Ordovician arc ophiolite, the Hayachine and Miyamori complexes, Kitakami Mountains, Northeast Japan: isotopic ages and geochemistry.
نویسندگان
چکیده
منابع مشابه
Ordovician ash geochemistry and the establishment of land plants
The colonization of the terrestrial environment by land plants transformed the planetary surface and its biota, and shifted the balance of Earth's biomass from the subsurface towards the surface. However there was a long delay between the formation of palaeosols (soils) on the land surface and the key stage of plant colonization. The record of palaeosols, and their colonization by fungi and lic...
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Mesozoic strata in the Cowhole Mountains, eastern Mojave block California, include 200–800 m of eolian quartz arenite (Aztec Sandstone) overlain by more than 575 m of silicic ignimbrites, lava flows, and minor sedimentary rocks (Cowhole volcanics). U-Pb zircon geochronologic data on a crystal-rich dacite lava flow in the Aztec Sandstone indicate that the sandstone is Middle Jurassic and is ther...
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منطقه مورد مطالعه در 23 کیلومتری جنوب غرب شهرستاشاهرود قرار دارد که در نقشه 100000/1 شاهرود قرار گرفته است.ناحیه مورد مطالعه در تقسیمات ساختاری ایران بخشی از زون البرز شرقی است . در طی سنوزوئیک این زون به شدت تحت تأثیر فازهای کوهزایی آلپی قرار گرفته و فعالیت های آتشفشانی انوسن در قسمت های غربی آن دیده می شود . از نظر ترکیب سنگ شناسی منطقه مورد مطالعه متنوع و بیشتر شامل سنگ های رسوبی مانند : آ...
15 صفحه اولPb, Nd, and Sr isotopic constraints on the origin of Miocene basaltic rocks from northeast Hokkaido, Japan: Implications for opening of the Kurile back-arc basin
Late Miocene (7–9 Ma) basaltic rocks from the Monbetsu-Kamishihoro graben in northeast Hokkaido have chemical affinities to certain back-arc basin basalts (referred to herein as Hokkaido BABB). Pb-, Ndand Sr-isotopic compositions of the Hokkaido BABB and arc-type volcanic rocks (11–13 Ma and 4–4.5 Ma) from the nearby region indicate mixing between the depleted mantle and an EM II-like enriched ...
متن کاملGeochemistry and clinopyroxene mineral chemistry of basalts in the Gasht-Masuleh area, Alborz Mountains
Basalts in the Gasht-Masuleh area crop out in the SW Fuman, Gilan Province, and are exposed in the Jurassic and Late Cretaceous units in this area. Whole rock chemistry shows that the rock samples have Mg numbers between 30 and 31.7. Rare earth element patterns (REE) indicate light REE (LREE) enrichment and heavy REE (HREE) depletion (LaN/YbN= 7.7-9.8). Nb, Ta and Ti negative anomalies in primi...
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ژورنال
عنوان ژورنال: GEOCHEMICAL JOURNAL
سال: 1992
ISSN: 0016-7002
DOI: 10.2343/geochemj.26.85