13C Depleted Carbon Microparticles in > 3700 Ma Sea Floor Sediments from the Isua Supracrustal Belt, West Greenland: Implications for Earth's Earliest Habitats?

1998 ◽  
Vol 62A (3) ◽  
pp. 1293-1294 ◽  
Author(s):  
M. T. Rosing
Keyword(s):  
Sea Floor ◽  
West Greenland ◽  
Supracrustal Belt

Early Tertiary basalts from the Labrador Sea floor and Davis Strait region

1989 ◽  
Vol 26 (5) ◽  
pp. 956-968 ◽  
Author(s):  
D. B. Clarke ◽  
B. I. Cameron ◽  
G. K. Muecke ◽  
J. L. Bates
Keyword(s):  
Volcanic Rocks ◽  
Labrador Sea ◽  
Baffin Island ◽  
Nd Isotope ◽  
Sea Floor ◽  
West Greenland ◽  
Depleted Mantle ◽  
Davis Strait ◽  
Isotope Systematics ◽  
Seawater Exchange

Fine- to medium-grained, phyric and aphyric basalt samples from ODP Leg 105, site 647A, in the Labrador Sea show little evidence of alteration. Chemically, these rocks are low-potassium (0.01–0.09 wt.% K2O), olivine- to quartz-normative tholeiites that compare closely with the very depleted terrestrial Paleocene volcanic rocks in the Davis Strait region of Baffin Island and West Greenland. However, differences exist in the Sr–Nd isotope systematics of the two suites; the Labrador Sea samples have ε Nd values (+9.3) indicative of a more depleted source, and are higher in 87Sr/86Sr (0.7040), relative to the Davis Strait basalts (ε Nd +2.54 to +8.97; mean 87Sr/86Sr 0.7034). The higher 87Sr/86Sr in the Labrador Sea samples may reflect seawater exchange despite no petrographic evidence for significant alteration. The Labrador Sea and early Davis Strait basalts may have been derived from a similar depleted mantle source composition; however, the later Davis Strait magmas were generated from a different mantle. None of the Baffin Island, West Greenland, or Labrador Sea samples show unequivocal geochemical evidence for contamination with continental crust.

scholarly journals Further work on the early Archaean rocks of the Isukasia area, southern West Greenland

1982 ◽  
Vol 110 ◽  
pp. 49-54
Author(s):  
A.P Nutman
Keyword(s):  
Field Work ◽  
Regional Mapping ◽  
West Greenland ◽  
North East ◽  
The North ◽  
Starting Point ◽  
Supracrustal Belt ◽  
Geochemical Studies

Work in 1981 on the early Archaean rocks of the Isukasia area (Ailaart, 1976) was an integral part of GGU's mapping programme of northern Godthåbsfjord, Fiskefjord and adjacent areas to the north-east. Within the Isukasia area, there was dose co-operation with Minik Rosing who was making detailed studies of certain aspects of the Isua supracrustal belt. The object of this summer's field work was to complete the study of the supracrustal belt and the central gneisses that was started last year (Nutman et al., in press), and to see as much as possibIe of the gneisses between the supracrustal belt and 65°N (fig. 18). For the mapping of the supracrustal belt, manuscript maps drawn by J. H. Allaart were an invaluable starting point. Besides regional mapping, detailed studies were made of the nature of the lithological units and the relationships between them; see Table 4 for chronology. Suites of rocks were collected for isotopic and geochemical studies. In connection with this, H. Baadsgaard spent 10 days working with the author in the area, as a guest of GGu. The results reported here supplement those given by Nutman et al. (in press).

scholarly journals Project Westmar, A shallow marine geophysical survey on the West Greenland continental shelf

1979 ◽  
Vol 87 ◽  
pp. 1-29
Author(s):  
C.P Brett ◽  
E.F.K Zarudzki
Keyword(s):  
Continental Shelf ◽  
Geophysical Survey ◽  
The West ◽  
Shallow Marine ◽  
Western Margin ◽  
Sea Floor ◽  
West Greenland ◽  
Maximum Water ◽  
Shelf Margin ◽  
Morphological Relationship

An extensive shallow geophysical survey has been carried out on the West Greenland continental shelf between 64° and 69°30'N. Preliminary interpretation of the data reveals that between 64° and 67°30'N at least, the entire shelf was glaciated to its western margin during the Pleistocene, the glaciation processes leaving a variable (< 20-200 m thick) cover on the Tertiary sedimentary wedge underlying the shelf. A morphological relationship exists between the degree of sea floor roughness and the types of glaciation forms. The distribution and contacts of the three main shallow bedrock units in the area (Precambrian gneisses, Lower Tertiary volcanics and Tertiary sediments) are delineated. Widespread prograding is observed in sediments along the shelf margin. Extensive iceberg scouring of the sea floor is observed north of 67°30'N reaching a maximum water depth of 340 m.

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