نتایج جستجو برای: mafic composition
تعداد نتایج: 261231 فیلتر نتایج به سال:
The island of Syros consists largely of possibly-repeated sequences of glaucophane-bearing calcareous schists, mafic schists, dolomite marbles, and calcite marbles containing abundant aragonite pseudomorphs (Dixon, 1969; Hecht, 1984). Several discrete, fault-bounded packages of blueschist/eclogite-facies mafic rocks with minor serpentinite are also found on the island. Although the mafic rocks ...
[1] High‐resolution compositional data from Moon Mineralogy Mapper (M) for the Moscoviense region on the lunar farside reveal three unusual, but distinctive, rock types along the inner basin ring. These are designated “OOS” since they are dominated by high concentrations of orthopyroxene, olivine, and Mg‐rich spinel, respectively. The OOS occur as small areas, each a few kilometers in size, tha...
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 ...
The ChemCam instrument, which provides insight into martian soil chemistry at the submillimeter scale, identified two principal soil types along the Curiosity rover traverse: a fine-grained mafic type and a locally derived, coarse-grained felsic type. The mafic soil component is representative of widespread martian soils and is similar in composition to the martian dust. It possesses a ubiquito...
Apatite minerals of I-type Zouzan granitoids and typical garnet-bearing S-type granites have been analyzed by electron microprobe to define trace element concentrations and compare them in different granites. Zouzan granites are composed of apatites with lower Fe, Mn, Na and HREE and higher REE and ∑REE relative to S-type ones. Trace elements abundances of apatite often vary with some parameter...
One of the characteristic features of Ordovician tectonism in the east Lachlan Fold Belt is the occurrence of calcalkaline to shoshonitic basalts, which have been recognised as part of an intraoceanic arc environment (Glen et al. 1998), consistent with early tectonic interpretations (Oversby 1971; Scheibner 1973). Aside from typical traceelement abundances of intraoceanic arcs, critical evidenc...
Major overturn within a magma chamber can bring together felsic and mafic magmas, prompting de-volatilisation and acting as the driver for Plinian eruptions. Until now identification of mixing has been limited to analysis of lavas or individual crystals ejected during eruptions. We have recovered partially developed cumulate material ('live' cumulate mush) from pyroclastic deposits of major eru...
[1] We investigated the continuous spectral features of fresh craters on the Moon accompanied by distinctive bright rays, with cavity diameters between 8 and 24 km.We used the data from the Spectral Profiler onboard SELENE (Kaguya) to gain a better understanding of the composition of the lunar highland crust. We found that the observed spectra exhibited strong symmetric absorption around 1 mm a...
There is overwhelming and incontrovertible petrological and geophysical evidence for the significant role played by mantle-derived mafic magma in the generation and growth of continental crust. Likewise, intrusion of mafic magmas beneath or into continental crust is very likely the major source of enthalpy that drives intracrustal differentiation. A simple dynamical model has been constructed t...
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...
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