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.
Xenoliths are rock fragments or inclusions that are torn from the sides of lava tubes and caught up in magma as it moves through Earth.
The xenolith rocks are slightly heavier on average, but their distribution of density overlaps that of the matrix.
Kaersutite and pargasite are amphiboles typical of alkaline basic rocks and metasomatised mantle xenoliths and their formation occurs early during the crystallization process (e.
The three additional representative samples reported upon, referenced as Matrix, Xenolith and ROM also continue to confirm and support the theory that most of the diamonds in this area are preferentially contained in the Xenolith portion of the rock outcrop.
6), with block structure comprising numerous xenoliths (up to ~100 m long) of pervasively recrystallised Unity anorthosite hosted by igneous-textured leucogabbronorite-leuconorite (Fig.
Research eventually established that diamonds come from the included bodies in kimberlite, not from the groundmass; that these bodies are xenoliths, not phenocrysts; and that the xenoliths (and, therefore, the diamonds) are much older than the kimberlite which carried them to the surface.
Hill and Ross (1983) concluded that the age of 238 [+ or -] 26 Ma obtained from a granulite xenolith represented the cooling age of the dyke, and is in close agreement with the 246 [+ or -] 4.
Some of them entrain deep crustal and mantle xenoliths to the surface, providing the only direct rock samples of the lithosphere available to us.
Albite occurs abundantly in fractures and as drusy coatings on altered granitic xenoliths in the Coal Hill vein.
1994): Composition and Sm-Nd isotopic data of the lower crust beneath San Luis Potosi, central Mexico: evidence from granulite-facies xenolith suite.
The nature of the subcontinental lithospheric mantle (SCLM) of the Slave is particularly well defined through geophysical and xenolith data.