scholarly journals Electromagnetic image of the Trans-Hudson orogen — THO94 transect

2005 ◽  
Vol 42 (4) ◽  
pp. 479-493 ◽  
Author(s):  
Xavier Garcia ◽  
Alan G Jones
Keyword(s):  
Regional Scale ◽  
Hudson Bay ◽  
Central Plains ◽  
Seismic Line ◽  
The North ◽  
Crustal Structures ◽  
The Subject ◽  
Surface Geology ◽  
Resistive Structure ◽  
East West

The North American Central Plains (NACP) anomaly in enhanced electric conductivity and its relationship with the Paleoproterozoic Trans-Hudson orogen (THO) has been studied under the auspices of Lithoprobe for over a decade. The NACP anomaly was the first geophysical evidence of the existence of the THO beneath the Phanerozoic sediments of the Central Plains. This anomaly, detected geomagnetically in the late 1960s, has been the subject of a number magnetotelluric studies from the early 1980s. The PanCanadian and Geological Survey of Canada experiments in the 1980s and the Lithoprobe experiments in the 1990s together comprise four east–west and one north–south regional-scale profiles in Saskatchewan perpendicular to the strike of the orogen. In this paper, data from the northernmost line, coincident with seismic line S2B, are analysed and interpreted, and are shown to be key in determining the northern extension of the NACP anomaly. Dimensionality analysis confirms the rotation of deep crustal structures eastward to Hudson Bay, as earlier proposed on the basis of broad-scale geomagnetic studies. On this profile, as with the profile at the edge of the Paleozoic sediments, the NACP anomaly is imaged as lying within the La Ronge domain, in contact with the Rottenstone domain, and structurally above the Guncoat thrust, a late compressional feature. The location of the anomaly together with the surface geology suggests that the anomaly is caused either by sulphide mineralization concentrated in the hinges of folds, by graphite, or by a combination of both. Our interpretation of the data is consistent with that from other profiles, and suggests that the NACP anomaly was formed as a consequence of subduction and collisional processes involving northward subduction of the internides of the THO beneath the Hearne craton. On the southern part of this profile, a resistive structure is identified as the Sask craton, suggesting that Proterozoic rocks are above Archean rocks in the THO.

Variable unroofing in the western Superior Province - metamorphic evidence and possible origin

2006 ◽  
Vol 43 (7) ◽  
pp. 805-819 ◽  
Author(s):  
Andrew Hynes ◽  
Zixin Song
Keyword(s):  
Superior Province ◽  
Surface Distribution ◽  
Seismic Line ◽  
The North ◽  
Metavolcanic Rocks ◽  
Limited Support ◽  
Greenstone Belts ◽  
Rotation Motion ◽  
East West ◽  
Broad Region

Western Superior Lithoprobe seismic-reflection line 1 exhibits a broad region of northward-dipping reflectors in the Uchi subprovince, which gives way to southward-dipping reflectors farther north in the Berens River sub province. Mafic metavolcanic rocks across the region of northward-dipping reflectors exhibit a decline in metamorphic pressure, from pressures of 6 kbar (1 kbar = 100 MPa) in the south to only 2 kbar 80 km to the north. This indicates that the southern edge of the Uchi subprovince has undergone significantly more unroofing than regions farther north. The differential unroofing is not consistent with a doubly vergent thrusting origin for the northward- and southward-dipping reflector pattern. It could result from a crustal-scale synform, of which the region of northward-dipping reflectors would make up the southern limb. Metamorphic pressures from samples off the seismic line, however, provide only limited support for a regional synform, and suggest that much of the pressure variation may result from deformation associated with motion on late faults that are widespread in the western Superior Province. These faults occur in a WNW-striking set with dextral offsets and an ENE-striking set with sinistral offsets. They could result from north–south compression and east–west extension, provided the faults have rotated towards the east–west direction during deformation. Regional tilting and (or) jostling of crustal blocks is attributed to deformation associated with the fault rotation. Motion on the faults and the associated deformation of intervening fault blocks may be important contributors to the present crustal architecture of the western Superior Province, including the surface distribution and form of the greenstone belts.

scholarly journals Bedrock geology, northwest part of Nuluujaak Mountain, Baffin Island, Nunavut, part of NTS 37-G/5

2021 ◽  
Author(s):  
G D Jackson
Keyword(s):  
Regional Scale ◽  
Iron Formation ◽  
Small Scale ◽  
Baffin Island ◽  
The North ◽  
Bedrock Geology ◽  
Iron Mine ◽  
Iron Deposits ◽  
Legacy Data ◽  
East West

The map area lies about 40 km northwest of Baffinland's iron mine. Dykes of unit mAnA3 within unit mAnA2 suggest that unit mAnA2 predates unit mAnA3. Unit nAMqf, basal Mary River Group unit, includes regolith material from units mAnA2 and mAnA3. Unit mAnAm may include some dykes of unit nAMb. The Mary River Group was deposited in a volcanic-arc environment, yielding zircon U-Pb ages mostly in the range of 2.88 to 2.72 Ga. Iron-formation (unit nAMi) is approximately 276 m thick locally, with oxide facies (unit nAMio) being most abundant. The quartzite triangle west of 'Iron lake' (unofficial name) may be a small horst. The main east-west-trending synclinal fold, including the area around 'Iron lake' and the no. 4 ore deposit, is upright, nearly isoclinal, and plunges mostly easterly at both ends with small scale anticlines and synclines in the middle. Magnetite constitutes about 75% of high-grade iron deposits in the north limb, whereas hematite predominates in south-limb deposits. K-Ar and Rb-Sr ages indicate middle Paleoproterozoic overprinting. Central Borden Fault Zone was active at ca. 1.27 Ga and during or after Ordovician time. Note: please be aware that the information contained in CGM 408 is based on legacy data from the 1960-1990s and that it has been superseded by regional-scale information contained in CGM 403.

scholarly journals A Low frequency Southern Sky Survey Using the Mauritius Radio Telescope

2002 ◽  
Vol 199 ◽  
pp. 25-31
Author(s):  
N. Udaya Shankar
Keyword(s):  
Radio Telescope ◽  
Low Frequency ◽  
Fourier Synthesis ◽  
North East ◽  
The North ◽  
Sky Survey ◽  
Correlation Receiver ◽  
Complex Correlation ◽  
Right Ascension ◽  
East West

The Mauritius Radio Telescope (MRT) is a Fourier synthesis instrument which has been built to fill the gap in the availability of deep sky surveys at low radio frequencies in the southern hemisphere. It is situated in the north-east of Mauritius at a southern latitude of 20°.14 and an eastern longitude of 57°.73. The aim of the survey with the MRT is to contribute to the database of southern sky sources in the declination range −70° ≤ δ ≤ −10°, covering the entire 24 hours of right ascension, with a resolution of 4' × 4'.6sec(δ + 20.14°) and a point source sensitivity of 200 mJy (3σ level) at 151.5 MHz.MRT is a T-shaped non-coplanar array consisting of a 2048 m long East-West arm and a 880 m long South arm. In the East-West arm 1024 fixed helices are arranged in 32 groups and in the South arm 16 trolleys, with four helices on each, which move on a rail are used. A 512 channel, 2-bit 3-level complex correlation receiver is used to measure the visibility function. At least 60 days of observing are required for obtaining the visibilities up to the 880 m spacing. The calibrated visibilities are transformed taking care of the non-coplanarity of the array to produce an image of the area of the sky under observation.This paper will describe the telescope, the observations carried out so far, a few interesting aspects of imaging with this non-coplanar array and present results of a low resolution survey (13' × 18') covering roughly 12 hours of right ascension, and also present an image with a resolution of 4' × 4'.6sec(δ + 20.14°) made using the telescope.

scholarly journals Influence of the North Atlantic oscillation on the atmospheric levels of benzo[a]pyrene over Europe

2021 ◽  
Author(s):  
Pedro Jiménez-Guerrero ◽  
Nuno Ratola
Keyword(s):  
Spatial Pattern ◽  
North Atlantic Oscillation ◽  
North Atlantic ◽  
Transport Model ◽  
Regional Scale ◽  
The South ◽  
Climatic Fluctuations ◽  
The North ◽  
The North Atlantic ◽  
The North Atlantic Oscillation

AbstractThe atmospheric concentration of persistent organic pollutants (and of polycyclic aromatic hydrocarbons, PAHs, in particular) is closely related to climate change and climatic fluctuations, which are likely to influence contaminant’s transport pathways and transfer processes. Predicting how climate variability alters PAHs concentrations in the atmosphere still poses an exceptional challenge. In this sense, the main objective of this contribution is to assess the relationship between the North Atlantic Oscillation (NAO) index and the mean concentration of benzo[a]pyrene (BaP, the most studied PAH congener) in a domain covering Europe, with an emphasis on the effect of regional-scale processes. A numerical simulation for a present climate period of 30 years was performed using a regional chemistry transport model with a 25 km spatial resolution (horizontal), higher than those commonly applied. The results show an important seasonal behaviour, with a remarkable spatial pattern of difference between the north and the south of the domain. In winter, higher BaP ground levels are found during the NAO+ phase for the Mediterranean basin, while the spatial pattern of this feature (higher BaP levels during NAO+ phases) moves northwards in summer. These results show deviations up to and sometimes over 100% in the BaP mean concentrations, but statistically significant signals (p<0.1) of lower changes (20–40% variations in the signal) are found for the north of the domain in winter and for the south in summer.

scholarly journals Rise and Fall of the Grand Canal in the Ancient Kaifeng City of China: Role of the Grand Canal and Water Supply in Urban and Regional Development

Water ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 1932
Author(s):  
Wenji Huang ◽  
Mingwang Xi ◽  
Shibao Lu ◽  
Farhad Taghizadeh-Hesary
Keyword(s):  
Song Dynasty ◽  
The Political ◽  
The South ◽  
Central Plains ◽  
Grand Canal ◽  
The North ◽  
Northern Song Dynasty ◽  
Political Center ◽  
Northern Song ◽  
The Grand Canal

In the long history of the feudal society of China, Kaifeng played a vital role. During the Northern Song Dynasty, Kaifeng became a worldwide metropolis. The important reason was that the Grand Canal, which was excavated during the Sui Dynasty, became the main transportation artery for the political and military center of the north and the economic center of the south. Furthermore, Kaifeng was located at the center of the Grand Canal, which made it the capital of the later Northern Song Dynasty. The Northern Song Dynasty was called “the canal-centered era.” The development of the canal caused a series of major changes in the society of the Northern Song Dynasty that were different from the previous ones, which directly led to the transportation revolution, and in turn, promoted the commercial revolution and the urbanization of Kaifeng. The development of commerce contributed to the agricultural and money revolutions. After the Northern Song Dynasty, the political center moved to the south. During the Yuan Dynasty, the excavation of the Grand Canal made it so that water transport did not have to pass through the Central Plains. The relocation of the political center and the change in the canal route made Kaifeng lose the value of connecting the north and south, resulting in the long-time fall of the Bianhe River. Kaifeng, which had prospered for more than 100 years, declined gradually, and by the end of the Qing Dynasty, it became a common town in the Central Plains. In ancient China, the rise and fall of cities and regions were closely related to the canal, and the relationship between Kaifeng and the Grand Canal was typical. The history may provide some inspiration for the increasingly severe urban and regional sustainable development issues in contemporary times.

Offshore Claims and Problems in the North Sea

1965 ◽  
Vol 59 (3) ◽  
pp. 505-522 ◽  
Author(s):  
Richard Young
Keyword(s):  
North Sea ◽  
Large Scale ◽  
Geneva Convention ◽  
Legal Principles ◽  
The North ◽  
Legal Problems ◽  
The North Sea ◽  
The Subject ◽  
First Time ◽  
Economic Considerations

The possible presence of very large petroleum and natural gas reserves in the area beneath the North Sea is currently the subject of intense investigation. If confirmed, as seems likely in at least some localities, this occurrence will raise legal problems of considerable interest and complexity. For the North Sea is not merely an oilfield covered by water: for centuries it has been one of the world's major fishery regions and the avenue to and from the world's busiest seaports. Thus all three of the present principal uses of the sea—fishing, navigation, and the exploitation of submarine resources—promise to meet for the first time on a large scale in an area where all are of major importance. The process of reconciling the various interests at stake will provide the first thoroughgoing test of the adequacy and acceptability of the general principles laid down in the 1958 Geneva Convention on the Continental Shelf and should add greatly to the practice and precedents available in this developing branch of the law. In the present article an attempt is made to review some of the geographical and economic considerations involved in the North Sea situation, to note some of the technical and legal developments that have already taken place, and to consider these elements in the light of the various interests and legal principles concerned.

scholarly journals Optimal design of the solar tracking system of parabolic trough concentrating collectors

2020 ◽  
Vol 15 (4) ◽  
pp. 613-619
Author(s):  
Li Kong ◽  
Yunpeng Zhang ◽  
Zhijian Lin ◽  
Zhongzhu Qiu ◽  
Chunying Li ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Solar Radiation ◽  
Tracking System ◽  
Low Cost ◽  
Parabolic Trough ◽  
The North ◽  
Tracking Mode ◽  
Solar Tracking ◽  
East West

Abstract The present work aimed to select the optimum solar tracking mode for parabolic trough concentrating collectors using numerical simulation. The current work involved: (1) the calculation of daily solar radiation on the Earth’s surface, (2) the comparison of annual direct solar radiation received under different tracking modes and (3) the determination of optimum tilt angle for the north-south tilt tracking mode. It was found that the order of solar radiation received in Shanghai under the available tracking modes was: dual-axis tracking &gt; north-south Earth’s axis tracking &gt; north-south tilt tracking (β = 15°) &gt; north-south tilt tracking (β = 45) &gt; north-south horizontal tracking &gt; east-west horizontal tracking. Single-axis solar tracking modes feature simple structures and low cost. This study also found that the solar radiation received under the north-south tilt tracking mode was higher than that of the north-south Earth’s axis tracking mode in 7 out of 12 months. Therefore, the north-south tilt tracking mode was studied separately to determine the corresponding optimum tilt angles in Haikou, Lhasa, Shanghai, Beijing and Hohhot, respectively, which were shown as follows: 18.81°, 27.29°, 28.67°, 36.21° and 37.97°.

The Villa Item and a Bride's Ordeal

1929 ◽  
Vol 19 (1) ◽  
pp. 67-87 ◽  
Author(s):  
Jocelyn Toynbee
Keyword(s):  
The South ◽  
Important Paper ◽  
The North ◽  
Dwelling House ◽  
South Wall ◽  
The Subject ◽  
The One ◽  
The Individual ◽  
North Wall ◽  
The Right

The paintings in the triclinium of the Villa Item, a dwelling-house excavated in 1909 outside the Porta Ercolanese at Pompeii, have not only often been published and discussed by foreign scholars, but they have also formed the subject of an important paper in this Journal. The artistic qualities of the paintings have been ably set forth: it has been established beyond all doubt that the subject they depict is some form of Dionysiac initiation: and, of the detailed interpretations of the first seven of the individual scenes, those originally put forward by de Petra and accepted, modified or developed by Mrs. Tillyard appear, so far as they go, to be unquestionably on the right lines. A fresh study of the Villa Item frescoes would seem, however, to be justified by the fact that the majority of previous writers have confined their attention almost entirely to the first seven scenes—the three to the east of the entrance on the north wall (fig. 3), the three on the east wall and the one to the east of the window on the south wall, to which the last figure on the east wall, the winged figure with the whip, undoubtedly belongs.

Transnationalism in Missionary Medicine

2017 ◽  
Vol 30 (1-2) ◽  
pp. 30-43
Author(s):  
Margo S. Gewurtz
Keyword(s):  
Formative Period ◽  
Tropical Medicine ◽  
Sand Fly ◽  
London School ◽  
The North ◽  
Kala Azar ◽  
Indian Medical ◽  
Medical Missionaries ◽  
The Subject ◽  
Missionary Medicine

Kala-azar is a parasitic disease that was endemic in India, parts of Africa and China. During the first half of the twentieth century, developing means of treatment and identification of the host and transmission vectors for this deadly disease would be the subject of transnational research and controversy. In the formative period for this research, two Canadian Medical missionaries, Drs. Jean Dow and Ernest Struthers, pioneered work on Kala-azar in the North Henan Mission. The great international prestige of the London School of Tropical Medicine and the Indian Medical Service would stand against recognition of the clinical discoveries of missionary doctors in remote North Henan. It was only after Struthers forged personal relations with Dr. Lionel. E. Napier and his colleagues at the Calcutta School of Tropical Medicine that there was a meeting of minds to promote the hypothesis that the sand fly was the transmission vector.

Sign in / Sign up

Export Citation Format

Share Document