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CLAY AND SILT MINERALOGY OF SOME SOILS FROM QASIM, SAUDI ARABIA
Author(s) -
MASHHADY A. S.,
REDA M.,
WILSON M. J.,
MACKENZIE R. C.
Publication year - 1980
Publication title -
journal of soil science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.244
H-Index - 111
eISSN - 1365-2389
pISSN - 0022-4588
DOI - 10.1111/j.1365-2389.1980.tb02068.x
Subject(s) - chlorite , clay minerals , palygorskite , kaolinite , silt , geology , mineralogy , geochemistry , calcite , soil water , pedogenesis , granulometry , quartz , plagioclase , illite , mica , hornblende , soil science , biotite , geomorphology , sediment , paleontology
Summary Qasim, some 500 km north‐west of Riyadh, is one of the agriculturally important areas of Saudi Arabia. Silt fractions of the soils of the Wadi ar Rimah and side wadis, classified as Torrifluvents, are characterized by high quartz contents and the universal occurrence of kaolinite and felspar, generally with plagioclase predominant; mica, chlorite and hornblende also generally occur. The clay fractions contain mainly palygorskite and a smectite‐mica interstratification with smaller amounts of kaolinite, traces of quartz and occasionally chlorite. Palygorskite generally increases in content with depth. Variations in mineralogy probably reflect changes in depositional conditions rather than pedogenic processes; possible reasons for the high palygorskite content are discussed. Sedentary soils (Torriorthents) reflect the mineralogy of the rock from which they were derived. In clay fractions from salt‐marsh soils (Salorthids) calcite reacts strongly with smectite‐mica during DTA.