scholarly journals Physical weathering by glaciers enhances silicon mobilisation and isotopic fractionation

2021 ◽  
pp. 7-12
Author(s):  
J.E. Hatton ◽  
K.R. Hendry ◽  
J.R. Hawkings ◽  
J.L. Wadham ◽  
L.G. Benning ◽  
...  
Keyword(s):  
Isotopic Fractionation ◽  
Physical Weathering

scholarly journals On the Thermal Stresses Due to Weathering in Natural Stones

2021 ◽  
Vol 11 (3) ◽  
pp. 1188
Author(s):  
William Hideki Ito ◽  
Talita Scussiato ◽  
Federico Vagnon ◽  
Anna Maria Ferrero ◽  
Maria Rita Migliazza ◽  
...  
Keyword(s):  
Building Materials ◽  
Thermal Stresses ◽  
Central Italy ◽  
Theory Of Elasticity ◽  
International Standards ◽  
Natural Material ◽  
Physical Weathering ◽  
Mechanism Of Degradation ◽  
Ancient Times ◽  
Natural Stones

Natural weathering is known as one of the key mechanisms causing degradation in building materials. Great efforts have been made to develop new materials and new processes for protecting those that already exist. Natural stones are an example of a natural material that has been extensively used for building construction since ancient times. In addition, they fit durability, aesthetic, and mechanical requirements. Thus, they still have great importance in the construction business nowadays. Though chemical interactions in natural stones, such as oxidation or hydrolyses, have been widely studied, in the last few decades, the physical weathering due to daily temperature variations has begun to be considered as a key mechanism of degradation and has been incorporated in international standards. This process is particularly important in calcitic marble slabs, where it can cause extensive damages to facades. Consequently, there are restrictive rules for the use of marble as an external coating material in many countries. In this paper, the thermal stresses induced by daily variations in temperature are calculated using geographic and meteorological information. The concept of sol-air temperature is used to estimate the temperatures of the hidden and exposed surfaces of a slab, and Fourier’s law and the theory of elasticity are used to calculate the temperature and stress distribution, respectively. The proposed methodology allows for a detailed reconstruction of the stress induced inside marble slabs using parameters commonly acquired in meteorological stations as input data. The developed methodology was validated by comparing in-situ measurements of the temperature of a building in Pescara (Central Italy). A good correlation between the theoretical and real temperatures was found; in particular, the peak tensile stresses inside the slabs were estimated at 75 kPa.

Magnesium isotopic fractionation during basalt differentiation as recorded by evolved magmas

2021 ◽  
Vol 565 ◽  
pp. 116954
Author(s):  
Xiao-Jun Wang ◽  
Li-Hui Chen ◽  
Takeshi Hanyu ◽  
Yuan Zhong ◽  
Jin-Hua Shi ◽  
...  
Keyword(s):  
Isotopic Fractionation ◽  
Basalt Differentiation

scholarly journals Isotopic Fractionation Accompanying CO2 Hydroxylation and Carbonate Precipitation from High pH Waters at The Cedars, California, USA

2021 ◽  
Author(s):  
John N. Christensen ◽  
James M. Watkins ◽  
Laurent S. Devriendt ◽  
Donald J. DePaolo ◽  
Mark E. Conrad ◽  
...  
Keyword(s):  
Isotopic Fractionation ◽  
Carbonate Precipitation ◽  
High Ph

scholarly journals Significant Zr isotope variations in single zircon grains recording magma evolution history

2020 ◽  
Vol 117 (35) ◽  
pp. 21125-21131 ◽  
Author(s):  
Jing-Liang Guo ◽  
Zaicong Wang ◽  
Wen Zhang ◽  
Frédéric Moynier ◽  
Dandan Cui ◽  
...  
Keyword(s):  
Isotopic Fractionation ◽  
Major Type ◽  
Strong Temperature Dependence ◽  
Calc Alkaline ◽  
Southern Tibet ◽  
Rayleigh Distillation ◽  
Single Zircon ◽  
Magmatic History ◽  
Fractionation Factors

Zircons widely occur in magmatic rocks and often display internal zonation finely recording the magmatic history. Here, we presented in situ high-precision (2SD <0.15‰ for δ94Zr) and high–spatial-resolution (20 µm) stable Zr isotope compositions of magmatic zircons in a suite of calc-alkaline plutonic rocks from the juvenile part of the Gangdese arc, southern Tibet. These zircon grains are internally zoned with Zr isotopically light cores and increasingly heavier rims. Our data suggest the preferential incorporation of lighter Zr isotopes in zircon from the melt, which would drive the residual melt to heavier values. The Rayleigh distillation model can well explain the observed internal zoning in single zircon grains, and the best-fit models gave average zircon–melt fractionation factors for each sample ranging from 0.99955 to 0.99988. The average fractionation factors are positively correlated with the median Ti-in-zircon temperatures, indicating a strong temperature dependence of Zr isotopic fractionation. The results demonstrate that in situ Zr isotope analyses would be another powerful contribution to the geochemical toolbox related to zircon. The findings of this study solve the fundamental issue on how zircon fractionates Zr isotopes in calc-alkaline magmas, the major type of magmas that led to forming continental crust over time. The results also show the great potential of stable Zr isotopes in tracing magmatic thermal and chemical evolution and thus possibly continental crustal differentiation.

scholarly journals Quantum Genetic Terrain Algorithm (Q-GTA): A Technique to Study the Evolution of the Earth Using Quantum Genetic Algorithm

Proceedings ◽  
2019 ◽  
Vol 46 (1) ◽  
pp. 26
Author(s):  
Pranjal Sharma ◽  
Ankit Agarwal ◽  
Bhawna Chaudhary
Keyword(s):  
Genetic Algorithm ◽  
Isotopic Fractionation ◽  
Volcanic Eruptions ◽  
Temperature Characteristic ◽  
Isotopic Ratios ◽  
Mantle Lithosphere ◽  
Monitoring Networks ◽  
Temperature Changes ◽  
Quantum Genetic Algorithm ◽  
The Earth

In recent years, geologists have put in a lot of effort trying to study the evolution of Earth using different techniques studying rocks, gases, and water at different channels like mantle, lithosphere, and atmosphere. Some of the methods include estimation of heat flux between the atmosphere and sea ice, modeling global temperature changes, and groundwater monitoring networks. That being said, algorithms involving the study of Earth’s evolution have been a debated topic for decades. In addition, there is distinct research on the mantle, lithosphere, and atmosphere using isotopic fractionation, which this paper will take into consideration to form genes at the former stage. This factor of isotopic fractionation could be molded in QGA to study the Earth’s evolution. We combined these factors because the gases containing these isotopes move from mantle to lithosphere or atmosphere through gaps or volcanic eruptions contributing to it. We are likely to use the Rb/Sr and Sm/Nd ratios to study the evolution of these channels. This paper, in general, provides the idea of gathering some information about temperature changes by using isotopic ratios as chromosomes, in QGA the chromosomes depict the characteristic of a generation. Here these ratios depict the temperature characteristic and other steps of QGA would be molded to study these ratios in the form of temperature changes, which would further signify the evolution of Earth based on the study that temperature changes with the change in isotopic ratios. This paper will collect these distinct studies and embed them into an upgraded quantum genetic algorithm called Quantum Genetic Terrain Algorithm or Quantum GTA.

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