• Economic and Environmental Geology
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• v.35 no.5
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• pp.429-436
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• 2002

Core samples, drilled in the middle region of Bavaria, were analyzed to study the characteristics of organic matter in the Upper Jurassic Solnhofen limestone of southern Germany. The core (48$^{\circ}$53'N, 1-1$^{\circ}$19'E) contains Upper Jurassic Solnhofen strata ranging from the upper part of the Geisental Formation throughout the Solnhofen Formation to the lower part of the Mornsheim Formation. In the core, the Upper Jurassic lithologies consist of platy limestone, bedded limestone and massive limestone often interbedded with some chert layers. Geochemical variations (Carbon, Nitrogen and Total Organic Carbon) and Rock-Eval pyrolysis parameters (S$_2$ peak and Hydrogen Index) indicate that the organic matter in the Upper Jurassic limestone is mostly of marine origin. Particularly, the relation-ship of Hydrogen Index and S$_2$ as a function of Total Organic Carbon suggests that the upper formation of the core (Mornsheim Formation) was more influenced by terrigenous influx than the Solnhofen and Geisental Formations.

• Proceedings of the KSEEG Conference
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• 2001.04a
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• pp.378-382
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• 2001

• Journal of the Korean earth science society
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• v.38 no.1
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• pp.49-63
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• 2017

The geochemical results of the Chunyang granites located in the northeastern part of the Yeongnam Massif, indicate that these rocks have characteristics of calc-alkaline series in the sub-alkaline field, I-type and peraluminous. Most of the geochemical features in major and trace elements show systematic trends, which are similar to differentiation trends of the general Jurassic granitoids in South Korea. The Chunyang granite is largely enriched in mobile LILE (Sr, K, Rb and Ba) relatively immobile HFSE. They show LREE enriched patterns [$(La/Lu)_{CN}=41.8-73.2$] with a slightly negative Eu anomaly [$(Eu/Eu^*)_{CN}=0.89-1.10$]. There are no meaningful correlations in major and trace elements between the Chunyang granites and the Buseok plutonic rock which is the main unit of the Yeongju batholith. This result may suggest that these two plutonic rocks be not derived from the same parent magma. Tectonic discrimination diagrams indicate that the Chunyang granite was formed in volcanic arc environments. These geochemical characteristics results suggest that the Chunyang granite must have been generated at the active continental margin during the subduction of the Jurassic proto-Pacific plate.

• Korean Journal of Mineralogy and Petrology
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• v.33 no.4
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• pp.325-337
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• 2020

The Jurassic granitic rocks in the area of Gwangdeoksan located along the boundary between Hwacheon and Cherwon in northern Gyeonggi Massif consist of two-mica granite, garnet-bearing two-mica granite, mica-granite, and porphyritic biotite granite. These granitic rocks are calc-alkaline series and plotted in peraluminious domain in A/CNK vs. A/NK diagram. Petrographical and geochemical data indicate that the porphyritic biotite granite which intruded at the last period originated from distinct parental magma from two-mica granite, garnet-bearing two-mica granite, and mica-granite. On the basis of Rb/Sr vs. Rb/Ba diagram and Al2O3/TiO2 vs. CaO/Na2O, it is inferred the porphyritic biotite granite originated from protolith with less pelitic composition than 3 other granitic rocks. The enriched values of lithophile elements of Cs, Rb, and Ba and negative trough of Nb, P, Ti on spider diagram suggest that the peraluminous Jurassic granitic rocks in Gwangdeoksan area formed in subduction tectonic environment. Whole-rock zircon saturation thermometer indicates that the granitic rocks in the study area were melted at 692-795℃.

• Economic and Environmental Geology
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• v.34 no.3
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• pp.243-254
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• 2001

Variation in relative contents of clay minerals was used to genetically interpret depositional environment of the Upper Jurassic Solnhofen limestone. Mineralogical examination of whole rocks and clay fractions indicates that the faule and flinz beds are composed mainly of calcite and quartz with minor amount of clay minerals such as illite, kaolinite, and smectite. Smectite shows a trend of illitization: illite layers increase with increasing of burial depth. With increasing burial depth, relative abundance of kaolinite with quartz and illite increases. This implies that the Solnhofen basin was formed during the transgression based on reduce of terrigenous influx.

• Journal of the Korean earth science society
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• v.43 no.5
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• pp.618-638
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• 2022

The Middle Jurassic granite dike swarm intruding into the Paleoproterozoic banded gneiss is pervasively observed in Ueumdo, Hwaseong City, mid-western Gyeonggi Massif. Based on their cross-cutting relationships in a representative outcrop, there are four dikes (UE-A, UE-C, UE-D, UE-E), and depending on the direction, there are three granite dike groups, which are NW- (UE-A dike), NW to WNW- (UE-C dike), and NE-trending (UE-D and UE-E dikes). These granite dikes are massive, medium-to coarse-grained biotite granites, and their relative ages observed in outcrops are in the order of UE-A, UE-D (=UE-E), and UE-C. The geometric analysis of the dikes indicates that the UE-A and UE-C dikes intrude under approximately NE-SW trending horizontal minimum stress fields. The UE-A dike, which showed a relatively low average SiO2 content by major element analysis, is a product of early magma differentiation compared to other dikes; therefore, it is consistent with the relative age of each dike. The ²⁰⁶Pb/²³⁸U weighted mean ages for each dike obtained from SHRIMP zircon U-Pb dating were calculated to be 167 Ma (UE-A), 164 Ma (UE-C), 167 Ma (UE-D), and 167 Ma (UE-E), respectively. The samples of the UE-A, UE-D, and UE-E dikes showed very similar ages. The UE-C dike shows the youngest age, which is consistent with the results of the relative age in the outcrops and major element analysis. Therefore, the granite dikes intruded into the Middle Jurassic (approximately 167 and 164 Ma), coinciding with those of the Gyeonggi Massif, where the Middle Jurassic plutons are geographically widely distributed. This result indicates that the wide occurrence of the Middle Jurassic plutons on the Gyeonggi Massif was formed as a result of igneous activity moving in the northwest direction with the shallower subduction angle of the subducting oceanic plate during the Jurassic.

• Economic and Environmental Geology
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• v.44 no.2
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• pp.109-122
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• 2011

The major Mo deposits in South Korea were formed during the Jurassic Daebo orogeny, the Late Cretaceous and the Tertiary post-orogenic igneous activities, and are characterized by a variety of genetic types such as pegmatite, greisen, skarn, porphyry and vein types. The Jangsu mine is a pegmatite-style deposit which is genetically related to the Jurassic ilmenite-series two-mica granite with the Mo mineralization age of $159.6{\pm}4.5$ Ma. The Geumseong mine occurs as a skarn/porphyry-style deposit associated with highly fractionated granite. Its age of Mo mineralization within aplitic cupola is about 96.5~l07.5 Ma. The Yeonil mine is a porphyry-style deposit, and the Geumeum mine is a veinlet-style deposit along the fracture zone with their mineralization ages of $58.4{\pm}1.6$ and $54.4{\pm}1.2$ Ma, respectively. The contrasts in the style of Mo mineralization in Korea reflect the different environment of the related magmatism. The Jurassic mineralization, being related to deep-seated granitoids, occurs as a pegmatite-style deposit, whereas the Cretaceous one, being related to subvolcanic granitoids, occurs as skarn/porphyry/vein-type ore deposits. The Tertiary Mo mineralization has a close relationship with the igneous activities associated with the Tertiary basin formation along the east coast, Korean peninsular.

• The Journal of the Petrological Society of Korea
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• v.28 no.2
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• pp.85-109
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• 2019

Various Mesozoic igneous rocks such as biotite granite, leucogranites, granodiorite, hornblende gabbros, quartz gabbros and tonalite are identified in the Dangjin area, the western Gyeonggi Massif, Korea. The major Mesozoic igneous activities in the Dangjin area are recognized as periods of ca. 227 Ma, ca. 190 Ma, ca. 185 Ma and ca. 175 Ma. Gabbroic rocks consist mainly of hornblende gabbros and quartz gabbros which are characterized by dominant hornblende and occur as small stocks. The gabbroic rocks have intrusion ages between 185 and 175 Ma. Triassic biotite granite ($225{\pm}2.3Ma$) is considered to be a post-collisional granite similar in geochemistry to the southern Haemi granite ($233{\pm}2Ma$, Choi et al., 2009). Although the main magma source of biotite granite appears to be a granitic continental crust, the biotite granite could have a small amount of mafic rocks as a magma source, or a small amount of mantle-derived melts (i.e., mafic melts) could have contributed to the formation of primitive granite magma in composition. Jurassic granitoids and gabbroic rocks in the Dangjin area are considered to be continental arc igneous rocks associated with the subduction of the Paleo-Pacific plate. It is presumed that the leucogranites are formed by crustal anatexis of granitic materials and the gabbroic rocks are formed by partial melting of enriched mantle.

• The Science & Technology
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• no.5 s.444
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• pp.10-13
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• 2006

몸에 좋은 지방 가진 돼지 개발/ 국제연구팀, 중성미자 질량 재확인/ NASA, 2009년 달 충돌실험/ 직립원인과 현생인류 중간의 두개골 발견/ 곤충의 美경제 기여, 年 570억 달러 이상/ 공룡 멸종 소행성 충돌시기 논란/ 깃털 진화이론 뒤집는 쥐라기 화석 발견/ 남극권 기온상승 타지역의 3배/ '딥 임팩트'로 드러나는 혜성의 비밀/ 물을 위로 흐르게 하는데 성공/ 뇌세포-컴퓨터칩 결합시킨 '뉴로칩' 개발

• 한국지구과학회:학술대회논문집
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• 2005.09a
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• pp.32-39
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• 2005

최근 들어 북한 서해안 일대의 원유매장 가능성에 대한 보도가 국내외 언론에 자주 오르내리고 있다. 실제 북한의 서한만 분지는 일일 생산량 450 배럴의 원유가 생산되고 있어 석유부존 가능성이 확인되었고, 중국에서 큰 유전중 하나인 발해만 유전지대와 지리적으로 근접해 있어 대규모 매장 가능성도 있다. 지금까지 밝혀진 북한 서한만의 지질은 중국의 발해만과 유사하다. 후기 원생대와 초기 고생대에 생성된 기반암 위에는 최대 6 ${\sim}$ 10 km 두께의 탄산염암 및 중생대 퇴적암과 4 ${\sim}$ 5 km 두께의 퇴적암이 집적되어 있다. 근원암은 3 km 이상 되는 쥐라기 흑색 셰일과 1 ${\sim}$ 2 km 두께의 백악기 흑색 셰일 그리고 수 km 두께의 중생대 이전의 탄산염암으로 구성되어 있다. 저류층은 높은 공극률을 가진 중생대부터 신생대에 퇴적된 사암과 중생대전에 균열된 탄산염암이다. 원유 트랩은 배사구조, 단층구조, 파묻혀 있는 언덕 그리고 층서형 트랩 형태다. 따라서 서한만에서의 퇴적층들은 다양한 형태의 근원암을 가지며 또한 공극률과 투수율이 높고, 많은 단층에 의한 이동경로를 가지게 되므로, 사암으로 이루어진 석유 저장지만 발견하면 석유를 생산할 수 있을 것으로 추정된다.