Effect of alteration processes on the distribution of radionuclides in uraniferous sedimentary rocks and their environmental impact, southwestern Sinai, Egypt

2011 ◽  
Vol 289 (1) ◽  
pp. 173-184 ◽  
Author(s):  
Ibrahim E. El Aassy ◽  
Mohamed M. El Galy ◽  
Afaf A. Nada ◽  
Mohamed G. El Feky ◽  
Thanaa M. Abd El Maksoud ◽  
...  
Keyword(s):  
Environmental Impact ◽  
Sedimentary Rocks ◽  
Alteration Processes ◽  
Southwestern Sinai

Potential radiation hazards of sedimentary rocks in southwestern Sinai, Egypt

2021 ◽  
Author(s):  
R. S. Attia ◽  
E. S. Abd El-Halim ◽  
Ibrahim E. El Aassy ◽  
A. El-Shershaby ◽  
H. A. Abdel Ghany
Keyword(s):  
Sedimentary Rocks ◽  
Radiation Hazards ◽  
Southwestern Sinai

Diagenesis of Miocene pelitic sedimentary rocks in the Sava Depression (Croatia)

Clay Minerals ◽  
2011 ◽  
Vol 46 (1) ◽  
pp. 59-72 ◽  
Author(s):  
A. Grizelj ◽  
D. Tibljaš ◽  
M. Kovačić ◽  
D. Španić
Keyword(s):  
Elevated Temperatures ◽  
Pannonian Basin ◽  
Early Stage ◽  
Vitrinite Reflectance ◽  
Sedimentary Rocks ◽  
Depositional Environments ◽  
Diagenetic Processes ◽  
Alteration Processes ◽  
Three Stages ◽  
Basin System

AbstractMiocene pelitic sedimentary rocks from six wells in the Sava Depression (sub-basin in the south-western part of the Pannonian Basin System) were investigated in order to determine the degrees of diagenetic alteration.Qualitative and semiquantitative mineral compositions of samples and the content of smectite in illite-smectite (I-S) were determined by X-ray powder diffraction (XRD).Vitrinite reflectance and thermal alteration index (TAI) were measured in order to estimate the palaeotemperatures.Carbonate minerals, clay minerals and quartz are the main constituents of the pelitic sediments.Feldspars (albite), pyrite, opal-CT and hematite are present as minor constituents in some rocks. The mineral composition of the rocks, apart from previously known differences caused by various depositional environments and clastic material provenance, is dependent on the degree of diagenetic processes. At elevated temperatures and large burial depths the minerals formed by alteration processes or precipitated at the surface; smectite, kaolinite and calcite were gradually replaced by minerals formed by diagenetic processes, i.e. by illite-smectite, illite, chlorite, Ca-excess dolomite/ankerite and albite. Based on XRD data for smectite, I-S and illite, three stages of diagenetic development have been established. The early stage was characteristic of samples at depths <1.8 km containing smectite, I-S of the random R0 type and detrital illite.The middle stage begins with the appearance of the ordered R1 type of I-S at the depths >1.8 km and temperature above 80°C. At depths >4.6 km with corresponding temperatures >190ºC, the late stage began, characterized by the presence of R>1 I-S with <10% smectite.

In situreflectance measurements and TM data of some sedimentary rocks with emphasis on white sandstone, southwestern Sinai, Egypt

1994 ◽  
Vol 15 (18) ◽  
pp. 3785-3797 ◽  
Author(s):  
M. L. EL RAKAIBY ◽  
M. H. ASHMAWY ◽  
M. A. YEHIA ◽  
A. S. AYOUB
Keyword(s):  
Sedimentary Rocks ◽  
Southwestern Sinai

Direct Observation of Crystalline Ordering In Naturally Graphitized Carbon Produced by Low Grade Metamorphism

1977 ◽  
Vol 35 ◽  
pp. 162-163
Author(s):  
Thomas R. McKee ◽  
Peter R. Buseck
Keyword(s):  
Crystallite Size ◽  
Sedimentary Rocks ◽  
Carbonaceous Material ◽  
Low Grade ◽  
X Ray ◽  
Graphitized Carbon ◽  
Transmission Electron ◽  
Heat Treated ◽  
Commercial Carbon ◽  
Metamorphic Zone

Sediments commonly contain organic material which appears as refractory carbonaceous material in metamorphosed sedimentary rocks. Grew and others have shown that relative carbon content, crystallite size, X-ray crystallinity and development of well-ordered graphite crystal structure of the carbonaceous material increases with increasing metamorphic grade. The graphitization process is irreversible and appears to be continous from the amorphous to the completely graphitized stage. The most dramatic chemical and crystallographic changes take place within the chlorite metamorphic zone.The detailed X-ray investigation of crystallite size and crystalline ordering is complex and can best be investigated by other means such as high resolution transmission electron microscopy (HRTEM). The natural graphitization series is similar to that for heat-treated commercial carbon blacks, which have been successfully studied by HRTEM (Ban and others).

Stabilizing pyritic material

1989 ◽  
Vol 4 ◽  
pp. 244-248 ◽  
Author(s):  
Donald L. Wolberg
Keyword(s):  
Significant Contribution ◽  
Organic Materials ◽  
Sedimentary Rocks ◽  
Iron Sulfides ◽  
Decomposition Products ◽  
Iron Minerals ◽  
Pyrite Formation ◽  
Organic Sediments ◽  
Freshwater Environments

The minerals pyrite and marcasite (broadly termed pyritic minerals) are iron sulfides that are common if not ubiquitous in sedimentary rocks, especially in association with organic materials (Berner, 1970). In most marine sedimentary associations, pyrite and marcasite are associated with organic sediments rich in dissolved sulfate and iron minerals. Because of the rapid consumption of sulfate in freshwater environments, however, pyrite formation is more restricted in nonmarine sediments (Berner, 1983). The origin of the sulfur in nonmarine environments must lie within pre-existing rocks or volcanic detritus; a relatively small, but significant contribution may derive from plant and animal decomposition products.

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