scholarly journals Preliminary report on the geology and structural evolution of the Komaktorvik Zone of the early Proterozoic Torngat Orogen, Eclipse Harbour area, northern Labrador

1992 ◽  
Author(s):  
M J Van Kranendonk ◽  
D Scott
Keyword(s):  
Preliminary Report ◽  
Structural Evolution ◽  
Early Proterozoic ◽  
Harbour Area

Early Proterozoic deformation along the southern margin of the Kisseynew gneiss belt, Trans-Hudson Orogen: a 30 Ma progressive deformation cycle

1995 ◽  
Vol 32 (7) ◽  
pp. 875-894 ◽  
Author(s):  
A. R. Norman ◽  
P. F. Williams ◽  
K. M. Ansdell
Keyword(s):  
Time Scales ◽  
Structural Evolution ◽  
Progressive Deformation ◽  
Early Proterozoic ◽  
Movement Vector ◽  
Deformation Cycle ◽  
Southern Margin ◽  
Flin Flon ◽  
Relationship Of ◽  
The Relationship

Fold axes and lineations across the southern margin of the Kisseynew gneiss belt were progressively reoriented from northwesterly to northeasterly during an Early Proterozoic, southwest-directed, compressive deformation cycle. Partitioning of deformation resulted in a concentration of non-coaxial strain along the boundary between the Kisseynew gneiss belt and Flin Flon–Snow Lake belt. The structural evolution was complicated by streamlining of the movement vector around the comparatively rigid Flin Flon–Snow Lake belt. The relationship of metamorphic assemblages to kinematic fabrics indicates that deformation was coeval with a prograde–retrograde metamorphic cycle. Progressive deformation occurred during a period of 30 Ma, which is consistent with Phanerozoic orogenic time scales.

Structural evolution of an early Proterozoic strata-bound Cu-Co-Zn deposit, Outokumpu, Finland

1981 ◽  
Vol 72 (2) ◽  
pp. 115-158 ◽  
Author(s):  
T. J. Koistinen
Keyword(s):  
Structural Evolution ◽  
Ocean Floor ◽  
Convective System ◽  
Mica Schist ◽  
Early Proterozoic ◽  
Polyphase Deformation ◽  
Mineral Assemblages ◽  
Show Evidence ◽  
Stratigraphic Position ◽  
Black Schist

ABSTRACTThe massive pyrite-pyrrhotite-chalcopyrite-sphalerite deposit of Outokumpu, comprising the Keretti and Vuonos orebodies, is a deformed and metamorphosed strata-bound mass associated with mineralised stockworks. Mobilisation of much of the ore followed formation of large recumbent isoclinal folds that are the major structures of the surrounding rocks and associated with the modification of originally flat saucer-shaped ore lenses into elongate ruler-shaped masses. Further modification of shape took place at the mobilisation stage with much of the pyrrhotitic ore, particularly, now occupying the thickest parts of the orebodies in the form of breccia or microbreccia. In many parts gross original characters still exist and the pyritic and pyrrhotitic constituents of the ore have survived as separate entities while locally the pyritic ore retains pre-deformational characteristics and consistent stratigraphic position within a thin horizon.Both ore and country rocks show evidence of extensive polyphase deformation with the effects of six fold phases shown in the ore. Mineral assemblages in the country rocks indicate a middle amphibolite facies peak of metamorphism. The serpentinite-black schist-carbonate-quartzite rock assemblage, with which the ore is associated, was tectonically incorporated within the regionally extensive mica schist by even earlier subhorizontal thrusting. This is related to the movement of a thrust nappe with the interdigitation of an ocean-floor ophiolite assemblage and flysch deposited during ocean closure associated with Svecokarelian tectonism.The original formation of the Keretti and Vuonos sulphide masses took place in a marine exhalative environment with a pyritic layer overlying a pyrrhotitic layer in each of the two c. 4 km diameter irregularly oval-shaped depressions whose centres were c. 8 km apart. The mineralised stockwork below each mass represents the upper parts of the conduit for metalbearing fluids in a convective system.

Age and timing of igneous activity in the Temagami greenstone belt, Ontario: a preliminary report

1991 ◽  
Vol 28 (11) ◽  
pp. 1873-1876 ◽  
Author(s):  
R. J. Bowins ◽  
L. M. Heaman
Keyword(s):  
Greenstone Belt ◽  
Preliminary Report ◽  
Superior Province ◽  
Early Proterozoic ◽  
The North ◽  
Intrusive Rocks ◽  
Abitibi Subprovince ◽  
Igneous Activity ◽  
The Town ◽  
Volcanic Cycle

The southernmost remnants of Archean supracrustal and intrusive rocks in eastern Ontario are exposed through a window in the Early Proterozoic Huronian Supergroup near the town of Temagami. U–Pb zircon ages from this area indicate the presence of some of the oldest felsic magmatism so far discovered in this portion of the Superior Province. The Iceland Lake pluton (2736 ± 2 Ma) and a nearby rhyolite flow ([Formula: see text]) are contemporaneous, which establishes that at least some of the intrusive rocks in the region are synvolcanic and coeval with the oldest volcanic cycle. The youngest plutonic activity is the emplacement of a late rhyolite porphyry dike at 2687 ± 2 Ma, an age that is bracketed by the 2675–2700 Ma emplacement ages of late internal plutons found throughout the Abitibi Subprovince. The 2736 Ma dates, however, are older than the nearest portion of the exposed Abitibi, some 120 km to the north near Kirkland Lake.

Progress report on 21-cm observations at low latitude between longitudes (l 11) 0° and 66°

1967 ◽  
Vol 31 ◽  
pp. 177-179
Author(s):  
W. W. Shane
Keyword(s):  
Preliminary Report ◽  
Progress Report ◽  
Galactic Centre ◽  
Low Latitude ◽  
The Third ◽  
Introductory Lecture ◽  
Centre Region

In the course of several 21-cm observing programmes being carried out by the Leiden Observatory with the 25-meter telescope at Dwingeloo, a fairly complete, though inhomogeneous, survey of the regionl11= 0° to 66° at low galactic latitudes is becoming available. The essential data on this survey are presented in Table 1. Oort (1967) has given a preliminary report on the first and third investigations. The third is discussed briefly by Kerr in his introductory lecture on the galactic centre region (Paper 42). Burton (1966) has published provisional results of the fifth investigation, and I have discussed the sixth in Paper 19. All of the observations listed in the table have been completed, but we plan to extend investigation 3 to a much finer grid of positions.

Sign in / Sign up

Export Citation Format

Share Document