Paleomagnetism and time-stratigraphic correlation of Proterozoic redbeds of the Labrador Trough and outliers of northern Quebec

1983 ◽  
Vol 20 (11) ◽  
pp. 1725-1737 ◽  
Author(s):  
E. J. Schwarz ◽  
G. N. Freda
Keyword(s):  
Canadian Shield ◽  
Stratigraphic Correlation ◽  
End Points ◽  
Polar Wander ◽  
Northeastern Part ◽  
Apparent Polar Wander Path ◽  
South West ◽  
Group 2 ◽  
Magnetic North ◽  
Group 1

One hundred and forty-two oriented cores were collected from redbeds of the Sakami Formation near LG-4 (85), Dieter (19), Cambrian (18), and Snow-ball (4) lakes, all in Quebec, and from two outliers in Labrador: Evening Lake (6) and Sims Lake (10). A further 73 oriented drill cores were collected from the strongly folded Chakonipau Formation redbeds (44) in the Labrador Trough and undeformed redbeds near Lac Imbault (29) on the western edge of the trough. Thermal demagnetization of the trough redbeds yielded 52 core directions, each of which showed good specimen end points and sufficient homogeneity of magnetization, and 101 such core directions were obtained for the outlier redbeds. In most of these samples, there are no indications that the stable remanence is multi-component, and the fold test yields (for LG-4 Sakami Formation and the Chakonipau Formation) a significant (95% probability) improvement of the dispersion parameter K. Thus, the Chakonipau Formation remanence is probably pre-Hudsonian and the Sakami Formation remanence is probably pre-faulting (not dated). Furthermore, a near reversal (165°) in the Chakonipau Formation suggests that the stable remanence was acquired during or soon after deposition. The pole positions for Circum-Superior orogen rocks, the Proterozoic outliers, and the Sutton Lake inlier suggest: (1) a time-stratigraphic correlation between the LG-4 Sakami, Dieter Lake, Sutton Lake, and the upper part of the Belcher Island sequences; and (2) a time-stratigraphic correlation between the lower part of the Belcher Islands sequence and the Richmond Gulf sequence, which must be substantially older than group 1. The Circum-Superior apparent polar wander path (APWP) is drawn through magnetic North poles from the group 1 poles to the group 2 poles, yielding a slightly lower age for the trough sediments represented by the Chakonipau Formation (two opposing polarities) and the Lac Imbault redbeds. The general North American APWP is simplified by the deletion of the Richmond Gulf South poles, and seems to be positioned as much as about 30° north of the Circum-Superior APWP down to about 1800 Ma ago. This may indicate (pre-) Hudsonian movement between the northeastern part of the Canadian Shield and paleomagnetically better investigated parts to the (south-) west.

Paleomagnetism and structural history of the Ghost Range intrusive complex, central Abitibi Belt, Ontario: further evidence for the Late Archean geomagnetic field of North America

1982 ◽  
Vol 19 (11) ◽  
pp. 2085-2099 ◽  
Author(s):  
John Wm. Geissman ◽  
David W. Strangway ◽  
Ann M. Tasillo-Hirt ◽  
Larry S. Jensen
Keyword(s):  
North America ◽  
Blocking Temperature ◽  
High Coercivity ◽  
Thermal Methods ◽  
Virtual Geomagnetic Pole ◽  
Polar Wander ◽  
Apparent Polar Wander Path ◽  
Group 3 ◽  
Group 2 ◽  
Group 1

On the basis of their remanence properties, the lithologies of the Late Archean (2710–2703 Ma) Ghost Range Complex, an east–west-trending layered mafic–ultramafic extrusive sequence in the central Abitibi Greenstone Belt, can be divided into three groups. Group 1 units contain a high-coercivity, high-blocking temperature (greater than 520 °C) magnetite-dominated remanence characteristic of the complex (D = 280°, I = 2°, k = 5.5, α95 = 11.8°, virtual geomagnetic pole = 13°E, 7°S; isolated by both AF and thermal methods), in good agreement with the few previous results bearing on the Late Archean apparent polar wander path for North America. Group 2 units contain a low-coercivity, low-blocking-temperature (less than 310°C) scattered remanence residing in pyrrhotite. Often, both remanences coexist in a single lithology at a given site. Group 3 units contain distributed coercivity and blocking-temperature remanences, again residing in magnetite, that are more scattered but statistically identical to the mean group 1 direction. The order of magnetic blocking appears to have been group 1 before group 3 before group 2. The geologic setting of the Ghost Range suggests that it has remained essentially stable since emplacement and therefore the group 1 direction appears to reliably represent a Late Archean paleomagnetic pole.

A detailed 40Ar/39Ar age study of an Abitibi dike from the Canadian Superior Province

1979 ◽  
Vol 16 (5) ◽  
pp. 1060-1070 ◽  
Author(s):  
J. A. Hanes ◽  
Derek York
Keyword(s):  
Canadian Shield ◽  
Superior Province ◽  
Low Grade ◽  
Polar Wander ◽  
Mafic Mineral ◽  
Fine Grained ◽  
Apparent Polar Wander Path ◽  
Step Heating ◽  
Apparent Age ◽  
Hydrothermal Event

40Ar/39Ar step-heating analyses were performed on 11 felsic and mafic mineral separates from a 90 m wide Precambrian diabase dike of the Abitibi swarm in the Superior Province of the Canadian Shield. Deuterically altered minerals from the dike interior define a primary age of 2150 ± 25 Ma. Updated ages, obtained from felsic separates within 30, and mafic within 1.5 m of the dike border, are evidence of a previously undetected 'Hudsonian' (1.7–1.8 Ga) hydrothermal event in the area. It is possible to distinguish the deuteric from the later hydrothermal alteration by both dating and petrographic methods. The data from this study demonstrate the successful application of 40Ar/39Ar dating to early Proterozoic dikes which have suffered low grade metamorphism. The ages support a north to south sense of motion of the Track 5 apparent polar wander path (APWP). A monotonic decrease in apparent age of felsic spectra indicates reactor induced recoil effects which are correlated with the fine-grained saussurite in the feldspar.

Malley diabase dykes of the Slave craton, Canadian Shield: U–Pb age, paleomagnetism, and implications for continental reconstructions in the early Paleoproterozoic1Geological Survey of Canada Contribution 20110114.

2012 ◽  
Vol 49 (2) ◽  
pp. 435-454 ◽  
Author(s):  
Kenneth L. Buchan ◽  
Anthony N. LeCheminant ◽  
Otto van Breemen
Keyword(s):  
Relative Orientation ◽  
Canadian Shield ◽  
Dyke Swarm ◽  
Slave Craton ◽  
Polar Wander ◽  
Thermal Demagnetization ◽  
Contact Test ◽  
Apparent Polar Wander Path ◽  
Close Proximity ◽  
Superior Craton

The NE-trending Malley dyke swarm, dated herein at 2231 ± 2 Ma (U–Pb baddeleyite), extends from the central Slave craton to the vicinity of the Kilohigok basin, and may continue farther to the northeast as the geochemically similar Brichta dyke swarm, having been offset sinistrally along the prominent Bathurst fault. It carries a characteristic high unblocking temperature paleomagnetic component of single polarity directed up SE (mean direction: D = 138.3°, I = –53.8°), with corresponding paleopole at 50.8°S, 50.0°W. Lower unblocking temperature components, in some cases directed down SE, similar to ca 1.75 Ga post-Hudsonian overprints, are easily removed using combined alternating field (AF) thermal demagnetization, but difficult to remove using AF cleaning alone. The characteristic remanence has not been demonstrated primary, but is significantly older than 2.03 Ga, the age of Lac de Gras dykes, based on a baked contact test at a Lac de Gras – Malley dyke intersection. In addition, an E- to ESE-trending dyke carries a down WNW remanence, typical of 2.19 Ga Dogrib dykes near Yellowknife, suggesting that regional overprinting has not affected the study area since Dogrib emplacement, and that the Malley remanence was acquired at or shortly after Malley emplacement. Comparing Malley and Lac de Gras paleopoles with the 2.22–2.00 Ga Superior craton apparent polar wander path indicates that the two cratons were (i) not in their present relative orientation at 2.23 or 2.03 Ga, and (ii) likely not drifting in close proximity to one another as parts of a single (super)continent throughout the 2.23–2.03 Ga interval.

The 1830 Ma Trans-Hudson hairpin from paleomagnetism of the Wapisu gneiss dome, Kisseynew Domain, Manitoba

2000 ◽  
Vol 37 (6) ◽  
pp. 913-922
Author(s):  
D TA Symons ◽  
M J Harris
Keyword(s):  
Remanent Magnetization ◽  
Amphibolite Facies ◽  
Gneiss Dome ◽  
North Central ◽  
Polar Wander ◽  
Northeastern Part ◽  
Apparent Polar Wander Path ◽  
Peak Metamorphism ◽  
Superior Craton

The Wapisu gneiss dome is located in the northeastern part of the Kisseynew Domain of the Trans-Hudson Orogen (THO) in north-central Manitoba. The dome is circular, about 6 km in diameter, with steeply-dipping flanks. It is composed of upper amphibolite-facies gneisses derived from turbiditic sediments, with leucogranitic sill-like intrusions that were metamorphosed, starting at about 1830 Ma. Alternating field and thermal step demagnetization of 153 specimens from 17 sites around the perimeter of the dome isolated a characteristic remanent magnetization (ChRM) direction of D = 346.6°, I = 78.9° (α95 = 5.3°, k = 46, N = 17) that gives a pole of 119.5° W, 75.8° N (dp = 9.5°, dm = 10.0°). Unblocking temperatures and saturation isothermal remanence analyses show that the ChRM resides mostly in single to pseudosingle domain magnetite or titanomagnetite, with minor hematite commonly present and with minor pyrrhotite present in the leucogranites. The ChRM is found to be postfolding with >>99.9% confidence, indicating acquisition on cooling from peak metamorphism at ~1810 ± 10 Ma. This Wapisu gneiss dome paleopole is the first from the Kisseynew Domain and the first from the 1830 to 1770 Ma interval in the THO. It indicates an ~90° bend or hairpin in the apparent polar wander path for the THO juvenile terranes and Superior craton. It is speculated that the hairpin marks the collisional impact of the Archean Sask craton and (or) Hearne craton, which drove the Paleoproterozoic Kisseynew Domain into the Archean Superior craton.

Paleomagnetism of the Callander Complex and the Cambrian apparent polar wander path for North America

1991 ◽  
Vol 28 (3) ◽  
pp. 355-363 ◽  
Author(s):  
D. T. A. Symons ◽  
A. D. Chiasson
Keyword(s):  
Remanent Magnetization ◽  
Pole Position ◽  
Canadian Shield ◽  
Complete Spectrum ◽  
Isothermal Remanent Magnetization ◽  
Alkaline Complex ◽  
Grenville Province ◽  
Polar Wander ◽  
The Core ◽  
Apparent Polar Wander Path

The 7 km2 circular Callander alkaline complex was emplaced into anorthositic and granitic gneisses of the Grenville Province in the Canadian Shield about 575 ± 5 Ma ago at the start of the Cambrian. The complex has not been subsequently metamorphosed or tilted. Detailed alternating-field and thermal step demagnetization of 252 specimens from 29 sites led to the identification of a characteristic A magnetization component with a direction of D = 82.2°, I = 82.7° (α95 = 3.1°, k = 83, N = 26 sites) in 5 sites of mesocratic to leucocratic syenite from the core of the complex, in 5 sites of fenitized host rock from its aureole, and in 16 sites of lamprophyre from radiating dikes. Isothermal remanent-magnetization tests show that the A component is retained by both magnetite and hematite in a complete spectrum of domain sizes. A reversals test suggests and a contact test shows the A component to be primary. Its pole position at 46.3°S, 121.4°E(dp = 5.9°, dm = 6.1°) does not fall on published but poorly defined Cambrian apparent polar wander paths, leading to speculation on an alternative Cambrian path.

In-vivo evaluation of the effect of cyanoacrylate on prosthetic vascular graft infection – does cyanoacrylate increase the severity of infection?

VASA ◽  
2020 ◽  
Vol 49 (4) ◽  
pp. 281-284
Author(s):  
Atıf Yolgosteren ◽  
Gencehan Kumtepe ◽  
Melda Payaslioglu ◽  
Cuneyt Ozakin
Keyword(s):  
Vascular Graft ◽  
Graft Infection ◽  
Vascular Graft Infection ◽  
Group 4 ◽  
Significant Difference ◽  
Group 3 ◽  
Group 2 ◽  
Prosthetic Vascular Graft Infection ◽  
Group 1

Summary. Background: Prosthetic vascular graft infection (PVGI) is a complication with high mortality. Cyanoacrylate (CA) is an adhesive which has been used in a number of surgical procedures. In this in-vivo study, we aimed to evaluate the relationship between PVGI and CA. Materials and methods: Thirty-two rats were equally divided into four groups. Pouch was formed on back of rats until deep fascia. In group 1, vascular graft with polyethyleneterephthalate (PET) was placed into pouch. In group 2, MRSA strain with a density of 1 ml 0.5 MacFarland was injected into pouch. In group 3, 1 cm 2 vascular graft with PET piece was placed into pouch and MRSA strain with a density of 1 ml 0.5 MacFarland was injected. In group 4, 1 cm 2 vascular graft with PET piece impregnated with N-butyl cyanoacrylate-based adhesive was placed and MRSA strain with a density of 1 ml 0.5 MacFarland was injected. All rats were scarified in 96th hour, culture samples were taken where intervention was performed and were evaluated microbiologically. Bacteria reproducing in each group were numerically evaluated based on colony-forming unit (CFU/ml) and compared by taking their average. Results: MRSA reproduction of 0 CFU/ml in group 1, of 1410 CFU/ml in group 2, of 180 200 CFU/ml in group 3 and of 625 300 CFU/ml in group 4 was present. A statistically significant difference was present between group 1 and group 4 (p < 0.01), between group 2 and group 4 (p < 0.01), between group 3 and group 4 (p < 0.05). In terms of reproduction, no statistically significant difference was found in group 1, group 2, group 3 in themselves. Conclusions: We observed that the rate of infection increased in the cyanoacyrylate group where cyanoacrylate was used. We think that surgeon should be more careful in using CA in vascular surgery.

The influence of continuous local wound infusion on postoperative pain in patients undergoing transfemoral amputation

VASA ◽  
2015 ◽  
Vol 44 (5) ◽  
pp. 381-386 ◽  
Author(s):  
Christian Uhl ◽  
Thomas Betz ◽  
Andrea Rupp ◽  
Markus Steinbauer ◽  
Ingolf Töpel
Keyword(s):  
Pain Management ◽  
Pilot Study ◽  
Local Anaesthetic ◽  
Phantom Pain ◽  
Transfemoral Amputation ◽  
Postoperative Wound ◽  
Stump Pain ◽  
Management Protocol ◽  
Group 2 ◽  
Group 1

Abstract. Summary: Background: This pilot study was set up to examine the effects of a continuous postoperative wound infusion system with a local anaesthetic on perioperative pain and the consumption of analgesics. Patients and methods: We included 42 patients in this prospective observational pilot study. Patients were divided into two groups. One group was treated in accordance with the WHO standard pain management protocol and in addition to that received a continuous local wound infusion treatment (Group 1). Group 2 was treated with analgesics in accordance with the WHO standard pain management protocol, exclusively. Results: The study demonstrated a significantly reduced postoperative VAS score for stump pain in Group 1 for the first 5 days. Furthermore, the intake of opiates was significantly reduced in Group 1 (day 1, Group 1: 42.1 vs. Group 2: 73.5, p = 0.010; day 2, Group 1: 27.7 vs. Group 2: 52.5, p = 0.012; day 3, Group 1: 23.9 vs. Group 2: 53.5, p = 0.002; day 4, Group 1: 15.7 vs. Group 2: 48.3, p = 0.003; day 5, Group 1 13.3 vs. Group 2: 49.9, p = 0.001). There were no significant differences between the two groups, neither in phantom pain intensity at discharge nor postoperative complications and death. Conclusions: Continuous postoperative wound infusion with a local anaesthetic in combination with a standard pain management protocol can reduce both stump pain and opiate intake in patients who have undergone transfemoral amputation. Phantom pain was not significantly affected.

Abnormal Haemostasis and Blood Viscosity in Malignant Hypertension

1984 ◽  
Vol 52 (03) ◽  
pp. 253-255 ◽  
Author(s):  
C Isles ◽  
G D O Lowe ◽  
B M Rankin ◽  
C D Forbes ◽  
N Lucie ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Blood Viscosity ◽  
Renal Damage ◽  
Antithrombin Iii ◽  
Plasma Viscosity ◽  
Malignant Hypertension ◽  
Fibrin Deposition ◽  
Group 3 ◽  
Group 2 ◽  
Group 1

SummaryWe have previously shown abnormalities of haemostasis suggestive of intravascular coagulation in patients with malignant hypertension, a condition associated with retinopathy and renal fibrin deposition. To determine whether such abnormalities are specific to malignant hypertension, we have measured several haemostatic and haemorheological variables in 18 patients with malignant hypertension (Group 1), 18 matched healthy controls (Group 2), and 18 patients with non-malignant hypertension (Group 3) matched for renal pathology, blood pressure and serum creatinine with Group 1. Both Groups 1 and 3 had increased mean levels of fibrinogen, factor VIIIc, beta-thrombo- globulin, plasma viscosity and blood viscosity (corrected for haematocrit); and decreased mean levels of haematocrit, antithrombin III and platelet count. Mean levels of fast antiplasmin and alpha2-macroglobulin were elevated in Group 1 but not in Group 3. We conclude that most blood abnormalities are not specific to malignant hypertension; are also present in patients with non-malignant hypertension who have similar levels of blood pressure and renal damage; and might result from renal damage as well as promoting further renal damage by enhancing fibrin deposition. However increased levels of fibrinolytic inhibitors in malignant hypertension merit further investigation in relation to removal of renal fibrin.

Total Knee Arthroplasty after Previous Ipsilateral Hip Arthroplasty Showed Lower Clinical Outcomes and Higher Leg Length Discrepancy Perception

2020 ◽  
Author(s):  
Han-Jun Lee ◽  
Seong Hwan Kim ◽  
Nicolas Pujol ◽  
Yong-Beom Park
Keyword(s):  
Clinical Outcomes ◽  
Hip Arthroplasty ◽  
Leg Length ◽  
Function Score ◽  
Patient’S Satisfaction ◽  
Length Discrepancy ◽  
Total Knee ◽  
Group 2 ◽  
Ks Function ◽  
Group 1

AbstractThe purpose of this study is to compare perception of leg length discrepancy (LLD) and clinical results of total knee arthroplasties (TKA) in patients with or without previous ipsilateral hip arthroplasty. Between 2008 and 2015, navigation-assisted TKA was performed in 43 patients with previous hip arthroplasty after hip fracture. After 1:3 propensity score matching was performed, 108 patients of primary navigation-assisted TKA (group 1) and 36 patients with hip arthroplasty (group 2) were included. Knee Society (KS) scores, Western Ontario and McMaster Universities Index (WOMAC) scores, and patients' satisfaction including perception of LLD were evaluated. Radiographic evaluation included mechanical axis, component position, and LLD. Logistic regression analysis was performed to find the factors that affect the clinical outcomes. No significant differences in radiologic and clinical evaluations, except for KS function score, patient's satisfaction and LLD (p< 0.001), were detected between the groups. LLD and its perception were significantly higher in group 2 (1.8 ± 3.4 mm in group 1 and 9.7 ± 4.1 mm in group 2, p = 0.000). Risk factors for the low KS function score were found as LLD (odds ratio [OR]: 1.403, p = 0.008) and previous hip arthroplasty itself (OR: 15.755, p = 0.002), but much higher OR was found in previous hip arthroplasty. Although the outcomes of TKA in patients with ipsilateral hip arthroplasty are comparable to those of primary TKA, LLD was high and patient's satisfaction and functional outcomes were low in patients with previous ipsilateral hip arthroplasty. Care should be taken when considering TKA in patients with previous hip arthroplasty. This is a Level III, case control study.

Clinical and Radiological Changes after use of Alpha-1 Blocker Therapy in Patients of Posterior Urethral Valve with Bladder Neck Hypertrophy

JMS SKIMS ◽  
2009 ◽  
Vol 12 (1) ◽  
pp. 3-7
Author(s):  
Aejaz A Baba ◽  
Bajpai Minu
Keyword(s):  
Bladder Neck ◽  
Posterior Urethral Valve ◽  
Posterior Urethral Valves ◽  
Blocker Therapy ◽  
Urethral Valve ◽  
Novel Method ◽  
Radiological Changes ◽  
Group 2 ◽  
Mean Time ◽  
Group 1

Background: We evaluated the effects of alpha-1 blocker therapy on clinical and radiological abnormalities in patients of posterior urethral valve with bladder neck hypertrophy. Materials and Methods: A total of 74 patients with posterior urethral valves were seen at our department between 2003 and 2007. Out of these 24 had radiological evidence of bladder neck hypertrophy. Those patients with bladder neck hypertrophy who were seen before June 2006 and did not receive alpha-1 blocker (prazocin) therapy after valve ablation were assigned to group 1 (n=10). Group 2 consisted of 14 age matched patients with bladder neck hypertrophy and comparable prognostic factors who received alpha-1 blocker therapy after valve ablation (n=14). Micturating cystourethrography (MCU) was done periodically and a novel method used to calculate bladder neck hypertrophy. Trends in symptoms and radiological changes were evaluated throughout follow-up. Results: Mean patient age at presentation was 3.02±2.68 years in group 1 and 3.12±3.4 years in group 2. Bladder neck hypertrophy decreased from 2.3±1.0 to 2.0±0.5 in a mean time of 52.0 (34-52) weeks in group 1 where as it decreased from 2.2±0.5 to 1.6±0.3 in a mean time of 32.0 (22-52) weeks. Symptomatically patients in group 2 who received alpha-1 blocker therapy after valve ablation were better and had quick resolution of bladder neck hypertrophy. Conclusions: Use of alpha-1 blocker therapy in patients of posterior urethral valve with bladder neck hypertrophy helps in quick resolution of bladder neck hypertrophy. J Med Sci 2009;12(1):3-7.

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