• Journal of the Mineralogical Society of Korea
• /
• v.2 no.2
• /
• pp.90-99
• /
• 1989

Manganese deposits ar the Dongnam mine occur as vein in the Pungchon limestone of Ordovician age. Manganese ore veins consist of the hydrothermal manganese carbonate ores in the deeper part and the supergene manganese oxide ores in the shallow part. Manganese carbonate ores consist mainly of rhodochrosite, with minor amount of proxmangite, garnet, calcite, quartz, pyrite, galena and sphalerite. Manganese oxide ores consist of rancieite, buserite, birnessite, vernadite, todorokite, pydrolusite, nsutite, hydrohetaerosite and goethite. Manganese oxide minerals were formed in the following sequences; 1) rhodochrosite ${\rightarrow}$ vernadite ${\rightarrow}$ birnessite ${\rightarrow}$ nsutite ${\rightarrow}$ pyrolusite, 2) pyroxmangite ${\rightarrow}$ birnessite, 3) Buserite ${\rightarrow}$ ransieite. Todorokite, buserite and hydrohetaerolite were precipitated from solution in the later stage. The natural analogue of synthetic buserite has been discovered from the mine. It has been disclosed that buserite transforms to rancicite by dehydration, and that distinction between buserite and todorokite is possible by X-ray diffraction studies combined with dehydration experiment. Minerals identified from the mine have been characterized using various methods including polarizing microscopy, X-ray diffraction, thermal analysis, infrared spectroscopy, X-ray diffraction, thermal analysis, infrared spectroscopy, elecrton microscopy and dehydration experiment.

• Journal of the Mineralogical Society of Korea
• /
• v.23 no.4
• /
• pp.357-365
• /
• 2010

Optically stimulated luminescence (OSL) of quartz is commonly applied to the age dating of Quaternary sediments. However, one of the issues is that some of the quartz samples are not suitable to OSL dating. Mineralogical analysis of the quartz samples with diverse OSL signals are required to strengthen the reliability and applicability of the OSL dating. We analysed the OSL signal characteristics of sedimentary quartz samples from diverse geological environments and measured their trace element contents using laser-ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Quartz samples could be grouped into ones suitable to OSL dating and ones unsuitable on the basis of their OSL signal characteristics. The average trace element contents ranged from 73 to 260 ppm (Al), and from 61 to 248 ppm (Ti) with minor Li, Mg, Cr, Mn, and Fe contents below 40 ppm. We did not find any significant variation of trace element contents of quartz samples consistent with their OSL signal characteristics. This indicates unknown mineralogical factors causing diverse OSL characteristics which should be confirmed by further analysis of sufficient set of samples.

• Journal of the Korean Institute of Landscape Architecture
• /
• v.43 no.4
• /
• pp.50-61
• /
• 2015

This study investigates how Abies holophylla was planted as a tree sacred to the gods by Japan during the late Chosun and Japanese colonial periods. This study surveyed the current conditions of old Abies holophylla geological information, year planted, and the relationship between Abies holophylla and traditional Japanese values. The reasons that Abies holophylla was considered a tree sacred to the gods are as follows. Firstly, trees are planted on the spaces between Iljumun and Numun in Buddhist temples of Korea in the same way as trees are planted on the roads for worship in traditional temples of Japan. Secondly, tree diameter at breast height ranged from 60cm to 100cm. This means that the Abies holophylla trees range in age from 70 years to 138 years, showing that the trees were planted at the period between the beginning of Japanese Buddhism(1877) and the Japanese Colonial Period (1945). Thirdly, conclusions regarding why the Abies holophylla were planted in Korean temples at the beginning of Japanese Buddhism will be drawn based on the records that Jingu-Kogo's Conquest of Silla was taken care of the Suwataisha as a tree sacred to the gods in Japanese tradition. The reason for which Abies holophylla was planted in Korean temples should be evaluated through the remnants of Japan in the past. The issue of the old Abies holophylla in Korean temples should be investigated and further discussed in depth.

• The Korean Journal of Quaternary Research
• /
• v.24 no.2
• /
• pp.35-48
• /
• 2010

The purpose of this study is to investigate paleoenvironmental conditions of the shallow sea around Jeju Island during the Late Holocene using geochemical contents of the bivalve (Glycymeris albolineata) collected from the Sangmori Shell Mound. The bivalve shell used shows the archaeological age of 2,300 yr BP. Stable carbon and oxygen isotope compositions show that growth rates decreased with aging. Coeval trends of both isotope compositions can be observed: heavier values during winters and lighter values summers except for their young and old growth stages. The seasonality of bivalve shell appear to reflect seasonal variations of paleotemperature as well as paleosalinity. Especially China Coastal Water with low salinity was transported into the southern Jeju Strait from Changjiang River during summer periods. Heavier carbon isotope values during winter indicate higher productivity, and this is supported by high density of phytoplanktons and higher chlorophyll contents during winter time. For accurate interpretation, monitoring of present-day conditions of shallow marine water as well as additional geochemical analysis of the same Recent bivalve may be necessary.

• Journal of the Korean association of regional geographers
• /
• v.3 no.1
• /
• pp.165-182
• /
• 1997

The aim of this paper is to clarify geomorphic features on talus within ${\check{O}}rumkol$ and the origin of ${\check{O}}rumkol$. ${\check{O}}rumkol$ is located in Milyang of Kyungnam province, in South Korea. ${\check{O}}rumkol$ is good area to study talus. because it is characterized by following three geomorphic landscapes : free face surrounding ${\check{O}}rumkol$ ; ${\check{O}}rumkol$ with deep and wide valley floor ; lots of taluses typically developing within ${\check{O}}rumkol$. The main results can be summarized as follows: 1) The origin of ${\check{O}}rumkol$ may be suggested two assumptions : one is that its origin have been resulted from intrusion structure(intrusive rock might capture less resistant rock as tuff) ; the other is that its origin have been resulted from volcanic depression after intrusion or eruption. But these assumptions are not obvious. therefore more geological evidences will be supplemented after this 2) The characteristics of ${\check{O}}rumkol$ talus (1) Pattern ${\check{O}}rumkol$ taluses are tongue-shaped or cone-shaped in appearance. They are $50{\sim}200m$ in length and the range of the maximum width from 25 to 115m and one of their mean slope gradient from 32 to $36^{\circ}$ (2) Origin ${\check{O}}rumkol$ taluses have been formed under periglacial environment in the last glacial age and they are classified into rock fall talus type, considering in conjunction with the shape, hardness, sorting, weathering conditions of constituent debris. (3) The stage of landform development ${\check{O}}rumkol$ talus slope profiles are mainly concave slope. This concave slope type was eventually caused by talus creep at the lower end of the talus. That means new additions of debris from the free face have virtually ceased and there is no evidence of recent motion in the deposit. Now it is predominant that vegetation cover is gradually increasingly. Therefore ${\check{O}}rumkol$ taluses appear to be relict form stage. at present.

• Journal of Conservation Science
• /
• v.6 no.1 s.7
• /
• pp.31-60
• /
• 1997

Stone-cultural-properties, distributed in Naju, Hwasun and a part of Jangheung, have been investigated and studied on the characteristics, rock weathering and phases in the geological and conservational points of view. The properities involve pagoda and twelve stupas, four stone-buddha, three stone monuments, two stone-lantern, four stone-Jangseung, one and flag-pole. The rocks used are mainly pebble-bearing tuffaceous rocks of the Cretaceous age which are widely distributed in the area. However, granites are also used in some properties. These rocks are strongly influenced by weathering and pervasive moss. The mottled rock surfaces in some properties are in colors due to pervasive moss different. Parts of some cultural properties are broken which results in structurally unstable. Cultural properties in the area are relatively well conserved at the earth consolidated by ramming and by iron fence. However some cultural properties are partly repaired by using other hinds of rock phases which results in different colors in weathered rock surface. For conservation, rock phases, weathered surface colors, and relationships with original parts must be scientifically considered in repairment forward.

• The Korean Journal of Petroleum Geology
• /
• v.14 no.1
• /
• pp.63-73
• /
• 2008

The seismic interpretation was carried out to understand the evolution of the Sora and North Sora Sub-basins, South Sea of Korea. Both sub-basins belong to the Domi Basin, which is located in the northeastern margin of East China Sea Basin with Fukue Basin of Japan. Age assignment of each strata in this study was based on the data of boreholes and seismic interpretation in NW Japan. Four regional horizons were identified, and five geological units; Y(basement), Q(Eocene$\sim$Middle Oligocene), M(Middle Oligocene$\sim$Early Miocene), L(Early Miocene$\sim$Late Miocene) and D(Late Miocene$\sim$Present) groups in ascending order. Structural trends of the main boundary faults and the basin-fill sediment are different between the Sora and North Sora Sub-basins; i.e., trend of the main boundary-faults, dip of horizons, distribution of basin and development of growth fault. These results imply that the Sora Sub-basin would have opened earlier than the North Sora Sub-basin.

• The Journal of the Petrological Society of Korea
• /
• v.25 no.3
• /
• pp.231-240
• /
• 2016

Three Quaternary faults have been revealed in marine terraces nearby the Homigot and the Gurongpo in the southeastern offshore of Korean Peninsula. The Hajung fault cuts the $4^{th}$ marine terraces and the Guman fault the $2^{nd}$, respectively. The Hajung fault strikes $N55^{\circ}$ to $45^{\circ}W$ and dips $40^{\circ}$ to $45^{\circ}NE$ with reverse-displacement of 180cm vertically. There are four sets of colluvial sediment strata that would be produced by faulting and indicate four times of fault movements during MIS 7 and MIS 5c. The Guman fault site consists of three sets of reverse faults that strike $N80^{\circ}E$ to $N70^{\circ}W$ and dip $25^{\circ}{\sim}35^{\circ}SE$ to $30^{\circ}SW$ with vertical displacement of 9~18 cm. The Guman faulting occurred during 80 ka (MIS 5a) to 71 ka (MIS 4) but it extends only to the lowest bed, the pebble sand bed, lay just on the unconformity, and not to the upper. Considering the attitude of the faults, we inferred that the Hajung fault was activated under the ENE-WSW compression during MIS 7 to MIS 5c and the Guman under N-S trending compression during MIS 5a. Using the OSL age dating results, we reconfirmed that the $2^{nd}$ terrace is correlated to MIS 5a and the $4^{th}$ terraces to MIS 7.

• Journal of the Korean earth science society
• /
• v.40 no.2
• /
• pp.163-176
• /
• 2019

The Potosinian geological basement in central Mexico is comprised of the Upper Paleozoic metamorphic rocks, which crop out on the Sierra de Catorce nucleus located in the northeastern part of the state. The sedimentary sequence that covers unconformably the Paelozoic basement is represented by an Upper Triassic marine sedimentary sequence, correlating to the Zacatecas Formation and the Upper Triassic continental Huizachal Formation red beds, which in turn are covered either by La Joja Formation Jurassic red beds or by Upper Jurassic marine sediments. This sequence is overlain by the conformable Cretaceous calcareous marine sedimentary rocks in all the state of San Luis Potosi. The Cenozoic sequence unconformably covers some of the aforementioned rocks and is represented by undifferentiated volcanic rocks as well as by marine clastic rocks. The existing intrusive igneous rocks are felsic to intermediate composition, and they intrude the metamorphic basement and sedimentary rocks. Conglomerates with evaporitic sediments were deposited during the Pleistocene. The Quaternary sequence includes basalt flows, piedmont deposits, alluvium, and occasionally evaporites and caliche layers. In the state of San Luis Potosi, a great diversity of mineral deposit types is known as both metallic and nonmetallic. The host rocks of these deposits vary from one another including formations that represent from Paleozoic up to Tertiary. The mineralization age corresponds approximately to Tertiary (75%), and is mainly epigenetic. Conclusively, the data on geology and mineralization in San Luis Potosi, Mexico are helpful to predict a hidden ore body and select promising mineralized zone(s) when the domestic company makes inroads in the mining sector of Mexico.

• The Journal of the Petrological Society of Korea
• /
• v.28 no.2
• /
• pp.53-69
• /
• 2019

In the Jirisan area of the Yeongnam Massif, Korea, several ductile shear zones are developed within Precambrian gneiss complex (Jirisan metamorphic rock complex). The ductile shear zones have a general NS- and NNE-striking foliation with westward dipping directions. The foliation developed in the shear zones cut the foliation in gneiss complex. The stretching lineations are well developed in the foliated plane of the shear zone, showing ENE-trend with gentle plunging angle to the ESE direction. Within shear zone, several millimetric to centimetric size of porphyroclasts are deformed strongly as a sigmoid form by ductile shearing. The sigmoid patterns of porphyroclasts in the shear zones indicate the dextral shearing. The spatial distribution of ductile shear zone is characterized by the dominant NS- and NNE-striking dextral sense in the central and eastern regions respectively. In the western part, it develops in NE-striking dextral sense which is the general direction of the Honam shear zone. The U-Pb concordant ages obtained from the two samples, the strongly sheared leucocratic gneiss, are $1,868{\pm}3.8Ma$ and $1,867{\pm}4.0Ma$, respectively, which are consistent with the U-Pb ages reported around the study area. We supposed that the ductile shearing in the study area is occurred about 230~220 Ma during late stage of the continental collision around Korea and is preceded by granitic intrusion related to subduction during 260~230 Ma, which are supported by compiling the age data from sheared gneiss, deformed mafic dyke intruded gneiss complex, and non-deformed igneous rocks.