ARTYKUŁY NAUKOWE Wposzukiwaniu fragmentów najstarszej skorupy kontynentalnej na Labradorze

Monika A. Kusiak, Anna Sałacińska


Searching for pieces of the oldest crust in Labrador.
A b s t r a c t. There are few unresolved questions in the Earth Sciences which generate as much debate as the nature of the Hadean Earth: i.e. the rock record between theEarth’s formation and about 3.8 billion years ago. Current knowledge of the nature and origin of the earliest crust comes largely from studies of the mineral zircon (ZrSiO4). The oldest zircon grains on Earth (4.46 Ga) are found in Jack Hills, Australia. They represent a time capsule of what the Earth was like from ca. 4.4–4.0 Ga during the Hadean. The other ancien rocks (>3.8 Ga) are preserved in Antarctica, Canada, China, Greenland, Labrador, Western Australia and Swaziland, with the oldest known rocks on Earth from the Acasta gneiss in Northern Canada, dated at 4.03 Ga. Most likely, the second oldest rock record in the world (>3.9 Ga) may be derived from the Nanok gneiss in the Nain Complex of the Saglek–Hebron area in the northern part of the Labrador Peninsula. Extensive investigation of these rocks will allow further characterizing the nature of the earliest preserved crust.

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