page_title: Geology of North Korea
section_title: Paleozoic
hierarchical_section_title: Geology of North Korea / Paleozoic
caption_attribution_description: Seoraksan,South Korea 한국어: 설악산 울산바위
context_page_description: The geology of North Korea has been studied by the Central Geological Survey of Mineral Resources, rare international research and by inference from South Korea's geology.
context_section_description: The Late Ordovician Miru Series was identified beginning in 1971 as the Koksan Series and subsequently renamed after 1975. The 170 meter thick limestone and siltstone centered around the P'yongnam Basin has extensive crinoid, coral and gastropod fossils. Paleogeography researchers have suggested that corals formed in the Miru Sea—a branch of the South Yangtze Sea. The discovery of Ordovician fossils meant that the previous Koksan Series was revised to be younger, encompassing Silurian slate, limestone and siltstone in the Singye-Koksan area up to 280 meters thick. It includes trilobite and Rugosa fossils. 
  For years, geologists in the Korean Peninsula were puzzled about the early Paleozoic fossils found in the early Mesozoic Taedong Synthem (limestone pebbles in the Kyomipo Conglomerate). However, in 1991, Kang and Pak inferred an origin from the Koksan Series. 
  Marine fossils are also widespread in the Imjin Group, first recognized in 1962 in the Kaesong-Kumchon-Cholwon area. The three kilometer thick unit is subdivided into the Anhyop, Puapsan and Saknyong Series and is widespread throughout the Imjinang Fold Belt in central North Korea. The Anhyop Series represents one kilometer of  schist, limestone, phyllite and sandstone. The 1.1 kilometer Puapsan Series and one kilometer Saknyong Series are both very similar, although the Saknyong also has siltstone and volcanic rocks. North Korean geologists have identified the Imjin Group as a continental rift basin, correlated with similar rocks on the Shandong Peninsula across the Yellow Sea in China. Many of the rocks have experienced low-grade metamorphism and volcanic sequences are comparatively thick.
  At the base of the Taedong Synthem is the P'yong'an Supergroup, which lies disconformably atop older Paleozoic rocks. In the Pyongyang Coalfield it is divided into the 650 meter sandstone, shale and conglomerate of the Nogam Formation, the 500 meter Kobangsan Formation, 350 meter coal-bearing Sadong Formation and 250 meter chert-bearing Hongjom Formation, all typically assigned to an Upper Permian shallow marine environment.
caption: A view of Mount Seorak
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