Laf-117, Typical rock forming at oceanic-oceanic divergent margins
Item
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Title
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Laf-117, Typical rock forming at oceanic-oceanic divergent margins
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Description
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This mafic rock is very typical to oceanic-oceanic divergent margins and intra-plate volcanoes. Both the hand sample and thin section display phaneritic texture. The most recognizable minerals within this rock are 50% Feldspars, 30% Augite, and 20% Olivine. Due to Olivine making up more than 10% of the overall composition, the rock can be called an Olivine Gabbro. Based on the intergrain relationships within the thin section it is evident that Augite and Olivine formed first. The large embayments within the Augite and the surrounding Feldspar grains suggest resorption within the melt. The rock likely formed near an intra-plate volcano because as it rose through the mantle Augite and Olivine first crystallized, due to their mafic composition. As the location came closer to the surface the silica content increased and Feldspar grains demanded similar ions within the Augite crystals. This is what caused textures due to resorption of the crystals.
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Subject
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A highly mafic basaltic rock
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Creator
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Ryan Sanders
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Source
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Lafayette College Petrology Teaching Collection
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Date
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4/2/15
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Rights
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Lafayette College Department of Geology and Geo-Sciences
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Identifier
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Laf-117
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Mediator
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Tamara Carley, carleyt@lafayette.edu
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Rights Holder
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Lafayette College Geology Department
