• Nuclear Engineering and Technology
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• v.56 no.6
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• pp.2239-2246
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• 2024

The present study aimed to assess the radioactive hazards associated with the application of granitoid rocks in building materials. An HPGe spectrometer was used to detect the levels of the radioactive elements uranium-238, thorium-232, and potassium-40 in the granitoid rocks. The results showed that the levels of these elements were lower (38.32 < 33 Bq kg^-1), comparable (47.19-45 Bq kg^-1) and higher (992.26 ≫> 412 Bq kg^-1) than the worldwide limits for ²³⁸U, ²³²Th, and ⁴⁰K concentration, respectively. The exposure to gamma radiation of granitoid rocks was studied by various radiological hazard variables like the absorbed dose rate (D_air), the outdoor and indoor annual effective dose (AED_out and AED_in), and excess lifetime cancer risk (ELCR). A variety of statistical methods, including Pearson correlation, principal component analysis (PCA), and hierarchical cluster analysis (HCA) was used, to study the relationship between the radioactive elements and the radiological hazards. According to statistical analysis, the main radioactive risk of granitoid rocks is contributed to by the elements uranium-238, thorium-232, and potassium-40. Granitoid rocks can be applied in building materials, but under control to prevent risk to the public.

• The Journal of the Petrological Society of Korea
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• v.20 no.4
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• pp.191-206
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• 2011

The emplacement ages, whole-rock geochemistry and Sr-Nd isotopic compositions of granitoid rocks from Cheongju area, South Korea, were investigated for delineating their petrogenetic link to the Jurassic Daebo granitoid rocks. Zircon crystals were collected from the diorite, biotite granite and acidic dyke samples in a single outcrop. Cross-cutting relationships show that the emplacement of diorite was postdated by the intrusion of biotite granite. Both rocks have been subsequently intruded by acidic dyke. The U-Pb isotopic compositions of zircon from the diorite, biotite granite, and acidic dyke were measured using a SHRIMP-II ion microprobe, yielding the crystallization ages of $174{\pm}2Ma$, $170{\pm}2Ma$, and $170{\pm}5Ma$, respectively, with 95% confidence limits ($t{\sigma}$). The emplacement ages are consistent with those determined from the above relative ages. The major and trace element patterns of the rocks are consistent with those of the Jurassic Daebo granitoid rocks, possibly suggesting a subduction-related I-type granite. The geochemical signature is, however, betrayed by the Sr and Nd isotopic compositions of these rocks. The isotopic signatures suggest that the rocks were produced either by the partial melting of lower-crust or by the mantle-derived magma contaminated by the basement rocks during its ascent and/or emplacement. In addition, the inherited ages of zircons of the rocks (ca. 2.1, 1.8, 0.8 and 0.4 Ga) suggest a possible assimilation with crustal rocks from the Gyeonggi massif and Ogcheon metamorphic belt.

• Economic and Environmental Geology
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• v.30 no.2
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• pp.153-161
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• 1997

Diagrams of $^{87}Sr/^{86}Sr$ versus Ba/Nb and MgO/FeO are scattered, and $^{87}Sr/^{86}Sr$ variation with the increase of $SiO_2$ are scattered in Gwangju granitoid. Diagrams of $(^{87}Sr/^{86}Sr)$i versus $(^{143}Nd/^{144}Nd)$i and ${\varepsilon}Nd$ versus 1/Nd variation are also scattered in Gwangju granitoid. It shows that the source magma of Gwangju granitoid are derived from partial melting materials of heterogeneous upper crust. Very low ${\varepsilon}Nd$ values (-15.19~-19.49) and very high ${\varepsilon}Sr$ values (92.72~308.85) mean that the source magma of Gwangju granitoid is derived from sedimentary substance melting. According to $(^{87}Sr/^{86}Sr)$ 180Ma, and the plot of ${\varepsilon}Sr$ versus ${\varepsilon}Nd$, the Gwangju granitoid shows that the source magma is derived from upper crust materials. Nd model ages of Gwangju granitoid (1.82~2.42G.A.) are older than meta-sediments of Okcheon formation (1.15~1.60G.A.) and similar or close to Pre-Cambrian gneiss complex of Ryoungnam massif (2.17~2.47G.A.or 2.11~2.38G.A.).Therefore, the source magma of the Gwangju granitoid could be derived from the partial melting of Pre-Cambrian gneiss complex of Ryoungnam massif.

• The Journal of the Petrological Society of Korea
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• v.7 no.1
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• pp.15-26
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• 1998

The Dabie-Sulu ultra-high pressure metamorphic (UHPM) zone is commonly suggested to be a collisional belt between the Sino-Korea craton (North China craton) and Yangtze craton (Zhai and Cong, 1996). Two important questions in formulating the tectonic evolution of the northeast Asia are : (1) the boundary between the UHPM zone and the Sino-Korea craton in the Shandong peninsula and (2) the extension of this Chinese UHPM zone into the Korean peninsula. There have been different opinions on the boundary between UHPM zone and the Sino-Korea craton in the Shandong peninsula. For example, the boundary has been suggested to be the Tan-Lu fault (Bai et al., 1993; Wang and Cong, 1996), or Wulian-Rongcheng fault (Cao et al., 1990). Our recent study finds out new evidences, indicating that the possible boundary is the Kunyushan granitoid complex zone, which occurs along the Wulian-Muping fault. Our new evidences are : (1) the basic rocks west to the Kunyushan granitoid zone are high-pressure granulites rather than eclogites (Zhai, 1996) with their Sm-Nd isotopic ages of 1750 Ma and 2788 Ma, representing their retrograde metamorphic and petrogenetic ages, respectively (Li et al., 1997b); (2) the orthogneisses west to the Kunyushan granitoid zone yield 2600-2900 Ma zircon ages and 1600-2020 Ma Rb-Sr and chemical U-Th-total Pb ages, with no younger data (Enami et al., 1993; Ishizaka et al., 1994), having a typical characteristic for the early Precambrian rocks in the Sino-Korea craton; (3) the orthogneisses east to the Kunyushan granitoid zone have 110-320 Ma isotopic ages with a peak value of 180-230 Ma, showing a typical characteristic of metamorphic rocks in the UHPM zone; (4) the Kunyushan granitoid zone consists of numerous granitic bodies, stocks and veins, which have 1900-2000 Ma, 610-710 Ma and 124-180 Ma istotopic ages indicating a long and complicated evolution history of this granitoid zone. There are many lenses and enclosures of metamorphic rocks from the Sino-Korea craton and Sulu UHPM belt in the Kunyushan granitoid zone. Zhai et al. (1998) have defined the Kunyushan granitoid zone as the Jiaodong Boundary complex zone. Some geologists suggested that the UHPM zone extend eastward to the Korea peninsula (Yin and Nie, 1993; Wang and Cong, 1996) and possibly to the Imjingang belt (Chang, 1994; Ree et al., 1996). Unfortunately, there has not been a conclusive evidence indicating that UHPM rocks occur in the Korea peninsula. In this regard, it becomes more important to compare metamorphic rocks in the Shandong peninsula with those in northern and southern Korea peninsula.

• Journal of Industrial Technology
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• v.10
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• pp.33-48
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• 1990

The Imgye and the Samhwa granitoids distributed in the northeastern part of the Okchon Zone are known to be emplaced during the Mesozoic time. These granitoids intruded the Precambrian metasedimentary bedrocks and Cambro-ordovician sedimentary rocks. Petrographically the Samhwa granitoid is a biotite granite of mainly coars-grained texture with some fine-grained exceptions and the Imgye granitoid contains typically large phenocrysts of pinkish K-feldspars. Geochemical discriminators in terms of major elements suggest that the Samhwa and the Imgye granitoids are I-type and magnetite series. These granitoids are also classified as calc-alkalic rocks of subalkalic series. The Imgye and the Samhwa granitoids could have been evolved mainly by fractional crystallization and minimum partial melting respectively.

• Economic and Environmental Geology
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• v.25 no.4
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• pp.463-477
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• 1992

The study area consists of sedimentary and volcanic rocks of Gyeongsang Supergroup, granitoid intrusives, and hornfelses around the granitoids. Granitoid intrusives occur in small stocks in Nijeon-ri, Uggogri, and Yul-ri area. The masses in Nijeon-ri and Uggog-ri are hornblende-biotite granodiorite, biotite granodiorite respectively, and Yul-ri mass is biotite granite. Surrounding sediments of these masses were thermally metamorphosed and contact aureoles were formed. The studied granitoids are considered to be formed by sequential crystallization-differentiation from calc-alkalic granitoid magma. Metamorphic minerals occurring in contact aureole are chlorite, actinolite, epidote, and biotite. Diopside and hornblende are observed in small amount in some lithology around contact aureole. The lithology of contact aureole is predominantly silty and sandy, and characteristic metamorphic minerals were poorly developed because of low temperature metamorphism. Low temperature in contact aureole could be deduced from the facts that the intrusions were small size, shallow depth, low temperature, and rare movement of volatiles from magma.

• Proceedings of the KSEEG Conference
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• 2003.04a
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• pp.320-324
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• 2003

The Andong batholith is a Jurassic plutonic complex intruding metamorphic rocks of the RRyeongnam massif that extends from NE to SW in the southern Korean Peninsula. Detailed mapping and petrographic studies show that the batholith exhibits five sparate plutons: Andong, Dosan, Pungsan, Imha, and Nokjeon. The oldest Andong pluton among them exhibits reverse zoning. This feature contrasts with typical modal and chemical zoning trends in calc-alkaline plutons in which higher color index and more mafic rocks in the outer rim surround lower color index felsic rocks in the interior. (omitted)

• Economic and Environmental Geology
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• v.19 no.2
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• pp.147-151
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• 1986

K-Ar ages on biotites have been determined from the Proterozoic Buncheon and Hongjesa granitic rocks in comparison with the Rb-Sr whole-rock ages to investigate the ages of metamorphic events. The Rb-Sr whole-rock ages determinations on the Buncheon and Hongjesa granitoid rocks were previously reported as 2,100Ma and 1,700Ma, respectively. K-Ar ages on biotites separated from the studied rock have revealed three different age groups such as 1) 1,200~1,300Ma, 2) 600~700Ma and 3) 300~400Ma. The Rb-Sr whole-rock ages for the granitic rocks represent the time of emplacement, whereas the K-Ar ages on biotites generally indicate the time of metamorphism or alteration. The large discordance in the two age systems may not be explained as indicating the cooling period of the granitic batholiths. The K-Ar ages on biotites from the granitoid rocks might not be simply interpreted as the age of the last phase of metamorphism, since the granitic rocks had been undergone multistages of amphibolite facies-metamorphism in the Precambrian period. During the multistages of intermediate grade metamorphism, $^{40}Ar$-loss could be inevitably taken place as the metamorphic temperatures went up above the blocking temperature of biotite ($300{\pm}50^{\circ}C$). The results of the K-Ar dating on biotites from this study are probably minimum ages or hydrothermal alteration ages.

• Economic and Environmental Geology
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• v.23 no.2
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• pp.127-133
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• 1990

Relation between fluid inclusions and mineralization has been studied for 30 granitoid specimens from 19 localities in South Korea. Polyphase inclusions are found in granitoid specimens of 9 localities. In the vicinities of 6 localities among them occurs any of W, Cu or Fe deposits of the vein-, stockwork-, skarn-or pegmatite-type. On the contrary, no ore deposit is reported near the granitoids characterized by no polyphase inclusion except only one locality. This fact implies that the occurrence of polyphase inclusions is a good indicator for such kinds of mineralization. Ores and country rocks of some of the deposits contain polyphase inclusions in their quartz crystals. The fact that many polyphase inclusions occur in granitoids and ore constituents suggests that highly saline hydrothermal solution played an important role for the formation of such kinds of deposits. On the contrary, the granite and the ore of the Mugug gold deposit have many fluid inclusions, but are free from the polyphase type.

• The Journal of the Petrological Society of Korea
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• v.28 no.2
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• pp.85-109
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• 2019

Various Mesozoic igneous rocks such as biotite granite, leucogranites, granodiorite, hornblende gabbros, quartz gabbros and tonalite are identified in the Dangjin area, the western Gyeonggi Massif, Korea. The major Mesozoic igneous activities in the Dangjin area are recognized as periods of ca. 227 Ma, ca. 190 Ma, ca. 185 Ma and ca. 175 Ma. Gabbroic rocks consist mainly of hornblende gabbros and quartz gabbros which are characterized by dominant hornblende and occur as small stocks. The gabbroic rocks have intrusion ages between 185 and 175 Ma. Triassic biotite granite ($225{\pm}2.3Ma$) is considered to be a post-collisional granite similar in geochemistry to the southern Haemi granite ($233{\pm}2Ma$, Choi et al., 2009). Although the main magma source of biotite granite appears to be a granitic continental crust, the biotite granite could have a small amount of mafic rocks as a magma source, or a small amount of mantle-derived melts (i.e., mafic melts) could have contributed to the formation of primitive granite magma in composition. Jurassic granitoids and gabbroic rocks in the Dangjin area are considered to be continental arc igneous rocks associated with the subduction of the Paleo-Pacific plate. It is presumed that the leucogranites are formed by crustal anatexis of granitic materials and the gabbroic rocks are formed by partial melting of enriched mantle.