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be aware that the information contained in CGM 408 is based on legacy data from the 1960-1990s and that it has been superseded by regional-scale information contained in CGM 403.

Eocene paleo-physiography and drainage directions, southern Interior Plateau, British Columbia

2005 ◽  
Vol 42 (2) ◽  
pp. 215-230 ◽  
Author(s):  
Selina Tribe
Keyword(s):  
British Columbia ◽  
Middle Eocene ◽  
Regional Scale ◽  
River Valley ◽  
Coast Mountains ◽  
Base Level ◽  
The North ◽  
Bedrock Geology ◽  
River Valleys ◽  
Early Cenozoic

A map of reconstructed Eocene physiography and drainage directions is presented for the southern Interior Plateau region, British Columbia south of 53°N. Eocene landforms are inferred from the distribution and depositional paleoenvironment of Eocene rocks and from crosscutting relationships between regional-scale geomorphology and bedrock geology of known age. Eocene drainage directions are inferred from physiography, relief, and base level elevations of the sub-Eocene unconformity and the documented distribution, provenance, and paleocurrents of early Cenozoic fluvial sediments. The Eocene landscape of the southern Interior Plateau resembled its modern counterpart, with highlands, plains, and deeply incised drainages, except regional drainage was to the north. An anabranching valley system trending west and northwest from Quesnel and Shuswap Highlands, across the Cariboo Plateau to the Fraser River valley, contained north-flowing streams from Eocene to early Quaternary time. Other valleys dating back at least to Middle Eocene time include the North Thompson valley south of Clearwater, Thompson valley from Kamloops to Spences Bridge, the valley containing Nicola Lake, Bridge River valley, and Okanagan Lake valley. During the early Cenozoic, highlands existed where the Coast Mountains are today. Southward drainage along the modern Fraser, Chilcotin, and Thompson River valleys was established after the Late Miocene.

A review on the Huoqiu banded iron formation (BIF), southeast margin of the North China Craton: Genesis of iron deposits and implications for exploration

2014 ◽  
Vol 63 ◽  
pp. 418-443 ◽  
Author(s):  
Xiaoyong Yang ◽  
Lei Liu ◽  
Insung Lee ◽  
Bohua Wang ◽  
Zhenbao Du ◽  
...  
Keyword(s):  
North China Craton ◽  
North China ◽  
Iron Formation ◽  
Banded Iron Formation ◽  
The North ◽  
Iron Deposits

Multiple Deformation in Archean Rocks of the Vermilion District, Northeastern Minnesota

1971 ◽  
Vol 8 (4) ◽  
pp. 423-434 ◽  
Author(s):  
P. R. Hooper ◽  
R. W. Ojakangas
Keyword(s):  
Iron Formation ◽  
Rock Outcrop ◽  
Kink Bands ◽  
Precambrian Rocks ◽  
The North ◽  
Multiple Deformation ◽  
North And South ◽  
East West

The structure of the Precambrian rocks of the Vermilion district is critically examined. It is demonstrated that two significant deformations (F1 and F2) have affected the area in addition to a later set of faults, joints, and kink-bands (F3). The F1 folds are tight to isoclinal with gently plunging axes and vertical axial planes trending west–northwest and containing iron formation and greenstones in anticlinal cores. The second deformation forms a series of open to close asymmetric folds (F2) with steep axes and vertical axial planes trending east–west. Of these, F1 has the more significant effect on the pattern of rock outcrop and it is suggested that it is directly related to the diapiric rise of the batholiths lying immediately to the north and south. The F2 folds may be accounted for by further compression between the two granite bodies.

Essai de corrélation stratigraphique et structurale à l'est de Val-d'Or: implication pour la prospection aurifère du secteur

1987 ◽  
Vol 24 (12) ◽  
pp. 2412-2421 ◽  
Author(s):  
Robert Marquis ◽  
Normand Goulet
Keyword(s):  
Regional Scale ◽  
Shear Zones ◽  
Iron Formation ◽  
Banded Iron Formation ◽  
Gold Exploration ◽  
Third Phase ◽  
Structural Relationships ◽  
Regional Tectonic ◽  
Ubiquitous Presence ◽  
East West

Stratigraphic and structural relationships show that the Trivio and Garden Island sedimentary groups could be lateral equivalents. The ubiquitous presence of shear zones between the sedimentary (Trivio and Garden Island) and volcanic (Kinojévis and Malartic) groups indicates that these contacts are tectonic and not stratigraphic. Moreover, the shearing along the Malartic–Trivio contact is located along the extension of the Larder Lake – Cadillac fault zone and could be its equivalent east of Val-d'Or, Quebec.Three major periods of deformation have been recognized in the field. The main east–west deformation, D2, has produced isoclinal folds inclined to the southwest and plunging 60° to the northeast. The axial-plane schistosity associated with D2 is responsible for the regional tectonic grain. Its orientation, 290°/70°, closely parallels the shearing direction along the major volcanic–sedimentary contacts. At Chimo mine, on a mesoscopic scale, the isoclinal D2 folds refold D1 structures, producing interference patterns intermediate between types 2 and 3. On a regional scale the D1 folds do not affect the lithologic pattern.A late deformation, D3, becomes progressively more noticeable toward the Grenville Front. Folds related to this third phase are inclined toward the northwest and plunge to the northeast. The orientation of the fracture cleavage associated with this deformation is 040°/60°. The proximity of the Grenville Front, north of Lake Matchi-Manitou, is shown by strike faults oriented northeast–southwest. The sinistral movement of these faults was determined using a banded iron formation as marker horizon.All gold exploration criteria suggest that the study area is a favourable target for gold exploration.

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.

A new volcanic province: evidence from glacial erratics in western North Greenland

2000 ◽  
pp. 35-41 ◽  
Author(s):  
Peter R. Dawes ◽  
Bjørn Thomassen ◽  
T.I. Hauge Andersson
Keyword(s):  
Volcanic Rocks ◽  
Iron Formation ◽  
Banded Iron Formation ◽  
Common Component ◽  
Volcanic Province ◽  
North West ◽  
North East ◽  
The North ◽  
Surficial Deposits ◽  
North Greenland

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Dawes, P. R., Thomassen, B., & Andersson, T. H. (2000). A new volcanic province: evidence from glacial erratics in western North Greenland. Geology of Greenland Survey Bulletin, 186, 35-41. https://doi.org/10.34194/ggub.v186.5213 _______________ Mapping and regional geological studies in northern Greenland were carried out during the project Kane Basin 1999 (see Dawes et al. 2000, this volume). During ore geological studies in Washington Land by one of us (B.T.), finds of erratics of banded iron formation (BIF) directed special attention to the till, glaciofluvial and fluvial sediments. This led to the discovery that in certain parts of Daugaard-Jensen Land and Washington Land volcanic rocks form a common component of the surficial deposits, with particularly colourful, red porphyries catching the eye. The presence of BIF is interesting but not altogether unexpected since BIF erratics have been reported from southern Hall Land just to the north-east (Kelly & Bennike 1992) and such rocks crop out in the Precambrian shield of North-West Greenland to the south (Fig. 1; Dawes 1991). On the other hand, the presence of volcanic erratics was unexpected and stimulated the work reported on here.

scholarly journals Ritual Economy and the Organization of Scioto Hopewell Craft Production: Insights from the Outskirts of the Mound City Group

2020 ◽  
Vol 85 (2) ◽  
pp. 279-304
Author(s):  
Timothy D. Everhart ◽  
Bret J. Ruby
Keyword(s):  
Craft Production ◽  
Small Scale ◽  
Magnetic Survey ◽  
Middle Woodland ◽  
The North ◽  
Large Structures ◽  
Production Site ◽  
Production And Consumption ◽  
Ritual Economy ◽  
City Group

This article offers insights into the organization of Scioto Hopewell craft production and examines the implications of this organization through the lens of ritual economy. We present a novel analysis of investigations at the North 40 site, concluding that it is a craft production site located on the outskirts of the renowned Mound City Group. High-resolution landscape-scale magnetic survey revealed a cluster of three large structures and two rows of associated pits; one of the buildings and three of the pits were sampled in excavations. Evidence from the North 40 site marks this as the best-documented Scioto Hopewell craft production site. Mica, chert, and copper were crafted here in contexts organized outside the realm of domestic household production and consumption. Other material remains from the site suggest that crafting was specialized and embedded in ceremonial contexts. This analysis of the complex organization of Scioto Hopewell craft production provides grounds for further understanding the elaborate ceremonialism practiced by Middle Woodland (AD 1–400) societies and adds to the known complexity of craft production in small-scale societies. Furthermore, this article contributes to a growing body of literature demonstrating the utility of ritual economy as a framework for approaching the sociality of small-scale societies.

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 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°.

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