A prolonged granitoid formation in Saglek Block, Labrador: Zonal growth and crustal reworking of continental crust in the Eoarchean

Komiya, Tsuyoshi; Yamamoto, Shinji; Aoki, Shogo; Koshida, Keiko; Shimojo, Masanori; Sawaki, Yusuke; Aoki, Kazumasa; Sakata, Shuhei; Yokoyama, Tomoya; Maki, Kazushige; Ishikawa, Akira; Hirata, Takafumi; Collerson, K. D.

doi:10.1016/j.gsf.2016.06.013

Cited by 34 publications

(30 citation statements)

References 91 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The styles of deformation are similar, at all scales, throughout time, and the mineralogical and geochemical components are the same in similar plate boundary settings (Keller and Schoene, 2018). It is clear from the geological record that plate tectonics, in a form similar to that of today, has operated on planet Earth since at least 4.0 Ga, the age of the oldest preserved rocks, as documented by abundant geological, geochemical, isotopic, and theoretical data (Maruyama et al, 2018;Komiya et al, 2017;Nutman et al, 2015;Korenaga, 2013;Polat, 2012;Shibuya et al, 2010;Richardson and Shirey, 2008). Despite this, there are some differences between rocks produced by plate tectonics on the early Earth, and those produced by simi-lar processes in the modern world.…”

Section: Secular Changes In Plate Tectonic Style Through the Archeanmentioning

confidence: 88%

See 1 more Smart Citation

Geological Evidence for the Operation of Plate Tectonics throughout the Archean: Records from Archean Paleo-Plate Boundaries

2018

View full text Add to dashboard Cite

Plate tectonics describes the horizontal motion of rigid lithospheric plates away from midoceanic ridges and parallel to transforms, towards deep-sea trenches, where the oceanic lithosphere is subducted into the mantle. This process is the surface expression of modern-day heat loss from Earth. One of the biggest questions in Geosciences today is "when did plate tectonics begin on Earth" with a wide range of theories based on an equally diverse set of constraints from geology, geochemistry, numerical modeling, or pure speculation. In this contribution, we turn the coin over and ask "when was the last appearance in the geological record for which there is proof that plate tectonics did not operate on the planet as it does today". We apply the laws of uniformitarianism to the rock record to ask how far back in time is the geologic record consistent with presently-operating kinematics of plate motion, before which some other mechanisms of planetary heat loss may have been in operation. Some have suggested that evidence shows that there was no plate tectonics before 800 Ma ago, others sometime before 1.8-2.7 Ga, or before 2.7 Ga. Still others recognize evidence for plate tectonics as early as 3.0 Ga, 3.3-3.5 Ga, the age of the oldest rocks, or in the Hadean before 4.3 Ga. A key undiscussed question is: why is there such a diversity of opinion about the age at which plate tectonics can be shown to not have operated, and what criteria are the different research groups using to define plate tectonics, and to recognize evidence of plate tectonics in very old rocks? Here, we present and evaluate data from the rock record, constrained by relevant geochemical-isotopic data, and conclude that the evidence shows indubitably that plate tectonics has been operating at least since the formation of the oldest rocks, albeit with some differences in processes, compositions, and products in earlier times of higher heat generation and mantle temperature, weaker oceanic lithosphere, hotter subduction zones caused by more slab-melt generation, and under different biological and atmospheric conditions.

show abstract

Section: Secular Changes In Plate Tectonic Style Through the Archeanmentioning

confidence: 88%

“…Cleaverville (Kato et al, 1998); 3.5 Ga Pilbara (Kato and Nakamura, 2003); Saglek (Komiya et al, 2017(Komiya et al, , 2015. erupted through or deposited on older continental crust.…”

Section: Geological Evidence For the Operation Of Plate Tectonics In mentioning

confidence: 99%

Geological Evidence for the Operation of Plate Tectonics throughout the Archean: Records from Archean Paleo-Plate Boundaries

2018

View full text Add to dashboard Cite

show abstract

“…Younger ages for these rocks have however also been proposed, ranging between 3612 ± 130 Myr (Re-Os, Ishikawa et al, 2017) and 3782 ± 93 Myr (Sm-Nd, Morino et al, 2017). The complex has undergone a complicated protracted thermal history with several magmatic and metamorphic episodes (Komiya et al 2017;Kusiak et al 2017). The peak of metamorphism reached upper amphibolite to granulite facies occurred around 2600 to 2700 Myr (Schiøtte et al, 1989;Wendt and Collerson, 1999).…”

Section: Saglek Blockmentioning

confidence: 99%

Widespread occurrences of variably crystalline 13C-depleted graphitic carbon in banded iron formations

Dodd

She

Manikyamba

et al. 2019

Earth and Planetary Science Letters

View full text Add to dashboard Cite

Almost all evidence for the oldest traces of life on Earth rely on particles of graphitic carbon preserved in rocks of sedimentary protolith. Yet, the source of carbon in such ancient graphite is debated, as it could possibly be non-biological and/or non-indigenous in origin. Here we describe the co-occurrence of poorly crystalline and crystalline varieties of graphitic carbon with apatite in ten different and variably metamorphosed banded iron formations (BIF) ranging in age from 1,800 to >3,800 Myr. In Neoarchean to Palaeoproterozoic BIF subjected to low-grade metamorphism, 13 C-depleted graphitic carbon occurs as inclusions in apatite, and carbonate and arguably represents the remineralisation of syngenetic biomass. In BIF subjected to high-grade metamorphism, 13 C-depleted graphite co-occurs with poorly crystalline graphite (PCG), as well as apatite, carbonate, pyrite, amphibole and greenalite. Retrograde minerals such as greenalite, and veins cross-cutting magnetite layers contain PCG. Crystalline graphite can occur with apatite and orthopyroxene, and sometimes it has PCG coatings. Crystalline graphite is interpreted to represent the metamorphosed product of syngenetic organic carbon deposited in BIF, while poorly crystalline graphite was precipitated from CO -H fluids partially sourced from the syngenetic carbon, along with fluid-deposited apatite and carbonate. The isotopic signature of the graphitic carbon and the distribution of fluiddeposited graphite in highly metamorphosed BIF is consistent with carbon in the fluids being derived from the thermal cracking of syngenetic biomass deposited in BIF, but, extraneous sources of carbon cannot be ruled out as a source for PCG. The results here show that apatite + graphite is a common mineral assemblage in metamorphosed BIF. The mode of formation of this assemblage is, however, variable, which has important implications for the timing of life's emergence on Earth.

show abstract

“…These elements maintain constant ratios thereby reflecting their immobility during hydrothermal alteration and metamorphism. Further, high‐field‐strength elements (HFSE; such as, Nb, Ta, and Zr) serve as reliable geochemical proxies to constrain the tectonic environments associated with magmatism in oceanic and continental realms (Komiya et al, ). Immobile trace element compositions are effective indicators of the mantle source characteristics, crustal assimilation, and fractional crystallization.…”

Section: Discussionmentioning

confidence: 99%

An appraisal of geochemical signatures of komatiites from the greenstone belts of Dharwar Craton, India: Implications for temporal transition and Archean upper mantle hydration

2019

View full text Add to dashboard Cite

Archean ultramafic–mafic magmatism associated with dynamic mantle melting processes represents an integral part of crustal evolution and continental growth. Archean mantle plumes and their high temperature derivatives in komatiitic magmas provide a cornerstone in understanding the thermal and chemical evolution of the early Earth and its mantle. In this study, we evaluate the geochemical characteristics of the temporally distinct Sargur Group and Dharwar Supergroup greenstone belts of Dharwar Craton in southern India. The komatiites associated with these greenstone belts are characterized by Al‐depleted and Al‐undepleted compositions. Their MgO, Ni, Co, and Cr concentrations reflect primitive, undifferentiated nature of precursor melts, whereas the HFSE and REE chemistry corroborates high‐degree (30–50%) partial melting of mantle with prominent role of majorite garnet and perovskite in the generation of komatiitic melts. The Al‐depleted komatiites were formed at a greater depth (~13 GPa) by equilibrium melting leaving a garnet‐bearing residue. The resultant komatiitic melt retained buoyancy under extreme pressure and high temperature conditions, segregated and accumulated in the ambient peridotite mantle source and subsequently escaped with progressive decrease in pressure in the ascending plume. The Al‐undepleted and relatively rare Al‐enriched komatiites were derived by fractional melting at intermediate to shallow depths after the discharge of a large proportion of melt ensued by the collapse and entrance of residual garnet into the melt phase. The Mesoarchean–Neoarchean Dharwar komatiites provide evidence for heterogeneous, hydrated Archean upper mantle trapped by ascending mantle plumes. The non‐plume, arc‐related signatures invoke contributions from (a) sub‐cratonic lithospheric mantle roots influenced by ancient subduction events and (b) hydrated Archean upper mantle. The Sargur Group and Dharwar Supergroup komatiites record a distinct temporal transition and geochemical heterogeneity in the Archean mantle beneath the Dharwar Craton and can be attributed to Archean upper mantle hydration by flat slab subduction of >3.3 Ga oceanic crust at shallow level with vestiges of primordial oceanic crust forming deep cratonic mantle roots beneath the Dharwar Craton. The temporal transition towards mantle hydration beneath Dharwar Craton during the Mesoarchean can be correlated with the onset of subduction‐driven plate tectonics and ocean–crust–mantle interactions.

show abstract

A prolonged granitoid formation in Saglek Block, Labrador: Zonal growth and crustal reworking of continental crust in the Eoarchean

Cited by 34 publications

References 91 publications

Geological Evidence for the Operation of Plate Tectonics throughout the Archean: Records from Archean Paleo-Plate Boundaries

Geological Evidence for the Operation of Plate Tectonics throughout the Archean: Records from Archean Paleo-Plate Boundaries

Widespread occurrences of variably crystalline 13C-depleted graphitic carbon in banded iron formations

An appraisal of geochemical signatures of komatiites from the greenstone belts of Dharwar Craton, India: Implications for temporal transition and Archean upper mantle hydration

Contact Info

Product

Resources

About