نتایج جستجو برای: diagenetic origin
تعداد نتایج: 200395 فیلتر نتایج به سال:
Shahmirzad village is located on the southern parts of the Eastern Alborz Mountain Ranges. One of the sedimentary rock units that crops out in this area is Soltanieh Formation (Upper Precambrian Lower Cambrian). Thin section and oxygen isotope studies have been used in order to determine the petrological characteristics and the temperature of Soltanieh dolomites formation environment. E...
Source of Cement in the Great Oolite Reservoir, Storrington Oil Field, Weald Basin, South of England
The source of cement in oilfields is critical to the prediction of the distribution of cements in the reservoirs and also prediction of reservoir quality. The source of mineral forming cements has been determined for the Storrington oolitic carbonate reservoir (Middle Jurassic Great Oolite Formation, Weald Basin, onshore UK) using a combination of petrography, electron microscopy, fluid inclusi...
Massive Zn-Cu-Fe sulfide deposits at the Garon Lake Mine occur in three sulfide lenses in a group of metamorphosed rhyolite crystal tuffs, metasediments and basalts. The major ore minerals are sphalerite, chalcopyrite, pyrrhotite and pyrite. Minor associated silicates are actinolite, tremolite, chlorite, albite and quartz. Rounded detrital pyrite, magnetite and chert grains and diagenetic p...
Sedimentary rocks at Eagle crater in Meridiani Planum are composed of fine-grained siliciclastic materials derived from weathering of basaltic rocks, sulfate minerals (including magnesium sulfate and jarosite) that constitute several tens of percent of the rock by weight, and hematite. Cross-stratification observed in rock outcrops indicates eolian and aqueous transport. Diagenetic features inc...
Diagenetic theory, as it is often stated, is formally incomplete in the sense that it contains more dependent variables than the number of equations in the theory. Heretofore, this situation has been resolved ordinarily by introducing an empirical equation for porosity, , or equivalently the solid volume fraction, s 1 , as a function of depth. In contrast, the theory of compaction, that is comb...
The occurrence of intact sterols has been restricted to immature Cretaceous (~125 Ma) sediments with one report from the Late Jurassic (~165 Ma). Here we report the oldest occurrence of intact sterols in a Crustacean fossil preserved for ca. 380 Ma within a Devonian concretion. The exceptional preservation of the biomass is attributed to microbially induced carbonate encapsulation, preventing f...
Early diagenetic sediment-hosted stratiform copper (eSSC) mineralization results from low-temperature cuprous chloride complexes carried by saline aqueous solution circulating through footwall aquifers. Favorable copper solubilities are attained in moderately oxidizing, near-neutral pH solutions. That specific oxidation level is not determined by co-existence with hematite, with its near-indisc...
Human and animal skeletal remains can provide information about the food chain of inhabitant’s nutrition of archaeologicalsites. The food chain which at it minerals and organic materials transferred from soil to the plants, from plants to theanimals, and from herbivores animals to the carnivores, is the benchmark system in ancient diet. Although Chemicalinteractions between soils, animal and hu...
Residual layers and lenses of the Borhan area (SE Mahabad, NW Iran) contain considerable volume of ferrite ores, which are surrounded by carbonate rocks of the Ruteh Formation of Permian age. Petrographic examinations show that these ores have polycyclic nature and allogenic origin and their evolution is largely affected by the diagenetic and epigenetic processes. Mineralogical studies reveal t...
Abundant pyrite in black shales at the Permian-Triassic Boundary (PTB) from several localities around world has been regarded as evidence of oceanic anoxia during end-Permian mass extinction (EPME). However, a significant amount “pyrite” these rocks is not actually but marcasite, orthorhombic polymorph FeS2. Marcasite particularly sensitive to changes pH and fO2, which theoretically enables it ...
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