Phlogopite and Ti-Pargasite-Bearing Ultramafic Rocks From the Mikabu Zone, Central Japan

Abstract

Phlogopite-bearing ultramafic rocks (wehrlite, hornblende-clinopyroxenite) occur in the Mikabu zone of Sambagawa metamorphic belt, Japan. Phlogopites and their coexist ing minerals:olivine, diopside and titano-pargasite were analyzed by an electron microprobe. In the present paper the chemical characteristics of phlogopite and pargasite and the problem on the solid solution of Na-and K-phlogopite are discussed. Titano-pargasite and titano-phlogopite seem to have formed from a late-stage liquid trapped among olivine and clinopyroxene which crystallized from certain alkalic basaltic magma.

Upper-mantle amphiboles: a review

“…Broadly, there are two different types of such ultramafic rocks; (a) those formed by accumulation of marie phases in either concentrically zoned or layered igneous bodies; and (b) lens-shaped bodies of peridotite that have faulted contacts with surrounding rocks and which are interpreted as being inthrust, detached bodies of original upper-mantle peridotite that have been tectonically up-thrusted during plate collisions. Hornblende was reported as an intercumulus phase in peridotite from the Finero complex, northern Italy (Cawthorn, 1975) and kaersutite was regarded as the product of an intercumulus liquid in wehrlite ultramafic rocks from the Mikabu zone, central Japan (Inomata and Tazaki, 1974) and the northern Kanto mountains, central Japan (Tazaki and Inomata, 1974). Because this type of complex is crystallized at crustal levels, as witnessed by the presence of plagioclase in associated gabbros, it will not be considered further, and readers are referred to the review by Cawthorn (1975).…”

Titaniferous Phlogopite From the Green Rocks of the Paleozoic Terrain of the Minami-Noma Area, Tokushima Prefecture, Shikoku, Japan.

“…Miyashiro, 1965), which is supported by the fact that the metamorphic biotite contains usually less than 5 per cent of TiO2 (Kwak, 1968). Recent experimental results (Forbes and Flower, 1974), on the other hand, show that Ti-phlogopite is preserved at higher Inomata and Tazaki, 1974 …”

“…The relationship between the titan ium content and the Mg/(Mg+Fe) ratio of phlogopites of various origins are compiled in Figure 3, which indicates that the titanium content varies with the occurrence of the host rocks (Inomata and Tazaki, 1974) and that the phlogopite in question con tains as high titanium as those from per alkaline rocks. DISCUSSION Kaji et at.…”

“…(1973) have pointed out that the rocks from the Minami-noma area are of alkaline affinity, based on the chemistry of clinopyroxene. It has been ascertained that the titanium content of phlogopite relates with the origin of the host rocks (Inomata and Tazaki, 1974;Robert, 1975), then based on the analytical data of phlogopites from various literatures the structural formulae were recalculated based on O=22 and were compiled and plotted in Figure 3, which indicates that the phlogopite in question is one of the phlogopites containing the highest titanium and also one of the group containing highest Al+Fe and that the Minami-noma phlogopite has a chemical feature similar to that from peralkaline rocks. This mica may not be of metamorphic but ignious origin, because the temperature of the Sambagawa metamorphism is not so high (e.g.…”

Titano-Penninite From the Phlogopite-Bearing Ultramafic Rocks in the Ufu-San Ultramafic Body, the Mikabu Zone, Central Japan

“…Some of these ultramafic complexes contain a trace amount of phlogopite-bearing ultramafic rocks. In the previous paper the phlogopites from the Kurouchi-yama, the Tonmaku-yama and the Ufu-san ultra mafic bodies were described (Inomata and Tazaki, 1974;Tazaki and Inomata, 1974). These phlogopites are characterized by high titanium content but frequently altered into penninite and serpentine minerals.…”