Stratigraphy and structure of the Early Proterozoic Wilson Island Group, East Arm thrust-fold belt, N.W.T.

1990 ◽  
Vol 27 (4) ◽  
pp. 552-569 ◽  
Author(s):  
Bradford J. Johnson
Keyword(s):  
Crustal Extension ◽  
Early Proterozoic ◽  
Clastic Rocks ◽  
Marine Sedimentation ◽  
Volcanic Suite ◽  
Island Group ◽  
Regional Tectonic ◽  
Sediment Deformation ◽  
Tectonic Style ◽  
Feldspathic Sandstone

Investigation of the stratigraphy and structure of the 1.9 Ga Wilson Island Group has led to sedimentological and tectonic interpretations that are consistent with models for an Early Proterozoic collision between the Slave and Rae provinces. The lower part of the 8 km thick Wilson Island Group consists of alluvial clastic rocks and a bimodal volcanic suite. These are overlain by mixed siliciclastic and carbonate rocks that are inferred as representing a combination of alluvial and shallow-marine sedimentation. Finally, an upward-fining succession of feldspathic sandstone, ironstone, and mudstone records progradation of an alluvial system followed by a major transgression. Soft-sediment deformation structures, intrabasinal coarse detritus, and abrupt vertical facies changes collectively indicate that the early stages of deposition were tectonically controlled.Regional penetrative foliations and a steeply plunging stretching lineation reflect deformation concomitant with greenschist-facies to lower amphibolite-facies metamorphism. Open to tight, plunging, northwesterly overturned folds formed synchronously with axial-plane cleavage in quartzites and deformed an older cleavage in pelites. These synmetamorphic structures were refolded by postmetamorphic kinks and dissected by transcurrent and normal faults.The Wilson Island Group evolved during postcollisional convergence, when thrusting and dextral transcurrent shearing characterized the regional tectonic style. However, the bimodal volcanic suite indicates a component of crustal extension that, in the regional context, favours a pull-apart-basin origin for the Wilson Island Group.

Research on Sedimentary Environment of the Wayaobao Formation in Ordos Basin

2013 ◽  
Vol 448-453 ◽  
pp. 363-366
Author(s):  
Zhi Rong Liu ◽  
Qi Tian
Keyword(s):  
Trace Element ◽  
Sedimentary Environment ◽  
Ordos Basin ◽  
Biological Characteristics ◽  
Coarse Grained ◽  
Late Triassic ◽  
Clastic Rocks ◽  
Sedimentary Structures ◽  
Fluvial Deposit ◽  
Feldspathic Sandstone

Wayaobao Formation of late Triassic, in Ordos Basin is composed of clastic rocks, such as grey green thick-bedding medium-coarse-grained lithic arkose, lithic feldspathic sandstone, fine-medium-grained lithic feldspathic greywacke, quartzose feldspathic sandstone, et al. Detailed study of Wayaobao Formation in Shenmu was carried out about lithology, sedimentary structures, biological characteristics, heavy mineralogy and trace element characteristics, then a conclusion was drawn that Wayaobao Formation in Shenmu, Ordos Basin was fluvial deposit.

A bimodal volcanic–plutonic system: the Zarembo Island extrusive suite and the Burnett Inlet intrusive complex

2004 ◽  
Vol 41 (4) ◽  
pp. 355-375 ◽  
Author(s):  
Jennifer Lindline ◽  
William A Crawford ◽  
Maria Luisa Crawford
Keyword(s):  
Volcanic Rocks ◽  
Intrusive Complex ◽  
Crustal Extension ◽  
Mafic Enclaves ◽  
Volcanic Suite ◽  
Silica Concentration ◽  
Plutonic Complex ◽  
Igneous Activity ◽  
Tectonic Motion ◽  
Igneous Layering

The Zarembo Island volcanic rocks and the Burnett Inlet plutonic complex in central southeastern Alaska were investigated to determine if they are genetically related. The Zarembo Island volcanic suite consists of basalt, andesite, and rhyolite lava flows, which exhibit features that suggest simultaneous eruptions of mafic and felsic lavas. Five kilometres to the southeast, the broadly layered Burnett Inlet plutonic complex consists of gabbro–diorite and granite plutons that also show characteristics of contemporaneous mafic and felsic magmatism. These bimodal volcanic and plutonic rocks are similar in age, ranging from 18.5 to 21.5 Ma. Both suites show a gap in silica concentration between 60 and 65 wt.% and have similar major, trace, and rare-earth element composition. Both suites also show igneous layering, either as interlayered basalt and rhyolite flows or as alternating gabbro and granite sheets. Additionally, both groups contain magma mingling and mixing textures, including mafic enclaves in felsic members and quartz xenocrysts rimmed by clinopyroxene in enclaves. These characteristics suggest that the Burnett Inlet intrusive complex and the Zarembo Island volcanic suite represent an eroded, shallow-level plutonic center and its eruptive cover. The style of volcanism and the bimodal nature of magmatism suggest that igneous activity occurred during crustal extension and thinning that accompanied strike-slip tectonic motion in southeastern Alaska during the Tertiary. The volcanic–plutonic rock associations now exposed at the surface indicate that at least 7° of post-20 Ma crustal tilting has affected the region and can help to explain aberrant paleomagnetic poles in mid-Cretaceous intrusions of the Cordillera Coast belt.

Tectonic style and mechanism of early proterozoic successor basin development, Southern Africa

1988 ◽  
Vol 156 (3-4) ◽  
pp. 275-291 ◽  
Author(s):  
C.W. Clendenin ◽  
E.G. Charlesworth ◽  
S. Maske
Keyword(s):  
Southern Africa ◽  
Early Proterozoic ◽  
Basin Development ◽  
Tectonic Style

Rubidium–strontium ages of Archean and Proterozoic rocks in the Nejanilini and Great Island domains, Churchill Province, northern Manitoba, Canada

1988 ◽  
Vol 25 (2) ◽  
pp. 246-254 ◽  
Author(s):  
G. S. Clark ◽  
D. C. P. Schledewitz
Keyword(s):  
Granitic Rocks ◽  
Granitic Magma ◽  
Initial Ratio ◽  
Early Proterozoic ◽  
Metasedimentary Rocks ◽  
Field Evidence ◽  
Southern District ◽  
Island Group ◽  
Minimum Age ◽  
Archean Basement

Rubidium–strontium whole-rock ages are reported from the Nejanilini – Great Island area in northeastern Manitoba. This area is part of an extensive zone of Archean basement that was metamorphosed and intruded by granitic magma during the Proterozoic; it extends into Saskatchewan and southern District of Keewatin, Northwest Tertitories. An age of 2577 ± 42 Ma (1σ error) for the extensive Nejanilini granulite massif (Nejanilini domain), considered one of the oldest rock units in the area, is interpreted as a minimum age for late Archean granulite-facies metamorphism. A minimum age of 2052 ± 41 Ma (initial ratio 0.7150) for quartz–feldspar porphyry that intrudes the Seal River volcanic suite constrains the age of these volcanics and could represent a partially reset Archean age. Early Proterozoic quartzite and metagreywacke of the Great Island Group unconformably overlies the quartz–feldspar porphyry. These metasedimentary rocks, which are probably correlative with the Daly Lake Group (Saskatchewan) or the Hurwitz Group (southern District of Keewatin), give an age of 1885 ± 85 Ma, with an initial ratio of 0.7093. The age records the time of closure of the Rb–Sr isotopic system subsequent to early Proterozoic metamorphism. The age and initial ratio are consistent with published results for other, possibly correlative, metasedimentary rocks in this zone. Modelling the Rb–Sr isotopic data constrains the time of sedimentation to between ca. 2100 and 2000 Ma ago. Syn- to late-kinematic, early Proterozoic granite to granodiorite batholiths, which intruded metasedimentary rocks of the Great Island Group, may largely be the product of melting of Archean basement, based on field evidence and high initial 87Sr/86Sr ratios. The Caribou Lake porphyritic quartz monzonite gives an age of 1795 ± 35 Ma, with an initial 87Sr/86Sr ratio of 0.7084. High initial ratios seem to typify early Proterozoic granitic rocks in this remobilized craton.

scholarly journals Structural evolution of Djebel Debadib Anticline: A clue to the regional tectonic style of the Tunisian Atlas

Tectonics ◽  
1988 ◽  
Vol 7 (3) ◽  
pp. 497-516 ◽  
Author(s):  
Arthur W. Snoke ◽  
Steven Schamel ◽  
Richard M. Karasek
Keyword(s):  
Structural Evolution ◽  
Regional Tectonic ◽  
Tunisian Atlas ◽  
Tectonic Style

3D soft-sediment deformation structures: evidence for Quaternary seismicity in the Madrid basin, Spain

Terra Nova ◽  
1997 ◽  
Vol 9 (5) ◽  
pp. 208-212 ◽  
Author(s):  
P.G. Silva ◽  
J.C. Canaveras ◽  
S. Sanchez-Moral ◽  
J. Lario ◽  
E. Sanz
Keyword(s):  
Soft Sediment ◽  
Deformation Structures ◽  
Sediment Deformation ◽  
Soft Sediment Deformation
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