کمپلکس اولترامافیک- مافیک سیخوران در پهنه ساختاری سنندج- سیرجان قرار دارد و شامل واحد هارزبورژیت و دونیت پورفیروکلاستیک و واحد کومولا‌های گابرویی لایه‌ای است. با مطالعه ریزساختار‌ها و ویژگی‌های ژئوشیمی سرپانتینیت‌هایی از هارزبورژیت‌ها و دونیت‌ها درک بهتری از فرایند‌های سرپانتینی شدن و جایگیری این کمپلکس به دست می‌آید. بر پایه این مطالعه سه نوع ریزساختار شامل ریزساختار حالت جامد دما بالا که بیشتر در بخش شمال خاوری واحد دونیت پورفیروکلاستیک دیده می‌شود، ریزساختار حالت جامد دما پایین که در بخش شمال خاوری و مرکزی دونیت‌ها و هارزبورژیت‌ها گسترش یافته و ریزساختار‌های ساب‌میلونیتی و میلونیتی بیشتر در بخش هارزبورژیتی گسترش دارند، شناسایی شد. همچنین ریزساختار‌های رگه‌ای نیز در بخش میلونیتی و ساب میلونیتی دیده شده‌اند. رگه‌های مطالعه شده در اثر دو فرایند 1) انحلال و 2) بسته شدن شکاف (Crack – Seal) تشکیل شده‌اند. دگرشکلی‌ها بیشتر در نمونه‌های مجاور گسل آشین متمرکز بوده است. سیال‌های گرمابی سبب سرپانتینی شدن و تحرک آهن و عناصر دیگر از کانی‌های فرومنیزیم در پریدوتیت اولیه شده‌اند. سرپانتینیت‌ها محدوده SiO2(38.8-41.7Wt%) و تهی‌شدگی از Al2O3(0.1-1.3) و CaO (0.3-0.9 ) نشان می‌دهند. تهی‌شدگی از اکسید کلسیم و آلومینیم و غنی شدگی از کروم و نیکل نشان‍دهنده سنگ مادر دونیت یا هارزبورژیت گوشته‌ای تهی شده است و آنها در نمودار Cr-TiO2 در منطقه فرافرورانش قرار گرفته‌اند.
Three intrusive granitoid bodies from northwest Saveh, central Iran, are embedded in volcanic sedimentary rocks of the Eocene,forming isolated small outcrops: Khalkhab quartz monzodioritic units (SiO2: ~52-57 wt %) to the northwest, Neshveh granodioriticunits (SiO2: ~62-71 wt %) to the northeast, and Selijerd granodioritic units (SiO2: ~63-69 wt %) to the southeast. The Khalkhab unit iscomposed of quartz monzogabbro and quartz monzodiorite with medium- to coarse-grained textures. The Neshveh unit is composedmainly of granodiorite with subordinate granite of medium grain size and a porphyritic texture with plagioclase megacryst. The Selijerdunit ranges from granodiorite to tonalite with a medium- to coarse-grained granophyric texture. The rocks studied display a relativelyhigh Na2O content,with a molecular A/CNK ratio less than 1.1, Na2O/ K2O ratio of ~2.06 and calc-alkaline affinity. They containmodal clinopyroxene, hornblende, magnetite and titanite, suggesting I-type characteristics for these rocks and formation in an activecontinental margin. Isotopic data (87Sr/86Sr39Ma= 0.704536-0.704860; e(Nd)39Ma= 2.2-3.9) from northwest Saveh intrusive rocks areplotted to the left of bulk silicate Earth. These ratios, together with geochemical data, suggest that the parent magmas of the rocksstudied might be generated by crystal fractionation of arc basalts in crustal magma chambers, coupled with some lower crustalassimilation prior to silica enrichment, to form quartz monzogabbros. Consequently, granodiorites formed dominantly by crystalfractionation from evolved parental magmas that ascended into the upper crustal magma chambers.
Mineral resources and mining are the pillars of development in any country. Mining development must be performed based on the pillars of sustainable development to prevent the damage to water, soil, air, plants, wildlife and social life of local communities by exploiting valuable minerals and economic development. Lack of attention towards the pillars of sustainable development in the long-term can turn into serious damages to environment and social life of local communities. There would probably be needed to spend multiple times more than the added value earned by the mineral production in order to recompense the environmental and social damages caused by unauthorized mining. Therefore, from the late 2001 the beginning of mining activities in the Bauxite mine of the village of Tash has caused challenges for the environment, natural resources and social issues. Some of the most important of which are loss of water reserves in the region, the pollution of ground and surface waters, soil erosion, susceptibility of the region to dust, loss of vegetation and rangelands, the endangerment of wildlife, flooding due to inappropriate tailings depot. This paper addresses to the causes of these pollutions and how to stop further damages of the process.
The Roshtkhar area is located in the Khaf-Kashmar-Bardaskan volcano-plutonic belt to the northeastern Iran along the regional E–W trending Dorouneh Fault, northeastern of the Lut Block. There are several outcrops of subvolcanic rocks occurring mainly as dikes in the area, which intruded into Cenozoic intrusive rocks. We present U–Pb dating of zircons from a diabase dike and syenite rock using LA-ICP-MS that yielded an age of 1778 ± 10 Ma for the dike, indicating this Cenozoic dike has zircon xenocrysts inherited from deeper sources; and 38.0 ± 0.5 Ma, indicating an Late Eocene crystallization age for the syenite. Geochemically, the dikes typical of high-K calc-alkaline to shoshonitic magmas. Petrographic observations and major and trace element variations suggest that diabase melts underwent variable fractionation of clinopyroxene, olivine, and Fe-Ti oxides and minor crustal contamination during the differentiation process. Primitive mantle-normalized multi-element diagrams display enrichment in LILE, such as Rb, Ba, Th, U, and Sr compared to HFSE, as well as negative anomalies of Nb, Ta, P, and Ti, suggesting derivation from subduction-modified mantle. Chondrite-normalized REE plots show moderately LREE enriched patterns (<3.83 LaN/YbN <8.27), and no significant Eu anomalies. Geochemical modelling using Sm/Yb versus La/Yb and La/Sm ratios suggests a low-degree of batch melting (~1–3%) of a phlogopite-spinel peridotite source to generate the mafic dikes. The geochemical signatures suggest that the Roshtkhar mafic dikes cannot be related directly to subduction and likely resulted from melting of upper mantle in an extensional setting where the heat flow was provided from deeper levels. These dikes presumably derived the zircon xenocrysts from the assimilation of upper crust of Gondwanian basement. Processes responsible for partial melting of metasomatized lithospheric mantle and post-collision magmatism in NE Iran was triggered by heating due to asthenospheric upwelling in an extensional setting.
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