Xenolith

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Related to Xenoliths: Phreatomagmatic, Phenocrysts, Plutons

xenolith

[′zēn·ə‚lith]
(petrology)
An inclusion in an igneous rock which is not genetically related, such as an unmelted fragment of country rock. Also known as accidental inclusion; exogenous inclusion.

Xenolith

 

a rock fragment that is foreign to the igneous rock in which it occurs. If the igneous rock enclosing the xenolith solidified at a great depth, then the xenoliths are usually greatly altered fragments of those rocks into which the magma intruded. But if the xenoliths are enclosed in the lava of a volcano, then they are usually fragments from the walls of the volcanic vent. The dimensions of the xenoliths vary greatly; they may be as small as individual crystals and their fragments, which can be distinguished only under a microscope (xenocrysts), or as large as several dozens or hundreds of meters.

References in periodicals archive ?
The presence of the granite xenoliths in the doleritic rock suggests that the latter is younger.
The Bogan Brook Granodiorite is a medium to dark grey, fine- to medium-grained, equigranular biotite or hornblende-biotite granodiorite displaying a weak fabric and containing numerous xenoliths and enclaves of paragneiss or migmatized paragneiss (Fig.
1988: Explosive interaction of magma with ground water: insights from xenoliths and geothermal drillings.
The diamonds are produced either by mining the rock, which contains the xenoliths or by mining the soils and sediments that formed as the diamond-bearing rock weathered away.
Unit G is composed of sparsely to moderately porphyritic basalt, with gabbroid xenoliths, plagioclase glomerocrysts and olivine microphenocrysts.
Megacrysts and/or mafic xenoliths are usually absent but clustering of clinopyroxene microphenocrysts is relatively frequent.
Pellet-rich tuffistic (volcaniclastic) serpentine kimberlite breccia occupies the southern fissure appendage of the pipe which is extremely rich in mantle xenocrysts, megacrysts and xenoliths.
On your way to the lake, look for xenoliths --fragments of ancient dark rock that have been "absorbed' over time into the now dominant granite.
The emplacement of the volcanic edifice affected the marllimestone rhythmite and oncolitic limestones, promoting in situ mineralogical changes as well as the genesis of white carbonate clasts incorporated into the phreatomagmatic breccia and xenoliths in the lamproites.
Mesozoic A-Type Granitoids and Xenoliths in the Lujiang-Zongyang Area, Anhui Province: Significance in Post-Collisional Magmatic Evolution.