes of the area are hyperthermi...

pedogenesis and clay mineralogy of soils and rock samples were studied in a transect of calcareous, gypsiferous, saline soils and sediments of bakhtegan lake bank in southern iran. the main objectives of study were to determine the occurrence of clay minerals and factors controlling their distribution pattern and relative abundance in soils and parent materials. the soil parent material is high...