Crustal evolution of Archean rocks in the Kakagi Lake area, Wabigoon Subprovince, Ontario, as interpreted from high-precision U–Pb geochronology

1986 ◽  
Vol 23 (2) ◽  
pp. 182-192 ◽  
Author(s):  
D. W. Davis ◽  
G. R. Edwards
Keyword(s):  
Volcanic Rocks ◽  
Time Span ◽  
Time Interval ◽  
Lake Area ◽  
Volcanic Group ◽  
Regional Deformation ◽  
Felsic Volcanism ◽  
Plutonic Complex ◽  
Late Event ◽  
History Of

The evolution of the Archean volcanic–plutonic complex in the Kakagi Lake area occurred during a time interval of ca. 32 Ma. The earliest age is [Formula: see text] from analysis of zircon and baddeleyite in a gabbro intruding the lowermost Katimiagamak Volcanic Group. An age of 2723.2 ± 1.8 Ma on a tonalite gneiss from the interior of the underlying Sabaskong Batholith is indistinguishable from a previously dated massive border phase of the batholith and shows no evidence for inheritance from an older sialic component. An early tonalite phase from the adjacent Aulneau Batholith is dated at [Formula: see text], and the latest granodiorite phase is dated at [Formula: see text]. This defines a time span of about 7 Ma for intrusion of the bulk of the batholith and indicates that previously dated felsic volcanism from the uppermost sequence, above the Kakagi Lake Volcanic Group, is coeval with late plutonic activity in the Aulneau Batholith. The end of regional deformation in the area is given by the ages of two late-tectonic intrusions, the Heronry Lake pluton and the Stephen Lake pluton, dated at 2701.0 ± 1.2 and 2699.2 ± 1.9 Ma, respectively.U–Pb analyses of sphene were carried out on four of the samples in an effort to establish details of the post-folding thermal history of the area. Sphene is least reset in the Heronry Lake pluton (2699.2 ± 1.6 Ma), which is spatially most closely associated with the volcanic rocks and most reset in the Sabaskong gneiss (2673.7 ± 6.6 Ma), the sample most strongly affected by diapirism. The data indicate that regional deformation was a relatively late event, possibly caused by diapirism in the centres of the large batholiths and driven by a long-lived heat source in the mantle or lower crust.

Deposition and imbrication of a 2670-2629 Ma supracrustal sequence in the Indin Lake area, southwestern Slave Province, Canada

1999 ◽  
Vol 36 (7) ◽  
pp. 1149-1168 ◽  
Author(s):  
S J Pehrsson ◽  
M E Villeneuve
Keyword(s):  
Volcanic Rocks ◽  
Lake Area ◽  
Regional Deformation ◽  
Tectonic History ◽  
Slave Province ◽  
Gneiss Complex ◽  
Supracrustal Belt ◽  
History Of ◽  
Felsic Volcanic ◽  
Felsic Volcanic Rocks

New U-Pb age data from the southwestern Slave Province demonstrate that units of the Indin Lake supracrustal belt form an imbricated structural stack. The oldest rocks of the belt are undated mafic volcanic flows of the Hewitt Lake group that are crosscut by a 2670 Ma felsic sill, itself coeval with mafic through felsic volcanic rocks of the 2668-2671 Ma Leta Arm group. The youngest rocks of the belt are 2647-2629 Ma turbidites and felsic volcanic rocks of the unconformably overlying Chalco Lake group. Tonalite orthogneiss of the adjacent Cotterill gneiss complex is 2680 Ma, suggesting that it does not represent in situ basement to the supracrustal belt. Intercalation of the older Hewitt Lake and Leta Arm groups with the younger Chalco Lake group is interpreted to result from D1 imbrication and folding between 2629 and 2609 Ma, the age of a crosscutting tonalite intrusion. Subsequent D2 folding and regional low-pressure metamorphism occurred between 2609 Ma and ca. 2590 Ma. D3 normal faulting between the belt and Cotterill gneisses, ca. 2590 Ma, is interpreted to overlap with retrograde amphibolite-facies metamorphism and decompression of the gneiss complex. Comparisons between the tectonic history of the Indin Lake area and the central Slave Province show that turbidite deposition was regionally diachronous and overlapped with regional deformation elsewhere, supporting existing models favouring some form of accretionary orogenesis. The imbricated and intercalated 2670-2629 Ma supracrustal sequence may characterize a distinct crustal block in the southwestern Slave Province.

ARCHAEAN SEDIMENTARY ROCKS OF NORTH SPIRIT LAKE AREA, NORTHWESTERN ONTARIO

1965 ◽  
Vol 2 (6) ◽  
pp. 622-647 ◽  
Author(s):  
J. A. Donaldson ◽  
G. D. Jackson
Keyword(s):  
Volcanic Rocks ◽  
Sedimentary Rocks ◽  
Sole Source ◽  
Lake Area ◽  
Red Lake ◽  
Sedimentary Sequences ◽  
The North ◽  
Northwestern Ontario ◽  
History Of ◽  
Granitoid Rocks

Archaean sedimentary rocks of the North Spirit Lake area show little evidence of having been derived predominantly from associated Archaean volcanic rocks. Instead, compositions of the sediments reflect significant sedimentary and (or) granitoid provenance. A remarkably high content of clastic quartz in thick units of sandstone and conglomerate suggests either reworking of older quartzose sediments, or reduction of the labile constituents in quartz-rich granitoid rocks through prolonged weathering and rigorous transport. Observations for other sedimentary sequences in the region between Red Lake and Lansdowne House suggest that the North Spirit sediments are not unique in the Superior Province. Quartzose sandstones commonly are regarded as atypical of the Archaean, but such rocks arc abundant in northwestern Ontario. Frameworks of many Archaean greywackes actually are richer in quartz than typical greywackes from numerous Proterozoic and Phanerozoic sequences.The concept of rapidly rising volcanic arcs as the sole source of Archaean sedimentary detritus is rejected for the North Spirit area. The volcanies, rather than representing relicts of protocontinents, probably record events removed from initial volcanism in the history of the earth by one or more orogenic cycles. Major unconformities may therefore exist not only between sedimentary and volcanic units, but also between these units and older granitoid rocks.

An Archean metamorphic core complex in the southern Slave Province: basement–cover structural relations between the Sleepy Dragon Complex and the Yellowknife Supergroup

1992 ◽  
Vol 29 (10) ◽  
pp. 2133-2145 ◽  
Author(s):  
Donald T. James ◽  
James K. Mortensen
Keyword(s):  
Regional Metamorphism ◽  
Volcanic Rocks ◽  
Lake Area ◽  
Metasedimentary Rocks ◽  
Kinematic Indicators ◽  
The North ◽  
Slave Province ◽  
Gneiss Granite ◽  
History Of ◽  
Metamorphic Core

Archean rocks in the Fenton Lake – Brown Lake area, southern Slave Province, are subdivided into two lithotectonic domains: a supracrustal domain, which consists mainly of the Archean Yellowknife Supergroup, and a gneiss–granite domain. The latter is composed of gneissic and metaigneous rocks of the Sleepy Dragon Complex, determined to be basement to the Yellowknife Supergroup, and granite plutons, including the 2641 ± 3.5 Ma Suse Lake granite and the 2583.5 ± 1 Ma Morose Granite. Volcanic rocks of the Cameron River Belt and greywacke–mudstone turbiditic metasedimentary rocks of the Burwash Formation constitute the supracrustal domain.A late Archean, amphibolite- to greenschist-facies, ductile to local brittle, high-strain zone separates the domains. Kinematic indicators demonstrate that the zone experienced two kinematically opposed episodes of displacement. The older episode involved pre- to synthermal peak thrusting of the supracrustal rocks over the gneiss–granite domain. Thrusting is kinematically and temporally consistent with late Archean, pre- to synthermal peak, regional contractional deformation. Structural and metamorphic relations and kinematic indicators suggest that thrusting and regional contraction were followed shortly by intrusion of the peraluminous Morose Granite and thereafter by a late syn- to post-thermal peak episode of extension, resulting in tectonic unroofing of the gneiss–granite domain.The sequential history of contraction and attendant regional metamorphism, granite intrusion, and, ultimately, extensional collapse, which is documented in the Archean rocks in the area, is a common feature of Phanerozoic collisional orogens. Moreover, the tectonic history of the gneiss–granite domain is broadly similar to the evolution of metamorphic core complexes in the North American Cordillera.

Collision zone between the Kohistan arc and the Asian plate in NW Pakistan

1985 ◽  
Vol 76 (4) ◽  
pp. 463-479 ◽  
Author(s):  
C. J. Pudsey ◽  
M. P. Coward ◽  
I. W. Luff ◽  
R. M. Shackleton ◽  
B. F. Windley ◽  
...  
Keyword(s):  
Volcanic Rocks ◽  
Deep Levels ◽  
Suture Zone ◽  
Island Arc ◽  
Central Unit ◽  
Volcanic Group ◽  
Collision Zone ◽  
Structural History ◽  
History Of ◽  
Layered Complex

ABSTRACTThis paper describes the suture zone between the Asian plate and the accreted Kohistan island arc in the Chitral district of NW Pakistan.The southern part of the Asian plate consists of two tectonic units separated by the N-dipping Reshun fault. The northwestern unit comprises Devonian carbonates and quartzites overlain by Devonian to Permian shales and slates with some limestones (Lun shales). Its structure is complex with S-verging thrusts and isoclinal folds. Along the Reshun fault, the relatively undeformed Reshun Formation may represent molasse. The central unit includes N-dipping Upper Palaeozoic slates and quartzites (Darkot Group), probably faulted against an antiformal tract of slates, schists derived from a volcanic assemblage and Cretaceous limestones (Chitral slate, Koghozi greenschist, Krinj and Gahiret limestones). Asian plate sediments are intruded by granitic and granodioritic plutons, variably deformed and locally porphyritic.The Northern suture melange of volcanic, sedimentary and serpentinite blocks in a slate matrix separates the Asian plate from the southeastern unit, the Kohistan arc. This comprises Cretaceous volcanic rocks with some sediments (Shamran Volcanic Group, Drosh, Purit and Gawuch Formations) intruded by aphyric diorites, tonalites and granites. These intermediate plutonic rocks pass southwards into a mafic layered complex and amphibolites representing deep levels of the arc. The volcanic rocks and sediments dip to the N and have a horizontal lineation. The structural history of southern Asia and Kohistan is consistent with an originally curved Northern suture: motion of the arc was initially to the NE relative to Asia and subsequently to the NW.

U–Pb geochronology of the eastern Abitibi Subprovince. Part 2: Noranda – Kirkland Lake area

1993 ◽  
Vol 30 (1) ◽  
pp. 29-41 ◽  
Author(s):  
J. K. Mortensen
Keyword(s):  
Tectonic Setting ◽  
Volcanic Rocks ◽  
Rapid Onset ◽  
Detrital Zircons ◽  
Lake Area ◽  
Sedimentary Sequences ◽  
South Central ◽  
Abitibi Subprovince ◽  
History Of ◽  
Main Period

U–Pb zircon ages for 15 volcanic and plutonic units in the Noranda and Kirkland Lake areas help constrain the history of volcanism, plutonism, sedimentation, and deformation in the south-central part of the Abitibi belt. Volcanism occurred over an interval of at least 50 Ma, beginning with the deposition of the volcanic and volcaniclastic units within the Pacaud Structural Complex at 2747 Ma. Following a period of apparent quiescence, magmatism resumed at 2730–2725 Ma with the eruption of volcanic rocks in the Normétal and Lac Abitibi area. From 2715 until about 2698 Ma, volcanism occurred sporadically throughout much of the area, culminating in the eruption of the Blake River Group from 2703 to 2698 Ma. Several large intrusive bodies yield ages that indicate that they are plutonic equivalents of the Blake River Group. Plutons that are considered to have been emplaced during the Kenoran orogeny give ages that are only slightly younger than the youngest volcanic units of the Blake River Group, emphasizing the very rapid onset of Kenoran deformation following the cessation of volcanic activity.The Cléricy syenite, dated at 2682 ± 3 Ma, postdates the main period of Kenoran deformation in this area and intrudes sedimentary rocks of the Kewagama Group which contain detrital zircons as young as 2687 Ma. These data suggest that the Kewagama Group is the same age as late sedimentary sequences such as the Timiskaming Group and may have been deposited in a similar tectonic setting.

scholarly journals Current understanding on the Cambrian Explosion: questions and answers

PalZ ◽  
2021 ◽  
Author(s):  
Xingliang Zhang ◽  
Degan Shu
Keyword(s):  
Environmental Changes ◽  
Size Variation ◽  
Progressive Increase ◽  
Cambrian Explosion ◽  
Time Interval ◽  
Early Cambrian ◽  
Ecological Processes ◽  
Questions And Answers ◽  
Evolutionary Event ◽  
History Of

AbstractThe Cambrian Explosion by nature is a three-phased explosion of animal body plans alongside episodic biomineralization, pulsed change of generic diversity, body size variation, and progressive increase of ecosystem complexity. The Cambrian was a time of crown groups nested by numbers of stem groups with a high-rank taxonomy of Linnaean system (classes and above). Some stem groups temporarily succeeded while others were ephemeral and underrepresented by few taxa. The high number of stem groups in the early history of animals is a major reason for morphological gaps across phyla that we see today. Most phylum-level clades achieved their maximal disparity (or morphological breadth) during the time interval close to their first appearance in the fossil record during the early Cambrian, whereas others, principally arthropods and chordates, exhibit a progressive exploration of morphospace in subsequent Phanerozoic. The overall envelope of metazoan morphospace occupation was already broad in the early Cambrian though it did not reach maximal disparity nor has diminished significantly as a consequence of extinction since the Cambrian. Intrinsic and extrinsic causes were extensively discussed but they are merely prerequisites for the Cambrian Explosion. Without the molecular evolution, there could be no Cambrian Explosion. However, the developmental system is alone insufficient to explain Cambrian Explosion. Time-equivalent environmental changes were often considered as extrinsic causes, but the time coincidence is also insufficient to establish causality. Like any other evolutionary event, it is the ecology that make the Cambrian Explosion possible though ecological processes failed to cause a burst of new body plans in the subsequent evolutionary radiations. The Cambrian Explosion is a polythetic event in natural history and manifested in many aspects. No simple, single cause can explain the entire phenomenon.

scholarly journals Massive hemobilia caused by rupture of gastroduodenal artery pseudoaneurysm, a delayed complication of laparoscopic cholecystectomy: a case report

2021 ◽  
Vol 15 (1) ◽  
Author(s):  
Kurniawan Kurniawan ◽  
I Dewa Nyoman Wibawa ◽  
Gde Somayana ◽  
I Ketut Mariadi ◽  
I Made Mulyawan
Keyword(s):  
Laparoscopic Cholecystectomy ◽  
Gastrointestinal Bleeding ◽  
Abdominal Trauma ◽  
Upper Gastrointestinal Bleeding ◽  
Rare Complication ◽  
Gastroduodenal Artery ◽  
Time Interval ◽  
Artery Pseudoaneurysm ◽  
History Of ◽  
Upper Gastrointestinal

Abstract Background Hemobilia is a rare cause of upper gastrointestinal bleeding that originates from the biliary tract. It is infrequently considered in diagnosis, especially in the absence of abdominal trauma or history of hepatopancreatobiliary procedure, such as cholecystectomy, which can cause arterial pseudoaneurysm. Prompt diagnosis is crucial because its management strategy is distinct from other types of upper gastrointestinal bleeding. Here, we present a case of massive hemobilia caused by the rupture of a gastroduodenal artery pseudoaneurysm in a patient with a history of laparoscopic cholecystectomy 3 years prior to presentation. Case presentation A 44-year-old Indonesian female presented to the emergency department with complaint of hematemesis and melena accompanied by abdominal pain and icterus. History of an abdominal trauma was denied. However, she reported having undergone a laparoscopic cholecystectomy 3 years prior to presentation. On physical examination, we found anemic conjunctiva and icteric sclera. Nonvariceal bleeding was suspected, but esophagogastroduodenoscopy showed a blood clot at the ampulla of Vater. Angiography showed contrast extravasation from a gastroduodenal artery pseudoaneurysm. The patient underwent pseudoaneurysm ligation and excision surgery to stop the bleeding. After surgery, the patient’s vital signs were stable, and there was no sign of rebleeding. Conclusion Gastroduodenal artery pseudoaneurysm is a rare complication of laparoscopic cholecystectomy. The prolonged time interval, as compared with other postcholecystectomy hemobilia cases, resulted in hemobilia not being considered as an etiology of the gastrointestinal bleeding at presentation. Hemobilia should be considered as a possible etiology of gastrointestinal bleeding in patients with history of cholecystectomy, regardless of the time interval between the invasive procedure and onset of bleeding.

scholarly journals Were they really laughed at? That much? Gelotophobes and their history of perceived derisibility

2009 ◽  
Vol 22 (1-2) ◽  
Author(s):  
René T. Proyer ◽  
Christian F. Hempelmann ◽  
Willibald Ruch
Keyword(s):  
Empirical Study ◽  
Large Degree ◽  
Time Span ◽  
Corpus Study ◽  
The Past ◽  
History Of ◽  
University Of Zurich

AbstractThe List of Derisible Situations (LDS; Proyer, Hempelmann and Ruch, List of Derisible Situations (LDS), University of Zurich, 2008) consists of 102 different occasions for being laughed at. They were retrieved in a corpus study and compiled into the LDS. Based on this list, information on the frequency and the intensity with which people recall being laughed at during a given time-span (12 months in this study) can be collected. An empirical study (N = 114) examined the relations between the LDS and the fear of being laughed at (gelotophobia), the joy of being laughed at (gelotophilia), and the joy of laughing at others (katagelasticism; Ruch and Proyer this issue). More than 92% of the participants recalled having been laughed at at least once over the past 12 months. Highest scores were found for experiencing an embarrassing situation, chauvinism of others or being laughed at for doing something awkward or clumsy. Gelotophobia, gelotophilia, and katagelasticism were related about equally to the recalled frequency of events of being laughed at (with the lowest relation to katagelasticism). Gelotophobia, gelotophilia, and katagelasticism yielded a distinct and plausible pattern of correlations to the frequency of events of being laughed at. Gelotophobes recalled the situations of being laughed at with a higher intensity than others. Thus, the fear of being laughed at exists to a large degree independently from actual experiences of being laughed at, but is related to a higher intensity with which these events are experienced.

scholarly journals Longitudinal study of fingerprint recognition

2015 ◽  
Vol 112 (28) ◽  
pp. 8555-8560 ◽  
Author(s):  
Soweon Yoon ◽  
Anil K. Jain
Keyword(s):  
Statistical Models ◽  
Recognition Accuracy ◽  
Temporal Stability ◽  
Poor Quality ◽  
Time Span ◽  
Fingerprint Recognition ◽  
Time Interval ◽  
General Belief ◽  
Probability Of Error ◽  
Fingerprint Database

Human identification by fingerprints is based on the fundamental premise that ridge patterns from distinct fingers are different (uniqueness) and a fingerprint pattern does not change over time (persistence). Although the uniqueness of fingerprints has been investigated by developing statistical models to estimate the probability of error in comparing two random samples of fingerprints, the persistence of fingerprints has remained a general belief based on only a few case studies. In this study, fingerprint match (similarity) scores are analyzed by multilevel statistical models with covariates such as time interval between two fingerprints in comparison, subject’s age, and fingerprint image quality. Longitudinal fingerprint records of 15,597 subjects are sampled from an operational fingerprint database such that each individual has at least five 10-print records over a minimum time span of 5 y. In regard to the persistence of fingerprints, the longitudinal analysis on a single (right index) finger demonstrates that (i) genuine match scores tend to significantly decrease when time interval between two fingerprints in comparison increases, whereas the change in impostor match scores is negligible; and (ii) fingerprint recognition accuracy at operational settings, nevertheless, tends to be stable as the time interval increases up to 12 y, the maximum time span in the dataset. However, the uncertainty of temporal stability of fingerprint recognition accuracy becomes substantially large if either of the two fingerprints being compared is of poor quality. The conclusions drawn from 10-finger fusion analysis coincide with the conclusions from single-finger analysis.

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