Plate tectonics at 3.8-3.7 Ga

Field evidence from the Isua Accretionary Complex, southern West Greenland

Tsuyoshi Komiya, Shigenori Maruyama, Toshiaki Masuda, Susumu Nohda, Mamoru Hayashi, Kazuaki Okamoto

Research output: Contribution to journalArticle

194 Citations (Scopus)

Abstract

A 1:5000 scale mapping was performed in the Isukasia area of the ca. 3.8-Ga Isua supracrustal belt, southern West Greenland. The mapped area is divided into three units bounded by low-angle thrusts: the Northern, Middle, and Southern Units. The Southern Unit, the best exposed, is composed of 14 subunits (horses) with similar lithostratigraphy, bound by layer-parallel thrusts. Duplex structures are widespread in the Isua belt and vary in scale from a few meters to kilometers. Duplexing proceeded from south to north and is well documented in the relationship between link- and roof-thrusts. The reconstructed lithostratigraphy of each horse reveals a simple pattern, in ascending order, of greenstone with low-K tholeiitic composition with or without pillow lava structures, chert/banded iron-formation, and turbidites. The cherts and underlying low-K tholeiites do not contain continent- or arc-derived material. The lithostratigraphy is quite similar to Phanerozoic 'oceanic plate stratigraphy,' except for the abundance of mafic material in the turbidites. The evidence of duplex structures and oceanic plate stratigraphy indicates that the Isua supracrustal belt is the oldest accretionary complex in the world. The dominantly mafic turbidite composition suggests that the accretionary complex was formed in an intraoceanic environment comparable to the present-day western Pacific Ocean. The duplex polarity suggests that an older accretionary complex should occur to the south of Isua complex. Moreover, the presence of seawater (documented by a thick, pillow, lava unit at the bottom of oceanic plate stratigraphy) indicates that the surface temperature was less than ca. 100°C in the Early Archean. The oceanic geotherm for the Early Archean lithosphere as a function of age was calculated based on a model of transient half-space cooling at given parameters of surface and mantle temperatures of 100°and 1450°C, respectively, suggesting that the Archean oceanic lithosphere was rigid. These conclusions-rigidity and lateral plate movement-support the idea that the modern style of plate tectonics was in operation only 0.7-0.8 G.yr. after the formation of the Earth.

Original languageEnglish
Pages (from-to)515-554
Number of pages40
JournalJournal of Geology
Volume107
Issue number5
DOIs
Publication statusPublished - Sep 1999
Externally publishedYes

Fingerprint

lithostratigraphy
duplex
plate tectonics
pillow lava
Archean
stratigraphy
thrust
horse
banded iron formation
greenstone
oceanic lithosphere
chert
half space
turbidite
rigidity
Phanerozoic
roof
lithosphere
surface temperature
mantle

ASJC Scopus subject areas

  • Geology

Cite this

Komiya, T., Maruyama, S., Masuda, T., Nohda, S., Hayashi, M., & Okamoto, K. (1999). Plate tectonics at 3.8-3.7 Ga: Field evidence from the Isua Accretionary Complex, southern West Greenland. Journal of Geology, 107(5), 515-554. https://doi.org/10.1086/314371

Plate tectonics at 3.8-3.7 Ga : Field evidence from the Isua Accretionary Complex, southern West Greenland. / Komiya, Tsuyoshi; Maruyama, Shigenori; Masuda, Toshiaki; Nohda, Susumu; Hayashi, Mamoru; Okamoto, Kazuaki.

In: Journal of Geology, Vol. 107, No. 5, 09.1999, p. 515-554.

Research output: Contribution to journalArticle

Komiya, T, Maruyama, S, Masuda, T, Nohda, S, Hayashi, M & Okamoto, K 1999, 'Plate tectonics at 3.8-3.7 Ga: Field evidence from the Isua Accretionary Complex, southern West Greenland', Journal of Geology, vol. 107, no. 5, pp. 515-554. https://doi.org/10.1086/314371
Komiya, Tsuyoshi ; Maruyama, Shigenori ; Masuda, Toshiaki ; Nohda, Susumu ; Hayashi, Mamoru ; Okamoto, Kazuaki. / Plate tectonics at 3.8-3.7 Ga : Field evidence from the Isua Accretionary Complex, southern West Greenland. In: Journal of Geology. 1999 ; Vol. 107, No. 5. pp. 515-554.
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