نتایج جستجو برای: mafic magma
تعداد نتایج: 8846 فیلتر نتایج به سال:
Over the last several hundred years, Stromboli has been characterized by steady-state Strombolian activity. The volcanic products are dominated by degassed and highly porphyritic (HP-magma) black scoria bombs, lapilli and lava flows of basaltic shoshonitic composition. Periodically (about one to three events per year), more energetic explosive eruptions also eject light coloured volatile-rich p...
The Bushveld Complex formed by the crystallization of successive basaltic magmatism may be of the order of several million years. For example, the Columbia River Basalts (Hooper, injections of magma, which were sufficiently closely spaced in time that each previous magma had not cooled and differentiated 1988) were erupted in the period 17–12 Ma, with minor eruptions for a further 5 my, althoug...
The Piedade Granite (approximately 600 Ma) was emplaced shortly after the main phase of granite magmatism in the Agudos Grandes batholith, Apiaí-Guaxupé Terrane, SE Brazil. Its main units are: mafic mineral-rich porphyritic granites forming the border (peraluminous muscovite-biotite granodiorite-monzogranite MBmg unit) and core (metaluminous titanite-bearing biotite monzogranite BmgT unit) and ...
[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...
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...
Xenoliths of metamorphic country rocks are locally abundant within breccia sequences in gabbroic to troctolitic rocks of the Voisey's Bay Intrusion, Labrador, Canada. Thermochemical interaction with mafic magma has produced restite assemblages in the xenoliths that are composed of Ca-rich plagioclase, corundum, hercynite and minor magnetite. Hercynite was produced as a result of the breakdown o...
Large igneous provinces (LIPs) form in both oceanic and continental settings by the emplacement and eruption of voluminous magmas ranging from basalt to rhyolite in composition. Continental flood basalt provinces are the best studied LIPs and consist of crustal intrusive systems, extensive flood lavas and ignimbrites, and mafic volcaniclastic deposits in varying proportions. Intrusive rocks are...
In order to explore the materials’ complexity induced by bubbles rising through mixing magmas, bubbleadvection experiments have been performed, employing natural silicate melts at magmatic temperatures. A cylinder of basaltic glass was placed below a cylinder of rhyolitic glass. Upon melting, bubbles formed from interstitial air. During the course of the experimental runs, those bubbles rose vi...
Crystallization coupled with gravity removal of depleted interstitial melt has long been recognized as a mechanism of magma differentiation. Similarly, heat released by synplutonic basaltic magma intrusions has long been recognized as capable of driving convection in granite chambers. Direct evidence of these processes has seldom been described in granites. In the Tavares pluton, we mapped a nu...
: Despite that, in the Alvand complex, the mafic-intermediate rocks (gabbros, diorites and tonalites) are mostly older than felsic rocks (granodiorites and monzogranites), and mineralogical and geochemical discontinuity is seen between them, there are evidence that indicate they have sometimes been co-existed. With the studies on field relationship of rocks, xenocrysts assemblages, synplutonic ...
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