نتایج جستجو برای: mafic rocks
تعداد نتایج: 23127 فیلتر نتایج به سال:
منطقه قوشچیٌ در شمال غرب ایران شامل طیف وسیع سنگ شناسی از گابرودیوریت تا آلکالی گرانیت است که در بخش هایی در هم نفوذ کرده و حجم های مختلفی از آنکلاوهای مافیک را شکل داده و یا در برخی موقعیت ها با هم ادغام شده و سنگ حدواسط را تشکیل داده است. آنکلاوهای موجود با ترکیب سنگ شناسی گابرودیوریت دانه ریز بوده، به طوری که با نزدیک شدن به حاشیه آنکلاو ریز دانه تر شده و براثر تجمع کانی های مافیک در حاشیه ...
East-northeast extension ca. 24 Ma at Rodeo and Nazas, México, was accompanied by eruption of hawaiites, marking some of the earliest intraplate-type mafic alkalic volcanism associated with development of the southern Basin and Range Province. An earlier extensional pulse, 32.3–30.6 Ma, concurrent with subductionrelated rhyolitic volcanism of the Sierra Madre Occidental, is the earliest establi...
Delbar metamorphic complex composed of schists, amphibolites and gneisses with migmatitic views belong to Neoprotrozoiec (Precambrian) is located in southeast of Shahrood. Debar metamorphic complex crosscut by at least three series of mafic dikes, with different ages (Precambrian, Jurassic and Tertiary). Jurassic dikes intruded in Precambrian metamorphic complex and upper Triassic - lower Juras...
Oxygen isotope data are reported for clinopyroxene phenocrysts from volcanic rock samples from Filicudi island, Italy, with the aim of investigating mechanisms of magma evolution and mantle source characteristics in a continental arc volcano. Filicudi rocks range from calc-alkaline basalt to high-K andesite and dacite. Mafic rocks have MgO 6-7 wt%, Mg# 60, Ni < 50 ppm and Cr < 200 ppm, suggesti...
The Bozjani copper deposit is located about 30 km west of Fariman city, Khorasan Razavi Province. Host rocks to mineralization are mostly pridotites and basalts of Fariman ophiolitic sequence. Ore body consists of two parts: lower and upper. Lower part has formed a stringer of primary sulfides as stockwork, veinlets, and disseminated. Uppermost part has lenticular shaped dominated by ribbon-lik...
On the basis of petrographic observations and electron microprobe analyses data set on major and minor minerals from ultramafic- mafic rock suite with komatiitic to picritic - tholeiitic affinity, East of Fariman, we have investigated some of the petrological features of their parental magmas and condition of minerals crystallization. Major minerals in ultramafic rocks show various disequilibri...
The carbonatite problem can be stated as follows: Are carbonatites genetically related to sedimentary carbonate rocks, or are they derived from a silicate parent material? The isotopic composition of strontium in 21 carbonatites and in several related alkaline rocks has been determined. The mean Sr87/$r86 ratio for the 21 carbonatites is 0.7065 + 0.0003. The Sr87/sr86 ratios of sedimentary carb...
The Piranshahr ophiolitic complex is located in NW Iran, and at north west of the Piranshahr town. Tectonically, the NW Piranshahr ophiolitic complex is severely mélanged and the boundary of different units in this complex is undistinguishable. Piranshahr ophiolite includes ultramafic, mafic, sedimentary and metamorphic rocks. Mafic rocks with basalt and diabase compositions are exposed in seve...
[1] Theoretical geochemical modeling has been used to evaluate the formation conditions of amorphous silica during aqueous alteration of typical Martian igneous rocks at 0 C. The models show that some silica can form during low-temperature alteration of mafic to ultramafic rocks over a large range of pH and water/rock ratios. Silica-dominated deposits, like those found at the Columbia Hills in ...
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