• Proceedings of the KSEEG Conference
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• 2005.04a
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• pp.333-336
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• 2005

• The Journal of the Petrological Society of Korea
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• v.3 no.2
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• pp.128-137
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• 1994

The northeastern shore of the Anmyondo consists mainly of tuff, basalt, andesite and dacite. The K-Ar ages of the two mugearites are $89.4{\pm}2.4$ Ma and $91.9{\pm}2.3$ Ma which correspond to the middle Cretaceous age. Petrochemical reviews on the volanic rocks of the Cretaceous, Tertiary and Quaternary ages in the Korean Peninsula show that marked differences exist in chemical compositions according to the age of eruption.

• The Journal of the Petrological Society of Korea
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• v.21 no.2
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• pp.217-233
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• 2012

Major elements abundances of Cretaceous to Tertiary volcanic rocks in Kyongsang basin are similar with Southern Volcanic Zone (SVZ) in Andes. Sr, K, Rb, $Ba{\pm}Th$ abundances, which have low ionic charge, are selectively fertile, on the other hand Ta, Nb, Ce, P, Zr, Hf, Sm, Ti, Y, Yb, Sc, Cr abundances are low. K, Sr, Th show characteristic spikes and Nb show remarkable trough on trace elements spider diagram. Trace elements abundances are higher than that of Andes which is supposed to mantle sources of Kyongsang basin volcanic rocks are produced lower degree of partial melting than SVZ in Andes.

• The Journal of the Petrological Society of Korea
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• v.18 no.2
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• pp.93-114
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• 2009

Lithological and petrochemical characteristics and tectonic setting of the Cretaceous volcanic rocks in Hampyeong area located in the southwestern part of Okchon Zone, were studied by field survey and petrochemistry of major, trace, and rare earth elements. The $SiO_2$contents of the volcanic rocks range from 50.8 to 77.2wt.%. With increasing $SiO_2$, $Al_2O_3$, $Fe_2O_3\;^T$, $TiO_2$, MnO, CaO and MgO contents decrease and $K_2O$content increase, but $Na_2O$content is scatter to the trend. According to TAS and AFM diagrams, the Cretaceous volcanic rocks are calc-alkaline series. On the discrimination diagram of $K_2O$versus $SiO_2$, the volcanic rocks belong to high-K rocks series. The trace element compositions and REE patterns of the volcanic rocks, characterized by a high LILE/HFSE ratio and enrichments in LREE, indicate that they are typical of continental margin arc calc-alkaline volcanic rocks associated with the subduction environment. The ratios of Ba/Ta and Ba/La indicate that they are associated with volcanic arc-related magmatism. The Cretaceous volcanic rocks in Hampyeong area might be located in the Eurasian continental margin, related to the Pacific type tectonic environment during the Cretaceous times.

• Proceedings of the KSEEG Conference
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• 2005.04a
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• pp.101-103
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• 2005

• Economic and Environmental Geology
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• v.34 no.1
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• pp.119-131
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• 2001

A mean characteristic remanent magnetization was obtained for the first time in Korea from volcanic and pyroclastic sedimentary rocks distributed in Haenam Area, located in southwestern part of the Korean Peninsula. The age of the prevailing rocks in this area belongs mostly to Late Cretaceous, with a few exceptions of Early Cretaceous, mainly based on K/Ar whole rock age dating. Characteristic remanent magnetizations of these have both normal and reverse polarities with antipodal direction, which were interpreted to be the primary remanent magnetizations obtained by the ambient Earth's magnetic field at the time of formation of the concerned rocks. The source magnetic minerals of the remanent magnetization has been identified as magnetite. The mean direction of characteristic remanent magnetization obtained from the Late Cretaceous rocks in this study is Dm/Im=21.4 supper(o)/57.1 supper(o) (${\alpha}_{95}=13.4^{\circ}$, k=350.0). The paleomagnetic pole position calculated from this result for the Late Cretaceous, is $72.5^{\circ}N/199.9^{\circ}E$ (dp/dm= $14.2^{\circ}/19.5^{\circ}E$), which matches well with those of 80 Ma ($76.2^{\circ}N/198.9^{\circ}E$) and 90 Ma ($76.2^{\circ}N/200.1^{\circ}E$) of the Eurasian Continent's APWP (Apparent Polar Wander Path). This result strongly indicates that the studied area, belonging to the Eurasian Continent, have suffered very little geotectonic movement after the Late Cretaceous. The deflection of declination of remanence from Early Cretaceous rocks in the study area may indicate that the micro-block was counterclockwisely rotated with vertical axis between the late of Early Cretaceous and the early of Late Cretaceous.

• Journal of the Korean earth science society
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• v.33 no.7
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• pp.618-626
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• 2012

The Cretaceous fossil sites of Seoyuri in Hwasun was designated as the Korean Natural Monument No. 487 in November 2007. It provides important resources for paleoenvironmental studies, including theropod trackways, plant fossils, mudcracks, ripple marks, and horizontal bedding. The Cretaceous sedimentary strata contain a wide variety of volcanic pebbles, 5-40 cm in diameter in the lower portion and are overlain by the Late Cretaceous Hwasun andesite. Whole rock absolute K-Ar age determinations were performed on six volcanic pebbles from the Cretaceous sedimentary strata and on two samples from the overlaying Hwasun andesite. These ages indicate that the rocks belong to the period between the Turonian of the late Cretaceous (91-70 Ma) and the Pliocene age of the early Cenozoic ($63.4{\pm}1.2$ and $62.1{\pm}1.2$ Ma). Thus, the K-Ar ages indicate that the maximum geological age of the dinosaur track-bearing sedimentary deposits is about ca. 70 Ma. Therefore, it suggests that the age is comparable to the formation ages of the dinosaur footprints-bearing deposits in Sado area of Yeosu (71-66Ma).

• The Korean Journal of Petroleum Geology
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• v.7 no.1_2 s.8
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• pp.28-34
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• 1999

The Cretaceous Poongam sedimentary Basin in Kangwon-do, Korea consists alluvial deposits of conglomerates, sandstones, mudstones or siltstones, and volcaniclastics. The Poongam Basin was formed as a fault margin sag or a transpressional basin developed along a strike-slip fault zone, and received huge amount of clastic sediments from the adjacent fault-scaip. It formed an aggrading alluvial fan system and a volcaniclast-supplied marginal lake environment, while tectonic activity and volcanism attenuated toward the end of basin formation. Following the Folk's classification, the sandstones of the Poongam Basin are identified as lithic wackes or feldspathic wackes. The areal and sequential variation of the mineral composition in the sandstones is not distinct. The results of K-Ar age dating from the intruding andesites, volcaniclastics and volcanic fragments in sedimentary rocks show a range of 70 Ma to 84 Ma. It suggests that volcarism occurred sequentially within a relatively short period as the pre-, syn-, and post-depositional events. It was the short period in the late Cretaceous that the basin had evolved i.e., the basin formation, the sediment input and fill, and the , intrusion and extrusion of volcanic rocks occurred. The Poongam sedimentary sequence is a typical tectonic-controlled coarse sedimentary facies which is texturally immature.

• Proceedings of the Petrological Society of Korea Conference
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• 2000.05a
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• pp.16-16
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• 2000

• Proceedings of the Petrological Society of Korea Conference
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• 2000.05a
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• pp.20-20
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• 2000