| In addition to scoria and ash, other volcanic ejecta include blocks, bombs, and xenoliths. |
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| To date, the only described mantle xenoliths from NW Namibia occur in an alnoite diatreme emplaced in the Mesozoic Okenyenya alkaline complex. |
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| The basalt, inferred to be of Miocene age, appears to be an alkali basalt that contains xenoliths of ultramafic rocks up to a few centimeters in size. |
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| The granite contains abundant xenoliths of the country rock. |
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| However, rare xenoliths of sedimentary rocks occur in the granite. |
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| Partial melting models, isotopic studies and the petrology of entrained ultramafic xenoliths suggest that many basanitic magmas are sourced in the asthenosphere. |
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| If the magma has risen quickly from the source region of the volcano, the xenoliths may represent country rock from all levels of the crust through which it has travelled. |
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| The dykes and sheets sharply truncate structures in the wall rock gneisses and greenstones, and large wall-rock xenoliths may be completely engulfed by the intrusive sheets. |
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| Diamonds are most commonly associated with Archean subcontinental lithosphere but nanodiamonds were recently reported from mantle xenoliths in EM1like Hawaiian basalts. |
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| Lower crustal garnet granulite xenoliths from beneath the Kola-Karelian domain of the Fennoscandian Shield were brought to the surface in Devonian lamprophyre diatremes. |
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| None of the glass in these xenoliths can be directly related to metasomatism or any other process that occurred in situ in the mantle. |
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| Unit G is composed of sparsely to moderately porphyritic basalt, with gabbroid xenoliths, plagioclase glomerocrysts and olivine microphenocrysts. |
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| As a result, xenoliths are older than the rock which contains them. |
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| The later group contain more common basic microgranite xenoliths. |
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| Hornblende is found in some of the summit samples, as are small gabbroic, plagioclase-magnetite, and ultramafic xenoliths that may represent disaggregated cumulates. |
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| The outer archways, which were added later in 1907, are a pink, massive, coarse-grained, K-feldspar porphyritic biotite granite containing biotite psammite xenoliths. |
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| A similar situation with igneous rocks occurs when xenoliths are found. |
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| Xenoliths of dunite, peridotite and spinel lherzolite in basaltic lava flows are one example. |
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| Xenoliths in granodiorite of the Alta Stock, Little Cottonwood Canyon, Utah. |
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| Xenoliths and xenocrysts provide important information about the composition of the otherwise inaccessible mantle. |
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