scholarly journals The kyanite quartzite of Bosland (Suriname): evidence for a Precambrian metamorphosed alteration system

2016 ◽  
Vol 95 (4) ◽  
pp. 447-465
Author(s):  
Ginny Bijnaar ◽  
Manfred J. van Bergen ◽  
Theo E. Wong
Keyword(s):  
Greenstone Belt ◽  
Mineral Content ◽  
Regional Metamorphism ◽  
Complete Removal ◽  
Fault System ◽  
Stability Field ◽  
Alkaline Earth Elements ◽  
Argillic Alteration ◽  
History Of ◽  
Felsic Volcanic

AbstractThis article investigates the origin of a rare occurrence of kyanite quartzites in the Palaeoproterozoic greenstone belt of Suriname. The rocks form elongated hills in the Bosland area, Brokopondo district, where they are associated with meta-sedimentary, meta-volcanic and granitic lithologies. Their mineral content and unusual Si- and Al-rich chemical composition are inferred to be the result of advanced argillic alteration of felsic volcanic tuffs and a later overprint by regional metamorphism up to lower amphibolite facies during the Trans-Amazonian orogeny. Structurally, the Bosland area seems centred within a contractional strike-slip duplex of a major dextral fault system. The alteration was probably associated with a high-sulphidation environment and involved significant to almost complete removal of alkali and alkaline earth elements. Pseudosection modelling and textures suggest that the precipitation–temperature (P–T) history of the kyanite quartzites started with shallow (<2kbar) hydrothermal alteration of the acidic tuffaceous volcanics, possibly in the andalusite stability field (T>350°C), and ended in peak metamorphic conditions in the kyanite–staurolite stability field (P>4kbar andT=500–650°C). Alteration events that preceded the peak of Trans-Amazonian metamorphism may be more common in the rock record of Suriname's greenstone belt, which lends support to the hypothesis that gold mineralisations in the region can be pre-orogenic.

Structural history of the Manitouwadge greenstone belt and its volcanogenic Cu-Zn massive sulphide deposits, Wawa subprovince, south-central Superior Province

1999 ◽  
Vol 36 (4) ◽  
pp. 605-625 ◽  
Author(s):  
Virginia L Peterson ◽  
Eva Zaleski
Keyword(s):  
Base Metal ◽  
Greenstone Belt ◽  
Regional Metamorphism ◽  
Massive Sulphide ◽  
Iron Formation ◽  
Deformation History ◽  
South Central ◽  
Structural History ◽  
History Of ◽  
Map Scale

Structural analysis of the Manitouwadge greenstone belt, integrated with detailed mapping and geochronological and petrographic studies, reveals a complex early deformation history that significantly modified the primary distribution of base-metal deposits and alteration zones. The (D3) Manitouwadge synform dominates the map pattern; however, penetrative fabric development and establishment of the tectono-stratigraphy of base-metal deposits mostly predated D3. The D1 Garnet Lake fault, which repeats mineralized horizons within a distinctive lithological sequence, is delineated locally by annealed mylonite. D1 planar fabrics are preserved locally in outcrop and thin section. D2 folding accompanied peak regional metamorphism at upper amphibolite facies. The F2 Agam Lake syncline repeats the volcanic sequence across the southern limb of the Manitouwadge synform. A map-scale F2 sheath fold deforms the Garnet Lake fault. Minor D2 structures include prevalent outcrop-scale folds, locally with sheath geometry, the dominant S2 foliation, and mineral lineations (parallel to fold axes). Northwest-southeast-directed D3 shortening produced the Manitouwadge synform and related regional folds without extensive penetrative fabric development. Flexural slip folding is evident in the inner hinge of the synform where rocks of differing competency are interlayered. Higher strain, stronger fabric development, and a component of simple shear were preferentially partitioned to fold limbs. Relative pre-D3 structural geometries in the inner hinge region of the Manitouwadge synform are not significantly complicated by D3 and younger deformation. Retrodeformation of the mineralized sequence shows systematic stratigraphic patterns in iron formation types, stacked massive sulphide orebodies, and alteration types that can be applied to exploration models.

Polymetamorphism in the Archean Hemlo – Heron Bay greenstone belt, Superior Province: P–T variations and implications for tectonic evolution

1993 ◽  
Vol 30 (5) ◽  
pp. 985-996 ◽  
Author(s):  
Yuanming Pan ◽  
Michael E. Fleet
Keyword(s):  
Greenstone Belt ◽  
Regional Metamorphism ◽  
Mineral Chemistry ◽  
Superior Province ◽  
Low Grade ◽  
Garnet Porphyroblasts ◽  
Metamorphic History ◽  
Tectonic Environment ◽  
History Of ◽  
Archean Greenstone Belt

The tectono-metamorphic history of the late Archean (2800–2600 Ma) Hemlo – Heron Bay greenstone belt in the Superior Province has been delineated from textural relationships, mineral chemistry, and P–T paths in metapelites, cordierite–orthoamphibole rocks, and metabasites from the White River exploration property, Hemlo area, Ontario. An early low-temperature, medium-pressure metamorphism (about 500 °C and 6–6.5 kbar (1 kbar = 100 MPa)) is indicated by the occurrence of relict kyanite and staurolite porphyroblasts and zoned garnet porphyroblasts in metapelites and the presence of zoned calcic amphiboles in metabasites. This early metamorphism appears to have been coeval with the previously documented D1 deformation that is associated with, for example, low-angle thrusts. A second regional metamorphism predominates in the Hemlo – Heron Bay greenstone belt and is generally of relatively low grade, at about 510–530 °C and 3.2–3.5 kbar, over most of the study area and increases to medium grade (550–650 °C and 4–5 kbar) towards the southern margin with the Pukaskwa Gneissic Complex and along the central axis enclosing the Hemlo Shear Zone. The second regional metamorphism was contemporaneous with the D3 deformation and was probably related to plutonism. This type of polymetamorphism in the Hemlo – Heron Bay greenstone belt may be equivalent to those in Phanerozoic subduction complexes and therefore supports the arc–arc accretion model for the development of the southern Superior Province. Although the Hemlo – Heron Bay greenstone belt most likely represents a single tectonic environment (an oceanic island arc), the restricted occurrence of the relict kyanite and staurolite indicates that the central portion of this Archean greenstone belt probably was at a deeper crustal level at the time of the first metamorphic event.

Tectonic and thermal history of the Anialik River area, northwestern Slave Province, Canada

1999 ◽  
Vol 36 (7) ◽  
pp. 1207-1226 ◽  
Author(s):  
C Relf ◽  
H A Sandeman ◽  
M E Villeneuve
Keyword(s):  
Shear Zone ◽  
Continental Crust ◽  
Greenstone Belt ◽  
Volcanic Rocks ◽  
Crustal Thickening ◽  
South Central ◽  
Slave Province ◽  
History Of ◽  
Arc Setting ◽  
Felsic Volcanic

The Anialik River area in the northwestern Slave Province comprises two geological domains of different age and origin that were tectonically juxtaposed at ca. 2650 Ma. The older domain, the Kangguyak gneiss belt, comprises ca. 3300-2700 Ma orthogneisses and paragneisses, interpreted as the remnants of a Mesoarchean continental margin. The younger domain, the Anialik River greenstone belt, consists of ca. 2680 Ma mafic to felsic volcanic rocks interpreted to have formed in an ensimatic island-arc setting. Structural and geochronological evidence suggest collision of the two domains began around 2650 Ma in a transpressive regime that involved oblique (sinistral) subduction of the greenstone belt beneath the Kangguyak domain along the Tokhokatak shear zone. Displacement continued until at least ca. 2600 Ma, when late, two-mica granites intruded along and were deformed in the shear zone. Following ca. 2600 Ma, rocks in both domains and along the fault cooled rapidly to about 350°C. Strongly overprinted muscovite spectra and the young ages for biotite throughout the region imply that a thermal event reset all biotites (but not muscovite) at ca. 2000-1900 Ma, possibly associated with crustal thickening associated with Wopmay (Calderian) orogenesis. The tectonic history of the Anialik River area is significantly different from that documented in the south-central part of the Slave Province, suggesting the Kangguyak domain is a distinct fragment of continental crust that accreted independently from continental crust in the southern Slave Province.

Genesis of gabbroic intrusions in the Arabian Shield, Saudi Arabia: mineralogical, geochemical and tectonic fingerprints of the Neoproterozoic arc magmatism

2021 ◽  
pp. 1-18
Author(s):  
Shehata Ali ◽  
Abdullah S. Alshammari
Keyword(s):  
Saudi Arabia ◽  
Fault System ◽  
Geochemical Data ◽  
Stability Field ◽  
Arabian Shield ◽  
Red Sea Rift ◽  
Nubian Shield ◽  
Najd Fault System ◽  
Garnet Stability Field ◽  
Arabian Nubian Shield

Abstract The Arabian Shield of Saudi Arabia represents part of the Arabian–Nubian Shield and forms an exposure of juvenile continental crust on the eastern side of the Red Sea rift. Gabbroic intrusions in Saudi Arabia constitute a significant part of the mafic magmatism in the Neoproterozoic Arabian Shield. This study records the first detailed geological, mineralogical and geochemical data for gabbroic intrusions located in the Gabal Samra and Gabal Abd areas of the Hail region in the Arabian Shield of Saudi Arabia. Geological field relations and investigations, supported by mineralogical and geochemical data, indicate that the gabbroic intrusions are generally unmetamorphosed and undeformed, and argue for their post-collisional emplacement. Their mineralogical and geochemical features reveal crystallization from hydrous, mainly tholeiitic, mafic magmas with arc-like signatures, which were probably inherited from the previous subduction event in the Arabian–Nubian Shield. The gabbroic rocks exhibit sub-chondritic Nb/U, Nb/Ta and Zr/Hf ratios, revealing depletion of their mantle source. Moreover, the high ratios of (Gd/Yb)N and (Dy/Yb)N indicate that their parental mafic melts were derived from a garnet-peridotite source with a garnet signature in the mantle residue. This implication suggests that the melting region was at a depth exceeding ∼70–80 km at the garnet stability field. They have geochemical characteristics similar to other post-collisional gabbros of the Arabian–Nubian Shield. Their origin could be explained by adiabatic decompression melting of depleted asthenosphere that interacted during ascent with metasomatized lithospheric mantle in an extensional regime, likely related to the activity of the Najd Fault System, at the end of the Pan-African Orogeny.

scholarly journals Western Medical Rehabilitation through Time: A Historical and Epistemological Review

2014 ◽  
Vol 2014 ◽  
pp. 1-5 ◽  
Author(s):  
Andrea A. Conti
Keyword(s):  
Social Life ◽  
Complete Removal ◽  
Medical Rehabilitation ◽  
Western World ◽  
Human Beings ◽  
Physical Damage ◽  
Renaissance Period ◽  
History Of ◽  
Management Approaches ◽  
Everyday Reality

Medical rehabilitation is the process targeted to promote and facilitate the recovery from physical damage, psychological and mental disorders, and clinical disease. The history of medical rehabilitation is closely linked to the history of disability. In the ancient western world disabled subjects were excluded from social life. In ancient Greece disability was surmounted only by means of its complete removal, and given that disease was considered a punishment attributed by divinities to human beings because of their faults and sins, only a full physical, mental, and moral recovery could reinsert disabled subjects back in the society of “normal” people. In the Renaissance period, instead, general ideas functional for the prevention of diseases and the maintaining of health became increasingly technical notions, specifically targeted to rehabilitate disabled individuals. The history of medical rehabilitation is a fascinating journey through time, providing insights into many different branches of medicine. When modern rehabilitation emerges, around the middle of the twentieth century, it derives from a combination of management approaches focusing on the orthopaedic and biomechanical understanding of patterns of movement, on the mastering of neuropsychological mechanisms, and on the awareness of the social-occupational dimension of everyday reality.

Heavy minerals in stream sediments from Churchill Falls, Labrador—an aid in bedrock mapping

1980 ◽  
Vol 17 (2) ◽  
pp. 244-253
Author(s):  
John Edward Callahan
Keyword(s):  
Frequency Distribution ◽  
Mineral Content ◽  
Regional Metamorphism ◽  
Stream Sediments ◽  
Heavy Mineral ◽  
Heavy Minerals ◽  
Sediment Samples ◽  
Fluvial Deposits ◽  
Geologic Map ◽  
High Concentrations

Stream sediments from a 13 000 km2 previously glaciated area in central Labrador near Churchill Falls were examined for their heavy mineral content. The minus 0.25 mm (60 mesh) nonmagnetic heavy mineral fraction from 846 stream sediment samples consists mainly of magnetite, ilmenite. garnet, hornblende, epidote and minor clinopyroxene, orthopyroxene. kyanite. sillimanite, biotite. apatite, and zircon. Changes in the frequency distribution of epidote, hornblende, garnet, and sillimanite in the stream sediments correspond well with those reported in previously mapped underlying bedrock lithologies. The occurrence of kyanite and sillimanite, high concentrations of garnet and opaques (mainly ilmenite), and lower concentrations of hornblende and epidote were used to determine grades of regional metamorphism, resulting in revision of the geologic map of this area. Heavy minerals in glacial drift or fluvial deposits may be useful as an aid in mapping in glaciated areas.

scholarly journals Formation age and metamorphic history of the Nuvvuagittuq Greenstone Belt

2012 ◽  
Vol 220-221 ◽  
pp. 23-44 ◽  
Author(s):  
Jonathan O’Neil ◽  
Richard W. Carlson ◽  
Jean-Louis Paquette ◽  
Don Francis
Keyword(s):  
Greenstone Belt ◽  
Metamorphic History ◽  
History Of

Use of pyrite microfabric as a key to tectono-thermal evolution of massive sulphide deposits – an example from Deri, southern Rajasthan, India

1998 ◽  
Vol 62 (2) ◽  
pp. 197-212 ◽  
Author(s):  
Anju Tiwary ◽  
Mihir Deb ◽  
Nigel J. Cook
Keyword(s):  
Thermal Evolution ◽  
Regional Metamorphism ◽  
Massive Sulphide ◽  
Ductile Deformation ◽  
Sulphide Deposit ◽  
Fine Grained ◽  
Thermal Metamorphism ◽  
Sulphide Ores ◽  
History Of ◽  
South Delhi Fold Belt

AbstractPyrite is an ubiquitous constituent of the Proterozoic massive sulphide deposit at Deri, in the South Delhi Fold Belt of southern Rajasthan. Preserved pyrite microfabrics in the Zn-Pb-Cu sulphide ores of Deri reveal a polyphase growth history of the iron sulphide and enable the tectono-thermal evolution of the deposit to be reconstructed.Primary sedimentary features in Deri pyrites are preserved as compositional banding. Regional metamorphism from mid-greenschist to low amphibolite facies is recorded by various microtextures of pyrite. Trails of fine grained pyrite inclusions within hornblende porphyroblasts define S1-schistosity. Pyrite boudins aligned parallel to S1 mark the brittle–ductile transformation of pyrite during the earliest deformation in the region. Isoclinal to tight folds (F1 and F2) in pyrite layers relate to a ductile deformation stage during progressive regional metamorphism. Peak metamorphic conditions around 550°C, an estimation supported by garnet–biotite thermometry, resulted in annealing of pyrite grains, while porphyroblastic growth of pyrite (up to 900 µm) took place along the retrogressive path. Brittle deformation of pyrite and growth of irregular pyritic mass around such fractured porphyroblasts characterize the waning phase of regional metamorphism. A subsequent phase of stress-free, thermal metamorphism is recorded in the decussate and rosette textures of arsenopyrite prisms replacing irregular pyritic mass. Annealing of such patchy pyrite provides information regarding the temperature conditions during this episode of thermal metamorphism which is consistent with the hornblendehornfels facies metamorphism interpreted from magnetite–ilmenite geothermometry (550°C) and sphalerite geobarometry (3.5 kbar). A mild cataclastic deformation during the penultimate phase produced microfaults in twinned arsenopyrite prisms.

scholarly journals The role of Central American barriers in shaping the evolutionary history of the northernmost glassfrog,Hyalinobatrachium fleischmanni(Anura: Centrolenidae)

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e6115 ◽  
Author(s):  
Angela M. Mendoza ◽  
Wilmar Bolívar-García ◽  
Ella Vázquez-Domínguez ◽  
Roberto Ibáñez ◽  
Gabriela Parra Olea
Keyword(s):  
Genetic Structure ◽  
Central America ◽  
Population Expansion ◽  
Central American ◽  
Fault System ◽  
Mountain Range ◽  
Amphibian Species ◽  
Biogeographic History ◽  
History Of ◽  
The Impact

The complex geological history of Central America has been useful for understanding the processes influencing the distribution and diversity of multiple groups of organisms. Anurans are an excellent choice for such studies because they typically exhibit site fidelity and reduced movement. The objective of this work was to identify the impact of recognized geographic barriers on the genetic structure, phylogeographic patterns and divergence times of a wide-ranging amphibian species,Hyalinobatrachium fleischmanni. We amplified three mitochondrial regions, two coding (COI and ND1) and one ribosomal (16S), in samples collected from the coasts of Veracruz and Guerrero in Mexico to the humid forests of Chocó in Ecuador. We examined the biogeographic history of the species through spatial clustering analyses (Geneland and sPCA), Bayesian and maximum likelihood reconstructions, and spatiotemporal diffusion analysis. Our data suggest a Central American origin ofH. fleischmanniand two posterior independent dispersals towards North and South American regions. The first clade comprises individuals from Colombia, Ecuador, Panama and the sister speciesHyalinobatrachium tatayoi; this clade shows little structure, despite the presence of the Andes mountain range and the long distances between sampling sites. The second clade consists of individuals from Costa Rica, Nicaragua, and eastern Honduras with no apparent structure. The third clade includes individuals from western Honduras, Guatemala, and Mexico and displays deep population structure. Herein, we synthesize the impact of known geographic areas that act as barriers to glassfrog dispersal and demonstrated their effect of differentiatingH. fleischmanniinto three markedly isolated clades. The observed genetic structure is associated with an initial dispersal event from Central America followed by vicariance that likely occurred during the Pliocene. The southern samples are characterized by a very recent population expansion, likely related to sea-level and climatic oscillations during the Pleistocene, whereas the structure of the northern clade has probably been driven by dispersal through the Isthmus of Tehuantepec and isolation by the Motagua–Polochic–Jocotán fault system and the Mexican highlands.

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