• Korean Journal of Plant Resources
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• v.35 no.4
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• pp.515-540
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• 2022

The ultramafic serpentine area, the small size of 3 km², remains in Andong, South Korea. We researched the ecological flora and its structure through the 12 times field investigations from 2013 till 2018. A total of 527 taxa including the previously recorded species-list was analyzed. Among them, 331 taxa were filed up as a real flora of the serpentine area. On the vegetation land-cover map describing a characteristic aspect of species distribution, a matrix of the sparse forest by Pinus densiflora and the grassland patches were the main landscape. The study area was acknowledged as a home for the ethnobotanical species and grassland components, and clearly distinctive from the non-serpentine area. The original habitat was too deteriorated by introducing the non-site soils and exotic plants. Conclusionally a designation of a protected area and the long-term ecological monitoring were requested.

• The Journal of the Petrological Society of Korea
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• v.18 no.3
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• pp.223-236
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• 2009

Ultramafic xenoliths from southeastern part of Jeju Island can be grouped into two types: Type I and Type II. Type I xenoliths are magnesian and olivine-rich peridotite (mg#=89-91), which are commonly found at the outcrop. Most previous works have been focused on Type I xenoliths. Type II xenoliths, consisting of olivine, orthopyroxene and clinopyroxene with higher Fe and Ti components (mg#=77-83) and lower Mg, Ni, Cr, are reported in this study. They are less common with a more extensive compositional range. The studied Type II xenoliths are wehrlite, olivine-clinopyroxenite, olivine websterite, and websterite. They sometimes show ophitic textures in outcrops indicating cumulate natures. The textural characteristics, such as kink banding and more straight grain boundaries with triple junctions, are interpreted as the result of recrystallization and annealing. Large pyroxene grains have exsolution textures and show almost the same major compositions as small exsolution-free pyroxenes. Although the exsolution texture indicates a previous high-temperature history, all mineral phases are completely reequilibrated to some lower temperature. Orthopyroxenes replacing clinopyroxene margin or olivine indicate an orthopyroxene enrichment event. Mineral phases of Type II are compared with Type I xenoliths, gabbroic xenoliths, and the host basalts. Those from Type II xenoliths show a distinct discontinuity with those from Type I mantle xenoliths, whereas they show a continuous or overlapping relation with those from gabbroic xenoliths and the host basalts. Our petrographic and geochemical results suggest that the studied type II xenoliths appear to be cumulates derived from the host magma-related system, being formed by early fractional crystallization, although these xenoliths may not be directly linked to the host basalt.