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Article: A non–plate tectonic model for the Eoarchean Isua supracrustal belt

TitleA non–plate tectonic model for the Eoarchean Isua supracrustal belt
Authors
KeywordsCrust-mantle dynamics
Field constraints
Field observations
Isua supracrustal belts
Metamorphic conditions
Issue Date2020
PublisherGeoScienceWorld. The Journal's web site is located at https://pubs.geoscienceworld.org/lithosphere
Citation
Lithosphere, 2020, v. 12 n. 1, p. 166-179 How to Cite?
AbstractThe ca. 3.8–3.6-b.y.-old Isua supracrustal belt of SW Greenland is Earth’s only site older than 3.2 Ga that is exclusively interpreted via plate-tectonic theory. The belt is divided into ca. 3.8 Ga and ca. 3.7 Ga halves, and these are interpreted as plate fragments that collided by ca. 3.6 Ga. However, such models are based on idiosyncratic interpretations of field observations and U-Pb zircon data, resulting in intricate, conflicting stratigraphic and structural interpretations. We reanalyzed published geochronological work and associated field constraints previously interpreted to show multiple plate-tectonic events and conducted field-based exploration of metamorphic and structura l gradients previously interpreted to show heterogeneities recording plate-tectonic processes. Simpler interpretations are viable, i.e., the belt may have experienced nearly homogeneous metamorphic conditions and strain during a single deformation event prior to intrusion of ca. 3.5 Ga mafic dikes. Curtain and sheath folds occur at multiple scales throughout the belt, with the entire belt potentially representing Earth’s largest a-type fold. Integrating these findings, we present a new model in which two cycles of volcanic burial and resultant melting and tonalite-trondhjemite-granodiorite (TTG) intrusion produced first the ca. 3.8 Ga rocks and then the overlying ca. 3.7 Ga rocks, after which the whole belt was deformed and thinned in a shear zone, producing the multiscale a-type folding patterns. The Eoarchean assembly of the Isua supracrustal belt is therefore most simply explained by vertical stacking of volcanic and intrusive rocks followed by a single shearing event. In combination with well-preserved Paleoarchean terranes, these rocks record the waning downward advection of lithosphere inherent in volcanism-dominated heat-pipe tectonic models for early Earth. These interpretations are consistent with recent findings that early crust-mantle dynamics are remarkably similar across the solar system’s terrestrial bodies.
Persistent Identifierhttp://hdl.handle.net/10722/290901
ISSN
2023 Impact Factor: 1.8
2023 SCImago Journal Rankings: 0.490
ISI Accession Number ID

 

DC FieldValueLanguage
dc.contributor.authorWebb, AAG-
dc.contributor.authorMüller, T-
dc.contributor.authorZUO, J-
dc.contributor.authorHaproff, PJ-
dc.contributor.authorRamírez-Salazar, A-
dc.date.accessioned2020-11-02T05:48:42Z-
dc.date.available2020-11-02T05:48:42Z-
dc.date.issued2020-
dc.identifier.citationLithosphere, 2020, v. 12 n. 1, p. 166-179-
dc.identifier.issn1941-8264-
dc.identifier.urihttp://hdl.handle.net/10722/290901-
dc.description.abstractThe ca. 3.8–3.6-b.y.-old Isua supracrustal belt of SW Greenland is Earth’s only site older than 3.2 Ga that is exclusively interpreted via plate-tectonic theory. The belt is divided into ca. 3.8 Ga and ca. 3.7 Ga halves, and these are interpreted as plate fragments that collided by ca. 3.6 Ga. However, such models are based on idiosyncratic interpretations of field observations and U-Pb zircon data, resulting in intricate, conflicting stratigraphic and structural interpretations. We reanalyzed published geochronological work and associated field constraints previously interpreted to show multiple plate-tectonic events and conducted field-based exploration of metamorphic and structura l gradients previously interpreted to show heterogeneities recording plate-tectonic processes. Simpler interpretations are viable, i.e., the belt may have experienced nearly homogeneous metamorphic conditions and strain during a single deformation event prior to intrusion of ca. 3.5 Ga mafic dikes. Curtain and sheath folds occur at multiple scales throughout the belt, with the entire belt potentially representing Earth’s largest a-type fold. Integrating these findings, we present a new model in which two cycles of volcanic burial and resultant melting and tonalite-trondhjemite-granodiorite (TTG) intrusion produced first the ca. 3.8 Ga rocks and then the overlying ca. 3.7 Ga rocks, after which the whole belt was deformed and thinned in a shear zone, producing the multiscale a-type folding patterns. The Eoarchean assembly of the Isua supracrustal belt is therefore most simply explained by vertical stacking of volcanic and intrusive rocks followed by a single shearing event. In combination with well-preserved Paleoarchean terranes, these rocks record the waning downward advection of lithosphere inherent in volcanism-dominated heat-pipe tectonic models for early Earth. These interpretations are consistent with recent findings that early crust-mantle dynamics are remarkably similar across the solar system’s terrestrial bodies.-
dc.languageeng-
dc.publisherGeoScienceWorld. The Journal's web site is located at https://pubs.geoscienceworld.org/lithosphere-
dc.relation.ispartofLithosphere-
dc.rightsLithosphere. Copyright © GeoScienceWorld.-
dc.rightsThis work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.-
dc.subjectCrust-mantle dynamics-
dc.subjectField constraints-
dc.subjectField observations-
dc.subjectIsua supracrustal belts-
dc.subjectMetamorphic conditions-
dc.titleA non–plate tectonic model for the Eoarchean Isua supracrustal belt-
dc.typeArticle-
dc.identifier.emailWebb, AAG: aagwebb@hku.hk-
dc.identifier.authorityWebb, AAG=rp02135-
dc.description.naturepublished_or_final_version-
dc.identifier.doi10.1130/L1130.1-
dc.identifier.scopuseid_2-s2.0-85081737549-
dc.identifier.hkuros318499-
dc.identifier.volume12-
dc.identifier.issue1-
dc.identifier.spage166-
dc.identifier.epage179-
dc.identifier.isiWOS:000517774400010-
dc.publisher.placeUnited States-
dc.identifier.issnl1947-4253-

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