Geology and geochemistry of the granitic rocks and associated dykes,East Gabal Nuqra,South Eastern Desert,Egypt

作     者：Ibrahim H.Ibrahim Mostafa E.Darwish Ibrahim H. Ibrahim;Mostafa E. Darwish

作者机构：Nuclear Material Authority530 P.O.El MaadiCairoEgypt 

出 版 物：《Chinese Journal Of Geochemistry》 (中国地球化学学报)

年 卷 期：2012年第31卷第4期

页      面：376-389页

核心收录：

学科分类：070902[理学-地球化学] 0709[理学-地质学] 0819[工学-矿业工程] 07[理学] 070901[理学-矿物学、岩石学、矿床学] 0708[理学-地球物理学] 

主　　题：碱长花岗岩 地球化学特征 堤坝 沙漠 埃及 轻稀土元素 碱性流纹岩 元素富集特征 

摘      要：A crescent-shape granitic stock and associated dykes is located to the East Gabal Nuqra at the extreme western part of Wadi Natash,South Eastern Desert,*** examined granites are classified as alkali-feldspar granites and mainly consist of quartz,potash feldspars,plagioclases,and ***,zircon,apatite and allanite are accessories representing the source of Y,U,Th and REEs in these *** granites are characterized by high K2O,Na2O and Zn contents and Rb/Sr ***,they are highly enriched in high field strength elements(HFSE),especially Zr(1529×10-6),Nb(100×10-6),Hf(91×10-6) and Y(624×10-6) and light rare-earth elements(LREE,141×10-6) concentrations and strongly depleted in Ca,Mg,Sr and Eu *** features suggest that they are similar to A-type granites(type-2).The rhyolite dykes and granites have similar geochemical characteristics whereas the chondrite-normalized REE patterns show a LREE enriched feature with strong negative Eu-anomaly,whereas the REE pattern of trachydacites show slightly fractionated pattern with no *** is suggested that the trachydacites were generated by small degree of partial-melting deep-seated basic *** liquid,when subjected to fractional crystallization involving separation of plagioclases as residue,generated the alkali-feldspar *** further fractional crystallization gave rise to the alkali *** igneous rock suite originated from metaluminous to alkaline trachytic magma,and was developed in a within-plate tectonic *** extension caused by NW-SE right-lateral shear in area led to the emplacement of the alkali-feldspar *** later extrusion of the alkali rhyolite and trachydacite dykes was due to cauldron subsidence.