scholarly journals The Germania Land deformation zone and related structures, North-East Greenland

1994 ◽  
Vol 162 ◽  
pp. 113-127
Author(s):  
J.M Hull ◽  
J.A Gilotti
Keyword(s):  
Deformation Zone ◽  
Strike Slip ◽  
Low Grade ◽  
High Grade ◽  
Normal Faulting ◽  
East Greenland ◽  
North East ◽  
Parallel Movement ◽  
Land Deformation ◽  
Dextral Strike Slip

The Germania Land deformation zone in North-East Greenland consists of two subparallel, NW-striking strands of mylonites and cataclasites. The quasiplastic mylonites formed under low grade (biotite zone) conditions following high grade Caledonian metamorphism. Displacements on the Germania Land deformation zone and parallel zones at Danmarkshavn were predominantly dextral strike slip. Along with the similar, but sinistral, Storstrømmen shear zone, these zones record a late Caledonian phase of orogen-parallel movement. The Germania Land deformation zone is also the locus of Carboniferous normal faulting and basin development.

Geology and timing of dextral strike-slip shear zones in Danmarkshavn, North-East Greenland Caledonides

2006 ◽  
Vol 143 (4) ◽  
pp. 431-446 ◽  
Author(s):  
C. SARTINI-RIDEOUT ◽  
J. A. GILOTTI ◽  
W. C. McCLELLAND
Keyword(s):  
Deformation Zone ◽  
Shear Zones ◽  
Amphibolite Facies ◽  
Ultrahigh Pressure ◽  
High Mass ◽  
Weighted Mean ◽  
East Greenland ◽  
North East ◽  
The North ◽  
Land Deformation

The North-East Greenland eclogite province is divided into a western, central and eastern block by the sinistral Storstrømmen shear zone in the west and the dextral Germania Land deformation zone in the east. A family of steep, NNW-striking dextral mylonite zones in the Danmarkshavn area are geometrically and kinematically similar to the ductile Germania Land deformation zone, located 25 km to the east. Amphibolite facies deformation at Danmarkshavn is characterized by boudinage of eclogite bodies within quartzofeldspathic host gneisses, pegmatite emplacement into the boudin necks and subsequent deformation of pegmatites parallel to gneissosity, a widespread component of dextral shear within the gneisses, and localization of strain into 10–50 m thick dextral mylonite zones. The gneisses and concordant mylonite zones are cut by a swarm of weakly to undeformed, steeply dipping, E–W-striking pegmatitic dykes. Oscillatory-zoned zircon cores from two boudin neck pegmatites give weighted mean 206Pb/238U sensitive, high mass resolution ion microprobe (SHRIMP) ages of 376 ± 5 Ma and 343 ± 7 Ma. Cathodoluminescence images of these zircons reveal complex additional rims, with ages from ranging from c. 360 to 320 Ma. Oscillatory-zoned, prismatic zircons from two late, cross-cutting pegmatites yield weighted mean 206Pb/238U SHRIMP ages of 343 ± 5 Ma and 332 ± 3 Ma. Zircons from the boudin neck pegmatites record a prolonged growth history, marked by fluid influx, during amphibolite facies metamorphism beginning at c. 375 Ma. The cross-cutting pegmatites show that dextral deformation in the gneisses and ductile mylonite zones had stopped by c. 340 Ma. Ultrahigh-pressure metamorphism in the eastern block at 360 Ma requires that the Greenland Caledonides were in an overall contractional plate tectonic regime. This, combined with 20% steep amphibolite facies lineations in the eclogites, gneisses and mylonites suggests that dextral transpression may have been responsible for a first stage of eclogite exhumation between 370 and 340 Ma.

scholarly journals Search for Archaean basement in the Caledonian fold belt of North-East Greenland

1994 ◽  
Vol 162 ◽  
pp. 129-133
Author(s):  
A.P Nutman ◽  
F Kalsbeek
Keyword(s):  
High Grade ◽  
Metamorphic Zircon ◽  
Fold Belt ◽  
Pb Isotope ◽  
Zircon Age ◽  
East Greenland ◽  
Early Proterozoic ◽  
North East ◽  
History Of ◽  
High Grade Metamorphism

SHRIMP U-Pb isotope data on zircon crystals from a gneiss sample near Danmarkshavn, where the presence of Archaean rocks has earlier been documented, show that the rock has undergone a complex history of igneous and metamorphic zircon growth. At least three generations of zircon are present with ages of c. 3000 Ma, c. 2725 Ma and 1967 ±8 Ma (2 α). Apparently the rock was formed from an Archaean protolith which underwent high grade metamorphism during the early Proterozoic. Another sample from the easternmost exposures of the Caledonian basement, collected further north, yielded only early Proterozoic zircons with an age of 1963 ± 6 Ma. Together with a SHRIMP U-Pb zircon age of 1974 ± 17 Ma reported earlier, these results give evidence of a major igneous and metamorphic event in North-East Greenland about 1965 Ma ago.

scholarly journals Reaction of Precambrian high-grade gneisses to mid-crustal ductile deformation in western Dove Bugt, North-East Greenland

1994 ◽  
Vol 162 ◽  
pp. 53-70
Author(s):  
B Chadwick ◽  
C.R.L Friend
Keyword(s):  
Shear Zones ◽  
Ductile Deformation ◽  
Small Scale ◽  
High Grade ◽  
East Greenland ◽  
North West ◽  
North East ◽  
Basin Development ◽  
Ductile Shear Zones ◽  
Partial Melts

Mid-crustal deformation of an Early Proterozoic high-grade gneiss complex in western Dove Bugt gave rise to at least two sets of nappes. Structures in mylonites in low-angle ductile shear zones associated with the younger nappes indicate north-easterly-directed displacements. The nappes and mylonites are folded by upright to inclined folds that verge north-west and which appear to be associated with decollements that dip south-east. Hornblende, sillimanite and anatectic partial melts that developed with the nappes, mylonites and younger folds show that deformation took place under amphibolite facies conditions. Several lines of evidence suggest that the younger nappes, the mylonites and the upright to inclined folds formed during the Caledonian orogeny. Some pre-Caledonian deformation may be represented by the oldest isoclinal folds. Numerous, small-scale, ductile extensional shear zones and more brittIe fractures that were superimposed across the Caledonian structures are believed to have formed during orogen-parallel collapse which may be related IO Devonian basin development farther south in central East Greenland. Younger fauIts and major joints are correlated with Carboniferous, Mesozoic and Tertiary basin development in North-East Greenland.

scholarly journals The high-grade gneisses in the south-west of Dove Bugt: an old gneiss complex in a deep part of the Caledonides of North-East Greenland

1991 ◽  
Vol 152 ◽  
pp. 103-111
Author(s):  
B Chadwick ◽  
C.R.L Friend
Keyword(s):  
Granitic Rocks ◽  
Small Scale ◽  
High Grade ◽  
Deep Part ◽  
The South ◽  
East Greenland ◽  
North East ◽  
Gneiss Complex ◽  
South West

The complex range of orthogneisses has been subdivided on the basis of field characteristics into an old polyphase group, grey phlebitic gneisses, younger varieties of pink granitic gneisses that occur principally as extensive sheets, mixed orthogneisses with schlieric facies and undifferentiated gneisses with dioritic facies. Mafic sheets, now amphibolites, were emplaced at various stages in the evolution of the gneisses. Enclaves and sheets of supracrustal rocks include paragneisses, graphitic schists, marble, amphibolite and stratiform gabbroic complexes with anorthosite. Nappes with curvilinear hinge lines and belts of mylonite developed in high amphibolite conditions after emplacement of the sheets of pink granitic rocks (now variably deformed gneisses) into the old orthogneisses and supracrustal rocks. Principal displacements in the mylonites were shallow and N-directed. The nappes and mylonites were deformed by upright-inclined folds with north-westerly vergence. The nappes, mylonites and north-westerly verging folds are presumed to be Caledonian. N- and S-directed extensions indicated by small-scale ductile structures younger than the regional folding suggest that longitudinal collapse predominated in this part of the Caledonian belt in the south-west of Dove Bugt.

Mineralogy of the Au-Ag mineralization from the Finsterort and Anton vein system, Štiavnické vrchy Mts. (Slovakia)

2021 ◽  
Vol 29 (2) ◽  
pp. 255-269
Author(s):  
Jozef Vlasáč ◽  
Martin Chovan ◽  
Rastislav Vojtko ◽  
Peter Žitňan ◽  
Tomáš Mikuš
Keyword(s):  
Middle Miocene ◽  
Precious Metals ◽  
Central Zone ◽  
Strike Slip ◽  
Normal Faults ◽  
Normal Faulting ◽  
Vein System ◽  
Štiavnica Stratovolcano ◽  
Dextral Strike Slip ◽  
Strike Slip Movement

The Finsterort and Anton vein system is located in the central zone of the Middle Miocene Štiavnica Stratovolcano between Vyhne and Hodruša-Hámre villages. The vein system contains several partial veins and veinlets and has generally NNE - SSW strike with moderate to steep eastward dip. Kinematics of the veins is characterised by older dextral strike-slip movement replaced by younger normal faulting. The mineralization is associated with the normal faults and the veins contain interesting paragenesis of Au-Ag bearing minerals. Minerals of precious metals are represented by argentotetrahedrite-(Zn) and rozhdestvenskayaite-(Zn), Au-Ag alloys, members of polybasite-pearceite and pyrargyrite-proustite solid solutions, acanthite and uytenbogaardtite. Au-Ag mineralization is accompanied by older paragenesis comprising mainly pyrite, galena, sphalerite and chalcopyrite. Besides quartz, carbonates (calcite, siderite and dolomite) are the main gangue minerals.

A new occurrence of musgravite, a rare beryllium oxide, in the Caledonides of North-East Greenland

1993 ◽  
Vol 57 (386) ◽  
pp. 121-129 ◽  
Author(s):  
B. Chadwick ◽  
C. R. L. Friend ◽  
M. C. George ◽  
W. T. Perkins
Keyword(s):  
Beryllium Oxide ◽  
Mobile Belt ◽  
High Grade ◽  
East Greenland ◽  
North East ◽  
Granite Emplacement ◽  
Internal Part ◽  
Icp Ms ◽  
Cell Dimensions ◽  
Unit Cell Dimensions

AbstractMusgravite, Be(MgFeZn)2Al6O12, is associated with norbergite and minor chlorite in a Precambrian calcite marble within the gneissic basement in an internal part of the Caledonian mobile belt in Dove Bugt, North-East Greenland. It commonly occurs as vitreous black, idioblastic crystals (<7 mm in size) with combined rhombohedral and basal pinacoid forms. XRD data show that its space group is R3m and its unit cell dimensions are a 5.687 ± 0.002 Å and c 41.16 ± 0.02 Å. Electron microprobe and ICP-MS analyses have yielded BeO 5.51 wt.% and ranges in abundance (wt.%): Al2O3 68.74-70.63; Tot, Fe as FeO 6.76-7.89; MgO 12.17-13.98; and ZnO 3.22-4.47. ICP-MS analysis also revealed significant trace amounts of V 249 ppm, Cr 740 ppm and Ga 178 ppm. The crystallographic parameters and composition are broadly in accord with those of musgravite from the two other recorded occurrences, in Precambrian high-grade terrains in Australia and Antarctica, although mineral and rock associations in these localities differ from those in Dove Bugt. The source of beryllium in each of the musgravite occurrences is uncertain, although a metasomatic source related to granite emplacement is favoured for the occurrence in North-East Greenland.

Structural evolution of basement gneisses and Hadrynian cover, Bulldog Creek area, Rocky Mountains, British Columbia

1988 ◽  
Vol 25 (10) ◽  
pp. 1687-1702 ◽  
Author(s):  
Michael R. McDonough ◽  
Philip S. Simony
Keyword(s):  
British Columbia ◽  
Structural Evolution ◽  
Rocky Mountain ◽  
Strike Slip ◽  
Normal Faulting ◽  
The West ◽  
Kinematic Indicators ◽  
Thrust Sheets ◽  
Dextral Strike Slip ◽  
Southern Rocky Mountain

Two gneiss bodies are contained in thrust sheets on the west edge of the Rocky Mountain Main Ranges near Valemount, British Columbia. The Bulldog Gneiss comprises Aphebian or older paragneiss and amphibolitic gneiss intruded by Aphebian orthogneiss sheets. The Yellowjacket Gneiss is granodioritic orthogneiss of unknown age. Both gneiss bodies are basement highs with thin Hadrynian metasediment cover sequences. The cover sequences are assigned to the lower Miette Group and are correlated with Horsethief Creek Group.Internal shortening of gneiss thrust sheets is expressed by recumbent folding and stacking of thin thrust sheets of gneiss and cover. The Bulldog Gneiss and its cover were carried on the postmetamorphic Purcell Thrust. The Yellowjacket Gneiss and its cover were carried on the pre- to synmetamorphic Bear Foot Thrust. Northeast and northwest displacement is documented on the moderately southwest-dipping Bear Foot Thrust, and a dextral oblique-slip – thrust model is proposed to explain the duality of thrust and dextral strike-slip kinematic indicators in mylonite from the fault. An estimate of shortening in the fore-land suggests that basement thrust sheets were translated more than 200 km to the northeast.Correlation of gneisses and cover with the westerly adjacent Malton Gneiss and its cover precludes major dextral strike-slip motion on the Southern Rocky Mountain Trench (SRMT) during and after thrusting. The SRMT was the locus of post-thrusting and postmetamorphic, Eocene(?), brittle, west-side-down, normal faulting.

Record of Late Mississippian tectonics in the new Percé Group (Viséan) of eastern Gaspésie, Quebec

2005 ◽  
Vol 42 (5) ◽  
pp. 815-832 ◽  
Author(s):  
Pierre Jutras ◽  
Gilbert Prichonnet
Keyword(s):  
Slip System ◽  
Marine Sediments ◽  
Strike Slip ◽  
Alluvial Fan ◽  
Normal Faulting ◽  
Broad Area ◽  
Tectonic Events ◽  
Upper Paleozoic ◽  
Maritimes Basin ◽  
Dextral Strike Slip

Viséan clastic units and structures at the northwest margin of the upper Paleozoic Maritimes Basin provide information on tectonic events that are only poorly recorded in more central parts of the basin. These continental units are time equivalent to marine sediments of the Windsor Group of Nova Scotia. They are herein assigned to the new Percé Group, which includes the La Coulée and Bonaventure formations, as well as a new unit, the Cap d'Espoir Formation. The latter unit unconformably underlies the Bonaventure Formation in a small but thick sub-basin of the Ristigouche Basin in eastern Quebec. It is characterized by a succession of sandstone and mudstone rhythmites that contrast with the coarse alluvial fan deposits of the overlying Bonaventure Formation. The Cap d'Espoir Formation was sourced from a broad area of subdued topography occupied by the Viséan La Coulée Formation and underlying units. Erosional remnants of the La Coulée Formation are unconformably overlain by the Bonaventure Formation in marginal parts of the Ristigouche Basin, whereas these units are separated by the Cap d'Espoir Formation in more central areas of the basin. The La Coulée and Cap d'Espoir formations underwent tilting and erosion during a normal faulting event that preceded deposition of the fault-controlled Bonaventure Formation. This series of events is interpreted to represent different steps in the reactivation of a pre-Carboniferous dextral strike-slip system in response to northwest–southeast compression during the Viséan in Gaspésie.

scholarly journals Regional geology and Caledonian structure, Dronning Louise Land, North-East Greenland

1994 ◽  
Vol 162 ◽  
pp. 71-76
Author(s):  
R.A Strachan ◽  
J.D Friderichsen ◽  
R.E Holdsworth ◽  
H.F Jepsen
Keyword(s):  
Trace Fossils ◽  
Strike Slip ◽  
The West ◽  
East Greenland ◽  
Regional Geology ◽  
Sedimentary Sequences ◽  
North East ◽  
Regional Deformation ◽  
Thrust Zone

A major N-S trending thrust zone exposed in Dronning Louise Land marks the western limit of intense Caledonian deformation in East Greenland. Foreland basement to the west of the thrust zone is dominated by orthogneisses which are overlain unconformably by two sedimentary sequences (Trekant Series and Zebra Series). The Zebra Series contains Skolithos trace fossils which indicate that it is no older than latest Proterozoic. Metamorphosed correlatives of the Trekant Series and the Zebra Series can be recognised as tectonic slices within the thrust zone, and also as infoIds within the allochthonous gneisses which overlie the thrust zone. The dominant Caledonian structures are thought to have resulted from sinistral transpression, which involved partitioning of regional deformation between sinistral strike-slip movements in the east of the region, and generally NW-directed oblique thrusting and folding further to the west.

scholarly journals Structure of the Eleonore Bay Supergroup at Ardencaple Fjord, North-East Greenland

1994 ◽  
Vol 162 ◽  
pp. 91-101
Author(s):  
A.K Higgins ◽  
N.J Soper
Keyword(s):  
Shear Zones ◽  
The Other ◽  
Low Grade ◽  
Precambrian Basement ◽  
East Greenland ◽  
Late Proterozoic ◽  
North East ◽  
Basement Rocks ◽  
Erosion Level ◽  
Caledonian Orogeny

The Caledonian structures in the late Proterozoic Eleonore Bay Supergroup of the Ardencaple Fjord area were controlled by the position and shape of the contacts with older basement rocks. Those contacts that are not late faults are likely to have been extensional shear zones of Vendian age which were reactivated in compression during the Caledonian orogeny. This interpretation may aIso be applied to the other large tracts of low grade Eleonore Bay Supergroup sediments in East Greenland, and explains their preservation at the present erosion level, surrounded by Precambrian basement rocks.

Sign in / Sign up

Export Citation Format

Share Document