• 한국지구과학회:학술대회논문집
• /
• 한국지구과학회 2004년도 춘계학술발표회 논문집
• /
• pp.58-58
• /
• 2004

• 한국지구과학회:학술대회논문집
• /
• 한국지구과학회 2006년도 춘계학술발표회 논문집
• /
• pp.116-117
• /
• 2006

• 한국지구과학회지
• /
• 제27권7호
• /
• pp.745-756
• /
• 2006

Early Ordovician graptolites from the Mungok Formation of Yeongwol area, Korea comprise seven species belonging to six genera: Callograptus curvithecalis, Callograptus sinicus, Aspidograptus lotolatzensis, Dendrograptus suni, Dictyonema uniforme, Adelograptus cf. tenellus, and Psigraptus jacksoni. Two graptolite zones with three subzones are recognized in the eight sections of the Mungok Formation. The Adelograptus Zone is correlated with (1) La 1b of the Lancefield Formation of Victoria, Australia, (2) the Adelograptus-Clonograptus Zone of the Yehli Formation of Jilin, China, and (3) the Adelograptus Zone of the Road River Formation of Yukon, Canada. It suggests that the upper part of the Mungok Formation corresponds to early Late Tremadocian of Early Ordovician.

• 한국지구과학회:학술대회논문집
• /
• 한국지구과학회 2001년도 정기총회 및 추계학술발표 논문요약집
• /
• pp.66-66
• /
• 2001

• Ocean and Polar Research
• /
• 제21권2호
• /
• pp.127-136
• /
• 1999

Radiolarian assemblages from KODOS area were analyzed in order to understand the biostratigraphy and paleoceanography of deep-sea sediment from the Northeast Equatorial Pacific. The sediment core was divided into two or three units on the basis of the chemical and physical properties. In the upper sediment, mixtures of Quaternary and Tertiary radiolarians are found indicating active reworking processes. Dissolution of radiolarians seem to increase with depth. Radiolarians are seldom in Unit III presumably due to dissolution and corrosion. The middle part of unit I appears to correspond to Collosphaera invaginata Zone (0.21 Ma). Unit II belongs to Collosphaera tuberosa Zone. Based on the absence of Stylatractus universus, we estimate its age to be younger than 0.42 Ma. Based on our analyses of radiolarians in Unit I and II, we estimated the age of unit III as Tertiary, particularly from Oligocene to Miocene. There may to be hiatuses of more than 3 My from late Miocene to Pliocene, which probably resulted from erosion and dissolution by the Antarctic Bottom Water Sedimentation rates during Quaternary range from 0.15 to 0.50 mm/ky with significant variabilities among stations. Radiolarians in the study area were mostly warm-water species.

• 한국지구과학회지
• /
• 제31권5호
• /
• pp.419-429
• /
• 2010

The Pyeongan Supergroup can be divided into seven lithostratigraphic units (Moscovian to Early Triassic?) in the Samcheok coalfield and four lithostratigraphic units (Bashkirian to Artinskian) in the Yeongwol coalfield of South Korea. On the basis of fusulinid biostratigrapic data in the Yeongwol coalfield, the boundary between the Carboniferous and Permian strata of the Pyeongan Supergroup has been considered as unconformity since the Kasimovian and Gzhelian strata are missing. Protriticites and Triticites, which are the cosmopolitan index fusulinids indicating the Kasimovian and Gzhelian age, are not found from the uppermost part of the Geumcheon and Pangyo Formations. Recently some fusulinids such as Xenostaffella koreaensis, Hanostaffella magna, and Fusulina danyangensis found from the uppermost part of the Geumcheon and Pangyo Formations are recognized as the early Kasimovian-type fusulinids, although the upper Kasimovian- to Gzhelian-type fusulinids are still missing.

• 한국지구과학회지
• /
• 제28권4호
• /
• pp.497-540
• /
• 2007

지금까지 보고된 하부 오르도비스기의 Tremadocian과 Arenigian에 속하는 방산충 군집들 간에는 유사성이나 연관성이 거의 보이지 않았다. Tremadocian에서 Arenigian의 방산충 군집의 진화경향을 알 수 없었던 이유는 후기 Tremadocian 방산충 군집에 대해 알려진 바가 없었기 때문이다. 캐나다 뉴파운드랜드의 Cow Head Group에서 후기 Tremadocian에 속하는 방산충 화석 군집들이 처음으로 발견되었다. 이 새로운 방산충 군집들은 모두 6과, 11속, 26종에 속한다. 이들 가운데 6속 17종이 새로이 발견된 것들이다. Arenigian에서만 보고되었던 Proventocitidae에 속하는 종들이 다양하게 산출되었다. 초기 Tremadocian에 번성했던 Protoentactiniidae와 Echidniniidae에 속하는 것들은 감소하고 Aspiculumidae에 속하는 것들은 더욱 분화되어 다양하고 풍부하게 산출되었다. 방산충과 함께 출현하는 코노돈트 연구로 Low Diversity Interval에서 M. dianae Zone 그리고 하부 P. proteus Zone에 속하는 후기 Tremadocian 방산충 군집들로 밝혀졌다. 또한 R. manitouensis Zone에 속하는 코노돈트 화석군집이 발견되어 중기와 후기 Tremadocian에 속하는 Cow Head Group이 분포하는 여러 지역 간의 (Martin Point, Western Brook Pond, Broom Point, 그리고 St. Paul's Inlet) 층서대비를 보다 정확하게 할 수 있었고, 코노돈트 생층서에서는 R. manitouensis Zone, Low Diversity Interval, M. dianae Zone, 그리고 하부 P. proteus Zone이 식별되었다.

• 한국지구과학회지
• /
• 제27권7호
• /
• pp.768-777
• /
• 2006

The goal of this study is to elucidate the fusulinid biostratigraphy of the Carboniferous limestones distributed in the Gangdong area of Samcheok coalfield, Korea. The Carboniferous strata of the study area mainly comprise alternaton of dark gray shale, dark gray and reddish sandstone, and gray limestone. The limestones consist mainly of wackestonepackstone containing various fossil fragments such as crinoid, coral, brachiopod, foraminifera, fusulinid, and bryozoa; this observation thus suggests that the study site was the shallow marine environments. A tital of 12 species belonging to 5 genera of fusulinids are identified from the limestones of the Gangdong geologic section: Ozawainella turgida Sheng, Ozawainella sp. A, Ozawainella magna Sheng, Pseudostaffella antiqua (Dutkevich), Pseudostaffella paracompressa Safonova, Pseudostaffella kimi Cheong, Pseudostaffella sp., Beedeina lanceolata (Lee and Chen), Beedeina samarica (Rauser-Chernoussova), Beedeina sp. A, Neostaffella sphaeroidea cuboides Rauser-Chernoussova, and Hanostaffella hanensis Cheong. Such fusulinids species were reported from the lower part of the Geumcheon Formation in Samcheok coalfield and the middle Moscovian stage in Eurasia. On the basis of the fusulinid biostratigraphic correlation of the Gangdong geologic sections (A) to (C), the limestone should be overlapped by faults and folds. Moreover the stratigraphic thickness of the limestone is thinner than the thickness of the limestone outcrop of the Gangdong geologic section. Therefore, the stratigraphic sequence of the Gangdong geologic section is represented as the Gangdong geologic section (A).

• Ocean and Polar Research
• /
• 제37권1호
• /
• pp.23-35
• /
• 2015

A 450 m-long sediment section was recovered from Hole U1359D located at the eastern levee of the Jussieau submarine channel on the Wilkes Land continental rise (East Antarctica) during IODP Expedition 318. The age model for Hole U1359D was established by paleomagnetic stratigraphy and biostratigraphy, and the ages of core-top and core-bottom were estimated to be about 5 Ma and 13 Ma, respectively. Biogenic opal content during this period varied between 3% and 60%. In the Southern Ocean, high biogenic opal content generally represents warm climate characterized by the increased light availability due to the decrease of sea-ice distribution. The surface water productivity change in terms of biogenic opal content at about 10.2 Ma in the Wilkes Land continental rise was related to the development of Northern Component Water. After about 10.2 Ma, more production of Northern Component Water in the North Atlantic caused to increase heat transport to the Southern Ocean, resulting in the enhanced diatom production. Miocene isotope events (Mi4~Mi7), which are intermittent cooling intervals during the Miocene, appeared to be correlated to the low biogenic opal contents, but further refinement was required for precise correlation. Biogenic opal content decreased abruptly during 6 Ma to 5.5 Ma, which most likely corresponds to the Messinian salinity crisis. Short-term variation of biogenic opal content was related to the extent of sea-ice distribution associated with the location of Antarctic Polar Front that was controlled by glacial-interglacial paleoclimate change, although more precise dating and correlation will be necessary. Diatom production in the Wilkes Land continental rise increased during the interglacial periods because of the reduced sea-ice distribution and the southward movement of Antarctic Polar Front.

• 한국석유지질학회:학술대회논문집
• /
• 한국석유지질학회 1999년도 제6차 학술발표회 발표논문집
• /
• pp.50-67
• /
• 1999

Biostratigraphic and paleoenvironmental analyses are carried out on cutting samples from the Dolgorae wells drilled in the Ulleung basin. The clayey, silty, and sandy sediments of the wells yield various microfossil assemblages of relatively good preservation, among which five fossil groups are reported; a total of 97 foraminiferal species of 66 genera, 19 nannofossil species of 12 genera, 86 ostracod species of 41 genera, 107 diatom species of 44 genera, and 124 dinoflagellate cysts species of 45 genera. Based on microfossils the geologic ages of the Dolgorae wells are dated to be from late Early Miocene to Early Pleistocene. Several biohorizons are defined in Neogene successions by the LOD (Last Ocurrence Datum) and FOD (First Ocurrence Datum) of marker species including G. truncatulinoides (LOD: 1.9 Ma) of foraminifera; C. macintyeri (LOD: 1.64-1.60), G. oceanica (FOD: 1.65 Ma), G. caribbeanica (1.72 Ma), D. brouweri (LOD: 2 Ma), R. pseudoumbilica (LOD: 3.66 Ma), P. lacunosa (FOD: 4.2 Ma) of nannofossils; S. ellipsoideus (LOD: 4 Ma), S. palcacantha (LOD: 10.2), C. giusepei (LOD: 14 Ma) of dinocysts; D. seminae v. fossilis (FOD: 3.7 Ma), T. antiqua (LOD: 1.7 Ma), T. convexa (LOD: 2.4 Ma), N. kamtschatica (LOD: 2.58 Ma), T. oestrupii(FOD: 5.1 Ma) of diatoms. Abundance patterns of microfossils throughout the wells reflect changes in paleoenvironmental and sedimentological settings of the basin in relation to sea-level variations. According to these data the large-cycle and small-cycle changes of transgression and regression phases are observed in terrestrial to marine sediments. This high-resolution sequence biostratigraphy established by various fossil groups enabled more reliable correlation between strata and refined interpretation on deposition systems of the basin. It also proved to provide fundamental and precise informations regarding stratigraphic correlation, tectonic events, basin, and depositional history for hydrocarbon explorations, especially in collaboration with seismic-stratigrahic analyses.