K–Ar geochronology of a middle Miocene submarine volcano-plutonic complex in southwest Japan

2004 ◽  
Vol 141 (1) ◽  
pp. 1-13 ◽  
Author(s):  
T. IMAOKA ◽  
T. ITAYA
Keyword(s):  
Basaltic Andesite ◽  
Large Scale ◽  
Middle Miocene ◽  
Tectonic Setting ◽  
Japan Sea ◽  
Contact Metamorphism ◽  
Southwest Japan ◽  
Tectonic Event ◽  
Plutonic Complex ◽  
In The Beginning

A volcano-plutonic complex in the Susa area, southwest Japan, consists of the Yamashima andesites, the Koyama gabbros and syn-plutonic porphyrite dykes derived from a common basaltic andesite magma. The complex is closely associated with middle Miocene turbidite deposits. The Yamashima andesites are composed mainly of basaltic andesite feeder dykes, massive submarine lavas with hyaloclastites, and their reworked deposits. The lavas and deposits immediately overlie turbidite deposits, indicating submarine volcanic activity. The Koyama gabbros formed hornfels by contact metamorphism of the surrounding turbidites and andesites. Highly purified clinopyroxene and plagioclase mineral separates from the Yamashima andesites were dated by a K–Ar method using an ultra-low blank K analysis procedure. Ages obtained from duplicate analyses are 16.5±1.5, 15.2±1.4, 15.8±1.7, and 16.5±2.0 Ma for clinopyroxene, and 14.2±0.8, 15.2±0.9, and 15.6±0.9 Ma for plagioclase. The clinopyroxene and plagioclase data define a mineral isochron age of 14.7±0.9 (1σ) Ma with an initial 40Ar/36Ar ratio of 297.3±2.4 (1σ), suggesting that clinopyroxene has no excess argon and can be reliably dated by K–Ar. Most of the groundmass ages are considerably younger (12.1–14.6) than the isochron age, perhaps due to argon loss during alteration. The gabbros give ages of 14.2±0.3 and 14.1±0.3 Ma for biotite, and 13.7±0.3 and 13.7±0.7 Ma for green hornblende. The porphyrite dyke yields an age of 12.5±0.3 Ma for the groundmass, and the pelitic hornfels gives a biotite age of 14.8±0.3 Ma. Our new K–Ar ages, together with previous studies, show that a series of geological events took place in the Susa area between 16 and 13 Ma. Conglomerates and sandstones were deposited in the beginning of marine transgression. Subsequent abrupt deepening led to deposition of a thick black shale unit, turbidite deposits and large-scale submarine channel-fill deposits. Coeval igneous activity formed the volcano-plutonic complex. The magmato-tectonic event was synchronous with the opening of the Japan Sea and the associated clockwise rotation of the southwest Japan arc sliver, recording a unique tectonic setting.

Large-scale folding in the Asemi-gawa region of the Sanbagawa Belt, southwest Japan

Island Arc ◽  
2009 ◽  
Vol 19 (2) ◽  
pp. 357-370 ◽  
Author(s):  
Hiroshi Mori ◽  
Simon Wallis
Keyword(s):  
Large Scale ◽  
Southwest Japan

TRADITION AND INNOVATION IN MODERN KAZAKH POETRY (XX century and independence)

2021 ◽  
Vol 76 (2) ◽  
pp. 118-128
Author(s):  
Sh. Kuttybaev ◽  
◽  
Е. Abdimomynov ◽  
Keyword(s):  
20Th Century ◽  
Large Scale ◽  
Point Of View ◽  
Soviet Period ◽  
Evolutionary Development ◽  
Spiritual Values ◽  
Literary Traditions ◽  
New Perspective ◽  
National Poetry ◽  
In The Beginning

The article analyzes views on innovation in the literary science of the early twentieth century and the work of Alash representatives in an era that is a period filled with profound changes and large-scale innovations in Kazakh society. In addition, works related to freedom, enlightenment, politics, spiritual values, the position of the people as a whole and social changes are considered the idea of independence and continuity. On the way of evolutionary development of the Kazakh literature, artistic power, thematic and ideological character, substantial and stylistic features of poetry of poets in the beginning of the XX century and during the Great Patriotic War, in subsequent years and years of independence are discussed in detail. In addition, on the basis of literary traditions and novelty, the works of prominent poets of Kazakh poetry of the 20th century and Independence are considered and comprehensively characterized, i.e. internal motives, the content of life phenomena in national poetry are analyzed in close connection with the works of poets. The original vision of the traditional and differentiated in the literature of the Soviet period in the works of poets from a new perspective, from the point of view of today. In addition, the works of outstanding poets of Kazakh poetry in the period of the 20th century and independence are considered on the basis of classical tradition and novelty in literature.

scholarly journals Estimating Total Factor Productivity and Its Components: Evidence from Major Manufacturing Industries of Pakistan

2008 ◽  
Vol 47 (4II) ◽  
pp. 677-694 ◽  
Author(s):  
Abdul Raheman ◽  
Talat Afza ◽  
Abdul Qayyum ◽  
Mahmood Ahmed Bodla
Keyword(s):  
Textile Industry ◽  
Large Scale ◽  
Manufacturing Sector ◽  
Vital Role ◽  
Fiscal Year ◽  
Cotton Production ◽  
Oil Refineries ◽  
Used Cars ◽  
In The Beginning ◽  
Textile Sector

Manufacturing sector of Pakistan accounts for 19.1 percent of GDP and is the second largest sector of the economy. It grew by 8.4 percent during 2007 as against 10 percent last year. In the manufacturing sector, large scale manufacturing (LSM), plays a vital role and accounts for approximately 70 percent of overall manufacturing [Economic Survey of Pakistan (2006-07)]. During 2006-07 relatively slower pace of expansion exhibits signs of moderation on accounts of higher capacity utilisation, difficulties in the textile sector and lower than expected scale of operations of oil refineries. A number of other factors have also contributed to the low pace of expansion in manufacturing including zero percent growth in raw cotton production which is a critical input for the textile industry, vegetable ghee and cooking oil which comprise about 5.5 percent of the LSM sector, showed uninspiring performance due to unparalleled rise in international palm and soybean oil prices. The performance of the automobile sector has been far less impressive this year as compared to previous five years due to a fall in domestic demand for cars on account of increasing auto financing rates. The higher imports of used cars in the beginning of fiscal year 2006-07 also affected the performance of domestic auto mobile sector.

Shear zone development and structurally-controlled skarn ore mineralization in the Rosas district, SW Sardinia.

2021 ◽  
Author(s):  
Matteo Luca Deidda ◽  
Antonio Attardi ◽  
Fabrizio Cocco ◽  
Dario Fancello ◽  
Antonio Funedda ◽  
...  
Keyword(s):  
Shear Zone ◽  
Large Scale ◽  
Ore Deposits ◽  
Axial Plane ◽  
Contact Metamorphism ◽  
Upper Ordovician ◽  
Fold And Thrust Belt ◽  
Ore Mineralization ◽  
Map Scale ◽  
Stratigraphic Succession

<p>The Rosas Shear Zone (RSZ) is a 1 km thick brittle-ductile shear zone that outcrops in the Variscan fold and thrust belt foreland of SW Sardinia, where several important ore deposits were mined in the last century. The RSZ lies in the footwall and strikes parallel to the NE-dipping regional thrust that separates the Variscan foreland from the nappe zone. Two thrusts that developed along the limbs of two km-scale overturned antiforms, with NE-dipping axial plane, bound the RSZ. The folds show a SW-facing direction and a well-developed axial plane cleavage, and affect a lower Cambrian-upper Ordovician stratigraphic succession mainly made, from bottom to top, by a sequence about 200 m thick of dolostones and massive limestone followed by 50 m of marly limestones overlain by about 150 m of sandstones, pelites and siltstones, finally unconformable capped by conglomerates and siltstones, ranging in thickness from a few to 200 m. Differently, within the RSZ the bedding is completely transposed along the cleavage and its internal structure is characterized by anastomosing thrusts that affect the stratigraphic succession defining map-scale slices mainly consisting of dolostones and limestones embedded into the siliciclastic formations. It is noteworthy the occurrence of a NE-dipping, up to 100 m thick gabbro-dyke that postdates the deformation phases and that can be related to the exhumation of the chain during late Carboniferous-Permian times.</p><p>In the whole area, contact metamorphic and metasomatic processes selectively affected the Cambrian carbonate tectonic slices, originating several skarn-type orebodies. Mineralized rocks display the mineralogical assemblages and textures of Fe-Cu-Zn skarns, with relicts of anhydrous calcic phases related to the prograde metamorphic stage (garnet, clinopyroxene, wollastonite), frequently enclosed in a mass of hydrous silicates (actinolitic amphibole, epidote) and magnetite related to the retrograde metasomatic stage, in turn followed by chlorite, sulfides, quartz and calcite associated to the hydrothermal stage. Metasomatic reactions also involved mafic rocks, producing a mineral association marked by clinopyroxene, amphibole, epidote, prehnite and Ba-rich K-feldspar. Sulfide ores are made of prevailing sphalerite, chalcopyrite and galena, with abundant pyrite and pyrrhotite and minor tetrahedrite and Ag-sulfosalts. Garnets are andraditic/grossularitic, distinctly zoned and optically anisotropic. Field surveys pointed out the tight structural controls on skarn and ore formation. On a local scale, the gabbro emplacement along high- to low-angle NNW-SSE structures bordering the carbonate tectonic slices accentuate the effects of contact metamorphism, and metric to decametric mineralogical zonation (garnet→pyroxene→wollastonite) are recognized. On a larger scale, extensive hydrothermal fluid circulations involved the structures of the RSZ. Infilling of metasomatic fluids in carbonate tectonic slices is fault-controlled and aided by the increase in permeability due to the alteration of prograde silicates. The causative intrusion related to skarn ores belongs to the early Permian (289±1 Ma) ilmenite-series, ferroan granite suite which intrudes the RSZ about 3 km east from the studied area. The Fe-Cu-Zn skarn ores of Rosas are best interpreted as distal, structurally-controlled orebodies, connected to large-scale circulation of granite-related fluids in the km-sized plumbing system represented by the RSZ.</p>

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