A Vestige of Earth's Oldest Ophiolite

A sheeted-dike complex within the ∼3.8-billion-year-old Isua supracrustal belt (ISB) in southwest Greenland provides the oldest evidence of oceanic crustal accretion by spreading. The geochemistry of the dikes and associated pillow lavas demonstrates an intraoceanic island arc and mid-ocean ridge–li...

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Bibliographic Details
Published in:Science
Main Authors: Furnes, Harald, de Wit, Maarten, Staudigel, Hubert, Rosing, Minik, Muehlenbachs, Karlis
Format: Article in Journal/Newspaper
Language:English
Published: American Association for the Advancement of Science (AAAS) 2007
Subjects:
Greenland
Online Access:http://dx.doi.org/10.1126/science.1139170
https://www.science.org/doi/pdf/10.1126/science.1139170
Description
Summary:A sheeted-dike complex within the ∼3.8-billion-year-old Isua supracrustal belt (ISB) in southwest Greenland provides the oldest evidence of oceanic crustal accretion by spreading. The geochemistry of the dikes and associated pillow lavas demonstrates an intraoceanic island arc and mid-ocean ridge–like setting, and their oxygen isotopes suggest a hydrothermal ocean-floor–type metamorphism. The pillows and dikes are associated with gabbroic and ultramafic rocks that together make up an ophiolitic association: the Paleoarchean Isua ophiolite complex. These sheeted dikes offer evidence for remnants of oceanic crust formed by sea-floor spreading of the earliest intact rocks on Earth.

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