Geology of the Eoarchean, >3.95Ga, Nulliak supracrustal rocks in the Saglek Block, northern Labrador, Canada: the oldest geological evidence for plate tectonics

Komiya, Tsuyoshi, Yamamoto, Shinji, Aoki, Shogo, Sawaki, Yusuke, Ishikawa, Akira, Tashiro, Takayaki, Koshida, Keiko, Shimojo, Masanori, Aoki, Kazumasa and Collerson, Kenneth D. (2015) Geology of the Eoarchean, >3.95Ga, Nulliak supracrustal rocks in the Saglek Block, northern Labrador, Canada: the oldest geological evidence for plate tectonics. Tectonophysics, 662 40-66. doi:10.1016/j.tecto.2015.05.003

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Author Komiya, Tsuyoshi
Yamamoto, Shinji
Aoki, Shogo
Sawaki, Yusuke
Ishikawa, Akira
Tashiro, Takayaki
Koshida, Keiko
Shimojo, Masanori
Aoki, Kazumasa
Collerson, Kenneth D.
Title Geology of the Eoarchean, >3.95Ga, Nulliak supracrustal rocks in the Saglek Block, northern Labrador, Canada: the oldest geological evidence for plate tectonics
Journal name Tectonophysics   Check publisher's open access policy
ISSN 0040-1951
Publication date 2015
Sub-type Article (original research)
DOI 10.1016/j.tecto.2015.05.003
Open Access Status File (Author Post-print)
Volume 662
Start page 40
End page 66
Total pages 27
Place of publication Amsterdam, Netherlands
Publisher Elsevier
Collection year 2016
Language eng
Abstract The Earth is a unique planet, which has been highly evolved, diversified and complicated through geologic time, and underwent many key events, including giant impact, magma ocean, core formation, large-scale mantle differentiation and late heavy bombardment, especially in its dawn. But, our knowledge of early Earth is limited due to the lack of the Hadean supracrustal rocks. The supracrustal rocks with the Eoarchean ages provide key evidence for the Earth's early evolution, but few supracrustal rocks have been comprehensively investigated. Therefore, we mapped in seven areas of the Saglek Block, northern Labrador, where ancient supracrustal sequences are interleaved with a diverse assemblage of orthogneisses. Early studies suggested that some of them have the Mesoarchean ages because of the lack of the Mesoarchean Saglek dyke, but we found the Saglek dykes in the areas to recognize the Eoarchean Nulliak supracrustal rocks and Uivak Gneiss in all the areas. Recent reassessment of U–Pb dating and cathodoluminescence observation of zircons from the oldest suites of the Uivak Gneiss showed that the Uivak Gneiss has the Eoarchean age, > 3.95 Ga, and forms the Iqaluk–Uivak Gneiss series. Because our geological survey clearly showed that the Iqaluk–Uivak Gneisses were intruded into the Nulliak supracrustal belts, the Nulliak supracrustal rocks are the oldest supracrustal rock in the world. The supracrustal belts consist of piles of fault-bounded blocks, which are composed of the ultramafic rocks, mafic rocks and sedimentary rocks in ascending order, similar to modern ocean plate stratigraphy (OPS). In addition, small-scale duplex structures are found over the areas. The presence of duplex structure and OPS indicates that the > 3.95 Ga Nulliak supracrustal belts originate from an accretionary complex. The presence of the accretionary complex, ophiolite and granitic continental crust provides the oldest evidence for the plate tectonics on the early Earth.
Keyword Eoarchean
Supracrustal rocks
Accretionary complex
Ocean plate stratigraphy
Plate tectonics
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: School of Earth Sciences Papers
Official 2016 Collection
 
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