scholarly journals Fault Zone Evolution and Development of a Structural and Hydrological Barrier: The Quartz Breccia in the Kiggavik Area (Nunavut, Canada) and Its Control on Uranium Mineralization

Minerals ◽  
2018 ◽  
Vol 8 (8) ◽  
pp. 319 ◽  
Author(s):  
Alexis Grare ◽  
Olivier Lacombe ◽  
Julien Mercadier ◽  
Antonio Benedicto ◽  
Marie Guilcher ◽  
...  
Keyword(s):  
Early Stage ◽  
Field Work ◽  
Uranium Mineralization ◽  
Isotopic Signatures ◽  
Thelon Basin ◽  
Tectonic History ◽  
Evolution And Development ◽  
Major Fault ◽  
History Of ◽  
Oxygen Isotopic

In the Kiggavik area (Nunavut, Canada), major fault zones along, or close to, where uranium deposits are found are often associated with occurrence of thick quartz breccia (QB) bodies. These bodies formed in an early stage (~1750 Ma) of the long-lasting tectonic history of the Archean basement, and of the Proterozoic Thelon basin. The main characteristics of the QB are addressed in this study; through field work, macro and microscopic observations, cathodoluminescence microscopy, trace elements, and oxygen isotopic signatures of the quartz forming the QB. Faults formed earlier during syn- to post-orogenic rifting (1850–1750 Ma) were subsequently reactivated, and underwent cycles of cataclasis, pervasive silicification, hydraulic brecciation, and quartz recrystallization. This was synchronous with the circulation of meteoric fluids mixing with Si-rich magmatic-derived fluids at depth, and were coeval with the emplacement of the Kivalliq igneous suite at 1750 Ma. These processes led to the emplacement of up to 30 m thick QB, which behaved as a mechanically strong, transverse hydraulic barrier that localized later fracturing, and compartmentalized/channelized vertical flow of uranium-bearing fluids after the deposition of the Thelon Basin (post 1750 Ma). The development and locations of QB control the location of uranium mineralization in the Kiggavik area.

scholarly journals Exploiting Thermochronology to Quantify Exhumation Histories and Patterns of Uplift Along the Margins of Tibet

2021 ◽  
Vol 9 ◽  
Author(s):  
Kevin P. Furlong ◽  
Eric Kirby
Keyword(s):  
Thermal History ◽  
Data Sets ◽  
The Tibetan Plateau ◽  
Tectonic History ◽  
Time Histories ◽  
Major Fault ◽  
History Of ◽  
Cooling Behavior ◽  
Exhumation Rates ◽  
The Impact

The utilization of thermal-chronological data to constrain mountain building processes exploits the links among rock uplift, exhumation, and cooling during orogenesis. Conceptually, periods of rapid uplift and associated denudation will lead to cooling of rocks as they approach Earth’s surface. The linkage between uplift and exhumation can be complex, but in practice exhumation is often assumed to directly track uplift. The reconstruction of temperature-time histories via thermochronologic systems provides a proxy method to relate the cooling of rock as it is exhumed toward the surface to orogenesis. For the rapid exhumation rates that can occur in active orogenic systems the thermal history will be complex as a result of heat advection, rates of propagation of thermal perturbations, and other processes that affect the cooling behavior. These effects become amplified as exhumation rates increase, and in regions experiencing exhumation rates greater than ∼0.2–0.3 mm/yr (0.2–0.3 km/Ma) simple assumptions of cooling through a constant geotherm will bias the subsequent interpretation. Here we explore, through a suite of generalized models, the impact of exhumation rate and duration on the resulting thermal history and apparent age results. We then apply lessons from these simple exhumation systems to data sets from the high-relief ranges along the eastern margin of the Tibetan Plateau to determine exhumation histories constrained by those data. The resulting exhumation histories provide constraints on the onset of Cenozoic exhumation, the subsequent pace of exhumation, and on the tectonic history of one of the major fault systems in the central Longmen Shan.

scholarly journals The pre-Alpine tectonic history of the Austroalpine continental basement in the Valpelline unit (Western Italian Alps)

2012 ◽  
Vol 150 (1) ◽  
pp. 153-172 ◽  
Author(s):  
PAOLA MANZOTTI ◽  
MICHELE ZUCALI
Keyword(s):  
Early Stage ◽  
Granulite Facies ◽  
Subsequent Stage ◽  
Italian Alps ◽  
Northern Margin ◽  
Tectonic History ◽  
Lithospheric Extension ◽  
History Of ◽  
Nw Italy ◽  
High Temperature Metamorphism

AbstractThe Valpelline unit is a large slice of continental crust constituting the Austroalpine Dent Blanche nappe (NW Italy). The pre-Alpine evolution of this unit holds important clues about the Palaeozoic crustal structure at the northern margin of the Adria continent, about the history of rifting in the Alpine region, and thus about the thermomechanical conditions that preceded the Alpine convergent evolution. Several stages of the deformation history and of partial re-equilibration were identified, combining meso- and micro-structural analyses with thermobarometry. Reconstructed pre-Alpine P–T–t–d paths demonstrate that the Valpelline unit experienced an early stage at pressures between 4.5 and 6.5 kbar followed by migmatite formation. A subsequent stage reached amphibolite to granulite facies conditions. This stage was associated with the development of the most penetrative fabrics affecting all of the Valpelline lithotypes. The pre-Alpine evolution ended with a weak deformation associated with a local mineral-chemical re-equilibration under greenschist facies conditions at ≈ 4 kbar and T < 450°C. A Permo-Mesozoic lithospheric extension is thought to be responsible for asthenosphere upwelling, thereby causing high temperature metamorphism at medium pressure and widespread partial melting, which led to upper crustal magmatic activity.

Nd isotopic evidence for crustal recycling in the ca. 2.0 Ga subsurface of western Canada

1991 ◽  
Vol 28 (8) ◽  
pp. 1140-1147 ◽  
Author(s):  
R. J. Thériault ◽  
G. M. Ross
Keyword(s):  
Isotopic Data ◽  
Tectonic Zone ◽  
Isotopic Signatures ◽  
Crustal Recycling ◽  
The North ◽  
Tectonic History ◽  
Depleted Mantle ◽  
History Of ◽  
Mantle Component ◽  
Northern Alberta

Sm–Nd isotopic data are presented for 23 drill-core samples from five aeromagnetically and geochronologically (U–Pb zircon) distinct domains of the Precambrian basement of northern Alberta. The domains in question are the Taltson (1.96–1.94 Ga), Buffalo Head (2.32–1.99 Ga), Chinchaga (2.19–2.09 Ga), Ksituan (1.99–1.90 Ga), and Nova (2.81 Ga). These domains are truncated to the north and south by the Great Slave Lake shear zone and the Snowbird tectonic zone, respectively.Initial εNd values are −5.0 to −9.7 for the Taltson, +0.2 to −6.3 for the Buffalo Head, +0.6 to −1.8 for the Chinchaga, −1.8 to −2.1 for the Ksituan and +5.6 for the Nova. Crustal residence model ages fall in the 2.5–2.8 Ga range. The Nd isotopic signatures may be viewed in terms of mixing a minimum of 10% Archean continental crust with a depleted-mantle component. Speculations on the tectonic history of the basement domains in question involve the assembly of Archean crustal nuclei to form the Buffalo Head – Chinchaga composite domain. Arc magmatism resulting from plate subduction to the east and west of the Buffalo Head – Chinchaga composite domain would have generated the Taltson and Ksituan domains. The Nd isotopic data suggest that the basement of northern Alberta consists of crust of late Archean crustal residence age which has been extensively remobilized in the Early Proterozoic.

scholarly journals Analysis of Palaeogene strike-slip tectonics along the southern East Greenland margin (Sødalen area)

1969 ◽  
Vol 23 ◽  
pp. 65-68 ◽  
Author(s):  
Pierpaolo Guarnieri
Keyword(s):  
Structural Data ◽  
Field Work ◽  
Strike Slip ◽  
Normal Faults ◽  
Large Area ◽  
East Greenland ◽  
Tectonic History ◽  
History Of ◽  
Host Rocks ◽  
Greenland Margin

This paper describes structural data collected during field work in southern East Greenland, a region characterised by a complex tectonic history. Here, 3D photogeology based on aerial and oblique photographs using high-resolution photogrammetry of a 150 km2 area in Sødalen in southern East Greenland shows ESE–WNW-trending faults cross-cutting Paleocene rift structures and flexure-related normal faults. The kinematic analysis highlights oblique and left-lateral strike-slip movements along faults oriented 120°. Strike-slip and dip-slip kinematic indicators on the walls of the chilled contacts between alkaline E–W-oriented dykes and the volcanic host rocks suggest that the faults and dykes formed at the same time, or maybe the faults were re-activated at a later stage. Palaeostress analysis, performed by inversion of fault-slip data, shows the presence of three different tectonic events. Coupling the 3D photogeological tool with structural analysis at key localities is a fundamental way to understand better the tectonic history of such a large area.

Tectonic History of Hoop Fault Complex, Barents Sea/Norway

2020 ◽  
Author(s):  
Volker Schuller ◽  
István Dunkl ◽  
Zsolt Schleder ◽  
Eirik Stueland
Keyword(s):  
Barents Sea ◽  
Early Stage ◽  
Upper Jurassic ◽  
Late Triassic ◽  
Tectonic Activity ◽  
Burial Depth ◽  
Seismic Section ◽  
Accommodation Space ◽  
Tectonic History ◽  
History Of

&lt;p&gt;The Barents Sea consists of several tectonic elements which were formed at different plate tectonic collisional and rifting stages. This work focuses on the Early Mesozoic to recent events of the central Barents Sea, the eastern edge of the Bjarmaland platform.&lt;/p&gt;&lt;p&gt;We have analysed the clastic deposits of Mid-Triassic to Upper Jurassic to reconstruct the tectonic history of the Hoop Fault Complex, Barents Sea/Norway. Apatite fission track and (U-Th)/He thermochronology were used to determine the maximum burial depths and exhumation history. According to the combined evaluation of results from shale ductility analysis (BIB-SEM), fault kinematic analysis and structural modelling (section balancing based on a 125 km long 2D seismic section line) the following tectonic evolution can be drawn: deflation of late Palaeozoic salt deposits was initiated by the tectonic activity on the early structures of the Hoop Fault zone. The orthogonal faults of the Hoop Fault Complex developed at the early stage, during Late Triassic to Early Jurassic times at relatively shallow depth, below 1000m. Ongoing subsidence related to the extension caused by the opening of the Atlantic Ocean created accommodation space for Upper Jurassic to Cenozoic deposits with maximum burial depth of 2000 m for the analysed Mid-Jurassic rocks. The exhumation of the Hoop Fault complex started around 10 Ma and remained constant until Quaternary times (140 m/Myr).&lt;/p&gt;

Oxfordian sedimentary dykes : tectonic and diagenetic implications for the eastern Paris basin

2004 ◽  
Vol 175 (6) ◽  
pp. 595-605 ◽  
Author(s):  
Grégoire André ◽  
Christian Hibsch ◽  
Bernard Beaudoin ◽  
Cédric Carpentier ◽  
Serge Fourcade ◽  
...  
Keyword(s):  
Late Jurassic ◽  
Material Point ◽  
Paris Basin ◽  
Isotopic Signatures ◽  
Tectonic History ◽  
Major Interest ◽  
History Of ◽  
Diagenetic History ◽  
Wall Geometry ◽  
Good Agreement

Abstract Vertical fractures in Oxfordian limestones of the eastern part of the Paris Basin are interpreted as resulting from synsedimentary extensional deformations which occurred during the Mesozoic. These NNE-SSW striking fractures are 10 to 20 meters in height, and filled with microgranular material. The fractures mainly affect crinoidal and oolitic grainstones. Their micritic to microsparitic, lithoclast-bearing infills may have resulted from the solidification of an ancient mud injected from non-lithified, overlying layers of marine sediments. They should therefore be referred to as sedimentary dykes. Graded layering suggests deposition under turbulent flow conditions, whereas later plastic deformation and breccia formation indicate a syndiagenetic reworking. Such observations are consistent with a predominance of the sedimentary dykes in grainstones, which are more rapidly lithified and therefore subject to early fracturing. On the contrary, these dykes are rare in mudstones which may constitute the source of the material for the infills in the grainstones. Both the analysis of the wall geometry and the reconstruction of the diagenetic history of the infills make possible to distinguish two types of sedimentary dykes. The first type corresponds to a fracturation characterized by irregular walls around the rock-constituting grains (i.e. crinoidal debris or ooids), whereas the walls in the second type are cross-cutting the grains and present a fringe of sparite predating the microsparite infill. The following scenario is proposed for the first type of sedimentary dykes: i) syntaxial cementation of crinoidal debris and early cementation of ooids; ii) fracturing along grain boundaries under low burial strain; iii) filling of fractures and open porosity by the mud. The second type of sedimentary dykes was formed under deeper burial conditions, which is indicated by both pre-existing bedding-parallel stylolites and the precipitation of sparite on the walls before the sedimentary infill. This early fracturation and the availability of a sedimentary filling, non-lithified material point to a late Jurassic age for these sedimentary dykes. The δ18OSMOW isotopic signatures measured for the infilling sparite and microsparite materials indicate that these were precipitated from meteoric waters, either early during the formation of the sedimentary dykes or during a later recrystallization event. The sedimentary dykes have recorded an E-W extension during the Oxfordian-Kimmeridgian period, which is in good agreement with the late Jurassic tectonic history of the western European platform. This early Oxfordian-Kimmeridgian fracturing and its associated fluid paleocirculations is of major interest in the context of the tectonic history of the Paris Basin, since most of these N-S to NNE-SSW tension gashes have been previously attributed to the Eocene Pyrenean shortening and Oligocene rifting stages.

Tectonic history of the Dent Blanche

2017 ◽  
Vol 9 (2.1) ◽  
pp. 1-73 ◽  
Author(s):  
Paola Manzotti ◽  
Michel Ballèvrei
Keyword(s):  
Tectonic History ◽  
History Of

Metasedimentary rocks, intrusions and deformation history in the south-east part of the c. 1800 Ma Ketilidian orogen, South Greenland: Project SUPRASYD 1996

1997 ◽  
pp. 60-65
Author(s):  
Adam A. Garde ◽  
Brian Chadwick ◽  
John Grocott ◽  
Cees Swager
Keyword(s):  
Field Work ◽  
Deformation History ◽  
The South ◽  
Present Contribution ◽  
East Part ◽  
Metasedimentary Rocks ◽  
Deformational History ◽  
Base Camp ◽  
History Of ◽  
Geological Map

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Garde, A. A., Chadwick, B., Grocott, J., & Swager, C. (1997). Metasedimentary rocks, intrusions and deformation history in the south-east part of the c. 1800 Ma Ketilidian orogen, South Greenland: Project SUPRASYD 1996. Geology of Greenland Survey Bulletin, 176, 60-65. https://doi.org/10.34194/ggub.v176.5063 _______________ The south-east part of the c. 1800 Ma Ketilidian orogen in South Greenland (Allaart, 1976) is dominated by strongly deformed and variably migmatised metasedimentary rocks known as the ‘Psammite and Pelite Zones’ (Chadwick & Garde, 1996); the sediments were mainly derived from the evolving Julianehåb batholith which dominates the central part of the orogen. The main purpose of the present contribution is to outline the deformational history of the Psammite Zone in the region between Lindenow Fjord and Kangerluluk (Fig. 2), investigated in 1994 and 1996 as part of the SUPRASYD project (Garde & Schønwandt, 1995 and references therein; Chadwick et al., in press). The Lindenow Fjord region has high alpine relief and extensive ice and glacier cover, and the fjords are regularly blocked by sea ice. Early studies of this part of the orogen were by boat reconnaissance (Andrews et al., 1971, 1973); extensive helicopter support in the summers of 1992 and 1994 made access to the inner fjord regions and nunataks possible for the first time.A preliminary geological map covering part of the area between Lindenow Fjord and Kangerluluk was published by Swager et al. (1995). Hamilton et al. (1996) have addressed the timing of sedimentation and deformation in the Psammite Zone by means of precise zircon U-Pb geochronology. However, major problems regarding the correlation of individual deformational events and their relationship with the evolution of the Julianehåb batholith were not resolved until the field work in 1996. The SUPRASYD field party in 1996 (Fig. 1) was based at the telestation of Prins Christian Sund some 50 km south of the working area (Fig. 2). In addition to base camp personnel, helicopter crew and the four authors, the party consisted of five geologists and M.Sc. students studying mafic igneous rocks and their mineralisation in selected areas (Stendal et al., 1997), and a geologist investigating rust zones and areas with known gold anomalies.

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