Eoarchean–Paleoproterozoic zircon inheritance in Japanese Permo-Triassic granites (Unazuki area,Hida Metamorphic Complex): Unearthing more old crust and identifying source terrranes     

Kenji Horie  Megumi Yamashita  Yasutaka Hayasaka  Yasuo Katoh  Yukiyasu Tsutsumi  Aya Katsube  Hiroshi Hidaka  Hyeoncheol Kim  Moonsup Cho 《Precambrian Research》2010

U–Pb zircon geochronology of two Permo-Triassic granites (samples OT-52 and OT-272 with ages of 229 ± 8 Ma and 256 ± 2 Ma, respectively) in the Unazuki area, Hida Metamorphic Belt, southwest Japan, revealed the presence of Eoarchean to Paleoproterozoic inheritance. Inheritance is consistent with both samples showing low zircon saturation temperatures for their bulk compositions. In OT-52, dark in CL, low Th/U zircon domains have a mean ²⁰⁷Pb/²⁰⁶Pb age of 1940 ± 17 Ma, which is consistent with an age of 1937 ± 6 Ma for anatexis in the Precambrian Busan gneiss complex in Korea. Eoarchaean inherited zircons with ²⁰⁷Pb/²⁰⁶Pb ages from ca. 3750 to 3550 Ma are common in OT-272 but are few in OT-52, suggesting a source from rocks with affinities to those in the Anshan area in the northeast China part of the North China Craton. On the other hand, a Hida Metamorphic Belt metasedimentary gneiss into which the granites were intruded contains ca. 1840, 1130, 580, 360, 285 and 250 Ma zircons (Sano et al., 2000). These ages suggest that the Unazuki Mesozoic granites did not originate from proximal Hida Metamorphic Complex rocks, but instead from unrelated rocks obscured at depth. The predominance of Eoarchean to Paleoproterozoic age components, and the marked lack of 900–700 Ma components suggest that the source was the (extended?) fringe of the North China Craton, rather than from Yangtze Craton crust. The Mesozoic evolution of Japan and its linkages to northeast Asia are discussed in the context of these results.  相似文献   

Comparison of microbial communities in petroleum-contaminated groundwater using genetic and metabolic profiles at Kyonggi-Do,South Korea     

Eun-Hee Lee  Jaisoo Kim  Ji-Young Kim  So-Yeon Koo  Sang-Dong Lee  Kyung-Seok Ko  Dong-Chan Ko  Byoung-Woo Yum  Kyung-Suk Cho 《Environmental Earth Sciences》2010,60(2):371-382

This research has been performed to determine the differences in microbial communities according to physicochemical properties such as concentrations of volatile aromatic hydrocarbons such as benzene, toluene, ethylbenzene, and xylene (BTEX), dissolved oxygen (DO), electron acceptors, etc., in oil-contaminated groundwaters at Kyonggi-Do, South Korea. The properties of bacterial and microbial communities were analyzed by 16S polymerase chain reaction (PCR) denaturing gradient gel electrophoresis (DGGE) fingerprinting method and community-level physiological profiling (CLPP) using Eco-plate, respectively. Based on the DGGE fingerprints, the similarities of bacterial community structures were high with similar DO levels, and low with different DO levels. Whereas the dominant bacterial groups in GW13 (highest BTEX and lowest DO) were acidobacteria, α-proteobacteria, β-proteobacteria, γ-proteobacteria, δ-proteobacteria, and spirochetes, those in GW7 (highest BTEX and highest DO) were actinobacteria, α-proteobacteria, β-proteobacteria, γ-proteobacteria, δ-proteobacteria, and sphingobacteria. Based on the CLPP results, the groundwater samples were roughly divided into three groups: above 4 mg/L in DO (group 1: GW3 and GW7), below 4 mg/L in DO (group 2: GW8, W1, W2, W3, and BH10), and highly contaminated with BTEX (group 3: GW13). Shannon index showed that the microbial diversities and equitabilities were higher in shallower aquifer samples. Overall, this study verified that the greatest influencing factors on microbial/bacterial communities in groundwaters were DO and carbon sources, although BTEX concentration was one of the major factors.  相似文献   

Propagation Characteristics of CMEs Associated with Magnetic Clouds and Ejecta     

R.-S. Kim  N. Gopalswamy  K.-S. Cho  Y.-J. Moon  S. Yashiro 《Solar physics》2013,284(1):77-88

We have investigated the characteristics of magnetic cloud (MC) and ejecta (EJ) associated coronal mass ejections (CMEs) based on the assumption that all CMEs have a flux rope structure. For this, we used 54 CMEs and their interplanetary counterparts (interplanetary CMEs: ICMEs) that constitute the list of events used by the NASA/LWS Coordinated Data Analysis Workshop (CDAW) on CME flux ropes. We considered the location, angular width, and speed as well as the direction parameter, D. The direction parameter quantifies the degree of asymmetry of the CME shape in coronagraph images, and shows how closely the CME propagation is directed to Earth. For the 54 CDAW events, we found the following properties of the CMEs: i) the average value of D for the 23 MCs (0.62) is larger than that for the 31 EJs (0.49), which indicates that the MC-associated CMEs propagate more directly toward the Earth than the EJ-associated CMEs; ii) comparison between the direction parameter and the source location shows that the majority of the MC-associated CMEs are ejected along the radial direction, while many of the EJ-associated CMEs are ejected non-radially; iii) the mean speed of MC-associated CMEs (946 km?s^?1) is faster than that of EJ-associated CMEs (771 km?s^?1). For seven very fast CMEs (≥?1500 km?s^?1), all CMEs with large D (≥?0.4) are associated with MCs and the CMEs with small D are associated with EJs. From the statistical analysis of CME parameters, we found the superiority of the direction parameter. Based on these results, we suggest that the CME trajectory essentially determines the observed ICME structure.  相似文献   

Multiwavelength Study of a Solar Eruption from AR NOAA 11112 I. Flux Emergence, Sunspot Rotation and Triggering of a Solar Flare     

Pankaj Kumar  Sung-Hong Park  K.-S. Cho  S.-C. Bong 《Solar physics》2013,282(2):503-521

We analyze the multiwavelength observations of an M2.9/1N flare that occurred in the active region (AR) NOAA 11112 in the vicinity of a huge filament system on 16 October 2010. SDO/HMI magnetograms reveal the emergence of a bipole (within the existing AR) 50 hours prior to the flare event. During the emergence, both the positive and negative sunspots in the bipole show translational as well as rotational motion. The positive-polarity sunspot shows significant motion/rotation in the south-westward/clockwise direction, and we see continuously pushing/sliding of the surrounding opposite-polarity field region. On the other hand, the negative-polarity sunspot moves/rotates in the westward/anticlockwise direction. The positive-polarity sunspot rotates ≈?70^° within 30 hours, whereas the one with negative polarity rotates ≈?20^° within 10 hours. SDO/AIA 94 Å EUV images show the emergence of a flux tube in the corona, consistent with the emergence of the bipole in HMI. The footpoints of the flux tube were anchored in the emerging bipole. The initial brightening starts at one of the footpoints (western) of the emerging loop system, where the positive-polarity sunspot pushes/slides towards a nearby negative-polarity field region. A high speed plasmoid ejection (speed ≈?1197 km?s^?1) was observed during the impulsive phase of the flare, which suggests magnetic reconnection of the emerging positive-polarity sunspot with the surrounding opposite-polarity field region. The entire AR shows positive-helicity injection before the flare event. Moreover, the newly emerging bipole reveals the signature of a negative (left-handed) helicity. These observations provide unique evidence of the emergence of twisted flux tubes from below the photosphere to coronal heights, triggering a flare mainly due to the interaction between the emerging positive-polarity sunspot and a nearby negative-polarity sunspot by the shearing motion of the emerging positive sunspot towards the negative one. Our observations also strongly support the idea that the rotation can most likely be attributed to the emergence of twisted magnetic fields, as proposed by recent models.  相似文献   

Large scale shaking table model test and analysis on seismic response of utility tunnel in non-homogeneous soil     

Cho Mya Darli  Tang Aiping  Huang Delong  Zhang Jiqiang 《地震工程与工程振动(英文版)》2021,20(2):505-515

Underground utility tunnels are the most fundamental and reliable lifeline network in urban cities,and are widely constructed throughout the world.In urban areas,most utility tunnels usually encounter the non-homogeneity of subsoil condition due to various construction effects.Studies have shown that the damage mechanism of shallow underground structures mainly depends on the inhomogeneity of the subsoil conditions.This would become a considerable factor for the stability of the underground utility tunnel structures.However,this type of research still needs to establish the vulnerable seismic design.In this study,a series of shaking table tests were conducted on non-homogenous soils to investigate the performance of seismic interaction between utility tunnels,surrounding soils and interior pipelines.The dynamic responses measured from the test account for the boundary condition of non-homogeneous soils,the internal forces,displacement of tunnel joints,the dynamic characteristics on interior pipelines and the reasonable spring stiffness with damping in the seismically isolated gas pipeline model inside the tunnel.The vulnerability of underground utility tunnel in non-homogeneous soil zone and the mechanism of the stability of interior facilities are the main topics discussed in this paper.  相似文献   

Restoration of an inner-city stream and its impact on air temperature and humidity based on long-term monitoring data     

Kyu Rang KIM  Tae Heon KWON  Yeon-Hee KIM  Hae-Jung KOO  Byoung-Cheol CHOI  Chee-Young CHOI 《大气科学进展》2009,26(2):283-292

Spatiotemporal changes in air temperature and humidity associated with the restoration of an inner-city stream in Seoul, Korea, are investigated based on long-term monitoring data. The Cheonggye stream, covered under a concrete structure for 46 years, was restored in 2005 and runs 5.8 km eastward through a central region of Seoul. Long-term monitoring of the air temperature and relative humidity was made along the stream throughout the restoration and across the stream after the restoration. The area along the stream had a higher air temperature than the entire metropolitan area. The temperature anomaly between the monitoring area and the surrounding metropolitan area was 0.13^oC lower on average at the center of the stream after the restoration. The stream's effect on the air temperature was also evident in the temperature distribution along a street traversing the stream. The relative and specific humidities were increased due to the restoration. The restored stream modified the nearby urban climate in the opposite direction compared to urbanization. The results could be used as a model case in mitigating urban climate by a stream in future urban planning practices.  相似文献   

A World-Wide Net of Solar Radio Spectrometers: e-CALLISTO     

A. O. Benz  C. Monstein  H. Meyer  P. K. Manoharan  R. Ramesh  A. Altyntsev  A. Lara  J. Paez  K.-S. Cho 《Earth, Moon, and Planets》2009,104(1-4):277-285

Radio spectrometers of the CALLISTO type to observe solar flares have been distributed to nine locations around the globe. The instruments observe automatically, their data is collected every day via internet and stored in a central data base. A public web-interface exists through which data can be browsed and retrieved. The nine instruments form a network called e-CALLISTO. It is still growing in the number of stations, as redundancy is desirable for full 24 h coverage of the solar radio emission in the meter and low decimeter band. The e-CALLISTO system has already proven to be a valuable new tool for monitoring solar activity and for space weather research.  相似文献   

Post-subduction margin structures along Boyd Strait, Antarctic Peninsula     

Young Keun Jin  Robert D. Larter  Yeadong Kim  Sang Heon Nam  Kyu Jung Kim 《Tectonophysics》2002,346(3-4)

The Pacific margin of the Antarctic Peninsula to the southwest of the Hero Fracture Zone (HFZ) is a former subducting margin which became inactive following the arrival of ridge crest segments of the Antarctic–Phoenix ridge at the margin during the Tertiary. In contrast, the part of the margin to the northeast of the HFZ remains active. Tertiary convergence was approximately perpendicular to the margin and ongoing motion is thought to have the same orientation. A new seismic reflection profile running along Boyd Strait, just northeast of the landward projection of the HFZ, shows major structural components similar to those typically observed along the margin to the southwest of the HFZ. In order of increasing proximity to the margin, these components are: the inner shelf, the shelf basin, the mid-shelf basement high (MSBH), and the outer shelf. The continuation of the post-subduction margin structures to the active margin suggests that the boundary between crust with passive and active margins characteristics is not sharply defined. Our postulated scenario for tectonic evolution along Boyd Strait is that: (1) before the arrival of the last ridge crest segment to the southwest of the HFZ, the inner shelf and the shelf basin were part of a Cretaceous–Tertiary arc and forearc area, (2) after the arrival, thermal effects resulting from interaction of the ridge crest with the margin just southwest of the HFZ lead to the formation of the MSBH to the northeast, but MSBH uplift in Boyd Strait did not prevent concurrent cross-shelf sediment transport contributing to development of an extensive outer shelf on the seaward flank of the MSBH, (3) Recent extension in Bransfield Strait, a marginal basin to the northeast of the landward projection of the HFZ, has caused about 10 km of seaward deflection in the strike of the part of the MSBH to the northeast of the projection of the HFZ.  相似文献   

Three-dimensional imaging of subsurface structures using resistivity data   总被引：5，自引：0，他引：5  

Myeong-Jong Yi  Jung-Ho Kim  Yoonho Song  Seong-Jun Cho  Seung-Hwan Chung  Jung-Hee Suh 《Geophysical Prospecting》2001,49(4):483-497

We have developed a three-dimensional inverse scheme for carrying out DC resistivity surveys, incorporating complicated topography as well as arbitrary electrode arrays. The algorithm is based on the finite-element approximation to the forward problem, so that the effect of topographic variation on the resistivity data is effectively evaluated and incorporated in the inversion. Furthermore, we have enhanced the resolving power of the inversion using the active constraint balancing method. Numerical verifications show that a correct earth image can be derived even when complicated topographic variation exists. By inverting the real field data acquired at a site for an underground sewage disposal plant, we obtained a reasonable image of the subsurface structures, which correlates well with the surface geology and drill log data.  相似文献   

Reviews     

R. W. Galloway  Arthur Conacher  J. M. Powell  Dennis Rumley  Melanie Beresford  George Cho 《The Australian geographer》1987,18(2):190-196

THE PERMAFROST ENVIRONMENT by S. A. Harris. 23 × 14 cm, viii and 275 pages. Croom Helm: London 1986 (ISBN 0 7099 3713 X) $A57.50 (hard).

ENVIRONMENTAL POLICIES: An International Review edited by C. C. Park. 14 × 22 cm, 315 pages. Croom Helm: London 1986 (ISBN 0 7099 2062 8) $A56.25 (hard).

A MODERN DICTIONARY OF GEOGRAPHY by J. Small and M. Witherick. 15 × 23 cm, vi and 233 pages. Edward Arnold: London 1986 (ISBN 0 7131 6434 4) $A28.95 (soft).

PROGRESS IN POLITICAL GEOGRAPHY edited by M. Pacione. 14 × 22 cm, 275 pages. Croom Helm: London 1985 (ISBN 0 7099 2087 3) $A56.25 (hard).

THE PRICE OF WAR: Urbanization in Vietnam 1954–1985, by N. Thrift and D. Forbes. 14 × 22 cm, xiv and 188 pages. Allen & Unwin: London 1986 (ISBN 0 04 3012108) $A59.95 (hard).

INDUSTRIALISATION AND LABOUR FORCE PROCESSES: A Case Study of Peninsular Malaysia (Research Papers on Development in East Java and West Malaysia No. 1) by T. G. McGee and seven others. 17 × 24 cm, xviii and 244 pages. Research School of Pacific Studies, Australian National University: Canberra 1986 (ISBN 0 86784 991 6) $A15.00 plus postage and packing (soft).

CITIES OF THE WORLD: A Compilation of Current Information on Cultural, Geographical, and Political Conditions in the Countries and Cities of Six Continents. Based on the Department of State's ‘Post Reports’ (second edition) edited by M. W. Young and S. L. Stetler. 16 × 23 cm, 3,056 pages in 4 volumes. Gale Research Company: Detroit 1985 (ISBN 0 8103 2059 2) $US235.00 (hard). Supplement 758 pages. 1986 (ISBN 0 8103 1110 0) $US84.00 (hard).  相似文献