Sedimentology
Mahmoud Sharafi; Mahdi Jafarzadeh; Aram Bayet-Goll; Razieh Lak
Abstract
The Urmia Lake, which is a tectonic depression in the northwest of Iran, has received a lot of eroded sediments of the geological records of the lake watershed. Because of the constant drought in the recent years, sediments have been subjected to the wind erosion and thus are an important source for ...
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The Urmia Lake, which is a tectonic depression in the northwest of Iran, has received a lot of eroded sediments of the geological records of the lake watershed. Because of the constant drought in the recent years, sediments have been subjected to the wind erosion and thus are an important source for local and regional emission during dust storms. In this research the south and west sediments of the Urmia playa lake have studied on the parent rock issue. Bivariate plots such as Th/Co versus La/Sc and TiO2 versus Al2O3 and comparison proportion of the trace elements such as La/Sc, Th/Sc, La/Co, Th/Co and Cr/Th display mainly the felsic and partly basic rocks source for the studied sediments. Major and trace spider plots of the studied sediments display their depletion with respect to Sc, V, Cr, Ni and enrichment with respect to Th and Sr, confirm mainly a felsic and partly mafic and ultramafic source rocks. Geochemistry of the major elements shows the dry climatic conditions during deposition of Urmia Lake sediments, suggested by bivariate plots of SiO2 against the sum of Al2O3, K2O and Na2O as well as the amount of chemical index of weathering.
Sedimentology
Javad Anjerdi; Mahdi Jafarzadeh; Adel Najafzadeh; Rahim Mahari
Abstract
In this research, a combination of petrography, geochemistry and heavy minerals analysis methods are implemented for investigating the provenance of quartzarenitic and subarkosic sandstones of Ilanqareh Formation with Late Devonian age in Azerbaijan, south of Jolfa. Investigation of the quartz types ...
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In this research, a combination of petrography, geochemistry and heavy minerals analysis methods are implemented for investigating the provenance of quartzarenitic and subarkosic sandstones of Ilanqareh Formation with Late Devonian age in Azerbaijan, south of Jolfa. Investigation of the quartz types in the studied sandstones, geochemical characteristics of sandstones and shales of Ilanqareh Formation including Al2O3/TiO2 ratio and La/Sc against Co/Th ratios, illustrates that the dominant parent rocks of most of these deposits are granitic igneous ones. The presence of granitic parent rock along with the presence of euhedral zircon and tourmaline among the well-rounded indicate the erosion of uplifted blocks of Iranian basement in the rifted basin of Paleotethys as effective factor in providing sediments. However, geochemistry and heavy mineral assemblages confirm the recycling of sediments from older formations as another source of sediment. The petrography, geochemistry and heavy minerals also indicate the craton provenance and passive margin tectonic setting at the deposition time of the Ilanqareh sediments. According to the present study, one can consider a combination of uplifted source rock (Cadomian basement) and sedimentary recycling of older formations as main sources and Arabian craton as a subsidiary source in the supply of detritus sanstones of Ilanqareh Formation.
M. Husseini Barzi; M. Jafarzadeh
Abstract
Petrofacies analyses of Asmari Formation carried out on thin sections, obtained from oil wells of number 11, 85 and 89 in Ahvaz oil field, show 5 carbonate-evaporate microfacies associations (related to a carbonate ramp) and 2 siliciclastic petrofacies. Point counting data plotted on Qt93.34F4.10Lt2.59 ...
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Petrofacies analyses of Asmari Formation carried out on thin sections, obtained from oil wells of number 11, 85 and 89 in Ahvaz oil field, show 5 carbonate-evaporate microfacies associations (related to a carbonate ramp) and 2 siliciclastic petrofacies. Point counting data plotted on Qt93.34F4.10Lt2.59 and Qm86.75F4.10L9.15 diagrams imply the cratonic and recycled orogen tectonic provenance. Furthermore, these results and the other petrographic evidences indicate a source rock with sedimentary and low to medium degree metamorphic composition for Ahvaz sandstone. Combining the obtaind results with global sea level changes, variation in sediment supply and regional and local tectonic evolution, assisted us to recognize 6 evolutionary stages for Samara basin. In fact, Asmari Formation deposited in a carbonate-evaporate ramp with different amount of sediment influx through the time.
