scholarly journals Relations between chemical composition of granitic rocks and metallization in the Outer Zone of Southwest Japan

1977 ◽  
Vol 9 ◽  
pp. 67-74 ◽  
Author(s):  
N. Oba ◽  
◽  
M. Miyahisa ◽  
Keyword(s):  
Chemical Composition ◽  
Outer Zone ◽  
Granitic Rocks ◽  
Southwest Japan

scholarly journals K-Ar ages of granitic rocks from the Outer Zone of Southwest Japan

1967 ◽  
Vol 1 (3) ◽  
pp. 131-137 ◽  
Author(s):  
Ken Shibata ◽  
Tamotsu Nozawa
Keyword(s):  
Outer Zone ◽  
Granitic Rocks ◽  
Southwest Japan

scholarly journals Two Contrasting Provenances of Prehistoric Obsidian Artifacts in South Korea: Mineralogical and Geochemical Characteristics

2019 ◽  
Vol 5 (1) ◽  
pp. 106-120 ◽  
Author(s):  
Yong-Joo Jwa ◽  
Seonbok Yi ◽  
Mi-Eun Jin ◽  
Ga-Hyun Hwang
Keyword(s):  
Rare Earth ◽  
Chemical Composition ◽  
Korean Peninsula ◽  
Parental Magma ◽  
Geochemical Characteristics ◽  
The Other ◽  
Southwest Japan ◽  
Glassy Material ◽  
Host Matrix ◽  
Fe Oxides

AbstractTwo provenances – Mount Baekdusan near Sino-Korean border and Kyushu of southwest Japan – are well known for Korean prehistoric obsidian artifacts. We examined the mineralogical and geochemical characteristics of the Baekdusan obsidians and the Kyushu obsidians. Though obsidians are of glassy material, microlites are easily found in the host matrix. Fe-oxides are the most abundant microlite phase, with a lesser amount of clinopyroxene, feldspar, and biotite. It is notable that the texture and chemical composition of the microlites in the Baekdusan obsidians are quite different from those in the Kyushu obsidians. Clinopyroxene in the Baekdusan obsidians occurs as oikocryst enclosing smaller Fe-oxides, and has the composition of hedenbergite to augite. On the other hand, clinopyroxene in the Kyushu obsidians is compositionally of clinoferrosilite, and shows intergrowth and/or overgrowth textures with Fe-oxides. Feldspar microlites in the Baekdusan obsidians are generally of sanidine to anorthoclase, whereas those in the Kyushu obsidians of oligoclase. Biotite microlites are often found in the Kyushu obsidians, but absent in the Baekdusan obsidians. Also, there exist prominent geochemical contrasts between the Baekdusan obsidians and the Kyushu obsidians. At the similar SiO2 range of 74 to 78 wt.% the host glasses of the Baekdusan obsidians have higher contents of TiO2, total FeO, K2O, Nb, Hf, Zr, Ta, Y and rare earth elements (REEs) than those of the Kyushu obsidians. The overall mineralogical and geochemical contrasts for the Baekdusan and Kyushu obsidians seem to reflect different parental magma composition and crystallization environment. This distinction can be used to establish the provenance of the obsidian artifacts from the prehistoric sites in the Korean Peninsula as well as contiguous areas such as China, Japan, and Russia.

scholarly journals Petrology and dating of the Permian lamprophyres from the Malá Fatra Mts. (Western Carpathians, Slovakia)

2018 ◽  
Vol 69 (5) ◽  
pp. 453-466 ◽  
Author(s):  
Ján Spišiak ◽  
Lucia Vetráková ◽  
David Chew ◽  
Štefan Ferenc ◽  
Tomáš Mikuš ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Granitic Rocks ◽  
Western Carpathians ◽  
Magma Ascent ◽  
Crustal Material ◽  
Calc Alkaline ◽  
Nd Isotopes ◽  
Granitoid Rocks ◽  
Alkaline Lamprophyres

Abstract Calc–alkaline lamprophyres are known from several localities in the Malá Fatra Mountains. They form dykes (0.5–3 m) of varying degree of alteration that have intruded the surrounding granitoid rocks which are often incorporated xenoliths. Clinopyroxenes (diopside to augite), amphiboles (kaersutitic), biotites (annite) and plagioclases are major primary minerals of the dykes, accessory minerals include apatite, ilmenite, rutile, pyrite, chalcopyrite, and pyrrhotite. Apatite has a relatively low F, but increased Cl content compared to typical apatite from lamprophyres or magmatic apatite from granitic rocks in the Western Carpathians. The chemical composition of the lamprophyres indicates their calc–alkaline character, but affinity to alkaline lamprophyres is suggested by the Ti enrichment in clinopyroxene, amphibole and biotite. According to modal classification of the minerals, the studied rocks correspond to spessartite. The differences in the chemical composition of the rocks (including Sr and Nd isotopes) probably result from the contamination of primary magma by crustal material during magma ascent. The age of the lamprophyres, based on U/Pb dating in apatite, is 263.4 ± 2.6 Ma.

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