منابع مشابه
When the Continental Crust Melts
The continental crust is 41.4 km thick on average and covers 39% of the Earth’s surface. Information from the isotopic and trace element composition of >4-billion-yearold (Ga) zircon grains and the evolution of mantle isotopic reservoirs indicates that 75%, and possibly more, of the continental crust was created before 2.5 Ga (Harrison 2009; Belousova et al. 2010). Thus, the continental crust i...
متن کاملDifferentiation of the continental crust by relamination
a r t i c l e i n f o Crust extracted from the mantle in arcs is refined into continental crust in subduction zones. During sediment subduction, subduction erosion, arc subduction, and continent subduction, mafic rocks become eclogite and may sink into the mantle, whereas more silica-rich rocks are transformed into felsic gneisses that are less dense than peridotite but more dense than the uppe...
متن کاملContinental crust beneath southeast Iceland.
The magmatic activity (0-16 Ma) in Iceland is linked to a deep mantle plume that has been active for the past 62 My. Icelandic and northeast Atlantic basalts contain variable proportions of two enriched components, interpreted as recycled oceanic crust supplied by the plume, and subcontinental lithospheric mantle derived from the nearby continental margins. A restricted area in southeast Icelan...
متن کاملChemical differentiation of the Earth: the relationship between mantle, continental crust, and oceanic crust
The average chemical compositions of the continental crust and the oceanic crust (represented by MORB), normalized to primitive mantle values and plotted as functions of the apparent bulk partition coefficient of each element, form surprisingly simple, complementary concentration patterns. In the continental crust, the maximum concentrations are on the order of 50 to 100 times the primitive-man...
متن کاملsurvey on the rule of the due & hindering relying on the sheikh ansaris ideas
قاعده مقتضی و مانع در متون فقهی کم و بیش مستند احکام قرار گرفته و مورد مناقشه فقهاء و اصولیین می باشد و مشهور معتقند مقتضی و مانع، قاعده نیست بلکه یکی از مسائل ذیل استصحاب است لذا نگارنده بر آن شد تا پیرامون این قاعده پژوهش جامعی انجام دهد. به عقیده ما مقتضی دارای حیثیت مستقلی است و هر گاه می گوییم مقتضی احراز شد یعنی با ماهیت مستقل خودش محرز گشته و قطعا اقتضاء خود را خواهد داشت مانند نکاح که ...
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ژورنال
عنوان ژورنال: Proceedings of the Imperial Academy
سال: 1934
ISSN: 0369-9846,1881-1140
DOI: 10.2183/pjab1912.10.260