The Discovery of Phlogopite Exsolution Lamellae in Garnets of Eclogite Inclusions, Liaoning Province

In No. 50 kimberlite pipe of Fuxian County, Liaoning Province, an eclogite inclusion(nodule), which is extremely rare in kimberlites, was discovered and phlogopite exsolutionlamellae were found in garnets of the inclusion. Microscopic, TEM and energy spectral observa-tions and studies confirmed that these lamellae are phlogopite. They are colourless and acicularin section, generally 0.5-5μm in width and 10-100μm in length. Nevertheless, fine lamellae,0.05-0.1μm wide and 1-2μm long, are also well developed. Along 111] of the garnet, three setsof phlogopite lamellae show oriented arrangement approximately at angles of 60°-70°, indi-cating that these lamellae might be the product of exsolution from garnet as a result ofpressure-release when eclogite ascended from the relatively deep level to the relatively shallowlevel of the mantle. Tiny acicular exsolution minerals (or inclusions) are commonly found ingarnet and pyroxene in eclogite inclusions of kimberlites all over the world and it has been re-ported that the identified exsolution minerals include pyroxene and rutile. This is the first timethat phlogopite exsolution lamillae were found in eclogite inclusions in the world.

The Discovery of Phlogopite Exsolution Lamellae in Garnets of Eclogite Inclusions, Liaoning Province

In No. 50 kimberlite pipe of Fuxian County, Liaoning Province, an eclogite inclusion (nodule), which is extremely rare in kimberlites, was discovered and phlogopite exsolution lamellae were found in garnets of the inclusion. Microscopic, TEM and energy spectral observations and studies confirmed that these lamellae are phlogopite. They are colourless and acicular in section, generally 0.5–5 μm in width and 10–100 μm in length. Nevertheless, fine lamellae, 0.05–0.1 μm wide and 1–2 μm long, are also well developed. Along 111] of the garnet, three sets of phlogopite lamellae show oriented arrangement approximately at angles of 60° ?70°, indicating that these lamellae might be the product of exsolution from garnet as a result of pressure–release when eclogite ascended from the relatively deep level to the relatively shallow level of the mantle. Tiny acicular exsolution minerals (or inclusions) are commonly found in garnet and pyroxene in eclogite inclusions of kimberlites all over the world and it has been reported that the identified exsolution minerals include pyroxene and rutile. This is the first time that phlogopite exsolution lamillae were found in eclogite inclusions in the world.