Geoelectric response and crustal electrical-conductivity structure of the Flin Flon Belt, Trans-Hudson Orogen, Canada

1999 ◽  
Vol 36 (11) ◽  
pp. 1917-1938 ◽  
Author(s):  
I J Ferguson ◽  
Alan G Jones ◽  
Yu Sheng ◽  
X Wu ◽  
I Shiozaki
Keyword(s):  
Geological Structure ◽  
The Body ◽  
Geomagnetic Induction ◽  
The North ◽  
Gneiss Complex ◽  
Conductivity Structure ◽  
Intrusive Rocks ◽  
Magnetotelluric Method ◽  
Flin Flon ◽  
Southern Flank

A Lithoprobe magnetotelluric survey across the Palaeoproterozoic Trans-Hudson Orogen included 34 sites within the Flin Flon Belt and adjacent geological domains. The magnetotelluric impedance tensors and geomagnetic induction vectors reveal four distinct geoelectric zones along this segment of the Lithoprobe transect. In the east and west, the geoelectric responses are dominated by the contrast between intrusive rocks and more conductive ocean-floor assemblages. A significant characteristic of the responses throughout the Flin Flon Belt is the very strong galvanic distortion of the electric field, which reflects the complexity of the upper crustal geological structure in the greenstone belt, requiring careful application of distortion removal methods. The responses at sites near the north of the Flin Flon Belt are related to the boundary with the southern flank of the Kisseynew gneiss belt. To the south, at sites near Athapapuskow Lake, the responses are dominated by a strong upper-crustal conductor. The magnetotelluric observations show that the Athapapuskow Lake conductivity anomaly extends for at least 40 km along strike (~N36°E), and is roughly two-dimensional in form. Numerical modelling shows that the top of the body dips southeast at 20-50° from a western edge coincident with the Athapapuskow Lake shear zone. The conductor lies in the eastern part of the Namew gneiss complex. The magnetotelluric method cannot resolve the exact spatial distribution of conductive rocks but it is probable that the anomaly is caused by a series of isolated conductors (with resistivity <1 Ω·m) associated with subordinate graphitic and sulphidic supracrustal gneisses.

Regional mapping of Precambrian basement beneath Phanerozoic cover in southeastern Trans-Hudson Orogen, Manitoba and Saskatchewan

1997 ◽  
Vol 34 (5) ◽  
pp. 618-634 ◽  
Author(s):  
A. D. Leclair ◽  
S. B. Lucas ◽  
H. J. Broome ◽  
D. W. Viljoen ◽  
W. Weber
Keyword(s):  
Gravity Data ◽  
Regional Mapping ◽  
Western Canada Sedimentary Basin ◽  
Gneiss Complex ◽  
Intrusive Rocks ◽  
Anomaly Pattern ◽  
Northern Edge ◽  
Flin Flon ◽  
Seismic Reflection Profiles ◽  
Canada Sedimentary Basin

The northern edge of Phanerozoic platformal rocks of the Western Canada Sedimentary Basin overlies the Flin Flon Belt (Trans-Hudson Orogen) in Manitoba and Saskatchewan. A program of regional mapping of the Phanerozoic-covered basement has been undertaken, involving the integration of high-resolution aeromagnetic and gravity data with extensive drill core information. Several major domains are recognized in the buried basement, each with a distinct lithotectonic character and potential field anomaly pattern. Three lithotectonic domains in the buried basement (Clearwater, Athapapuskow, and Amisk Lake domains) are characterized by northerly-trending positive gravity and aeromagnetic anomalies and correlate with the 1.92–1.83 Ga volcanic and plutonic rocks of the exposed Flin Flon Belt (Amisk collage and Snow Lake assemblage). An upper amphibolite grade orthogneiss complex (Namew Gneiss Complex), containing calc-alkaline intrusive rocks ranging in age from 1.88 to 1.83 Ga and screens derived from the older volcano-sedimentary rocks, is interpreted as the middle crust of a 1.88–1.84 Ga arc exposed in the Flin Flon Belt. Discordant intrusive complexes, such as the 1.830 Ga Cormorant Batholith, are centred on magnetic–gravity lows and truncate the structural trend of adjacent lithotectonic domains. Correlation of Flin Flon Belt geology with that beneath the Phanerozoic cover shows that its constituent lithotectonic elements have north–south strikes of up to 150 km, and form a predominantly east-dipping crustal section, consistent with Lithoprobe seismic reflection profiles.

Introduction to Special Issue 2 on the NATMAP Shield Margin Project: The Flin Flon Belt, Trans-Hudson Orogen, Manitoba and Saskatchewan

1999 ◽  
Vol 36 (11) ◽  
pp. 1763-1765 ◽  
Author(s):  
S B Lucas ◽  
E C Syme ◽  
K E Ashton
Keyword(s):  
Special Issue ◽  
Four Dimensions ◽  
Metasedimentary Rocks ◽  
Research Areas ◽  
Conductivity Structure ◽  
Tracer Isotope ◽  
Close Cooperation ◽  
Isotope Studies ◽  
Flin Flon ◽  
Southern Flank

The Shield Margin Project of the National Geoscience Mapping Program (NATMAP) resulted in a new understanding of the Paleoproterozoic Flin Flon Belt (Manitoba and Saskatchewan) in four dimensions. A multidisciplinary approach was utilized in the NATMAP project, based on partnerships with government, university, and private sector geoscientists, and close cooperation with the Lithoprobe's Trans-Hudson Orogen Transect. Research areas spanned from bedrock and surficial geoscience, to crustal and mantle geophysics, to high precision U-Pb geochronology and tracer isotope studies. This Special Issue contains nine papers covering a wide variety of topics related to the NATMAP Shield Margin Project, including volcanic-hosted massive sulphide deposits in the Flin Flon and Snow Lake camps; structural geology of the Flin Flon townsite and southern flank of the Kisseynew Domain; geochronology and the U-Pb systematics of monazite in metasedimentary rocks; and the geoelectrical and crustal conductivity structure of the Flin Flon Belt.

Subglacial topography and thickness of ice caps on the Argentine Islands

2019 ◽  
Vol 31 (6) ◽  
pp. 332-344 ◽  
Author(s):  
Jānis Karušs ◽  
Kristaps Lamsters ◽  
Anatolii Chernov ◽  
Māris Krievāns ◽  
Jurijs Ješkins
Keyword(s):  
Land Surface ◽  
Geological Structure ◽  
Aerial Images ◽  
Ice Thickness ◽  
Ice Caps ◽  
The North ◽  
Prevailing Wind Direction ◽  
Aerial Vehicle ◽  
Subglacial Topography ◽  
Ground Penetrating

AbstractThis study presents the first subglacial topography and ice thickness models of the largest ice caps of the Argentine Islands, Wilhelm Archipelago, West Antarctica. During this study, ground-penetrating radar was used to map the thickness and inner structure of the ice caps. Digital surface models of all studied islands were created from aerial images obtained with a small-sized unmanned aerial vehicle and used for the construction of subglacial topography models. Ice caps of the Argentine Islands cover ~50% of the land surface of the islands on average. The maximum thickness of only two islands (Galindez and Skua) exceeds 30 m, while the average thickness of all islands is only ~5 m. The maximum ice thickness reaches 35.3 m on Galindez Island. The ice thickness and glacier distribution are mainly governed by prevailing wind direction from the north. This has created the prominent narrow ice ridges on Uruguay and Irizar islands, which are not supported by topographic obstacles, as well as the elongated shape of other ice caps. The subglacial topography of the ice caps is undulated and mainly dependent on the geological structure and composition of magmatic rocks.

Fractures in the northern plains, stream patterns, and the midcontinent stress field

1987 ◽  
Vol 24 (6) ◽  
pp. 1086-1097 ◽  
Author(s):  
Mel R. Stauffer ◽  
Don J. Gendzwill
Keyword(s):  
Stress Field ◽  
Horizontal Stress ◽  
The Body ◽  
North American Plate ◽  
Plate Motion ◽  
Viscous Drag ◽  
Near Surface ◽  
The North ◽  
Elastic Rebound ◽  
Western North Dakota

Fractures in Late Cretaceous to Late Pleistocene sediments in Saskatchewan, eastern Montana, and western North Dakota form two vertical, orthogonal sets trending northeast–southwest and northwest–southeast. The pattern is consistent, regardless of rock type or age (except for concretionary sandstone). Both sets appear to be extensional in origin and are similar in character to joints in Alberta. Modem stream valleys also trend in the same two dominant directions and may be controlled by the underlying fractures.Elevation variations on the sub-Mannville (Early Cretaceous) unconformity form a rectilinear pattern also parallel to the fracture sets, suggesting that fracturing was initiated at least as early as Late Jurassic. It may have begun earlier, but there are insufficient data at present to extend the time of initiation.We interpret the fractures as the result of vertical uplift together with plate motion: the westward drift of North America. The northeast–southwest-directed maximum principal horizontal stress of the midcontinent stress field is generated by viscous drag effects between the North American plate and the mantle. Vertical uplift, erosion, or both together produce a horizontal tensile state in near-surface materials, and with the addition of a directed horizontal stress through plate motion, vertical tension cracks are generated parallel to that horizontal stress (northeast–southwest). Nearly instantaneous elastic rebound results in the production of second-order joints (northwest–southeast) perpendicular to the first. In this manner, the body of rock is being subjected with time to complex alternation of northeast–southwest and northwest–southeast horizontal stresses, resulting in the continuous and contemporaneous production of two perpendicular extensional joint sets.

Stages of Late Palaeozoic deformation and intrusive activity in the western part of the North Patagonian Massif (southern Argentina) and their geotectonic implications

2008 ◽  
Vol 146 (1) ◽  
pp. 48-71 ◽  
Author(s):  
W. VON GOSEN
Keyword(s):  
Regional Metamorphism ◽  
The North ◽  
Magmatic Rocks ◽  
Late Palaeozoic ◽  
Intrusive Rocks ◽  
Gondwana Margin ◽  
Intrusive Activity ◽  
Magmatic History ◽  
Crust Deformation ◽  
Deformational Event

AbstractAnalyses of structures in the western part of the North Patagonian Massif (southern Argentina) suggest a polyphase evolution, accompanied by continuous intrusive activity. The first two deformations (D1, D2) and metamorphism affected the upper Palaeozoic, partly possibly older Cushamen Formation clastic succession and different intrusive rocks. A second group of intrusions, emplaced after the second deformational episode (D2), in many places contain angular xenoliths of the foliated country rocks, indicating high intrusive levels with brittle fracturing of the crust. Deformation of these magmatic rocks presumably began during (the final stage of) cooling and continued under solid-state conditions. It probably coincided with the third deformational event (D3) in the country rocks. Based on published U–Pb zircon ages of deformed granitoids, the D2-deformation and younger event along with the regional metamorphism are likely to be Permian in age. An onset of the deformational and magmatic history during Carboniferous times, however, cannot be excluded. The estimated ~W–E to NE–SW compression during the D2-deformation, also affecting the first group of intrusive rocks, can be related to subduction beneath the western Patagonia margin or an advanced stage of collisional tectonics within extra-Andean Patagonia. The younger ~N–S to NE–SW compression might have been an effect of oblique subduction in the west and/or continuing collision-related deformation. As a cause for its deviating orientation, younger block rotations during strike-slip faulting cannot be excluded. The previous D2-event presumably also had an effect on compression at the northern Patagonia margin that was interpreted as result of Patagonia's late Palaeozoic collision with the southwestern Gondwana margin. With the recently proposed Carboniferous subduction and collision south of the North Patagonian Massif, the entire scenario might suggest that Patagonia consists of two different pieces that were amalgamated with southwestern Gondwana during Late Palaeozoic times.

An Early Burial from Gordon Creek, Colorado

1971 ◽  
Vol 36 (2) ◽  
pp. 170-182 ◽  
Author(s):  
David A. Breternitz ◽  
Alan C. Swedlund ◽  
Duane C. Anderson
Keyword(s):  
North America ◽  
Annual Meeting ◽  
Preliminary Report ◽  
Skeletal Remains ◽  
The Body ◽  
National Forest ◽  
Bone Material ◽  
The North ◽  
Northern Colorado ◽  
Early Human

AbstractAn isolated burial was excavated from the bank of a tributary of Gordon Creek, Roosevelt National Forest, northern Colorado. A preliminary report was prepared (D. Anderson 1966, 1967) but further analysis of the skeletal material and newly obtained cultural information add significantly to the documentation of the burial.The body of a woman, aged 25-30 years, was given primary interment in a pit coated with red ocher. The body was placed on its left side with the head to the north, was tightly flexed, and was also coated with red ocher. Burial accompaniments include a large precussion flaked biface or preform, a small biface used as a scraping tool, a hammerstone, an end scraper, a preform with fire pocks, cut and incised animal ribs, and a perforated elk incisor. A radiocarbon assay of bone material from the left ilium produced an age of 9700± 250 radiocarbon years: 7750 B.C. (GX-0530).No indications of habitation which might be associated with the burial were located in its immediate vicinity.A reconstruction of the burial ritual is attempted, and the skeletal remains are compared to other early human remains from North America.A summary of this paper was given at the 34th Annual Meeting of the Society for American Archaeology, May 3, 1969, in Milwaukee, Wisconsin.

Displacement and stress field along part of the Cobequid Fault, Nova Scotia

1969 ◽  
Vol 6 (5) ◽  
pp. 1095-1104 ◽  
Author(s):  
Gerhard H. Eisbacher
Keyword(s):  
Stress Field ◽  
Fault Zone ◽  
Maximum Compressive Stress ◽  
Clastic Rocks ◽  
The North ◽  
Total Displacement ◽  
Displacement Vectors ◽  
Lateral Displacements ◽  
Fault Trace ◽  
Southern Flank

The east-trending Cobequid Fault separates pre-Carboniferous rocks of the Cobequid Mountains to the north from Carboniferous clastic rocks along the southern flank of the mountains. A detailed study of the fault zone revealed tie predominance of right-lateral displacements. The orientation of the stress field that existed during deformation along the fault trace was determined by the study of systematic fractures in pebbles within Carboniferous conglomerate. Maximum compressive stress was aligned in a NW–SE direction, being compatible with the orientation of the displacement vectors in the fault zone. Transcurrent movement along the Cobequid Fault occurred in late Pennsylvanian time and involved both Carboniferous and pre-Carboniferous rocks; total displacement is unknown.

‘Tales of Wonder and Horror’: Coverage of insanity in the Leeds press, 1808-1840

2021 ◽  
Author(s):  
◽  
Evgeniya Kryssova
Keyword(s):  
Eighteenth Century ◽  
Lower Class ◽  
The Body ◽  
Upper Class ◽  
Press Coverage ◽  
Social Analysis ◽  
Periodical Literature ◽  
Legal Cases ◽  
The North ◽  
The Press

<p>The press was at the centre of the reform of the meaning of insanity, during its evolution from an equivocal eighteenth-century concept of melancholia to a medicalised Victorian notion of ‘lunacy’. During the late Georgian era newspapers provided a public forum for the opinion of newly emerging psychiatric practitioners and fostered the fears and concerns about mental illness and its supposed increase. The press was also the main source of news on crime, providing readers with reports on criminal insanity and suicide. In the first half of the nineteenth century, newspaper contents included official legal reports, as well as editorial commentary and excerpts from other publications, and newspaper articles can rarely be traced to one single author. Historians of British insanity avoid consulting periodical literature, choosing to use asylum records and coroners’ reports, as these sources are more straightforward than newspapers. However, Rab Houston’s recent study of the coverage of suicide in the north of Britain shows that the provincial press has been unjustly overlooked and can offer the material for a unique social analysis. Asylum records and coroners’ records do not contain the same detail provided in the press. Newspaper commentary can arguably reveal contemporary attitudes towards insanity and, moreover, sources such as asylum records only deal with the lower-class patients, as the middle- and upper-class insane were usually privately detained.  This thesis examines the press coverage of insanity in Leeds newspapers, and expands on previous research by looking at the way insanity was portrayed in the two most popular publications in the industrial region of Yorkshire: the Leeds Intelligencer and the Leeds Mercury. Chapter one focuses on legal cases that featured a verdict of insanity and explores the language used by the press in the reports of, mainly, violent domestic crime. Chapter two looks at reports of suicide and considers how contemporary views on financial and moral despondency influenced the portrayal of self-murder. Chapter three considers editorial articles that cannot be described as either crime or suicide reports. This chapter uncovers the presence of surprisingly humorous and entertaining articles on insanity found in editorials and the ‘Miscellany’ sections of the newspapers. Ultimately, this thesis argues that the reportage of insanity in the Leeds press was sensational, moralistic and selectively sympathetic; furthermore, such portrayal of insanity was reinforced throughout the body of the paper. Leeds newspapers segregated the insane by adopting a moralising tone and by choosing to use class-specific language towards the insane of different social ranks.</p>

Reconstruction of the Reservoir Fine Structure by Using Scattering Attributes

2021 ◽  
Author(s):  
Vladimir Cheverda ◽  
Vadim Lisitsa ◽  
Maksim Protasov ◽  
Galina Reshetova ◽  
Andrey Ledyaev ◽  
...  
Keyword(s):  
Seismic Data ◽  
Numerical Experiments ◽  
Seismic Waves ◽  
Fractured Reservoirs ◽  
Three Dimensional ◽  
Geological Structure ◽  
Discrete Elements ◽  
Digital Twin ◽  
The North ◽  
Slip Surfaces

Abstract To develop the optimal strategy for developing a hydrocarbon field, one should know in fine detail its geological structure. More and more attention has been paid to cavernous-fractured reservoirs within the carbonate environment in the last decades. This article presents a technology for three-dimensional computing images of such reservoirs using scattered seismic waves. To verify it, we built a particular synthetic model, a digital twin of one of the licensed objects in the north of Eastern Siberia. One distinctive feature of this digital twin is the representation of faults not as some ideal slip surfaces but as three-dimensional geological bodies filled with tectonic breccias. To simulate such breccias and the geometry of these bodies, we performed a series of numerical experiments based on the discrete elements technique. The purpose of these experiments is the simulation of the geomechanical processes of fault formation. For the digital twin constructed, we performed full-scale 3D seismic modeling, which made it possible to conduct fully controlled numerical experiments on the construction of wave images and, on this basis, to propose an optimal seismic data processing graph.

Notes on the Young of Blennius galerita, L

1902 ◽  
Vol 6 (3) ◽  
pp. 383-386 ◽  
Author(s):  
L. W. Byrne
Keyword(s):  
The Body ◽  
North Coast ◽  
Pectoral Fins ◽  
The North

No description of the young of this species seems to exist, with the exception of that given by Emery (1) of some examples from Naples.The specimens here described were captured at Newquay, on the north coast of Cornwall, in September, 1898, and have been preserved in formol. They were caught in sandy pools surrounding or surrounded by rocks in the shelter of which they seemed to be fond of lying. When disturbed they darted with considerable rapidity from place to place, and in doing so were seemingly assisted by the large pectoral fins which were carried nearly at right angles to the body by the fish when at rest.

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