نتایج جستجو برای: tholeiite
تعداد نتایج: 69 فیلتر نتایج به سال:
Haleakala volcano on East Maui, Hawaii, consists of a tholeiitic basalt shield which grades into a younger alkalic series that was followed by a post-erosional alkalic series. Fresh, stratigraphically controlled samples from the three volcanic series were analyzed for major element abundances, Sr and Nd isotopic ratios and trace element (K, Rb, Sr, Ba, Th, Ta, Nb, REE, Hf, Zr, Sc, V, Cr, Co, Ni...
Abstract Cretaceous High Arctic large igneous province (HALIP) sub-alkaline magmatic rocks in Canada are mostly evolved (MgO 2–7 wt%), sparsely plagioclase + clinopyroxene ± olivine-phyric tholeiitic basalts. There were two main HALIP continental flood basalt (CFB) eruption episodes: 135–120 Ma (Isachsen Fm.) and 105–90 (Strand Fiord Fm.), both associated with cogenetic doleritic sills dykes. B...
introduction hornblende-bearing gabbroic rocks are quite common in subduction-related magmatic suites and considered to represent magmatic differentiation process in arc magmas (heliker, 1995; hickey-vargas et al., 1995; mandal and ray, 2012). the presence of hornblende as an important mineral phase in gabbroic rocks of subduction zone has been considered either as an early crystallizing minera...
افیولیت بیبی مریم بخشی از مجموعه افیولیتی نهبندان، به سن کرتاسه، در بخش شمالی پهنه گسلی نهبندان، شرق ایران، است. سنگ های مافیک این مجموعه شامل بازالت، دیاباز و گابرو هستند. نبود سنگهای دگرگونی رخساره شیستسبز، شیستآبی و آمفیبولیت، فقدان سنگهای کومهای پریدوتیتی با وجود فراوانی پریدوتیتهای گوشتهای، عدم مشاهده گابروی کومهای علیرغم فراوانی گابروی ایزوتروپ، نبود دسته دایکهای دیابازی به صور...
Abstract Oceanic island basalts and related magmatic rocks from Hawaii are derived a compositionally heterogeneous mantle plume. Here we describe how this heterogeneity results the transport of filaments specific composition in plume, representing relatively small volume (~15 %) interbedded inside dry peridotite mantle. Four types considered: sub-primitive mantle, ultralow-velocity zone, fertil...
This paper presents results of modelling reaction between peridotite and fractionating tholeiitic basalt in simple and complex silicate systems. Reactions are outlined in appropriate binary and ternary silicate systems. In these simple systems, the result of reactions between 'basalt' and 'peridotite' may be treated as a combination of Fe-Mg exchange and mass transfer reactions at constant Fe/M...
Continental flood basalts and mid-ocean ridge (MOR) tholeiitic basalts have distinctly different 14 3 Ndf1 44 Nd which may permit a priori distinctwn between '"continental" and "oceanic" igneous rocks. Initial 14 3 NdJI 4 4 Nd of continental igneous rocks through time fall on a Sm/Nd evolution curve with chondritic REE abundance ratio. These observations indicate that many continental igneous r...
Abstract 1-Introduction Bazman volcano is located on Chgay - Makran magmatic arc. This magmatic arc with east-west trend is 500 km long and 150 km wide and extends from southeastern Iran to southwestern Pakistan. Early evolution of the Makran zone from the upper Oligocene to the upper Miocene is characterized by turbidite sediments deposited on the oceanic crust. There are several quaternary...
Subduction zones are the primary regions on Earth today where crust recycling takes place, and through geological time they have been the sites of continent formation. Many of the key elements (e.g., Th, rare earth elements, Ba, and Be) that are important in understanding crustal growth are sequestered in the sedimentary column and in the uppermost oxidized portions of the volcanic section of o...
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