کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
4407174 1307353 2008 30 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Earth's atmosphere – Hadean to early Proterozoic
موضوعات مرتبط
مهندسی و علوم پایه علوم زمین و سیارات ژئوشیمی و پترولوژی
پیش نمایش صفحه اول مقاله
Earth's atmosphere – Hadean to early Proterozoic
چکیده انگلیسی

The chemistry of Earth's atmosphere during its first 2–2.5 Ga bears on several branches of geoscience including the origin of prebiotic molecules and life itself, early surface processes, the “faint young sun” problem, carbon isotope systematics, and the transition to an oxidized surface. The geologic record, as sparse as it is for this era, presents several difficulties for attempts to model the atmosphere and its changes through time. The prevailing view for the past 50 years has centered around a moderately oxidized atmosphere of CO2 and N2, and most modeling efforts have been directed at reconciling geologic data, and atmospheric and chemical constraints, with such a composition. Improvements in modeling of early Earth processes and increased knowledge of Archean geology, including new geochemical methods and data, have largely helped support this view of the early atmosphere over the last 25 years, but have also left several nagging questions unanswered. How was a sufficient reservoir (and concentration) of prebiotic molecules produced? What were the major reservoirs for carbon, and how did they develop their isotopic signatures? Is there a solution to the problem of the “faint young sun”? Why was surface oxidation delayed following the advent of oxygenic photosynthesis? Lately, some attempts at answering these questions have suggested the importance of more reducing capacity at the early Earth's surface, but without abandoning the idea of a mainly CO2–N2 atmosphere. It may be that returning to ideas of the early atmosphere current during the 1940s and earliest 1950s could help resolve some of these problems. Such an approach may not only be consistent with the atmospheres of the other terrestrial planets, but may help answer significant questions about the surface history of Mars.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Chemie der Erde - Geochemistry - Volume 68, Issue 3, 5 August 2008, Pages 235–264
نویسندگان
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