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DOI | 10.1016/S0899-5362(02)00024-6 |
The origin of major talc deposits in the Eastern Desert of Egypt: relict fragments of a metamorphosed carbonate horizon? | |
Schandl, ES; Gorton, MP; Sharara, NA | |
通讯作者 | Schandl, ES |
会议名称 | 18th Colloquium of African Geology |
会议日期 | JUL 04-07, 2000 |
会议地点 | GRAZ, AUSTRIA |
英文摘要 | Detailed geochemical and mineralogical investigation of four talc deposits in the Eastern Desert of Egypt (Atshan, Abu Gurdi, Darhib and Kashira) suggests that the deposits form a distinct lithological unit within the Shadli metavolcanic rocks. The talc crystallized from the replacement of siliceous carbonate beds locally intercalated with elastic sediments. Th/Yb vs. Ta/Yb ratios of the rocks suggest that the sediments and the host volcanic rocks formed in an active continental margin (ACM) environment. Thus, the talc deposits may represent relict fragments of an ancient, regionally extensive carbonate horizon within the arc-related metavolcanics. The talc-rich rocks, which contain relict carbonate, serpentinized olivine and tremolite, have low (<3 wt%) Al2O3, Cr, Ni (<20 ppm), Co and Sc (<15 ppm) concentrations, precluding mafic or felsic igneous protoliths. The deposits were locally affected by contact metamorphism, giving rise to pyroxene-hornfels and granulite facies assemblages, and by regional metamorphism which produced greenschist-amphibolite grade assemblages. Disseminated sulfides commonly occur in the talc-tremolite-rich rocks (having low Al2O3 concentrations), suggesting that the metals were probably present in the original carbonate beds, but were remobilized and reconcentrated during the various metamorphic events. (C) 2002 Elsevier Science Ltd. All rights reserved. |
英文关键词 | talc siliceous carbonate beds ancient carbonate horizon clastic sediments trace elements rare earth elements low Al2O3 polymetamorphism |
来源出版物 | JOURNAL OF AFRICAN EARTH SCIENCES |
ISSN | 0899-5362 |
出版年 | 2002 |
卷号 | 34 |
期号 | 3-4 |
页码 | 259-273 |
出版者 | PERGAMON-ELSEVIER SCIENCE LTD |
类型 | Article;Proceedings Paper |
语种 | 英语 |
国家 | Canada |
收录类别 | CPCI-S ; SCI-E |
WOS记录号 | WOS:000177686600017 |
WOS关键词 | EVOLUTION ; SHIELD ; ARC |
WOS类目 | Geosciences, Multidisciplinary |
WOS研究方向 | Geology |
资源类型 | 会议论文 |
条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/293863 |
作者单位 | (1)Univ Toronto, Dept Geol, Toronto, ON M5S 3B1, Canada |
推荐引用方式 GB/T 7714 | Schandl, ES,Gorton, MP,Sharara, NA. The origin of major talc deposits in the Eastern Desert of Egypt: relict fragments of a metamorphosed carbonate horizon?[C]:PERGAMON-ELSEVIER SCIENCE LTD,2002:259-273. |
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