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

2000 ◽  
Vol 1 (12) ◽  
pp. n/a-n/a ◽  
Author(s):  
Yoshiyuki Tatsumi
Keyword(s):  
Continental Crust ◽  
Subduction Zones ◽  
Crust Formation ◽  
Enriched Mantle

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

2018 ◽  
Vol 483 (1) ◽  
pp. 165-182 ◽  
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.

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

2018 ◽  
Vol 376 (2132) ◽  
pp. 20170403 ◽  
Author(s):  
Bruno Dhuime ◽  
Chris J. Hawkesworth ◽  
Hélène Delavault ◽  
Peter A. Cawood
Keyword(s):  
Continental Crust ◽  
Subduction Zones ◽  
Plate Tectonics ◽  
Marked Decrease ◽  
Crust Formation ◽  
Temporary Reduction ◽  
Present Volume ◽  
Continental Growth ◽  
Earth Dynamics ◽  
Model Approach

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'.

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

2012 ◽  
Vol 4 (1) ◽  
pp. 745-781 ◽  
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.

scholarly journals Tectonic settings of continental crust formation: Insights from Pb isotopes in feldspar inclusions in zircon

Geology ◽  
2016 ◽  
Vol 44 (10) ◽  
pp. 819-822 ◽  
Author(s):  
Hélène Delavault ◽  
Bruno Dhuime ◽  
Chris J. Hawkesworth ◽  
Peter A. Cawood ◽  
Horst Marschall ◽  
...  
Keyword(s):  
Continental Crust ◽  
Pb Isotopes ◽  
Crust Formation ◽  
Tectonic Settings

Global factors of lead-zinc ore formation

2019 ◽  
pp. 3-10
Author(s):  
A. L. Dergachev
Keyword(s):  
Continental Crust ◽  
Island Arcs ◽  
Geological Time ◽  
Crust Formation ◽  
Ore Formation ◽  
Global Factor ◽  
Lead And Zinc ◽  
Lead Zinc ◽  
Cyclic Changes

Tectonic evolution of the Earth is a principle global factor responsible for uneven distribution of lead and zinc reserves in geological time. Cyclic changes in productivity of lead-zinc ore-formation processes resulted from periodical amalgamation of most blocks of continental crust, formation, stabilization and final break-up of supercontinents. Many features of age spectrums of lead and zinc reserves are caused by gradual increase of volume of continental crust resulting from accretion of island arcs to ancient cratons, widening of distribution of ensialic environments of ore-formation and increasing role of continental crust in magmatic processes.

Arc evolution and continental crust formation at the Izu–Bonin–Mariana arc system

2006 ◽  
Vol 70 (18) ◽  
pp. A638 ◽  
Author(s):  
Y. Tatsumi ◽  
N. Takahashi ◽  
S. Kodaira ◽  
Y. Kaneda
Keyword(s):  
Continental Crust ◽  
Crust Formation ◽  
Mariana Arc
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