scholarly journals Paleomagnetic data and U-Pb isotopic age determinations from Coats Land, Antarctica: Implications for late Proterozoic plate reconstructions

1997 ◽  
Vol 102 (B4) ◽  
pp. 7887-7902 ◽  
Author(s):  
Wulf A. Gose ◽  
Mark A. Helper ◽  
James N. Connelly ◽  
Fred E. Hutson ◽  
Ian W. D. Dalziel
Keyword(s):  
Paleomagnetic Data ◽  
Isotopic Age ◽  
Late Proterozoic ◽  
Plate Reconstructions ◽  
Age Determinations

scholarly journals Precambrian crystalline basement at the head of Victoria Fjord, North Greenland

1985 ◽  
Vol 126 ◽  
pp. 11-16
Author(s):  
N Henriksen ◽  
H.F Jepsen
Keyword(s):  
Lower Cambrian ◽  
Small Area ◽  
Crystalline Rocks ◽  
Crystalline Basement ◽  
Amphibolite Facies ◽  
Isotopic Age ◽  
Late Proterozoic ◽  
Inland Ice ◽  
North Greenland ◽  
Age Determinations

Precambrian granites and gneisses outcrop below late Proterozoic and Lower Cambrian sediments in a small area at the margin of the Inland Ice. The exposed crystalline rocks comprise orthogneisses with scattered amphibolite bands, and occasional horizons of metasediments. The rocks are folded, somewhat migmatised and metamorphosed under amphibolite facies conditions. Samples for Rb-Sr whole rock and Zr isotopic age determinations have been collected.

scholarly journals Isotopic age dating in Liverpool Land, East Greenland

1987 ◽  
Vol 134 ◽  
pp. 25-37
Author(s):  
B.T Hansen ◽  
J.D Friderichsen
Keyword(s):  
Age Dating ◽  
Isotopic Age ◽  
Pb Isotope ◽  
East Greenland ◽  
Isotope Age ◽  
Caledonian Orogeny ◽  
Plutonic Rocks ◽  
Age Determinations ◽  
Late Part

In Liverpool Land in the eastern part of the Scoresby Sund region gneisses and migmatites were intruded by a number of intermediate plutonites and by younger granites. A number of K-Ar, Rb-Sr and U-Pb isotope age determinations indicate that: 1) the gneisses have a pre-CaIedonian as well as a CaIedonian history, 2) the migmatites were thoroughly reworked during the late part of the Caledonian orogeny, while 3) the plutonic rocks all seem to have been intruded during the Caledonian orogeny.

scholarly journals Mapping in the Fiskefjord area, southern West Greenland

1982 ◽  
Vol 110 ◽  
pp. 55-57
Author(s):  
A.A Garde ◽  
V.R McGregor
Keyword(s):  
Granulite Facies ◽  
Amphibolite Facies ◽  
Isotopic Age ◽  
Supracrustal Rock ◽  
Granulite Facies Metamorphism ◽  
West Greenland ◽  
Facies Metamorphism ◽  
Geological Work ◽  
Age Determinations

Previous geological work on the 1:100000 map sheet 64 V.l N (fig. 15) includes published maps of smaller areas by Berthelsen (1960, 1962) and Lauerma (1964), mapping by Kryolitselskabet Øresund A/S (Bridgwater et al., 1976) and mapping by GGU geologists for the 1:500000 map sheet Frederikshåb Isblink - Søndre Strømfjord (Allaart et al., 1977, 1978). The Amltsoq and Niik gneisses and Malene supracrustal rock units south and east of Godthåbsfjord have not so far been correlated with rocks in the Fiskefjord area. Godthåbsfjord separates the granulite facies gneisses in Nordlandet from amphibolite facies Nûk gneisses on Sadelø and Bjørneøen; the granulite facies metamorphism occurred at about 2850 m.y. (Black et al., 1973), while no published isotopic age determinations from the Fiskefjord area itself are available.

Isotopic age determinations on clay minerals from lavas and tuffs of the Derbyshire orefield

1972 ◽  
Vol 109 (6) ◽  
pp. 501-512 ◽  
Author(s):  
P. R. Ineson ◽  
J. G. Mitchell
Keyword(s):  
Clay Minerals ◽  
Hydrothermal Alteration ◽  
Igneous Rocks ◽  
The Other ◽  
Mineral Deposits ◽  
Isotopic Age ◽  
Hydrothermal Mineralization ◽  
Pumice Tuff ◽  
Southern Section ◽  
Age Determinations

SummaryEpisodic hydrothermal mineralization has previously been recognized in the northern section of the Pennine orefield. Igneous rocks from the southern section (the Derbyshire orefield) have yielded isotopic ages, some of which are thought to represent ages of hydrothermal metasomatism (deuteric or subsequent). In order to ascertain whether epicyclic hydrothermal events gave rise to the Derbyshire mineral deposits, samples of highly altered doleritic lava and pumice tuff were collected adjacent to areas of mineralization. Clay-mineral concentrates from 34 samples were dated by the potassium–argon method. The conclusions drawn from these analyses support a hypothesis of repeated hydrothermal alteration of the clay minerals, reflecting at least two episodes of mineralization, one about 270 m.y., the other about 235 m.y. The geo-chronological significance of these and other results is considered.

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