This paper seeks to discuss, summarize and critique “Earth’s early O 2 cycle suppressed by primitive continents” article by Smit and Mezger (2017). Matthijs A. Smit is an affiliate of the University of British Columbia Vancouver V6T, Canada under the Earth, Ocean, and Atmospheric Sciences Department. Smit was responsible for conceiving, compiling, and evaluating all the data represented in this article. Other than designing the figures in the article, he prides himself in writing the first draft manuscript of the article. On the other hand, Mezger is an affiliate of the Institute of Geology at the University of Bern in Baltzerstrasse Switzerland. His significant contribution to the article was in providing intrinsic insights regarding the topic of the article as well as helping in co-writing the manuscript with Smit.
Summary of the Article
According to the authors, free oxygen began accumulating on the earth’s crust approximately between 2.4 and 3 billion years ago. Ever since the acknowledgment and realization of this fact, several scientists and geologists have tried creating a link between the variations in the earth’s crust and oxygenation during the period but to no avail. The article, therefore, provides methods and models for calculating the average composition of the exposed earth’s crust. This is done by gathering relevant data of the Cr/U ratio of the terrigenous sediments from as far as 3.7 billion years ago. From the results and findings of the analysis, it was discovered that results of the crust composition were consistent to the largely mafic crust before 3 billion years ago. This consistency was closely followed by a five-hundred to seven-hundred million years of transition to the modern day crust with the andesitic composition.
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It was also established that olivine together with other magnesium-rich minerals in the mafic Archaean crust was responsible for the formation of the serpentine minerals upon hydration. This led to the release of agents with high affinity for oxygen such hydrogen sulfide, methane and dihydrogen to the surroundings. However, the article fundamentally points out that the erosion of the mafic crust responsible for the first accumulation of oxygen in the atmosphere and oceans was the reason for the early oxygen limitation. In view of this, the authors conclude by asserting that the earth’s crust remained underdeveloped until the emergence of the modern andesitic continents.
Critique of the Article
To its credit, the article gives the gory details entailing how the earth’s mafic crust played a vital role in the release of oxygen into the atmosphere as well as the oceans. In addition, the authors give data and statistics on the age of the earth’s crust, its existence, and time evolution in the form of figures and charts. Various elements and factors of the earth’s crust that potentially enabled it to be the source of the modern day oxygen are further outlined. The authors source information from various fields such as geochemistry to give crucial evidence and explanation as to how the earth’s mafic crust started producing oxygen. Further, the authors present intimate scientific facts and evidence-based opinions with strong correlations with fields of sedimentology, petrology, Precambrian geology, and geochemistry. Essentially, both authors are experts and recognized in their own rights as mentioned before in the introduction.
As part of its limitations, the article does not give the full range and scope of research done with regards to the relationship between oxygenation and differences in the composition of the earth’s crust. Moreover, the authors do not recommend further research on the gaps presenting challenges in the comprehension of the link between oxygenation and the earth’s crust. Finally, the charts and figures incorporate detailed and complex formulas and abbreviations that are not adequately explained by the authors. The article can be improved by providing better explanations to the formulas and figures. The article should further point out further research areas and make recommendations on how to bridge the gap regarding the research.
Conclusion
The topic of the article mainly discusses oxygen and how it came to be. To this effect, the title of the article affects the earth in the sense that oxygen is primarily the basic requirement for life without which life becomes non-existent. Oxygen fundamentally impacts the earth especially the living organisms since they require oxygen for their basic biological processes such as breathing or photosynthesis. Oxygen gives life to the organisms that live on it. On a personal, basis, the article has been significant in imparting knowledge regarding the source of the oxygen that humans breathe which I was oblivious of before. To this effect, the article has made me more knowledgeable and curious to research more on the same.
References
Smit, M.A., & Mezger, K. (2017). Earth’s Early O 2 Cycle Suppressed by Primitive Continents. Nature Publishing Group, SN-1752-0908. Web. Retrieved from: https://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo3030.html#abstract
