https://repository.kopri.re.kr/handle/201206/9803 2026-04-17T23:51:14Z https://repository.kopri.re.kr/handle/201206/12088 Title: Geology, mineralogy and stable isotope geochemistry of the Dzuunmod area in northern Mongolia: Constraints for gold ore genesis and sources Authors: Kim, Yeongmin; Lee, Insung; Oyungerel, Sodnom; Altanzul, Chikalov; Jargal, Luvsanchultem; Kim, Nak Kyu Abstract: The Dzuunmod area located in the North Khentii Gold belt (NKGB) of northern Mongolia includes lode gold deposits such as Gatsuurt, Sujigtei and Boroo with several minor gold deposits and occurrences. They show similar hydrothermal alteration assemblages (sericitic, siliceous and potassic) and ore mineral assemblages (pyrite and arsenopyrite with minor amount of galena, sphalerite and chalcopyrite). Gold occurs as native form and invisible gold in pyrite and arsenopyrite. The major sulfide minerals are separated into earlier non-auriferous stage and later auriferous grains containing invisible gold. Native gold postdates the major sulfide mineralization. Gold and arsenic content of pyrite grains indicates that gold exists mainly as solid solution form (Au+1) in the Gatsuurt and Boroo deposit whereas gold nanoparticle (Au0) is present in the Sujigtei deposit. High Co/Ni and Mo/Ni ratios of pyrite grain suggest a post-sedimentary or hydrothermal origin and the ore-forming fluid was significantly affected by fluid-host rock interactions during mineralization processes. Large variation of δ34S values of pyrite and arsenopyrite from 2.6‰ to 17.2‰ indicates that sulfur seems to be mainly derived from a source with heterogeneous sulfur isotope composition, even though the role of magmatic sulfur as one of possible sulfur sources cannot be ruled out. Consistent with geological evidence, relatively positive δ34S values suggest that sulfidation plays an important role for gold and sulfide precipitation. The calculated δ18O values of hydrothermal fluid from the measured δ18O values of quartz samples (from 14.7‰ to 17.7‰) indicate a metamorphic derivation of ore-forming fluid. Gold mineralization processes in the Dzuunmod area seem to occur several times by multiple input of hydrothermal fluid and fluid-host rock interactions. The gold deposits in the Dzuunmod area are considered to be orogenic gold type influenced by fluid-host rock interactions in the deposit area. 2020-03-01T00:00:00Z https://repository.kopri.re.kr/handle/201206/13353 Title: Single-grain (U-Th)/He ages from Martian meteorites(Zagami, ALHA77005) and Acapulcoites (TIL07012,EET14074): Implications to their thermal histories Authors: 민경원 2019-09-06T00:00:00Z https://repository.kopri.re.kr/handle/201206/10871 Title: Occurrence of ice-rafted erratics and the petrology of the KR1 seamount trail from the Australian-Antarctic Ridge Authors: Yi, Sang-Bong; Lee, Mi Jung; Park, Sung Hyun; Han, Seung Hee; Yang, Yun Seok; Choi, Hakkyum Abstract: A multi-disciplinary study of the KR1 segment of the Australian-Antarctic Ridge has been conducted since 2011. We present geochemical and age dating results for samples dredged from three sites on the KR1 seamount trail. The majority of the samples are alkaline ocean island basalts with subdominant enriched tholeiites. The samples from the DG05 bathymetric depression include ice-rafted erratics from Antarctica, which consist of gabbro, diabase, various granitoids, volcanic rocks such as trachyte and rhyolite and deformed or undeformed sedimentary rocks. The main provenance of glacial erratics is considered to be the the Ross Sea region. However, Carboniferous to Cretaceous ages of erratics indicate that some of these may originate from the western regions of West Antarctica. Based on the size and topography of the volcanic features and geochemical characteristics of the alkaline ocean island basalts (La/SmN = 2.62-3.88; Tb/YbN = 1.54-2.67) and the enriched tholeiites, the KR1 seamount trail is interpreted to be a submarine hotspot chain that is the product of alkaline volcanic eruption and seafloor spreading. 2019-08-01T00:00:00Z https://repository.kopri.re.kr/handle/201206/11441 Title: Petrological Study of Antarctic meteorites Authors: Choi, ByeonGak 2019-07-29T00:00:00Z