Rates of generation and destruction of the continental crust: implications for continental growth

Less than 25% of the volume of the juvenile continental crust preserved today is older than 3 Ga, there are no known rocks older than approximately 4 Ga, and yet a number of recent models of continental growth suggest that at least 60–80% of the present volume of the continental crust had been generated by 3 Ga. Such models require that large volumes of pre-3 Ga crust were destroyed and replaced by younger crust since the late Archaean. To address this issue, we evaluate the influence on the rock record of changing the rates of generation and destruction of the continental crust at different times in Earth's history. We adopted a box model approach in a numerical model constrained by the estimated volumes of continental crust at 3 Ga and the present day, and by the distribution of crust formation ages in the present-day crust. The data generated by the model suggest that new continental crust was generated continuously, but with a marked decrease in the net growth rate at approximately 3 Ga resulting in a temporary reduction in the volume of continental crust at that time. Destruction rates increased dramatically around 3 billion years ago, which may be linked to the widespread development of subduction zones. The volume of continental crust may have exceeded its present value by the mid/late Proterozoic. In this model, about 2.6–2.3 times of the present volume of continental crust has been generated since Earth's formation, and approximately 1.6–1.3 times of this volume has been destroyed and recycled back into the mantle. This article is part of a discussion meeting issue ‘Earth dynamics and the development of plate tectonics'.

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The isotopic evolution of the Kohistan Ladakh arc from subduction initiation to continent arc collision

Geological Society London Special Publications ◽

10.1144/sp483.7 ◽

2018 ◽

Vol 483 (1) ◽

pp. 165-182 ◽

Cited By ~ 11

Author(s):

Oliver Jagoutz ◽

Pierre Bouilhol ◽

Urs Schaltegger ◽

Othmar Müntener

Keyword(s):

Continental Crust ◽

Subduction Zones ◽

Magmatic Evolution ◽

Crust Formation ◽

Secular Evolution ◽

Tethys Realm ◽

Isotopic Evolution ◽

History Of ◽

Active Locus

AbstractMagmatic arcs associated with subduction zones are the dominant active locus of continental crust formation, and evolve in space and time towards magmatic compositions comparable to that of continental crust. Accordingly, the secular evolution of magmatic arcs is crucial to the understanding of crust formation processes. In this paper we present the first comprehensive U–Pb, Hf, Nd and Sr isotopic dataset documenting c. 120 myr of magmatic evolution in the Kohistan-Ladakh paleo-island arc. We found a long-term magmatic evolution that is controlled by the overall geodynamic of the Neo-Tethys realm. Apart from the post-collisionnal melts, the intra-oceanic history of the arc shows two main episodes (150–80 Ma and 80–50 Ma) of distinct geochemical signatures involving the slab and the sub-arc mantle components that are intimately linked to the slab dynamics.

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Hydrated Peridotite – Basaltic Melt Interaction Part I: Planetary Felsic Crust Formation at Shallow Depth

Frontiers in Earth Science ◽

10.3389/feart.2021.640464 ◽

2021 ◽

Vol 9 ◽

Author(s):

Anastassia Y. Borisova ◽

Nail R. Zagrtdenov ◽

Michael J. Toplis ◽

Wendy A. Bohrson ◽

Anne Nédélec ◽

...

Keyword(s):

Continental Crust ◽

Plate Tectonics ◽

Mafic Magma ◽

Aqueous Fluid ◽

Early Earth ◽

Magma Ocean ◽

Crust Formation ◽

Basaltic Melt ◽

Low Pressures ◽

Direct Melting

Current theories suggest that the first continental crust on Earth, and possibly on other terrestrial planets, may have been produced early in their history by direct melting of hydrated peridotite. However, the conditions, mechanisms and necessary ingredients for this crustal formation remain elusive. To fill this gap, we conducted time-series experiments to investigate the reaction of serpentinite with variable proportions (from 0 to 87 wt%) of basaltic melt at temperatures of 1,250–1,300°C and pressures of 0.2–1.0 GPa (corresponding to lithostatic depths of ∼5–30 km). The experiments at 0.2 GPa reveal the formation of forsterite-rich olivine (Fo90–94) and chromite coexisting with silica-rich liquids (57–71 wt% SiO2). These melts share geochemical similarities with tonalite-trondhjemite-granodiorite rocks (TTG) identified in modern terrestrial oceanic mantle settings. By contrast, liquids formed at pressures of 1.0 GPa are poorer in silica (∼50 wt% SiO2). Our results suggest a new mechanism for the formation of the embryonic continental crust via aqueous fluid-assisted partial melting of peridotite at relatively low pressures (∼0.2 GPa). We hypothesize that such a mechanism of felsic crust formation may have been widespread on the early Earth and, possibly on Mars as well, before the onset of modern plate tectonics and just after solidification of the first ultramafic-mafic magma ocean and alteration of this primitive protocrust by seawater at depths of less than 10 km.

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Continental crust formation by crustal delamination in subduction zones and complementary accumulation of the enriched mantle I component in the mantle

Geochemistry Geophysics Geosystems ◽

10.1029/2000gc000094 ◽

2000 ◽

Vol 1 (12) ◽

pp. n/a-n/a ◽

Cited By ~ 86

Author(s):

Yoshiyuki Tatsumi

Keyword(s):

Continental Crust ◽

Subduction Zones ◽

Crust Formation ◽

Enriched Mantle

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Evaluating preservation bias in the continental growth record against the monazite archive

Geology ◽

10.1130/g49416.1 ◽

2021 ◽

Author(s):

Jacob A. Mulder ◽

Peter A. Cawood

Keyword(s):

Continental Crust ◽

Crustal Growth ◽

Strongly Correlated ◽

Crust Formation ◽

Zircon Age ◽

Selective Preservation ◽

Detrital Zircon Ages ◽

Collisional Orogens ◽

Continental Growth ◽

Collisional Orogenesis

Most recent models of continental growth are based on large global compilations of detrital zircon ages, which preserve a distinctly episodic record of crust formation over billion-year timescales. However, it remains unclear whether this uneven distribution of zircon ages reflects a true episodicity in the generation of continental crust through time or is an artifact of the selective preservation of crust isolated in the interior of collisional orogens. We address this issue by analyzing a new global compilation of monazite ages (n >100,000), which is comparable in size, temporal resolution, and spatial distribution to the zircon continental growth record and unambiguously records collisional orogenesis. We demonstrate that the global monazite and zircon age distributions are strongly correlated throughout most of Earth history, implying a link between collisional orogenesis and the preserved record of continental growth. Our findings support the interpretation that the continental crust provides a preservational, rather than generational, archive of crustal growth.

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Archaean Cratons Record a Duality of Melting Regimes During Early Continental Growth

10.21203/rs.3.rs-53939/v1 ◽

2020 ◽

Author(s):

S. Amrei Ladwig ◽

Priyadarshi Chowdhury ◽

Alex J. McCoy-West ◽

Oliver Nebel ◽

Peter Cawood

Keyword(s):

Rare Earth ◽

Plate Tectonics ◽

Direct Evidence ◽

Tectonic Setting ◽

Building Blocks ◽

Early Earth ◽

Crust Formation ◽

Mineral Assemblages ◽

Ree Patterns ◽

Continental Growth

Abstract The tectonic setting and pressure-temperature conditions responsible for the formation of felsic crust on the early Earth remain debated. Rare earth elements (REE) have been extensively used to study the formation of tonalite-trondhjemites-granodiorites (TTGs)- the building blocks of the early felsic crust, but conclusive interpretations based on the chondrite-normalized REE patterns have not materialised because of the inability to distinguish subtle differences. Here we apply a polynomial approach that quantifies the REE patterns by describing their slope and curvature using shaping coefficients to the TTG compositions from five different Archaean cratons. In combination with partial melting modelling, this enables an assessment of the effects of variations in pressure-temperature, degree of melting and residual mineral assemblages on the formation of TTGs. The REE composition of the Archaean TTGs display two distinct trends: (1) a horizontal-trend suggesting their formation in the presence of garnet-poor amphibolitic residues, possibly formed at the base of a thickened crust; and, (2) an inclined-trend consistent with their formation in equilibration with amphibole-poor, but garnet-rich residues at convergent settings (but not necessarily related to plate tectonics). These different melting regimes coexisted during the Paleoarchaean to Neoarchaean and provide direct evidence for a duality of petro-tectonic regimes of felsic crust formation on the early Earth.

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Crustal evolution and mantle dynamics through Earth history

Philosophical Transactions of The Royal Society A Mathematical Physical and Engineering Sciences ◽

10.1098/rsta.2017.0408 ◽

2018 ◽

Vol 376 (2132) ◽

pp. 20170408 ◽

Cited By ~ 30

Author(s):

Jun Korenaga

Keyword(s):

Continental Crust ◽

Mantle Convection ◽

Plate Tectonics ◽

Indirect Evidence ◽

Quantitative Model ◽

Early Earth ◽

Mantle Dynamics ◽

Earth History ◽

Geological Processes ◽

Earth Dynamics

Resolving the modes of mantle convection through Earth history, i.e. when plate tectonics started and what kind of mantle dynamics reigned before, is essential to the understanding of the evolution of the whole Earth system, because plate tectonics influences almost all aspects of modern geological processes. This is a challenging problem because plate tectonics continuously rejuvenates Earth's surface on a time scale of about 100 Myr, destroying evidence for its past operation. It thus becomes essential to exploit indirect evidence preserved in the buoyant continental crust, part of which has survived over billions of years. This contribution starts with an in-depth review of existing models for continental growth. Growth models proposed so far can be categorized into three types: crust-based, mantle-based and other less direct inferences, and the first two types are particularly important as their difference reflects the extent of crustal recycling, which can be related to subduction. Then, a theoretical basis for a change in the mode of mantle convection in the Precambrian is reviewed, along with a critical appraisal of some popular notions for early Earth dynamics. By combining available geological and geochemical observations with geodynamical considerations, a tentative hypothesis is presented for the evolution of mantle dynamics and its relation to surface environment; the early onset of plate tectonics and gradual mantle hydration are responsible not only for the formation of continental crust but also for its preservation as well as its emergence above sea level. Our current understanding of various material properties and elementary processes is still too premature to build a testable, quantitative model for this hypothesis, but such modelling efforts could potentially transform the nature of the data-starved early Earth research by quantifying the extent of preservation bias.This article is part of a discussion meeting issue ‘Earth dynamics and the development of plate tectonics’.

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Up the down escalator: the exhumation of (ultra)-high pressure terranes during on-going subduction

Solid Earth Discussions ◽

10.5194/sed-4-745-2012 ◽

2012 ◽

Vol 4 (1) ◽

pp. 745-781 ◽

Cited By ~ 5

Author(s):

C. J. Warren

Keyword(s):

High Pressure ◽

Subduction Zone ◽

Continental Crust ◽

Subduction Zones ◽

Crustal Material ◽

Time And Space ◽

Ultra High Pressure ◽

Tectonic Environment ◽

Tectonic Style ◽

Weak Material

Abstract. The exhumation of high and ultra-high pressure rocks is ubiquitous in Phanerozoic orogens created during continental collisions, and is common in many ocean-ocean and ocean-continent subduction zone environments. Three different tectonic environments have previously been reported, which exhume deeply buried material by different mechanisms and at different rates. However it is becoming increasingly clear that no single mechanism dominates in any particular tectonic environment, and the mechanism may change in time and space within the same subduction zone. In order for buoyant continental crust to subduct, it must remain attached to a stronger and denser substrate, but in order to exhume, it must detach (and therefore at least locally weaken) and be initially buoyant. Denser oceanic crust subducts more readily than more buoyant continental crust but exhumation must be assisted by entrainment within more buoyant and weak material such as serpentinite or driven by the exhumation of structurally lower continental crustal material. Weakening mechanisms responsible for the detachment of crust at depth include strain, hydration, melting, grain size reduction and the development of foliation. These may act locally or may act on the bulk of the subducted material. Metamorphic reactions, metastability and the composition of the subducted crust all affect buoyancy and overall strength. Subduction zones change in style both in time and space, and exhumation mechanisms change to reflect the tectonic style and overall force regime within the subduction zone. Exhumation events may be transient and occur only once in a particular subduction zone or orogen, or may be more continuous or occur multiple times.

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