نتایج جستجو برای: mafic rocks
تعداد نتایج: 23127 فیلتر نتایج به سال:
Article history: Received 6 October 2016 Accepted 29 January 2017 Available online 08 February 2017 Widespread Late Triassic granitoid rocks in the SouthQinling Belt (SQB) represent excellent subjects to study the geochemical and geodynamic evolution of magmatic rocks during the collision between the North China Craton and South China Block. In this study, we report new geological, geochemical,...
Introduction: The formation of the Nectaris basin is a key event defining the stratigraphy of the Moon. Its absolute age, therefore, is a linchpin for lunar bombardment history. Fernandes et al. [1] gave a thorough account of the history of different samples thought to originate in Nectaris, with the upshot being there is little agreement on what samples represent Nectaris, if any. We are revis...
u-pb ages obtained on zircons from the investigated migmatites place new constraints on the evolution of the crustal rocks in the takab area. shrimp u-pb dating of inherited zircon in the melanosome parts of mafic migmatites from the takab complex gives a discordant age with an upper intercept of 2961±72 ma (mswd=0.5) and a lower intercept of 24.2±5.7 ma (mswd=1.7). in the concordia diagram, th...
A wide range of plutonic rocks, ranging from mafic to felsic compositions, including various gabbros, diorites, tonalites, granodiorites, monzogranites, syenogranites and leucocratic granitoids, occur in the Alvand plutonic complex, Sanandaj-Sirjan zone, Iran. Age of this complex is middle Jurassic. In this complex, granitic and dioritic rocks occur as major constituents. Granites contain plagi...
Both Sangan and Tannurjeh magnetite deposits are Iron-oxides type. Geochemistry and petrography of source rocks at Tannurjeh and Sangan were studied in detail. The source rocks at Sangan are compused of quartz hornblende alkali syenite porphyry and quartz biotite-hornblende alkali syenite porphyry ; while The source rocks at Tannurjeh varies between hornblende quartz diorite porphyry and h...
The geochemical signatures like discordant variation of major and trace elements among felsic-intermediate and basic rocks and mafic enclaves of Malayer region on binary variation plots, decreasing values of FeOt, TiO2, MgO, MnO and CaO accompanied with increasing of SiO2 content from basic to felsic rocks, and decreasing Ni, Cr and Co with increasing SiO2 are considered as indications of mag...
Archean Quartzose Rocks at Akilia, Greenland Fedo and Whitehouse (1) presented data to support their hypothesis that granulite grade quartz magnetite rocks on the island of Akilia, southwest Greenland—which are conformably interposed with pyroxenite and hornblendite units that date from before 3830 million years ago (Ma) (2–4)—had a metasomatic ultramafic igneous origin. They offered that inter...
Amphibolites are one of the metamorphic rock units of Jandaq ophiolite and exposed in a considerable volume. These rocks are metamorphism products of basalts, pillow lavas and diabasic dikes of Jandaq ophiolite. Amphibolites contain amphibole, plagioclase, garnet, alkali feldspar (orthoclase), magnetite, biotite, muscovite, sphene, quartz, epidote and calcite minerals. These rocks contain very ...
Archean Quartzose Rocks at Akilia, Greenland Fedo and Whitehouse (1) presented data to support their hypothesis that granulite grade quartz magnetite rocks on the island of Akilia, southwest Greenland—which are conformably interposed with pyroxenite and hornblendite units that date from before 3830 million years ago (Ma) (2–4)—had a metasomatic ultramafic igneous origin. They offered that inter...
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