Dobongsan Peaks (도봉산_정산)

The geology of South Korea includes rocks dating to the Archean and two large massifs of metamorphic rock as the crystalline basement, overlain by thick sedimentary sequences, younger metamorphic rocks and volcanic deposits.[1] Although extent is small, Geology is diverse, and there are diverse rocks that were formed during the Precambrian to Cenozoic Era in the Korea Peninsula.[2]

Geologic History, Stratigraphy and Tectonics

The K'yŏnggi Massif and Yongnam Massif lie north and south of the Okch'on-T'aebaeksan Zone respectively. They are both polymetamorphic gneiss and schist complexes from the Precambrian and underlie the entire Republic of Korea. Units range in age from the Archean to the Proterozoic, with metamorphic facies from greenschist to amphibolite grade. Some geologists have attempted to correlate the rocks with North China-North Korea Paraplatform and Yangtze Paraplatform rocks although these categorizations are uncertain.

Precambrian (–539 million years ago)

The rate which Precambrian rocks occupy in Korean Peninsula is 40%.[3] It is confirmed that Korea peninsula is formed mostly after Paleoproterozoic (2,500 to 1,600 million years ago) and Archean rocks appear in portion region.[4]

Paleozoic (539–251 million years ago)

The 'Gumunso(ko:구문소)' - The place where early Paleozoic formation exists. (Joseon Supergroup Makgol limestone Formation)

The rock formation which is formed during Paleozoic is composed of Joseon Supergroup (lower) and Pyeongan Supergroup (upper).

Joseon Supergroup

From the early Cambrian to the Ordovician in the early Paleozoic, the Joseon Supergroup was formed, and it distributed in the Pyeongnam Basin and Okcheon Fold Belt. The early Paleozoic Joseon Supergroup in Korea has been divided into Taebaek, Yeongwol, Pyeongchang, Yongtan and Mungyeong groups, depending on the sequence of lithology.[5] Taebaek group that located in Taebaek, Samcheok is composed of Jangsan, Myobong, Daegi, Sesong, Hwajeol, Dongjeom, Dumugol (Dumu-dong), Makgol (Makgol), Jigunsan, Duwibong Formation. Yeongwol group is composed of Sambangsan, Machari, Wagok, Mungok, Yeongheung Formation.[6] The geological table of the Joseon Supergroup is as follows.[7][8][9]

Geologic time scale Taebaek Area Yeongwol Area Pyeongnam Area
division Formation Name Thickness(m) Distribution region[10] Formation Name Rock Thickness(m)
Ordovician
443.8–485.4 Mya		 upper
great limestone group		 Duwibong limestone 50 Yeongheung shale
limestone		 - Sangseo-ri
Mandal
Singok
Jigunsan shale 50~100
Makgol limestone 250~400 Taebaek
Dumugol shale (Odu) 150~200 Baegun Mt. Syncline Zone Mungok limestone
Dolomite		 120~200
Dongjeom Quartzite (Od) 50 Baegun Mt. Syncline Zone
Cambrian
485.4–538.8 Mya		 lower
great limestone formation		 Hwajeol (CEw)
Sesong		 200~260 Baegun Mt. Syncline Zone
East Danyang		 Wagok limestone
Dolomite		 200~500 Gopung
Daegi(Pungchone limestone) (CEp) 150~300 Baegun Mt. Syncline Zone
Southeast Jeongseon		 Machari
(Om)		 shale
limestone
Dolomite		 420 Mujin
Yangdeok Formation (C) Myobong Slate (CEm) 80~250 Sambangsan
(cs)		 Sandstone
shale		 - heuggyo(C)
Jangsan Quartzite (CEj) 150~200 Baegun Mt. Syncline Zone
Danyang		 Junghwa(C)

Pyeongan Supergroup

The border region of Gyeongsang Basin, Yongnam Massif, Okcheon Fold Belt in Sangju Area (using OpenStreetMap)[11][12]

From Carboniferous to Triassic, The Pyeongan Supergroup was formed, and it distributed in the Pyeongnam Basin and Okcheon Folded Zone.[13][14]

The geological table and stratigraphy of the Pyeongan Supergroup are as follows.[15]

Geologic time scale Area
period Epoch Age Samcheok Gangneung Jeongseon-Pyeongchang Yeongwol Danyang Boeun Pyeongnam Basin Duman Basin
Mesozoic Triassic
201.3–252.17 Mya		 Mid 237–247.2 Mya Anisian Donggo
(Formation)		 Bakjisan Donggo taejawon
Early 247.2–252.17 Mya Induan Sangwonsan
Paleozoic
Permian
252.17–298.9 Mya		 Lopingian 252.17–259.8 Mya Gobangsan Songsang
Guadalupian
259.8–272.3 Mya		 Capitanian Gohan Unbyeolri Okgapsan Gohan
Wordian Dosagok Mangdeoksan Dosagok
Roadian
Cisuralian
272.3–298.9 Mya		 Cisuralian Hambaeksan Hambaeksan Hambaeksan Hambaeksan Gyeryongsan
Artinskian Jangseong Jangseong Jangseong Mitan Jangseong Jangseong Sadong
Sakmarian Bamchi Bamchi Bamchi Amgi
Asselian ibseog
Paleozoic
Carboniferous
252.17–298.9 Mya		 Pennsylvanian
298.9–323.2 Mya		 Moscovian Geumcheon Geumcheon Geumcheon Pangyo Geumcheon hongjeom
Manhang Manhang Manhang Yobong Manhang Manhang
Bashkirian

Okchon (folded) Zone

The Okch'ŏn Zone likely formed in mid-Cambrian times with faulting, interpreted from olistolith limestone breccia. By contrast to the Chŏsun Supergroup, the Okch'ŏn Supergroup crops out in the central Okch'on-T'aebaeksan Zone with thick sequences of metasedimentary and metavolcanic rocks. Some geologists have interpreted the supergroup as a series of nappe formations that took shape in a Cambrian intracratonic basin. Above the volcanic and sedimentary sequence in the middle part of the supergroup are jumbled rocks formed from submarine debris flows during rifting and contain granite, gneiss, quartzite, limestone, mudstone and basic volcanic rock fragments.

At first, the Taebo orogeny was credited with the folding, thrusting and metamorphism but Cluzel, Jolivet and Cadet in 1991 named the Okch'on orogeny to explain Silurian and Devonian deformation.

South Korea has no Silurian or Devonian sedimentary rocks, but sedimentation began again on a sinking paralic platform inland from the proto-Japan as it formed beginning in the Carboniferous. The P'yŏngan Supergroup outcrops northeast of the Okch'on Zone, subdivided into the Hongjom Formation gray mudstone, limestone and mudstone, Sadong Formation sandstone, mudstone and coal seams, Kobangsan Formation coarse terrestrial sandstone and mudstone, and Nogam Formation green sandstone and mudstone. [16]

Mesozoic (251-66 million years ago)

In the Triassic at beginning of the Mesozoic as sedimentation continued in the P'yŏngan Supergroup, the Sŏngnim tectonic event affected the Okch'on-T'aebaeksan Zone, although it only caused slight faulting and warping of the major supergroup strata. Geologists have inferred that the event was related to deformation further west in Indonesia.

The event generated dextral strike-slip faulting in intermontane troughs in the Kyonggi Massif in which the terrestrial sediments of the Taedong Supergroup accumulated. The rocks in the basin include two sequences of conglomerate grading to sandstone, mudstone and coal beds. The Taedong Supergroup has extensive fossils, particularly crustaceans.

Taebo Orogeny

The Taebo orogeny in the Jurassic is broadly similar to the Yenshanian tectonism in China, although its effects are believed to have been less dramatic. The event ended with the batholith intrusions of the Taebo granites which outcrop over 30 percent of the country.

Gyeongsang Basin

The Geology map of Daegu City and Gyeongsan City located in the middle of Gyeongsang Basin[17]

The Gyeongsang Basin is the basin that is formed at Cretaceous.[18] it occupies most of the Yeongnam region and part of Honam region.

The Gyeongsang Basin is composed of Gyeongsang supergroup, which consists of Sindong, Hayang, Yucheon group, and Bulguksa Granite. The Sindong Group is the lowest stratigraphic sequence in the Cretaceous Gyeongsang Basin and comprises three stratigraphic units: the Nakdong, Hasandong, and Jinju Formation in ascending order.[19] Hayang group is mid group of Gyeongsang supergroup.[20] Yucheon group is the top group of Gyeongsang supergroup.[21]

Kyŏngsang rocks are intruded by microlite, diorite and granodiorite from the late Cretaceous. [22]

Cenozoic (66 million years ago-present)

Volcanic activity continued into the Cenozoic ending 50 million years ago. No Paleogene sedimentary rocks have been found onshore. Yangbuk Group conglomerates and alluvial fan sediments gathered in small fault-bounded basins in the Miocene. During the last 2.5 million years of the Quaternary, Cheju and other offshore islands formed from volcanism.

References

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  1. ↑ Moores, E.M.; Fairbridge, Rhodes W. (1997). Encyclopedia of European & Asian Regional Geology. Springer. pp. 475–482.
  2. ↑ Hyoun Soo, Lim (2019). "Cretaceous sedimentary basins and volcanic activity in Korea (KOR)". 지질학회지. The Geological Society of Korea. 55 (5): 493–494. doi:10.14770/jgsk.2019.55.5.493. S2CID 210247110.
  3. ↑ Seung Ryeol, Lee (2018). "Precambrian Geology of the Korean Peninsula (KOR)". 대한지질학회 학술대회. The Geological Society of Korea: 160.
  4. ↑ Chang Whan, Oh (2018). "The overview for the tectonic evolution of Korea Peninsular from Paleoproterozoic to Triassic (KOR)". 대한지질학회 학술대회. The Geological Society of Korea: 85.
  5. ↑ Ryoung Gyun, Kim (2019). "Stratigraphic implications of the Pyeongchang Group (Joseon Supergroup) in Korea (KOR/ENG)". 지질학회지. The Geological Society of Korea. 55 (6): 727–734. doi:10.14770/jgsk.2019.55.6.727. S2CID 213337130.
  6. ↑ Yi Kyun, Kwon (2019). "Basin Evolution of the Taebaeksan Basin during the Early Paleozoic (KOR/ENG)". 자원환경지질. The Korean Society of Economy and Environmental Geology. 52 (5): 427–448.
  7. ↑ Earth Science Introduction (in Korean). The Korean Earth Science Society. 2001. ISBN 8935401854.
  8. ↑ "Characteristics of rocks and geological structures in the central region of the Korean Peninsula". Korea Institute of Geoscience and Mineral Resources. {{cite journal}}: Cite journal requires |journal= (help)
  9. ↑ "Gravity Survey of the Subsurface Geology and Geologic Structure between Samcheog and Taebaek Area". 자원환경지질 = Economic and Environmental Geology. ScienceON. 28 (1): 79–88. 1995.
  10. ↑ https://data.kigam.re.kr/mgeo/map/main.do?process=geology_50k Geology map of Korea Institute of Geoscience and Mineral Resources
  11. ↑ "한반도 지체구조도". Korea Institute of Geoscience and Mineral Resources.
  12. ↑ "2012~2020년 속리산 일대에서 발생한 지진의 진원 요소 분석". 한국교원대학교, 2021.
  13. ↑ Mun Gi Kim, Kim (2017). "The stratigraphy and correlation of the upper Paleozoic Pyeongan Supergroup of southern Korean Peninsula - A review (KOR/ENG)". 지질학회지. The Geological Society of Korea. 53 (2): 321–338. doi:10.14770/jgsk.2017.53.2.321.
  14. ↑ Hyeong Soo, Kim (2017). "Reassessment of the Pyeongan Supergroup: Metamorphism and Deformation of the Songrim Orogeny (KOR)". 자원환경지질. The Korean Society of Economy and Environmental Geology. 52 (5): 367–379.
  15. ↑ Mun Gi, Kim (2017). "The stratigraphy and correlation of the upper Paleozoic Pyeongan Supergroup of southern Korean Peninsula - A review (KOR/ENG)". 지질학회지. The Geological Society of Korea. 53 (2): 321–338. doi:10.14770/jgsk.2017.53.2.321.
  16. ↑ Moores & Fairbridge 1997, pp. 476–478.
  17. ↑ "1:50,000 Geology map". KIGAM, Korea Institute of Geology and Mineral. {{cite journal}}: Cite journal requires |journal= (help)
  18. ↑ Youngbeom, Cheon (2017). "Geometry and kinematics of fault systems in the Uiseong block of the Gyeongsang Basin, and their roles on the basin evolution (KOR)". 지질학회지. The Geological Society of Korea. 53 (2): 241–264.
  19. ↑ Hyoun Soo, Lim (2019). "Trace-element composition of the Cretaceous Sindong Group, Gyeongsang Basin, Korea and its implication for provenance (KOR)". 지질학회지. The Geological Society of Korea. 55 (5): 531–549. doi:10.14770/jgsk.2019.55.5.531. S2CID 210268978.
  20. ↑ In Sung, Paik (2018). "Bidirectional paleocurrent records in the Jindong Formation of the Gyeongsang Supergroup, Korea : Occurrences and paleoenvironmental implications (KOR)". 지질학회지. The Geological Society of Korea. 54 (4): 321–333. doi:10.14770/jgsk.2018.54.4.321.
  21. ↑ In Sung, Paik (2006). "Goseong Formation (Yucheon Group) in the southern part of the Gyeongsang Basin, Korea (KOR)". 지질학회지. The Geological Society of Korea. 42 (4): 483–505.
  22. ↑ Moores & Fairbridge 1997, pp. 479–481.
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