Knowledge Resource Center for Ecological Environment in Arid Area
DOI | 10.1007/s12517-009-0054-0 |
Preliminary results of a first record of gold and uranium in marble from Central Eastern Desert, Egypt: a witness for (syn- and post-?) metamorphic mineralization in metasediments | |
Hamdy, M. M.1; Aly, G. A.2 | |
通讯作者 | Hamdy, M. M. |
来源期刊 | ARABIAN JOURNAL OF GEOSCIENCES
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ISSN | 1866-7511 |
出版年 | 2011 |
卷号 | 4期号:1-2页码:25-43 |
英文摘要 | This paper records, for the first time, the mineralization of gold (0.98-2.76 ppm) and uranium (133-640 ppm) in marbles from the Arabian-Nubian Shield of the Eastern Desert of Egypt. These auriferous and uraniferous marbles are hosted by sheared and altered ophiolitic serpentinized ultramafic rocks of Gebel El-Rukham (ER), Wadi Daghbag (DG), and Wadi Al Barramiyah (BM). They occur as massive or banded in pod-like or bedded shapes. The ER and BM-mineralized marbles are impure calcitic, whereas the DG marble is impure calcitic to impure dolomitic. Their protolith are pure limestones and dolomitic limestones with probable argillaceous components (BM marble), and their metamorphism (Pan-African) was retrograde. Peaks of metamorphism were at granulite-amphibolite facies for the ER and BM marbles, forming diopside (Al(2)O(3) = 0.17-1.07 wt.%) at 600-900A degrees C and augite (Al(2)O(3) = 2.45-9.40 wt.%) at 825-975A degrees C, and at the amphibolite facies for DG marble, recrystallising the carbonate minerals and forming tremolite. The lowest temperatures of metamorphism were at the upper subgreenschist facies as chlorite (ER and BM marbles) and kaolinite (DG marble) were formed. Metamorphic fluids were, most probably, essentially binary H(2)O-CO(2) mixtures with low NaCl and HF concentrations. Gold in the studied mineralized marbles occurs as native nuggets (10-35 mu m) having globule, rod, crescent, and streak shapes, in pores, vugs, and fissures. The source of gold in all marbles is mostly the country ultramafic rocks. Timing of gold mineralization relative to the marblization and metamorphism of the country source ultramafic rocks was both syn- and post-metamorphic. Concerning the ER and DG marbles, it was syn-metamorphic, where Au liberation and transportation were mostly by the metamorphic fluids. The composition and temperature of these fluids were most probably inappropriate for formation of the sulfide complexes of gold. The gold mineralization of BM marble, on the other hand, was mostly post-metamorphic. The mineralising fluid was of surficial origin under oxidizing conditions. The encountered uranium minerals are of secondary origin such as autunite, uranophane, and carnotite. These minerals occur as fine oval aggregates and irregular grains (10-50 mu m) usually filling fissures and vugs. The uranium mineralization can be classified as surficial of ages < 1.5 Ma. It is proposed that the U was transported from its source (might be flesite and trachyte dikes for the ER and DG marbles and granite rocks for BM marble) to the marble rocks by surface and/or underground water related to the pluvial periods in Egypt. In BM marble, U and Au have mutual mineralizing fluid but different paragenesis. |
英文关键词 | Mineralization records Auriferous-uraniferous marble Serpentinite Metamorphism Central Eastern Desert Egypt |
类型 | Article |
语种 | 英语 |
国家 | Egypt |
收录类别 | SCI-E |
WOS记录号 | WOS:000287095700003 |
WOS关键词 | FLUID INCLUSIONS ; NUBIAN SHIELD ; EVOLUTION ; DEPOSITS ; NOMENCLATURE ; MINERALS ; SYSTEM ; MODEL |
WOS类目 | Geosciences, Multidisciplinary |
WOS研究方向 | Geology |
资源类型 | 期刊论文 |
条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/167123 |
作者单位 | 1.Tanta Univ, Fac Sci, Dept Geol, Tanta 31527, Egypt; 2.Nucl Mat Author, Cairo, Egypt |
推荐引用方式 GB/T 7714 | Hamdy, M. M.,Aly, G. A.. Preliminary results of a first record of gold and uranium in marble from Central Eastern Desert, Egypt: a witness for (syn- and post-?) metamorphic mineralization in metasediments[J],2011,4(1-2):25-43. |
APA | Hamdy, M. M.,&Aly, G. A..(2011).Preliminary results of a first record of gold and uranium in marble from Central Eastern Desert, Egypt: a witness for (syn- and post-?) metamorphic mineralization in metasediments.ARABIAN JOURNAL OF GEOSCIENCES,4(1-2),25-43. |
MLA | Hamdy, M. M.,et al."Preliminary results of a first record of gold and uranium in marble from Central Eastern Desert, Egypt: a witness for (syn- and post-?) metamorphic mineralization in metasediments".ARABIAN JOURNAL OF GEOSCIENCES 4.1-2(2011):25-43. |
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