2024-03-28T15:14:57Z
https://nagoya.repo.nii.ac.jp/oai
oai:nagoya.repo.nii.ac.jp:00025216
2023-01-16T05:08:16Z
367:368:369:2061
Geochemistry of the Permian–Triassic volcano-plutonic rocks in the Oyut-uul area, northeast of Darkhan, Mongolia : Magmatism at southern margin of Siberian continent
TSUKADA, Kazuhiro
75279
PUREVSUREN, Nemekhbayar
75280
NURAMKHAAN, Manchuk
75281
GANTUMUR, Onon
75282
HASEGAWA, Hitoshi
75283
YAMAMOTO, Koshi
75284
Late Paleozoic–Early Mesozoic
adakites
southern margin of Siberian continent
Mongolia
2018-03-01
The geochemistry of the Late Paleozoic–Early Mesozoic volcano-plutonic rocks of northern Mongolia is a key factor to understand the subduction-related magmatism at the southern margin of “Siberian continent (Siberian craton + accreted geologic units).” Many studies have been carried out in the volcano-plutonic rocks; however, fundamental questions on its detail petrogenesis still remain unanswered. This paper describes the geochemistry of the Permian–Triassic volcanoplutonic rocks at the Oyut-uul area, northeast of Darkhan City, Mongolia. The mid-ocean ridge basalt (MORB)-normalized multi-element pattern (spidergram) for the examined rocks shows an enrichment of large-ion lithophile elements (LILE) against high-field-strength elements (HFSE) and rare earth elements (REE), with clear negative Nb anomaly to suggest an arc-related igneous activity. The most data are plotted in the calc-alkaline field in the SiO2 vs. FeO*/MgO diagram. It is, thus, concluded that the examined rocks are of calc-alkaline series formed at an arc environment. The present samples, 53– 78 wt.% SiO2, high Al2O3 and Sr concentrations, high La/Yb ratio, and low K2O/Na2O ratio, have adakitic nature derived from oceanic slab-melt. They are quite similar to the marginal facies of the Kitakami adakitic granite of Japan in Sr/Y-Y relationship, MgO concentration, spidergram, and REE chondrite-normalized pattern. It is considered that the marginal facies of the Kitakami adakitic granite was resulted from interaction between the slab-melt and mantle peridotite/lower crustal amphibolite during their ascent. The Oyut-uul rocks might be also derived from oceanic slab-melt interacted with mantle peridotite/lower crustal amphibolite.
departmental bulletin paper
名古屋大学博物館
2018-03-01
名古屋大学博物館報告
33
15
30
1346-8286
eng