Horoman peridotite - compositional layering

For a general description of the Horoman peridotite body, see the post of July 2, 2013: "Horoman Peridotite ... - olivine microfabfric".

As shown on the map by Niida (1974) the rocks of the Horoman peridotite body are mainly plagioclase lherzolite, lherzolite, and dunite, as well as small amounts of gabbro and pyroxenite. Interlayered plagioclase lherzolite and dunite account for almost all of the bedrock surface in the northern three-quarters of the body, from south of Mt. Apoi to north of Mt. Pinneshiri, a distance of about seven kilometers. Thus, these two rock types dominate the lithology of the body. The remaining southern one-quarter of the surface is mainly interlayered lherzolite and dunite. You can download Prof. Niida's 1984 paper, including the dramatic geological map, from: http://eprints.lib.hokudai.ac.jp/dspace/handle/2115/36729  This will take you to the abstract of Dr. Niida's paper in HUSCAP, Hokkaido University Scholarly and Academic Papers. To download the entire PDF (11.4 mb), click  the "View/Open" box. The map is on the fourth page (page 200).

Compositional layering in the upper zone of the Horoman peridotite complex.
This is the best picture of layering in the Horoman complex that I have seen. If
you have a better one, send it to me and I'll post it. If you happen to be the man
in the photograph, please let me know so I can identify you.
Photo: geomantleh1 via lherzharz1.exblog.jp

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University students on a field trip in the Horoman peridotite complex. Layering is clearly
visible in the fallen rock at right. Photo: geomantleh1 via lherzharz1.exblog.jp

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REFERENCES

Niida, K., (1974), Structure of the Horoman Massif of the Hidaka Metamorphic Belt, Jour. Geol Soc. Japan; 80:1, p. 31-44. (In English)

Niida, K., (1984), Petrology of the Horoman Ultramafic Rocks in the Hidaka Metamorphic Belt, Hokkaido, Japan, Journal of the Faculty of Science, Hokkaido University. Series 4, Geology and mineralogy, 21(2):197-250. (In English)

Niida, K.,  and Takazawa, E. (2007), Origin of Layering observed in the Horoman Peridotite Complex, Japan, Jour. Geol Soc. Japan; 113:Supplement, p. 167-184. (In Japanese except for some of the figure labels)

Takahashi, N., (1991), Origin of three peridotite suites from the Horoman peridotite complex, Hokkaido, Japan; Melting, melt segregation, and solidification processes in the upper mantle; Jour. Min.Petr. Econ. Geol.,  86: p. 199-215. (In English)