• Journal of the Korean earth science society
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• v.41 no.4
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• pp.367-380
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• 2020

LA-MC-ICP-MS zircon U-Pb dating was conducted to constrain the timing of fossil formation and the depositional age of the uppermost Jinju Formation located in Natural Monument No. 534 (Tracksite of Pterosaurs, Birds, and Dinosaurs in Hotandong, Jinju), and 87 Cretaceous, 1 Precambrian, and 2 Jurassic zircons were obtained from 90 valid analytical points. Most Cretaceous zircons were found to have a youngest graphical peak age of ca. 106.5 Ma, suggesting the depositional age of the uppermost Jinju Formation. Based on this study and previous works, the average sedimentation rate of the Jinju Formation was calculated to be approximately 0.17-0.31 mm/year in the Milyang Subbasin, and the Cretaceous zircons of the uppermost Jinju Formation seem to have originated mainly from the western or northwestern parts of the Gyeonggi Massif. Unlike the Nakdong and Hasandong formations of the Sindong Group, most zircons analyzed in the uppermost Jinju Formation were Cretaceous. This suggests that volcanic activity occurred in the area closer to the Gyeongsang Basin due to the roll-back of subducting paleo-Pacific Plates during the Jinju period.

• Journal of the Korean earth science society
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• v.30 no.5
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• pp.605-610
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• 2009

Cupressinocladus sp. found from the upper part of the Jinju Formation of the Shindong Group, Korea is described here based on the newly found leafy shoots. This species is characterized by the branched leafy shoot with decussate scale leaves. The presence of Cupressinocladus in the Jinju Formation indicates that the Early Cretaceous flora-sites in Eastern Eurasia are in a close association with territories of the mixed-type floras. The finding of this species records the first report for the Nakdong flora.

• Economic and Environmental Geology
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• v.56 no.4
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• pp.397-408
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• 2023

A total of 64 specimens of trace fossils were collected from the Jinju Formation of the construction site of Jinju Aviation Industrial Complex, and from the Haman Formation of Namhae Gain-ri fossil site. The fossils are continuously and regularly meandering sine-curve in shape. The fossil varies in morphology: width between 0.2 and 5.6 mm, wavelength between 1.5 and 28 mm, and amplitude between 0.9 and 7.9 mm; the Jinju specimens are commonly wider than the Haman ones. The ratio of wavelength to amplitude is more or less regular regardless of width of the specimen, and the linear correlation of the ratios shows that the Jinju specimens fit better than the Haman specimens. Taking all morphometric parameters, specimens in all size ranges are temporarily identified as ichnospecies Cochlichnus anguineus. In order to obtain more distinct and clearer images of Cochlichnus, we selected two specimens and applied a new imaging technology RTI. For photography of the trace fossils, 50 to 80 images were taken per set with photometric lighting close to the surface and horizontally. RTI technology clearly showed that the images of tiny fossils were improved: the surface contrast become sharper and messy and unnecessary information disappeared. Currently, RTI technology is used in many fields including preservation of cultural properties and archaeology. As a consequence, we hope to apply this technique to the field of paleontology, especially to the study of trace fossils of very small size.

• Journal of the Korean earth science society
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• v.21 no.6
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• pp.695-702
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• 2000

The ichnogenus Protovirgularia McCoy, 1850 is reported from nonmarine strata of the Cretaceous Jinju Formation of the Sacheon area Korea. There, the Jinju Formation is composed mainly of fine-grained sandstone, grey to brownish grey mudstone, and shale which were deposited in a freshwater lacustrine environment. This occurrence represents the fist formal recording of the ichnotaxon from Korea and the first, on a global basis, from a nonmarine depositional environment.

• Economic and Environmental Geology
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• v.18 no.3
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• pp.289-299
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• 1985

Sedimentary petrology and depositional environments of the Sindong Group, consisting of in ascending order the Nagdong, Hasandong and Jinju Formations, in the Euiseong Subbasin are studied. For these, the Sindong sequence over 1,000m thick is measured at the scale of 1:200 and 36 thin sections of sandstones of the Hasandong Formation are studied under the polarizing microscope. In addition, published paleontologic data are incorporated in the sedimentologic interpretation. Most of the sandstones are classified as arkose. They are moderately sorted, near symmetrical to fine skewed and mesokurtic. Relationship between the textural parameters suggests a fluviatile environment of the Hasandong Formation. The Sindong fauna and flora also indicate non-marine depositional environments. Sedimentologic data of the measured sections show that the Sindong Group is made up of from the bottom an alluvial fan (lower part of the Nagdong Formation), a fluvial plain (upper part of the Nagdong Formation and the Hasandong Formation) and a fluvial/lacustrine (the Jinju Formation) deposits.

• Journal of the Korean earth science society
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• v.43 no.5
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• pp.639-646
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• 2022

Occurrence of black opaque hydrocarbon (pyrobitumen) in some Cretaceous Jinju sandstones of the Sindong Group, Gyeongsang Basin in Korea is first reported in this study. The pyrobitumen is developed on chlorite pore-lining cement, or impregnated into the outer zone of chlorite cement. Therefore, it seems to have been formed after the precipitation of chlorite cement, indicating the former presence of crude oil. The liquid hydrocarbons migrated into sandstones during moderate burial and these sandstones seem to have acted as a liquid hydrocarbon reservoir. The presence of pyrobitumen in the Jinju Formation indicates that this formation underwent deep burial after liquid hydrocarbon migration. As reservoir temperatures increased further, hydrocarbons were cracked and a solid pyrobitumen residue remained in the reservoir.

• The Journal of the Petrological Society of Korea
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• v.19 no.1
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• pp.89-101
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• 2010

To constrain the depositional ages of the Gyeongsang sedimeantary formations, SHRIMP U-Pb ages were determined from detrital zircons in three samples: (1) a pebble-bearing sandstone from the lowermost Jinju Formation of the Sindong Group and (2) two conglomerates from the Silla Conglomerate of the Hayang Group. Their concordia ages are $112.4{\pm}1.3(2{\sigma})$ Ma and $110.4{\pm}2.0(2{\sigma})$ Ma respectively. Such ages represent the maximum deposition ages for the lowermost Jinju Formation and Silla Conglomerate, indicating the deposition of the Jinju Formation started from late Aptian and lasted to early Albian, then deposition of the rather thin Chilgok Formation and Silla Conglomerate was followed during the Albian. The age distribution of the analyzed detrital zircons indicates the presence of protoliths, or zircons derived from them, regarding a wide span of igneous activities from Mesozoic to Archean. Among such ages, there are Mesoproterozoic, Neoproterozoic and Paleozoic igneous activities, which have not been known or seldom reported from Korean peninsula. These ages further suggest the possible presence of rocks with such ages during the deposition periods or their derivation through a long river system developed into the continents at the time of deposition.

• Economic and Environmental Geology
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• v.31 no.4
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• pp.325-338
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• 1998

105 oriented samples (19 matrix samples, 86 cobble samples) were collected from the Silla Coglomerate Formation in Jinju and Goryeong areas to clarify the regional remagnetization of Cretaceous Kyongsang supergroup. Both the alternating field and thermal demagnetizations were conducted for the collected samples. The characteristic remanent magnetizations of these samples divided into three types in the Silla Conglomerate Formation: The ingredient magnetic minerals are magnetite, hematite, or both magnetite and hematite in a specimen. The characteristic remanent directions of cobble samples did not clustered to any direction. And the characteristic remanent directions of interbedded sandstones in the Silla Conglomerate Formation is $D/I=20.6^{\circ}/54.5^{\circ}$ (${\alpha}_{95}=11.1^{\circ}$, k=48.8) after tilting correction, agree with previous paleomagnetic studies on the Hayang group. These results implied that conglomerate test was passed indicating no regional remagnetization in the studied area after deposition of the Silla Conglomerate Formation.

• 한국지구과학회:학술대회논문집
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• 2001.09a
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• pp.41-41
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• 2001

• Proceedings of the Korean Society for Food Science of Animal Resources Conference
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• 2005.05a
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• pp.117-142
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• 2005