Joban Coal Field Research Articles

The End Process of the Joban Coalfield Ibaraki: A Case of Closure Measure for Takahagi Coal Mine Co. , Ltd. Kushigata Mining Station

The End Process of the Joban Coalfield Ibaraki: A Case of Closure Measure for Takahagi Coal Mine Co. , Ltd. Kushigata Mining Station

Temporal variations in channel patterns and facies architecture in a gravelly fluvial system: The Paleogene Iwaki Formation on the Joban Coalfield, a forearc basin in Northeast Japan

AbstractThis paper examined sequence‐stratigraphic features of a gravelly fluvial system of the Iwaki Formation, which developed in a forearc‐basin setting in Northeast Japan during the Eocene through Oligocene. On the basis of three‐dimensional architectural element analysis, we discriminated three major cycles of channel complexes, which contain ten component channel deposits in total in the fluvial succession. Component channel deposits in the uppermost part of each cycle are sandier and associated with overbank muddy deposits and coal beds as compared with those in the lower part of the cycle. Mean clast‐size also decreases upsection in the entire gravelly fluvial deposits. The fluvial succession is interpreted to have been deposited in response to an overall rise in relative sea level that was superimposed by three short‐term relative sea‐level rises on the basis of vertical stacking patterns and component lithofacies features of channel deposits, and of correlation of the fluvial succession with an age‐equivalent marine succession in an area about 50 km offshore. However, geometry and stacking patterns of the channel complexes do not exhibit any distinct temporal variation and amalgamated channel and bar deposits are dominant throughout the transgressive fluvial succession. On the other hand, an overall fining‐upward pattern of the entire Iwaki Formation fluvial deposits in association with three component fining‐upward patterns is distinct, and is interpreted to be consistent with the tenet of the standard fluvial sequence‐stratigraphic models. This indicates that the present example represents one type of variation in the standard fluvial sequence‐stratigraphic models, possibly reflecting the forearc‐basin setting, which is generally represented by higher valley slope, higher shedding of coarse‐grained sediments, and shorter longitudinal profiles to the coastal area as compared with a passive‐continental‐margin setting.

Geology of Natural Gas in the Joban Coal Field

Geology of Natural Gas in the Joban Coal Field

On the Coal-bearing Formation and Coal Seams of the Joban Coalfield, Japan

On the Coal-bearing Formation and Coal Seams of the Joban Coalfield, Japan

河川－陸棚堆積物に認められる粘土鉱物組成の変化：常磐炭田古第三系石城層の解析

河川－陸棚堆積物に認められる粘土鉱物組成の変化：常磐炭田古第三系石城層の解析

Psilonichnus quietis isp. nov. from the Eocene Iwaki formation, Shiramizu group, Joban coal field, Japan

Psilonichnus quietis isp. nov. is characterized as an unlined vertical‐to‐inclined burrow ranging in diameter from 0.4 to 2.8 cm, with four different shapes of swelling. It exhibits three intergradational architectural patterns, herein termed Type I, Type II and Type III. Psilonichnus quietis was produced by brachyuran crabs. Types I and Type II were constructed by adult crabs, but Type III by juveniles. Type I and Type III burrows were produced by continuous burrowing whereas Type II burrows were produced by intermittent burrowing. Psilonichnus quietis occurs in various host rocks ranging lithologically from mudstone to sandstone of the Eocene Iwaki Formation, Shiramizu Group, exposed at the Joban coal field, Japan.

A new species of Ancistrolepis (Gastropoda : Buccinidae) from the Iwaki Formation (lower Oligocene) of the Joban coal field, northern Japan

A new species of Ancistrolepis (Gastropoda : Buccinidae) from the Iwaki Formation (lower Oligocene) of the Joban coal field, northern Japan

常磐炭田石城層の流路充填堆積物

Channel fills in the Iwaki Formation of the Paleogene Shiramizu Group in the Joban Coalfield are deviled into two types, which are simple fills and complex fills. Their vertical distribution, steady paleocurrent direction and decreasing grain size imply upward change in fluvial environment.

常磐炭田南部に分布する下部中新統くぬぎ平の植物および軟体動物化石群

常磐炭田南部に分布する下部中新統くぬぎ平の植物および軟体動物化石群

常磐炭田第三系の花粉層序学的研究

常磐炭田第三系の花粉層序学的研究

Molluscan assemblages from the Miocene Nakayama Formation in the Kadono district, Joban Coal-Field, Fukushima Prefecture

Molluscan assemblages from the Miocene Nakayama Formation in the Kadono district, Joban Coal-Field, Fukushima Prefecture

INDUSTRIALIZATION IN THE JOBAN COAL FIELD REGION AFTER THE COLLAPSE OF THE COAL-MINING INDUSTRY

After the Second World War, especially in the period of high growth of Japanese economy which was led by the development of manufacture, the monopolistic position of coal in Japanese energy markets gave place to petroleum. Because of this replacement, most of the coalmining industries have collapsed. This study is an attempt to consider the industrial reorganization of the coal field district as one of the ways to solve its economic problems. As a case study, the author selects the Joban coal-field region and attempts to pursue its transformation into the new industrial development, the character of new industry, and the factors prescribing the new industrial character from the viewpoint of the labor force. The Joban coal-field region is located in Iwaki City of Fukushima Prefecture, Kitaibaraki City, Takahagi City, and Juo Town of Ibaraki Prefecture. These cities and town are located at least 150 km north of Tokyo. In 1976, the coal-mining industry in the Joban coal-field has ended its 125 years of history. There were 125 coal mines and about 32, 000 coal miners in 1951, which was a peak year of its coal industry. The following results were made clear by this study: 1. The modern industrialization of the Joban coal-field region was initiated in the 1930's by chemical fertilizer, rayon, and pulp industries that were located there due to the proximity to natural resources. But the chemical fertilizer industry based on Joban coal as the raw material did not develop sufficiently because of low quality of the coal. Hence, the greater part of its raw coal was brought from Hokkaido. An administrative agency has aided in the later industrial development with two special acts. These acts made available the spacious lands to the new manufacturing plants. Consequently, two industrialized districts were formed in the Joban coal-field region. One is the Onahama coastal industrial district which mainly consists of equipment type, chemical industries, and large-scale factories. The other is the inland industrial district which consists of the labor-intensive, small-scale factories. The latter district changed the pure coal-mining district to more diversified industrial district. This district is named the past coal-mining district. 2. Industrialization in the post coal-mining district was a result of action by the municipal authorities which during the economic crisis encouraged the new industries and the enterprises decentralizing from the Keihin industrial zone. Both industries depended on the national administration for the financial support. As a whole, these industrial development were included in the sphere of the Keihin industrial zone. 3. Industrialization in the post coal-mining district has two features. One is the timber and furniture industries represented by a joint corporation of a coal-mining company and a new company. The other is electric and electronic machine-parts industries relocated from the Keihin industrial zone. Most workers were recruited from the people of this district. Former coal-mining workers are now employed as manufactor lobers by timber and furniture industries. On the latter, the labor force is divided into two types. The surplus young workers after the completion of school are employed by the large-scale factories, and middle or old aged housewife workers are employed by the small-scale factories. Housewife workers enter the labor market, to help their husbands who lost their works when the coal-industry failed or were reduced their income by 25 percent due to re-employment in small industries. 4. Since the purpose of work in the coal mine was chiefly to mine coal, in essence it was manual labor operating simple machines. By changing coal-mining labor to manufacture labor, the work content became more complex and sophisticated. But fundamentally, the character of manual labor with machines remained unchanged.

Discovery of Triassic conodonts from the chert pebbles of the Tertiary conglomerates of Joban coal-field (The conglomerate of the eastern terrain of the Abukuma plateau, part 2)

Discovery of Triassic conodonts from the chert pebbles of the Tertiary conglomerates of Joban coal-field (The conglomerate of the eastern terrain of the Abukuma plateau, part 2)

Rock deformation and geologic structure:Shear fractures in the Iwaki area of the Joban coal-field

Rock deformation and geologic structure:Shear fractures in the Iwaki area of the Joban coal-field

The Abandonment of Poor Coal Seams Caused by the Rationalization of the Coal-Mining Industry in the Joban Coal Field

The Abandonment of Poor Coal Seams Caused by the Rationalization of the Coal-Mining Industry in the Joban Coal Field

Coal Petrographic Property and Formation Process of Coal Seam in the Jiiban Coal Field, Japan

The calorific value of coal in the Yeban coal field changes from 6, 400 (d. a. f.) kcal/kg to 8, 190 (d. a. f.) kcal/kg. The general results on microlithotype of coal by petrographic analyses changes from 19.6‰ to 63.3‰ in vitrite, from 17.1 ‰ to 63.2‰ in durite, from 14.1‰ to 21.1‰ in clarite and from 0.1‰ to 3.6‰ in fusite (Fig. 6).Durite is richest, clarite is the second and vitrite is the third, in carbon (d. a. f.), hydrogene (d. a. f.), volatile matter (d. a. f.) and calorific value (d. a. f.) (Fig. 4, 5).The coal in the Northern Iwaki district is the richest in durite, calorific value (d. a. f.) and volatile matter (d. a. f.), and is the highest in rankham other districts. These values are decreasing in order of the Futaba, Taga and Southern Iwaki districts (Fig. 6).As the depth of coal seams in each district increase, the calorific value (d. a. f.), degree of coalification and content of durite increase, while the content of vitrite decreases (Fig. 1-3. 7). The causes of regional difference in the degree of coalification are as follows:(1) The coal in the Northern Iwaki district was affected by geothermal metamorphism (Fig. 8).(2) In the Taga district, coal was affected by the dynamic metamorphism (Fig. 1).(3) The geological age (Early Miocene) of coal in the Southern Iwaki district where the rank is lowest, is younger than that (Oligocene) in the other districts.While, it is presumed that the aquatic dendroid plants grew on shore in the plant accumulating basin, the aquatic herbs grew off-shore in the basin; and there was two types in the plant accumulating mechanism the subsidence and upheaval. In the case of subsidence, as the basement of basin subside, the coastal plain turns into the swamp where the vegetation grow, and, then the thickness and width of the layer of plant accumulate. In the case of upheaval, as the basement upheave, the marginal area of basin turns into the land, and then the thickness and width of layer decrease. Joban coal field belongs to the type of subsidence (Table 1, Fig. 9, 10).

A New Florule from the Iwaki Coal-bearing Formation in the Joban Coal-Field, Fukushima Prefecture, Japan

A New Florule from the Iwaki Coal-bearing Formation in the Joban Coal-Field, Fukushima Prefecture, Japan

THE EXPANSION OF COAL PRODUCTION IN THE JÔBAN COAL FIELD

The modern coal mining in the Joban coal field was started on the exposed areas of the coal field near the foot of the Abukuma mountains in 1883. The volume of coal produced has been increased since, and 4.29 million tons of coal, about 8 per cent of the total coal production in Japan, was produced in 1958 (Fig. 3). Though the number of collieries is 71, the large collieries producing over 300 thousand tons in one year are only 3. The majority of collieries produces under 50 thousand tons in one year. The pattern of the mining activity in the field is roughly shown in Fig. 1. The results of the study are as follows. 1) The geologic conditions of the coal measures are also responsible for the pattern of the coal mining in the Joban coal field. The writer divided the field into four districts and made a comparative study of the natural conditions for mining-coal reserve, quality of coal and depth of coal series etc.-in each district (Tab. 1). It reveals that the best natural conditions for mining exist in the northern district of Iwaki and the Taga district, The southern district of Iwaki and the Futaba district are very inferior to the former districts. 2) In consequence, the two centers of the coal production in the Joban coal field are the northern district of Iwaki and the Taga district. These two districts produce about 91 per cent of the total coal production in the field. The collieries producing over 100 thousand tons of coal in one year are all concentrated inn this two districts. 3) In the coal field, especially in the northern district of Iwaki, almost all of the concessions which hold the abundant coal seams are monopolized by the Joban Coal Mining Co. Ltd., the largest coal mining company in the Joban coal field. The company has also increased the output of coal in the Taga district since 1935, and today, the company produces over 50 par cent of the total coal production in the field. 4) The central areas of coal mining-the northern district of Iwaki and the Taga district-were formed in the period 1897-1919 and in this time almost all of the main collieries were opened. From the beginning the Iwaki Coal Mining Co. and Iriyama Coal Mining Co. were the two largest producers. They were merged to be the Joban Coal Mining Co. in 1944. 5) In the area of the abundant coal seams such as the northern district of Iwaki and Taga districts, the centralization of coal production to the large collieries resulted in making the many small collieries subordinate to the large collieries. Because, in these two districts the small collieries are compelled to locate in the small concessions to mine the thin coal seams, and these concessions were already mined out the thick coal seams by the large collieries and were left as the areas which came to the end of mining. Moreover, the areas of the poor coal seams such as the southern district of Iwaki and the Futaba district are where many small collieries are operated. Such conditions are shown in Fig. 5.

A New Anthracothere from the Shiramizu Group in the Joban Coal-Field, Japan, with Notes on its Geological Age

A New Anthracothere from the Shiramizu Group in the Joban Coal-Field, Japan, with Notes on its Geological Age

磐城北部地区における炭田ガス

磐城北部地区における炭田ガス