Jinju Formation
Early Cretaceous geologic formation in South Korea
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The Jinju Formation (Korean: 진주층; Hanja: 晋州層; RR: Jinju-cheung), also known as the Dongmyeong Formation (Korean: 동명층; Hanja: 東明層; RR: Dongmyeong-cheung) in some literature is an Early Cretaceous geologic formation in South Korea.[2] Lithology of the Jinju Formation could be distinguished from overlying and underlying formations by lack of red beds in the entire formation.
Unit ofShindong Group
UnderliesChilgog Formation in Miryang Subbasin; Iljig Formation in Euiseong Subbasin
OverliesHasandong Formation
| Jinju Formation | |
|---|---|
| Stratigraphic range: Albian ~ | |
Outcrop of the Jinju Formation in Jinju | |
| Type | Geological formation |
| Unit of | Shindong Group |
| Underlies | Chilgog Formation in Miryang Subbasin; Iljig Formation in Euiseong Subbasin |
| Overlies | Hasandong Formation |
| Thickness | 600–1,800 m (2,000–5,900 ft) |
| Lithology | |
| Primary | Shale |
| Other | Sandstone |
| Location | |
| Coordinates | 35.1°N 128.1°E |
| Approximate paleocoordinates | 44.3°N 122.7°E |
| Region | Gyeongsang Province |
| Country | South Korea |
| Extent | Gyeongsang Basin(ko:경상 분지) |
| Type section | |
| Named for | Jinju |
| Named by | Tateiwa, 1929[1] |
  Jinju Formation (South Korea) | |
The depositional age of this formation spans from approximately 112.4 ± 1.3 to 106.5 million years ago (early Albian) based on detrital zircon U-Pb dating.[3] It predominantly consists of black shale, with sandstone packets, deposited in a fluvial-lacustrine setting. The entire paleoenvironment of the Jinju Formation is interpreted as a balanced-fill lake basin, with deltas and streams.[4]
A diverse arthropod fauna, including isopods, spiders, and insects, is known from the formation. Other notable fossils known from the formation include several freshwater fishes, ostracods, and plants. This formation has also "attracted global ichnological attention" for the variety of important ichnofossils.[5] Columnar and rod-shaped stromatolites have also been found here.[6]
Fossil content
Color key
|
Notes Uncertain or tentative taxa are in small text; |
Plants
Based on plant fossil records, the Jinju Flora is interpreted as a temperate intermontane savannah, due to mountain barriers blocking moisture. The assemblage was dominated by stress-tolerant, low-diversity flora adapted to the arid conditions or to localized waterlogged niches. Not only restricted to the Jinju Formation, but the entire floral diversity was relatively low throughout the entire Gyeongsang Supergroup.[7] Palynofossil records also suggest the Jinju Formation was overall arid.
Unnamed plant remains include 3 different types of unidentified ferns, at least 2 types of seed cones, a conifer pollen cone, detached conifer seed cone scales, a connate bractate organ of unknown affinity, and at least 9 different types of diaspores, including winged forms and likely fleshy forms.
| Plants of the Jinju Formation[7] | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Region | Member | Material | Notes | Image |
| Equisetum |
E. cf. burchardti[8] |
Horsetail | ||||
| E. sp. | ||||||
| Equisetites | E. naktongensis | Horsetail | ||||
| Hausmannia | H. sp. | Dipteridaceae fern | ||||
| cf. Klukia | cf. K. sp. | Schizaeaceae fern | ||||
| Ruffordia | R. sp.[4] | Schizaeaceae fern | ||||
| Onychiopsis | O. elongata[9] | leptosporangiate fern | ||||
| Cladophlebis |
C. sp. A |
Fern, family unknown. | ||||
| C. sp. B | ||||||
| C. sp. C | ||||||
| C. sp. D | ||||||
| C. sp. E | ||||||
| Sphenopteris |
S. sp. A |
|||||
| S. sp. B | ||||||
| S. sp. C | ||||||
| Sectilopteris |
S. sp. A |
|||||
| S. sp. B | ||||||
| Pseudofrenelopsis | P. sp. | Scale- and awl-leaved Cheirolepidiaceae conifer | ||||
| Platycladium | P. sp. | Scale- and awl-leaved conifer, family unknown. Cupressinocladus sp. described in Kim 2009[10] might allied with this taxon.[7] | ||||
| Geinitzia | G. sp. A | Divergent-leaved Geinitziaceae conifer | ||||
| G. sp. B | ||||||
| Pagiophyllum | P. sp. A | Scale- and awl-leaved conifer, family unknown. | ||||
| P. sp. B | ||||||
| Elatocladus | E. sp. A | Divergent-leaved conifer, family unknown. | ||||
| E. sp. B | ||||||
| Pityophyllum | P. sp. A | Divergent-leaved conifer | ||||
| P. sp. B | ||||||
| Brachyphyllum | B. japonicum[9] | Scale- and awl-leaved conifer, family unknown. | ||||
| B. sp. A | ||||||
| B. sp. B | ||||||
| B. sp. C | ||||||
| Cupressinocladus | C. sp. A | Scale- and awl-leaved conifer. The presence of this taxon indicates that a mixed type of the Tetori-Type and the Ryoseki-Type flora existed in this formation. | ||||
| C. sp. B | ||||||
| Podozamites | P. sp. | Broadleaf conifer, family unknown. | ||||
| Krassilovia | K. sp. | Seed cones | Krassiloviaceae conifer | |||
| cf. Elatides | cf. E. sp. | Seed cones | Cupressaceae conifer | |||
| Pityospermum | P. sp. | A diaspore | Pinaceae conifer | |||
| Desmiophyllum | D. sp. | Non-conifer broadleaf gymnosperm, family unknown. | ||||
| Doylea | D. sp. | Bifurcated seed-bearing cupulate unit | Doylealean gymnosperm | |||
| Jarudia | J. sp. | Seed-bearing cupulate unit with 2 distal seeds | Doylealean gymnosperm | |||
| Umaltolepis | U. sp. | Seed-bearing capulate units | Possible Ginkgoopsid | |||
Spiders
| Spiders of the Jinju Formation[11] | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Region | Member | Material | Notes | Image |
| Korearachne | K. jinju | Jinju | likely to be a lycosoid | |||
| Koreamegops | K. samsiki | a lagonomegopid | ||||
| Jinjumegops | J. dalingwateri | a lagonomegopid | ||||
| Mygalomorphae | Indeterminate | |||||
| Araneomorphae | Indeterminate | |||||
| Palpimanoidea | Indeterminate | |||||
| "Cribellate Entelegynae" | "species 1" | |||||
| "species 2" | ||||||
Insects
Odonata
| Dragonflies and damselflies of the Jinju Formation | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Region | Member | Material | Notes | Image |
| Hemeroscopus | H. baissicus[12][13] | Sacheon, Gunwi and Jinju | Both nymphs and adults | |||
|
H. jinjuensis[14] |
Sacheon | Two wings | ||||
| Koreapodagrion | K. coloratus[15] | Jinju | Isolated wings | |||
Dermaptera
| Earwigs of the Jinju Formation | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Region | Member | Material | Notes | Image |
| cf. Pygidicranoidea[16] | indeterminate | |||||
Orthoptera
| Orthopterans of the Jinju Formation | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Region | Member | Material | Notes | Image |
| Panorpidium | P. spica[17] | A member of Elcanidae | ||||
Dictyoptera
| Dictyopterans of the Jinju Formation[18][19] | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Region | Member | Material | Notes | Image |
| Cretophotina | C. smidovae | A member of Mantodea | ||||
| Juramantis | J. jinjuensis | |||||
| J. geongonrigam | ||||||
| Bubosa | B. petrarosa | A member of Blattidae | ||||
| Neoblattella | N. coockrock | A member of Ectobiidae | ||||
| Perlucipecta | P. jinjuicola | A member of Mesoblattinidae | ||||
| P. cyclopica | ||||||
| P. major | ||||||
| Praeblattella | P. tinctoria | |||||
| P. decolor | ||||||
| Mongoloblatta | M. koreaensis | |||||
| Archimesoblatta | A. basopicta | |||||
| Spinaeblattina | S. variabilitta | |||||
| Jinjublatta | J. cascadaerrorum | |||||
| Stictolampra | S. baqueuii | A member of Blaberidae | ||||
| Holocompsa | H. scleroptera | A member of Corydiidae | ||||
| Ioouoonool | I. taktobybolo | |||||
| Asioblatta | A. jeongchonensis | A member of Raphidiomimidae | ||||
| Cameloblatta | C. immaculata | |||||
| Tayphoonoblatta | T. correntini | |||||
| Elongatoblatta[19] | E. minsuki | |||||
| Ano | A. ale | A member of Liberiblattinidae | ||||
| Brutalista | B. masivny | |||||
| Blattula | B. pessimusestfinis | A member of Blattulidae | ||||
| Elisama | E. baeki | |||||
| E. simplex | ||||||
| E. gwanghyeoni[19] | ||||||
| Ocellonlattula | O. gyongsangensis | |||||
| Vrtula | V. jinjuensis | |||||
| V. gwanghyeonensis[19] | ||||||
| Memento | M. futuri | A member of Caloblattinidae | ||||
| Sclerotermes[20] | S. samsiki | Jinju | A termite known only from an isolated wing, uncertain placement | |||
| Umenocoleus[21] | U. minimus | A member of Umenocoleidae | ||||
| Pseudoblattapterix[21] | P. weoni | |||||
| Petropterix[21] | P. koreaensis | |||||
| P. oculata | ||||||
| P. nikdyviac | ||||||
| Blattapterix | B. reticulata | |||||
| Alienopterus | A. imposter | A member of Alienopteridae | ||||
| Recyklovany | R. koltoc | |||||
| Caputoraptor | C. ganggu | |||||
| Indeterminate | 5 indeterminate taxa | |||||
Hemiptera
| Hemipterans of the Jinju Formation | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Region | Member | Material | Notes | Image |
| Corixidae[22] | indeterminate | Sacheon | Not fully described | |||
| Jinjucixius | J. fui[23] | Jinju and Gunwi | A member of Cixiidae | |||
| Jinjupopovina | J. eosahwae[24] | Jinju | A member of Yuripopovinidae | |||
Hymenoptera
| Hymenopterans of the Jinju Formation | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Region | Member | Material | Notes | Image |
| Korehelorus | K. jinjuensis[25] | Jinju | A parasitic wasp belonging to the family Heloridae | |||
| Hanguksyntexis | H. haeretica[26] | A sawfly belonging to the family Anaxyelidae | ||||
| Cretosphecium | C. jinjuensis[27] | A wasp belonging to the family Angarosphecidae | ||||
| Ghilarella | G. jinjuensis[28] | Sepulcidae wasp | ||||
| Meiaghilarella | M. stanislawlemi[28] | |||||
Raphidioptera
| Snakeflies of the Jinju Formation | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Region | Member | Material | Notes | Image |
| Mesoraphidia[29] | M. koreensis | A member of Mesoraphidiidae | ||||
| M. phantasma | ||||||
Neuroptera
| Lacewings of the Jinju Formation | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Region | Member | Material | Notes | Image |
| Tachinymphes | T. koraiensis[30] | A member of the family Mesochrysopidae. | ||||
| Araripeneura | A. asiatica[31] | A member of Araripeneuridae | ||||
| Araripenymphes | A. koreicus[31] | A member of Cratosmylidae | ||||
Coleoptera
| Beetles of the Jinju Formation[32] | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Region | Member | Material | Notes | Image |
| Coptoclava[33] | C. spinosa[34] | Jinju and Gunwi | Larval remains abundant; Adult remains relatively rare | A member of the extinct family Coptoclavidae. |  | |
| Megalithomerus[35] | M. magolhalmii | A member of Elateridae | ||||
| Koreagrypnus[35] | K. jinju | |||||
| Cryptocoelus[36] | C. minimus | |||||
| Cretosaja[37] | C. jinjuensis | A member of Silphidae | ||||
| Notocupes[38] | N. premeris | A member of Archostemata | ||||
| Asiana[39] | A. pax | |||||
| Brochocoleus[39] | B. sacheonensis | A member of Ommatidae | ||||
| B. cf. punctatus | ||||||
| Omma[39] | O. sp. | |||||
| Zygadenia[39] | Z. cornigera | |||||
| Laetopsia[40] | L. leei | A member of Hydrophiloidea | ||||
| L. cf. hydraneoides | ||||||
| L. sp. | ||||||
| Cretotaenia[40] | C. pallida | |||||
| Psacodromeus[41] | P. recta | A member of Trachypachidae | ||||
| Necronectulus[41] | N. lazarus | |||||
Diptera
| Flies of the Jinju Formation | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Region | Member | Material | Notes | Image |
| Buccinatormyia[42] | B. gangnami | A member of the family Zhangsolvidae. Named after Gangnam Style, the famous K-Pop hit song | ||||
Crustaceans
Isopoda
| Isopods of the Jinju Formation | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Region | Member | Material | Notes | Image |
| Archaeoniscus[22] | A. coreaensis | Sacheon and Jinju | A freshwater occurrence of the genus Archaeoniscus |  | ||
Ostracoda
| Ostracods of the Jinju Formation[43][44] | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Region | Member | Material | Notes | Image |
| Scabriculocypris | S. yanbianensis | Jeongcheon | ||||
| Cypridea | C. jinjuria | C. jinjuria in Gwanghyeon | ||||
| C. khandae | ||||||
| C. samesi[45] | ||||||
| Mongolocypris | M. kohi[46] | |||||
| Lycopterocypris | L. cf. celsa | Jeongcheon | ||||
| Candona | C. sp. | |||||
| Djungarica | D. sp. | Jeongcheon | ||||
| Rhinocypris | R. sp. | Previously assigned to as Ilyocypris sp. | ||||
Spinicaudata
| Clam shrimps of the Jinju Formation | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Region | Member | Material | Notes | Image |
| Yanjiestheria[47] | Y. kyongsangensis | |||||
| Y. chekiangensis | ||||||
| Y. cf. wannanensis | ||||||
| Y. jinjuensis | ||||||
| Y. sp. | ||||||
Vertebrates
Source:[48]
Actinopterygii
| Fishes of the Jinju Formation[49] | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Region | Member | Material | Notes | Image |
| Wakinoichthys[50] | W. aokii | Multiple complete skeletons | An osteoglossiform |  | ||
| Jinjuichthys[51] | J. cheongi | Jinju | Articulated skeletons | A possible ichthyodectiform, though this classification remains controversial[52] |  | |
| Albuliformes | indeterminate | |||||
| Sinamia | S. sp. | Articulated incomplete tail | An amiiform | |||
| Lepidotes | L. sp. | Articulated skeleton, missing the anterior part of the head | Largest fish found in this formation, reaching 40 cm (1.3 ft) in total length. | |||
| Elopiformes | indeterminate | A small fish, reaching 3 cm (1.2 in) in total length. |  | |||
Reptiles
| Reptiles of the Jinju Formation | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Region[53] | Member | Material | Notes | Image |
| Crocodyliformes indet.[54] | Goryeong | a right mandible | ||||
| Titanosauriformes indet.[55][56] | Sacheon and Goryeong | teeth | A tooth from Sacheon was initially suggested to be of Asian Brachiosaurid by Lim, Martin and Baek (2001), but Barrett et al. (2002) and Choi & Lee (2017) consider it to be indeterminate titanosauriform. Meanwhile, another tooth from Goryeong was suggested to be of Diplodocoidea by Yun et al. (2007), but Choi and Lee (2017) also considered it indeterminate titanosauriform. | |||
| Pterodactyloidea indet.[55][57] | Goryeong | teeth | While the KPE 40001 suggested to be of Boreopterid origin by Choi & Lee (2017), Yun (2021) and Yun (2024) consider them to be Anhanguerian instead based on the morphological disparity from Boreopteridae and the results of two-dimensional geometric morphometric analyses.[58][59] | |||
Mollusks
Bivalvia
Gastropoda
| Gastropods of the Jinju Formation[4] | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Region | Member | Material | Notes | Image |
| Brotiopsis | B. kobayashi | Dominant gastropod of the formation | ||||
| Thiara | T. sp. | |||||
| Viviparus[62] | V. sp. | |||||
Ichnofossils
Unnamed ichnofossils from the Jinju Formation include Ornithopod[63] tracks and Caddisfly bioherms.[6]
| Ichnofossils of the Jinju Formation | ||||||
|---|---|---|---|---|---|---|
| Ichnogenus | Ichnospecies | Region | Member | Material | Notes | Image |
| Gyeongsangsauropus[64] | G. isp. | Jinju | Sauropod tracks | |||
| Grallator[65] | G. isp. | Jinju | Theropod track; similar to the ichnospecies G. yangi | |||
| Corpulentapus[65] | C. isp. | Jinju | Theropod track | |||
| Asianopodus[65] | A. isp. | Jinju | Theropod track | |||
| Minisauripus | M. isp.[5] | Jinju | One of the smallest known theropod tracks. Currently the oldest record of this ichnogenus from South Korea. |  | ||
| Dromaeosauriformipes[66] | D. rarus | Jinju | The smallest known non-avian dinosaur didactyl tracks possibly made by a small microraptorine, with indication of important flight behaviors such as flap-running, take-off, and landing.[67] |  | ||
| Dromaeosauripus[63] | D. jinjuensis | Sacheon | Didactyl tracks made by a 40 cm (1.3 ft) tall dromaeosaur. | |||
| Ignotornis | I. seoungjoseoi[68] | Sacheon | Bird Track | |||
| Jindongornipes | J. isp.[68] | Sacheon | Bird Track | |||
| Koreasaltipes[69] | K. jinjuensis | Jinju[53] | Traces left by a hopping mammal | |||
| Neosauroides | N. innovatus[70] | Jinju | The largest reported lizard trackway in South Korea. |  | ||
| cf. Chelichnus[71] | cf. C. isp. | Sacheon[53] | Turtle trackway; first identified as Chelonipus isp.[72] | |||
| Ranipes[71] | indeterminate | Jinju | Oldest known frog trackway. Made by a species that hopped in short distances. | |||
| Crocodylopodus[73] | C. isp. | Sacheon and Jinju | First report of this ichnogenus from Asia. | |||
| Batrachopus | B. grandis[74] | Sacheon | Archosaur track made by either a bipedal crocodylomorph or therizinosaur;[75] the pterosaur trackway ichnospecies Haenamichnus gainensis from the Haman Formation is now assigned to this species as B. cf. grandis.[74] Paleontologist James I. Kirkland expresses doubts on the ichnogenus assignment.[76] | |||
| Pteraichnus | P. gracilis[77] | Jinju | Pterosaur trackways. P. seopoensis is currently a naked name, since it was only described in a master's thesis. | |||
| "P. seopoensis"[78] | Sacheon | |||||
| Jinjuichnus[79] | J. procerus | Jinju | Pterosaur trackway associated with a small vertebrate trackway, showing possible stalking behavior. | |||
| Lockeia | L. gigantus[62] | Resting trace, made by bivalves | ||||
| Diplichnites | D. isp.[4] | Arthropod tracks | ||||
| Coclichnus | C. isp.[4] | Trace by Annelids | ||||
| Radialimbricatus[80] | R. bitoensis | Potential tracemakers include arthropods, cnidarians or annelids | ||||
| Protovirgularia[81] | P. dichotoma | First nonmarine occurrence of this ichnotaxon; possibly made by larvae of dragonfly[82] | ||||
| Fictovichnus[83] | indeterminate | Probable insect cocoon or pupation chamber; the earliest record of an insect pupation structure probably associated with a burrow | ||||
| Chondrites | C. isp.[84] | |||||
| Palaeophycus | P. tubularis[84] | |||||
| Helminthopsis | H. hieroglyphica[84] | |||||
| Skolithos | S. magnus[84] | |||||
| Taenidium | T. barretti[84] | |||||
| Torrowangea | T. rosei[84] | |||||