Mantle Differentiation Through Continental Crust Growth and Recycling and the Thermal Evolution of the Earth

2013 ◽  
pp. 55-71 ◽  
Author(s):  
Tilman Spohn ◽  
Doris Breuer
Keyword(s):  
Continental Crust ◽  
Thermal Evolution ◽  
The Earth

Thermal evolution of the Earth

2014 ◽  
pp. 300-316 ◽  
Author(s):  
Claude Jaupart ◽  
Jean-Claude Mareschal
Keyword(s):  
Thermal Evolution ◽  
The Earth

scholarly journals Geoneutrinos

2012 ◽  
Vol 2012 ◽  
pp. 1-34 ◽  
Author(s):  
Ondřej Šrámek ◽  
William F. McDonough ◽  
John G. Learned
Keyword(s):  
Continental Crust ◽  
Plate Tectonics ◽  
Detection Methods ◽  
Heat Sources ◽  
Radiogenic Heat ◽  
Interdisciplinary Field ◽  
The Earth ◽  
Directional Detection ◽  
Under Construction ◽  
Current Detection

Neutrino geophysics is an emerging interdisciplinary field with the potential to map the abundances and distribution of radiogenic heat sources in the continental crust and deep Earth. To date, data from two different experiments quantify the amount of Th and U in the Earth and begin to put constraints on radiogenic power in the Earth available for driving mantle convection and plate tectonics. New improved detectors are under construction or in planning stages. Critical testing of compositional models of the Earth requires integrating geoneutrino and geological observations. Such tests will lead to significant constraints on the absolute and relative abundances of U and Th in the continents. High radioactivity in continental crust puts limits on land-based observatories' capacity to resolve mantle models with current detection methods. Multiple-site measurement in oceanic areas away from continental crust and nuclear reactors offers the best potential to extract mantle information. Geophysics would benefit from directional detection and the detectability of electron antineutrinos from potassium decay.

scholarly journals Towards understanding how surface life can affect interior geological processes: a non-equilibrium thermodynamics approach

2011 ◽  
Vol 2 (1) ◽  
pp. 139-160 ◽  
Author(s):  
J. G. Dyke ◽  
F. Gans ◽  
A. Kleidon
Keyword(s):  
Continental Crust ◽  
Oceanic Crust ◽  
Mantle Convection ◽  
Dynamical Models ◽  
Geological Processes ◽  
The Earth ◽  
Uplift And Erosion ◽  
Life On Earth ◽  
Mantle Temperature ◽  
Non Equilibrium

Abstract. Life has significantly altered the Earth's atmosphere, oceans and crust. To what extent has it also affected interior geological processes? To address this question, three models of geological processes are formulated: mantle convection, continental crust uplift and erosion and oceanic crust recycling. These processes are characterised as non-equilibrium thermodynamic systems. Their states of disequilibrium are maintained by the power generated from the dissipation of energy from the interior of the Earth. Altering the thickness of continental crust via weathering and erosion affects the upper mantle temperature which leads to changes in rates of oceanic crust recycling and consequently rates of outgassing of carbon dioxide into the atmosphere. Estimates for the power generated by various elements in the Earth system are shown. This includes, inter alia, surface life generation of 264 TW of power, much greater than those of geological processes such as mantle convection at 12 TW. This high power results from life's ability to harvest energy directly from the sun. Life need only utilise a small fraction of the generated free chemical energy for geochemical transformations at the surface, such as affecting rates of weathering and erosion of continental rocks, in order to affect interior, geological processes. Consequently when assessing the effects of life on Earth, and potentially any planet with a significant biosphere, dynamical models may be required that better capture the coupled nature of biologically-mediated surface and interior processes.

General discussion

1987 ◽  
Vol 321 (1557) ◽  
pp. 271-273
Keyword(s):  
Mathematical Models ◽  
Continental Crust ◽  
Oceanic Crust ◽  
Continuous Medium ◽  
The Urals ◽  
The Earth ◽  
Scandinavian Caledonides ◽  
Fold Belts ◽  
Normal Thickness

E. V. Artyushkov ( Institute of Physics of the Earth, Moscow, U.S.S.R .). Shortening of the crust has been modelled by compression of a continuous medium. It has also been supposed that compression can start in continental crust of normal thickness. Mathematical models of the same type have recently been used by some other authors. It should be noted that an intense shortening of the crust in fold belts never occurred in such a way. In the main Phanerozoic fold belts (the Urals, Appalachians, Scandinavian Caledonides, the Alpine and Verkhoyansk belts, and others) no era tonic block with a normal continental crust and lithosphere was shortened (Artyushkov & Baer 1983, 1984, 1986). An intense compression took place only in deep basins on oceanic or continental crust. Most oceanic crust disappeared from the surface in the process of subduction. Now the fold belts are mainly built up of a strongly compressed crust of deep basins on continental crust. How can it be proven that this crust was really thin?

scholarly journals Measurement of geologic nitrogen using mass spectrometry, colourimetry, and a newly adapted fluorometry technique

2016 ◽  
Author(s):  
Benjamin W. Johnson ◽  
Natashia Drage ◽  
Jody Spence ◽  
Nova Hanson ◽  
Rana El-Sabaawi ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Continental Crust ◽  
Large Scale ◽  
Organic N ◽  
Stable Form ◽  
Earth System ◽  
N Budget ◽  
Rock Types ◽  
The Earth ◽  
Assess Quality

Abstract. Long viewed as a mostly noble, atmospheric species, recent work demonstrates that nitrogen in fact cycles throughout the Earth system, including the atmosphere, biosphere, oceans, and solid Earth. Despite this new-found behaviour, more thorough investigation of N in geologic materials is limited due to its low concentration (1 to 10 s ppm) and difficulty in analysis. In addition, N can exist in multiple species (NO3−, NH4+, N2, organic-N), and determining which species is actually quantified can be difficult. In rocks and minerals, NH4+ is the most stable form of N over geologic time scales. As such, techniques designed to measure NH4+ can be particularly useful. We measured a number of geochemical rock standards using three different techniques: mass spectrometry, colourimetry, and fluorometry. The fluorometry approach is a novel adaptation of a technique commonly used in biologic science, applied herein to geologic NH4+. Briefly, NH4+ can be quantified by HF-dissolution, neutralization, addition of a fluorescing reagent, and analysis on a standard fluorometer. We reproduce published values for several rock standards (BCR-2, BHVO-2, and G-2), especially if an additional distillation step is performed. While it is difficult to assess quality of each method, due to lack of international geologic N standards, fluorometry appears better suited to analyzing mineral-bound NH4+ than mass spectrometry, and is a simpler, quicker alternative to colourimetry. To demonstrate a potential application of fluorometry, we calculated a continental crust N budget based on new measurements. We used glacial tills as a proxy for upper crust and analyzed several poorly constrained rock types (volcanics, mid-crustal xenoliths) to determine that the continental crust contains ∼ 2 × 1018 kg N. This estimate is consistent with recent budget estimates, and shows that fluorometry is appropriate for large-scale questions where high sample throughput is helpful. Lastly, we report the first δ15N values of six rock standards: BCR-2 (1.05 ± 0.4 ‰), BHVO-2 (−0.3 ± 0.2 ‰), G-2 (1.23 ± 1.32 ‰), LKSD-4 (3.59 ± 0.1 ‰), Till-4 (6.33 ± 0.1 ‰), and SY-4 (2.13 ± 0.5 ‰). The need for international geologic N standards is crucial for further investigation of the Earth system N cycle, and we suggest that existing rock standards may be suited to this need.

Composition of the Canadian Precambrian shield and the continental crust of the earth

1986 ◽  
Vol 24 (1) ◽  
pp. 275-282 ◽  
Author(s):  
D. M. Shaw ◽  
J. J. Cramer ◽  
M. D. Higgins ◽  
M. G. Truscott
Keyword(s):  
Continental Crust ◽  
Precambrian Shield ◽  
The Earth
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