Relationships between granite-gneiss terrains, greenstone belts and granulite belts in the archean crust of Lapland (Fennoscandia)

1980 ◽  
Vol 69 (3) ◽  
pp. 648-658 ◽  
Author(s):  
P. Barbey ◽  
J. Convert ◽  
H. Martin ◽  
B. Moreau ◽  
R. Capdevila ◽  
...  
Keyword(s):  
Granite Gneiss ◽  
Archean Crust ◽  
Greenstone Belts

Early Archean crust of the Middle Dnepr and Azov domains, Ukrainian Shield--evidence from ages of detrital zircons in Mesoarchean greenstone belts

2010 ◽  
Vol 310 (10) ◽  
pp. 1595-1622 ◽  
Author(s):  
E. Bibikova ◽  
S. Claesson ◽  
A. Fedotova ◽  
G. Artemenko ◽  
L. Ilyinsky
Keyword(s):  
Detrital Zircons ◽  
Ukrainian Shield ◽  
Archean Crust ◽  
Greenstone Belts

Structural tests of diapir hypotheses in Archean crust of Ontario

1990 ◽  
Vol 27 (3) ◽  
pp. 387-402 ◽  
Author(s):  
W. M. Schwerdtner
Keyword(s):  
Solid State ◽  
Horizontal Displacement ◽  
Gneiss Dome ◽  
Gneiss Domes ◽  
Archean Crust ◽  
Structural Tests ◽  
Greenstone Belts ◽  
Ductile Shear

Detailed structural maps of two granitoid complexes in the Wabigoon Subprovince are used to test three diapir hypotheses advanced in earlier papers. The gneiss masses of, and individual domes within, the complexes fail the test for solid-state diapirism. The gneiss domes also fail the test for tensile bending caused by hypothetical magmatic diapirs in the subsurface. An oval pluton located near the best-exposed gneiss dome proves to be a synformal sheet rather than a funnel-shaped magmatic diapir. This pluton could be a syenite–diorite phacolith emplaced into a concordant zone of dilation during the late upright folding of the gneiss mass about horizontal axes. Earlier tight folds were probably recumbent and south verging and, like the gneissosity, generated in a ductile shear regime with subhorizontal glide planes. These observations have important implications for Archean tectonics, especially the relative horizontal displacement of large greenstone masses (potentially allochthonous greenstone belts).

scholarly journals Groundwater quality assessment using water quality index (WQI) under GIS framework

2021 ◽  
Vol 11 (2) ◽  
Author(s):  
Arjun Ram ◽  
S. K. Tiwari ◽  
H. K. Pandey ◽  
Abhishek Kumar Chaurasia ◽  
Supriya Singh ◽  
...  
Keyword(s):  
Water Quality ◽  
Groundwater Quality ◽  
Water Quality Index ◽  
Quality Index ◽  
Uttar Pradesh ◽  
Granite Gneiss ◽  
Total Hardness ◽  
Human Consumption ◽  
Anthropogenic Contamination ◽  
Quality Of Water

AbstractGroundwater is an important source for drinking water supply in hard rock terrain of Bundelkhand massif particularly in District Mahoba, Uttar Pradesh, India. An attempt has been made in this work to understand the suitability of groundwater for human consumption. The parameters like pH, electrical conductivity, total dissolved solids, alkalinity, total hardness, calcium, magnesium, sodium, potassium, bicarbonate, sulfate, chloride, fluoride, nitrate, copper, manganese, silver, zinc, iron and nickel were analysed to estimate the groundwater quality. The water quality index (WQI) has been applied to categorize the water quality viz: excellent, good, poor, etc. which is quite useful to infer the quality of water to the people and policy makers in the concerned area. The WQI in the study area ranges from 4.75 to 115.93. The overall WQI in the study area indicates that the groundwater is safe and potable except few localized pockets in Charkhari and Jaitpur Blocks. The Hill-Piper Trilinear diagram reveals that the groundwater of the study area falls under Na+-Cl−, mixed Ca2+-Mg2+-Cl− and Ca2+-$${\text{HCO}}_{3}^{ - }$$ HCO 3 - types. The granite-gneiss contains orthoclase feldspar and biotite minerals which after weathering yields bicarbonate and chloride rich groundwater. The correlation matrix has been created and analysed to observe their significant impetus on the assessment of groundwater quality. The current study suggests that the groundwater of the area under deteriorated water quality needs treatment before consumption and also to be protected from the perils of geogenic/anthropogenic contamination.

Evaluation of magma mixing in the subvolcanic rocks of Ghansura Felsic Dome of Chotanagpur Granite Gneiss Complex, eastern India

2017 ◽  
Vol 112 (3) ◽  
pp. 393-413 ◽  
Author(s):  
Bibhuti Gogoi ◽  
Ashima Saikia ◽  
Mansoor Ahmad ◽  
Talat Ahmad
Keyword(s):  
Magma Mixing ◽  
Granite Gneiss ◽  
Eastern India ◽  
Gneiss Complex

Granitoid complexes and the Archean tectonic record in the southern part of northwestern Ontario

1979 ◽  
Vol 16 (10) ◽  
pp. 1965-1977 ◽  
Author(s):  
W. M. Schwerdtner ◽  
D. Stone ◽  
K. Osadetz ◽  
J. Morgan ◽  
G. M. Stott
Keyword(s):  
Large Scale ◽  
Vertical Motion ◽  
Strike Slip ◽  
Horizontal Motion ◽  
Tectonic Deformation ◽  
Northwestern Ontario ◽  
Greenstone Belts ◽  
Second Period ◽  
Transcurrent Faults ◽  
Regional Compression

Two principal, possibly overlapping, periods of tectonic deformation can be distinguished in the Archean of northwestern Ontario, a period of dominantly vertical-motion tectonics and a period of dominantly horizontal-motion tectonics. Gigantic diapirs of foliated to gneissic tonalite–granodiorite developed during the first period and appear to be responsible for the gross structure of, and the major folds within, the metavolcanic–metasedimentary masses ("greenstone belts"). These diapirs are most likely due to mechanical remobilization of early tabular batholiths which originally intruded the oldest supracrustal rocks presently exposed. Later massive to foliated, dioritic to granitic plutons that vary from concordant, crescentic plutons to partly discordant plutons of various shapes and sizes were emplaced into the diapirs.The second period of tectonic deformation is characterized by large-scale dextral shearing and the development of major transcurrent faults under northwesterly regional compression. The strike-slip motions of this period outlasted the late plutonism, and led to the development of mylonitic zones which cut all Archean granitoid plutons.

Rubidium–strontium ages from the Oxford Lake – Knee Lake greenstone belt, northern Manitoba

1980 ◽  
Vol 17 (5) ◽  
pp. 560-568 ◽  
Author(s):  
G. S. Clark ◽  
S.-P. Cheung
Keyword(s):  
Greenstone Belt ◽  
Volcanic Rocks ◽  
Superior Province ◽  
Granitic Intrusion ◽  
Greenstone Belts ◽  
Archean Greenstone Belts

Rb–Sr whole-rock ages have been determined for rocks from the Oxford Lake – Knee Lake – Gods Lake greenstone belt, in the Superior Province of northeastern Manitoba.The age of the Magill Lake Pluton is 2455 ± 35 Ma (λ87Rb = 1.42 × 10−11 yr−1), with an initial 87Sr/86Sr ratio of 0.7078 ± 0.0043. This granitic stock intrudes the Oxford Lake Group, so it is post-tectonic and probably related to the second, weaker stage of metamorphism.The age of the Bayly Lake Pluton is 2424 ± 74 Ma, with an initial 87Sr/86Sr ratio of 0.7029 ± 0.0001. This granodioritic batholith complex does not intrude the Oxford Lake Group. It is syn-tectonic and metamorphosed.The age of volcanic rocks of the Hayes River Group, from Goose Lake (30 km south of Gods Lake Narrows), is 2680 ± 125 Ma, with an initial 87Sr/86Sr ratio of 0.7014 ± 0.0009.The age for the Magill Lake and Bayly Lake Plutons can be interpreted as the minimum ages of granitic intrusion in the area.The age for the Hayes River Group volcanic rocks is consistent with Rb–Sr ages of volcanic rocks from other Archean greenstone belts within the northwestern Superior Province.

Magmatic and tectonic emplacement of the Pukaskwa batholith, Superior Province, Ontario, CanadaThis article is one of a series of papers published in this Special Issue on the theme of Geochronology in honour of Tom Krogh.

2011 ◽  
Vol 48 (2) ◽  
pp. 187-204 ◽  
Author(s):  
Gary P. Beakhouse ◽  
Shoufa Lin ◽  
Sandra L. Kamo
Keyword(s):  
Partial Melting ◽  
Abrupt Change ◽  
Superior Province ◽  
Density Inversion ◽  
Tectonic Processes ◽  
Slab Breakoff ◽  
Greenstone Belts ◽  
Lower Crustal ◽  
Basaltic Crust ◽  
Structural Dome

The Neoarchean Pukaskwa batholith consists of pre-, syn-, and post-tectonic phases emplaced over an interval of 50 million years. Pre-tectonic phases are broadly synvolcanic and have a high-Al tonalite–trondhjemite–granodiorite (TTG) affinity interpreted to reflect derivation by partial melting of basaltic crust at lower crustal or upper mantle depths. Minor syn-tectonic phases slightly post-date volcanism and have geochemical characteristics suggesting some involvement or interaction with an ultramafic (mantle) source component. Magmatic emplacement of pre- and syn-tectonic phases occurred in the midcrust at paleopressures of 550–600 MPa and these components of the batholith are thought to be representative of the midcrust underlying greenstone belts during their development. Subsequent to emplacement of the syntectonic phases, and likely at approximately 2680 Ma, the Pukaskwa batholith was uplifted as a structural dome relative to flanking greenstone belts synchronously with ongoing regional sinistral transpressive deformation. The driving force for vertical tectonism is interpreted to be density inversion (Rayleigh–Taylor-type instabilities) involving denser greenstone belts and underlying felsic plutonic crust. The trigger for initiation of this process is interpreted to be an abrupt change in the rheology of the midcrust attributed to introduction of heat from the mantle attendant with slab breakoff or lithospheric delamination following the cessation of subduction. This process also led to partial melting of the intermediate to felsic midcrust generating post-tectonic granitic phases at approximately 2667 Ma. We propose that late density inversion-driven vertical tectonics is an inevitable consequence of horizontal (plate) tectonic processes associated with greenstone belt development within the Superior Province.

Petrogenesis of silicic magmatism related to the ∼2.44 Ga rifting of Archean crust in Koillismaa, eastern Finland

Lithos ◽  
2006 ◽  
Vol 86 (1-2) ◽  
pp. 137-166 ◽  
Author(s):  
L.S. Lauri ◽  
O.T. Rämö ◽  
H. Huhma ◽  
I. Mänttäri ◽  
J. Räsänen
Keyword(s):  
Archean Crust ◽  
Silicic Magmatism ◽  
Eastern Finland
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