scholarly journals The structural and geochemical evolution of the continental crust: Support for the oceanic plateau model of continental growth

1995 ◽  
Vol 33 ◽  
pp. 231 ◽  
Author(s):  
Dallas Abbott ◽  
Walter Mooney
Keyword(s):  
Continental Crust ◽  
Geochemical Evolution ◽  
Oceanic Plateau ◽  
Continental Growth

scholarly journals Geochemical Evolution of Earth's Continental Crust

2018 ◽  
Author(s):  
C. Brenhin Keller
Keyword(s):  
Continental Crust ◽  
Quantitative Information ◽  
Earth’S Crust ◽  
Geochemical Evolution ◽  
Geologic Time ◽  
Open Questions ◽  
Equable Climate ◽  
Earth's Crust ◽  
Life On Earth ◽  
Underlying Processes

Earth’s unique continental crust represents the active interface between the deep earth and the surface earth system, and is crucial for the survival and diversification of life on Earth, both as a source for nutrients and a component in the silicate weathering feedback that stabilizes Earth’s equable climate on billion-year timescales. However, many open questions remain regarding the formation and secular temporal evolution of Earth’s crust – in part due to the extremely poorly-mixed nature of Earth’s continental crust such that compositional heterogeneity at any one point in geologic time typically dwarfs any systematic variation over time. New computational approaches enabled by the emergence of large, freely accessible geochemical datasets provide a way to see through this heterogeneity and extract quantitative information about underlying processes and variables that drive the evolution of Earth’s crust over geologic time.

The geochemical evolution of the continental crust

1995 ◽  
Vol 33 (2) ◽  
pp. 241 ◽  
Author(s):  
Stuart Ross Taylor ◽  
Scott M. McLennan
Keyword(s):  
Continental Crust ◽  
Geochemical Evolution

Cold avalanche, “super subduction”, mantle overturn, followed by buoyant subduction of an oceanic plateau and the formation of TTG´s during the Eocene in Viti Levu, Fiji islands

2020 ◽  
Author(s):  
Holger Sommer ◽  
Alfred Kröner ◽  
Dorrit E. Jacob ◽  
Xiao-chao Che ◽  
Jean Wong ◽  
...  
Keyword(s):  
Continental Crust ◽  
Mantle Source ◽  
Granulite Facies ◽  
Amphibolite Facies ◽  
Oceanic Plateau ◽  
Fiji Islands ◽  
Episodic Growth ◽  
Depleted Mantle ◽  
Magmatic Underplating ◽  
Water Saturated

<p>Tonalite, Trondhjemite, Granodiorite (TTG) rocks in Viti Levu, Fiji islands formed through hydrous melting of gabbroic oceanic crust at low-pressure amphibolite-facies conditions caused by flat subduction of an oceanic plateau from Yavuna creek. During mid Miocene time, magmatic underplating took place and a Qtz-diorite unit was formed out of the gabbro under granulite-facies conditions. The investigated TTG´s occur as stocks and veins within the older gabbroic unit of the Yavuna Pluton.</p><p>Zircon ages show the parental gabbro to be ~47.5 Ma in age, whereas the TTG´s, which can be subdivided into a tonalite and a Qtz-diorite suite, are ~37.1 Ma and ~16.5 Ma, old respectively. The average d<sup>18</sup>O value of ~4.8 in zircon selected from the parental gabbro and the tonalite suggest a very homogenous mantle source. However, about 50% of the analyzed zircons from the gabbroic and tonalitic rock samples showing lower d<sup>18</sup>O values, and these are interpreted as reflecting interaction of hydrothermally altered seafloor with the deep depleted mantle source. eHf in zircon values of ~13 in the analyzed TTG´s are interpreted as reflecting typical juvenile continental crust. PerpleX whole-rock calculations suggest that the tonalite formed by melting of the gabbro through decompression under water-saturated amphibolite-facies conditions at a temperature of ~770 °C and a pressure of ~3.8 kbar, whereas the Qtz-diorite formed at a temperature up to ~900 °C at very shallow depth close to the Earth’s surface caused by the emplacement of a magmatic underplate during the mid Miocene. Our investigation provides new evidence for episodic growth of continental crust < 0.1 Ga in the South Pacific region.</p>

Archean granitoids of the Aravalli Craton, northwest India

2020 ◽  
Vol 489 (1) ◽  
pp. 215-234 ◽  
Author(s):  
Iftikhar Ahmad ◽  
M. E. A. Mondal ◽  
Md Sayad Rahaman ◽  
Rajneesh Bhutani ◽  
M. Satyanarayanan
Keyword(s):  
Partial Melting ◽  
Continental Crust ◽  
Mantle Wedge ◽  
Nd Isotope ◽  
Oceanic Plateau ◽  
Slab Breakoff ◽  
Northwest India ◽  
Aravalli Craton ◽  
Metasomatized Mantle ◽  
Asthenospheric Upwelling

AbstractThe Archean granitoids of the Aravalli Craton (NW India) are represented by orthogneisses (3.3–2.6 Ga) and undeformed granitoids (c. 2.5 Ga). Here we present whole-rock geochemical (elemental and Nd-isotope) data of the granitoids from the Aravalli Craton with an aim of understanding the evolution of the continental crust during the Archean. These Archean granitoids have been classified into three compositional groups: (1) TTG – tonalite–trondhjemite–granodiorite; (2) t-TTG – transitional TTG; and (3) sanukitoids. Based on the geochemical characteristics, it is proposed that the TTGs have formed from the partial melting of subducting oceanic plateau. The t-TTG formed owing to reworking of an older continental crust (approximately heterogeneous) in response to tectonothermal events in the craton. For the formation of the sanukitoids, a two-stage petrogenetic model is invoked which involves metasomatization of the mantle wedge, followed by slab breakoff and asthenospheric upwelling, which leads to the melting of asthenosphere and the metasomatized mantle wedge. It is also proposed that subducted sediments contributed to the genesis of sanukitoid magma.

Modification of an oceanic plateau, Aruba, Dutch Caribbean: Implications for the generation of continental crust

Lithos ◽  
1999 ◽  
Vol 46 (1) ◽  
pp. 43-68 ◽  
Author(s):  
R.V White ◽  
J Tarney ◽  
A.C Kerr ◽  
A.D Saunders ◽  
P.D Kempton ◽  
...  
Keyword(s):  
Continental Crust ◽  
Oceanic Plateau ◽  
Dutch Caribbean

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

Geology ◽  
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.

Age and isotope evidence for the evolution of continental crust

1978 ◽  
Vol 288 (1355) ◽  
pp. 401-413 ◽  
Keyword(s):  
Continental Crust ◽  
Isotopic Ratios ◽  
Geological Environment ◽  
Geological Time ◽  
Sialic Crust ◽  
Isotope Data ◽  
The Past ◽  
Isotope Evidence ◽  
Continental Growth ◽  
Infinite Reservoir

Irreversible chemical differentiation of the mantle’s essentially infinite reservoir for at least the past 3800 Ma has produced new continental, sialic crust during several relatively short ( ca . 100-300 Ma) episodes which were widely separated in time and may have been of global extent. During each episode (termed 'accretion—differentiation superevent’), juvenile sial underwent profound igneous, metamorphic and geochemical differentiation, resulting in thick ( ca . 25-40 km), stable, compositionally gradational, largely indestructible, continental crust exhibiting close grouping of isotopic ages of rock formation, as well as mantle-type initial Sr and Pb isotopic ratios for all major constituents. Isotopic evidence suggests that within most accretiondifferentiation superevents — and especially during the earlier ones - continental growth predominated over reworking of older sialic crust. Reworking of older sialic crust can occur in several types of geological environment and appears to have become more prevalent with the passage of geological time. It is usually clearly distinguishable from continental growth, by application of appropriate age and isotope data.

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