Laterites-bearing REEs,Wadi Natash,Southeastern Desert,Egypt
来源期刊：Journal of Rare Earths2010年第3期
论文作者：Mohamed El-Ahmady Ibrahim
文章页码：471 - 476
摘 要：The present paper recorded the occurrence of laterites-bearing REEs in Natash area.Natash laterite deposits occur as horizons（5-15 m in thickness） at the boundary between the Cretaceous sandstones,and Natash flows.Laterite was recorded in more than twenty six occurrence distributed over an area of about 500 km2 along and around Wadi Natash.It ranges in color from light-grey,dark-grey to reddish-brown.The distribution of laterite deposits is structural controlled.Mineralogical results of laterites proved the presence of both kaolinite and montmorillonite as clay minerals.The presence of hyperthene,diopside and tremolite indicated that their main source was basic Natash flows.The presence of gypsum,hematite,goethite,calcite and kaolinite indicated that,the Natash laterites were related to tropical weathering conditions.The presence of ilmenorutile and rutile in the laterites declared the reducing and low pH.All the Natash laterite samples were characterized by very highly irregular REE pattern with HREE enrichment.Generally,the ∑REEs+Y,ranged from 0.36%-0.71% with an average of about 0.59%.The LREE was less concentrated than the HREE by a factor of 0.57.∑（LREE/HREE=0.57） which suggested that,the HREE contents in laterites were derived from the basic and intermediate flows rather than from acidic lavas flows.
Mohamed El-Ahmady Ibrahim
摘 要：The present paper recorded the occurrence of laterites-bearing REEs in Natash area.Natash laterite deposits occur as horizons（5-15 m in thickness） at the boundary between the Cretaceous sandstones,and Natash flows.Laterite was recorded in more than twenty six occurrence distributed over an area of about 500 km2 along and around Wadi Natash.It ranges in color from light-grey,dark-grey to reddish-brown.The distribution of laterite deposits is structural controlled.Mineralogical results of laterites proved the presence of both kaolinite and montmorillonite as clay minerals.The presence of hyperthene,diopside and tremolite indicated that their main source was basic Natash flows.The presence of gypsum,hematite,goethite,calcite and kaolinite indicated that,the Natash laterites were related to tropical weathering conditions.The presence of ilmenorutile and rutile in the laterites declared the reducing and low pH.All the Natash laterite samples were characterized by very highly irregular REE pattern with HREE enrichment.Generally,the ∑REEs+Y,ranged from 0.36%-0.71% with an average of about 0.59%.The LREE was less concentrated than the HREE by a factor of 0.57.∑（LREE/HREE=0.57） which suggested that,the HREE contents in laterites were derived from the basic and intermediate flows rather than from acidic lavas flows.
关键词：
