The Nayband strike-slip fault forms the western margin of the micro-continental Lut block in Eastern Iran. Neogene and Quaternary mafic volcanic rocks collected near Tabas, along the northern part of the fault (NNF; 15 Ma), and further to the south, along the middle par More
The Nayband strike-slip fault forms the western margin of the micro-continental Lut block in Eastern Iran. Neogene and Quaternary mafic volcanic rocks collected near Tabas, along the northern part of the fault (NNF; 15 Ma), and further to the south, along the middle part of the fault (MNF; 2 Ma), are within-plate sodic-series alkali olivine basalts with high TiO2 and up to >16% normative nepheline. Their high MgO, Ni and Cr contents indicate that they crystallized from relatively primitive magmas. Their low La/Nb and Ba/Nb ratios are similar to oceanic island basalts (OIB) and unlike convergent plate boundary arc basalts (IAB). These alkali olivine basalts show enrichment in LREE relative to HREE and limited variation in Sr, Nd and Pb isotopic values which all plot in the range of OIB. Ce/Pb (>39), Nb/U (44-120) and P2O5/K2O (~0.4) ratios suggest that crustal contamination was not significant for MNF basalts. The data may be interpreted as indicating the participation of upwelling mantle asthenosphere and the deeper continental mantle lithosphere in the generation of these basalts. They formed by generally low, but variable degrees of partial mantle melting, which decreased with time from 15 Ma NNF relative to2 Ma MNF basalts. The small volume of melts that formed the MNF basalts rose to the surface along the deep Nayband strike-slip fault with no interaction with the continental crust. The larger volume of NNF basalts interacted to some degree with the crust and are associated with basaltic andesites and andesites.
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Pliocene and younger volcanic rocks are exposed in 120km northwest of Isfahan in urumieh-dokhtar magmaticbelt in centeraliran structural zone. Petrographical and geochemical studies show these rocks arecalcalkaline andconsist of Rhyodacite, Dacite, Andesite and Trachyan More
Pliocene and younger volcanic rocks are exposed in 120km northwest of Isfahan in urumieh-dokhtar magmaticbelt in centeraliran structural zone. Petrographical and geochemical studies show these rocks arecalcalkaline andconsist of Rhyodacite, Dacite, Andesite and Trachyandesite.Sr_Nd radiogenic isotopes used to interpretation ofpetrogenesis and tectonic setting, show a mantel array or near enrichmentedmantelEMlltype,sourcefor thisrocks.The enrichment can result of crust contamination or source metasomatism caused by subduction zonefluids.The absence of significance increase in Nd isotopes and significance decrease in Srisotopes show thatmelt don’t contaminated with lithosphere during upwarding.
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Barite can form in various geological environments, as it is found in a wide range of mineral deposit types. To determine the origin and physicochemical conditions under which the Ab Torsh barite deposit was formed, a comprehensive study was carried out using petrograph More
Barite can form in various geological environments, as it is found in a wide range of mineral deposit types. To determine the origin and physicochemical conditions under which the Ab Torsh barite deposit was formed, a comprehensive study was carried out using petrographical, REE geochemical, O and S isotopic. Barite mineralization occurs at Ab Torsh as a stratabound vein in the Senonian sedimentary rock units. Barite is accompanied by quartz and subordinate malachite, chrysocolla, Fe and Mn oxides and hydroxides, galena, azurite, fluorite, pyrite, and bornite. The brecciated host rocks cemented by barite imply an epigenetic origin for the barite mineralization. The ∑REE values are very low in barites (5.32-14.56 ppm), with chondrite-normalized patterns displaying LREE enrichment relative to HREE. The REE elemental ratios show that seawater with a highly modified geochemical signature (connate waters) acted as the barite depositing fluid. The δ18O and δ34S values in barites (+10.4‒+11.1‰ and +27.3‒+27.8‰, respectively) and δ34S values in galena (+6.3 and +7.9‰) indicate that sulfate (and thus sulfur) originated from sulfate carrying connate waters and/or evaporites. The Ab Torsh deposit is classified here as a structure (unconformity)-related barite deposit. It is concluded that intense faulting and the resulting brecciation of the host rocks probably provided the conduits needed for upward migration of the deep mineralizing fluids from a basinal brine source. Barite was formed where these ascending Ba-bearing hydrothermal fluids encountered sulfate-containing connate waters trapped within the overlying Senonian strata and or the descending meteoric waters that gained sulfate from evaporite-bearing rock units.
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کاربرد نتایج حاصل از آنالیز ایزوتوپ­های پایدار (SIA) در تحقیقات کشاورزی، اکولوژی و به طور کلی در برخی رشته­ها مانند زیست­شناسی، گیاه­شناسی، جانورشناسی، شیمی آلی، اقلیم شناسی و تغذیه، به یک رویکرد علمی استاندارد تبدیل شده است. اهداف اصلی این مقاله عبارتند More
کاربرد نتایج حاصل از آنالیز ایزوتوپ­های پایدار (SIA) در تحقیقات کشاورزی، اکولوژی و به طور کلی در برخی رشته­ها مانند زیست­شناسی، گیاه­شناسی، جانورشناسی، شیمی آلی، اقلیم شناسی و تغذیه، به یک رویکرد علمی استاندارد تبدیل شده است. اهداف اصلی این مقاله عبارتند از: (١) ارائه یک تعریف ساده از ایزوتوپ­های پایدار و (٢) بیان روش­های اندازه­گیری تحلیلی و کاربردهای عمومی ایزوتوپ­های پایدار در تغذیه حیوانات. ایزوتوپ­های پایدار کربن (13Cδ) و نیتروژن (15Nδ) ابزارهای قدرتمندی برای ارزیابی اولویت تغذیه­ای موجودات و جایگاه تغذیه­ای آنها هستند. همچنین ایزوتوپ­های پایدار در ارتباط با مدل­های مخلوط بایزین (Bayesian Stable Isotope Mixing Models)، توضیح ارتباطات تغذیه­ای بین گونه­ها و سپس شبکه­های غذایی پیچیده را ممکن می­سازند. داده­های ایزوتوپ پایدار باید با داده­های رژیم­های غذایی مرتبط با رفتارهای تغذیه­ای تکمیل شوند تا قادر به ارائه اطلاعات دقیق انتقال انرژی یا مواد مغذی باشند. امروزه، آنالیز ایزوتوپ­های پایدار جهت پرداختن به رژیم­های غذایی حیوانات و انسان در سراسر جهان مورد استفاده قرار می­گیرد.
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