Abundant geologic evidence shows that atmospheric oxygen levels were negligible until the Great Oxidation Event (GOE) at 2.4–2.1 Ga. The burial of organic matter is balanced by the release of oxygen, and if the release rate exceeds efficient oxygen sinks, atmospheric oxygen can accumulate until limited by oxidative weathering. The organic burial rate relative to the total carbon burial rate can be inferred from the carbon isotope record in sedimentary carbonates and organic matter, which provides a proxy for the oxygen source flux through time. Because there are no large secular trends in the carbon isotope record over time, it is commonly assumed that the oxygen source flux changed only modestly. Therefore, declines in oxygen sinks have been used to explain the GOE. However, the average isotopic value of carbon fluxes into the atmosphere–ocean system can evolve due to changing proportions of weathering and outgassing inputs. If so, large secular changes in organic burial would be possible despite unchanging carbon isotope values in sedimentary rocks. Here, we present an inverse analysis using a self-consistent carbon cycle model to determine the maximum change in organic burial since ~4 Ga allowed by the carbon isotope record and other geological proxies. We find that fractional organic burial may have increased by 2–5 times since the Archean. This happens because O₂-dependent continental weathering of ¹³C-depleted organics changes carbon isotope inputs to the atmosphere–ocean system. This increase in relative organic burial is consistent with an anoxic-to-oxic atmospheric transition around 2.4 Ga without declining oxygen sinks, although these likely contributed. Moreover, our inverse analysis suggests that the Archean absolute organic burial flux was comparable to modern, implying high organic burial efficiency and ruling out very low Archean primary productivity.

中文翻译：

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碳循环反演模型表明，有机埋藏部分的巨大变化与碳同位素记录一致，并可能促成了氧气的增加

丰富的地质证据表明，在 2.4-2.1 Ga 的大氧化事件 (GOE) 之前，大气中的氧气含量可以忽略不计。有机物的埋藏与氧气的释放相平衡，如果释放速率超过有效的氧汇，大气中的氧气可以积累直到受到氧化风化的限制。有机物埋藏率相对于总碳埋藏率可以从沉积碳酸盐和有机质中的碳同位素记录推断出来，这为氧源通量随时间的变化提供了代表。由于随着时间的推移，碳同位素记录中没有大的长期趋势，因此通常假设氧源通量仅适度变化。因此，氧汇的下降已被用来解释 GOE。然而，由于风化和除气输入比例的变化，进入大气-海洋系统的碳通量的平均同位素值可能会发生变化。如果是这样，尽管沉积岩中的碳同位素值不变，但有机埋藏的巨大长期变化是可能的。在这里，我们使用自洽碳循环模型进行逆分析，以确定碳同位素记录和其他地质代理允许的 ~4 Ga 以来有机埋藏的最大变化。我们发现，自太古代以来，部分有机埋葬可能增加了 2-5 倍。发生这种情况是因为 O 我们使用自洽碳循环模型进行逆分析，以确定自碳同位素记录和其他地质代理允许的~4 Ga 以来有机埋藏的最大变化。我们发现，自太古代以来，部分有机埋葬可能增加了 2-5 倍。发生这种情况是因为 O 我们使用自洽碳循环模型进行逆分析，以确定自碳同位素记录和其他地质代理允许的~4 Ga 以来有机埋藏的最大变化。我们发现，自太古代以来，部分有机埋葬可能增加了 2-5 倍。发生这种情况是因为 O^{消耗13 C 的有机物的}₂依赖大陆风化改变了大气-海洋系统的碳同位素输入。这种相对有机埋藏的增加与 2.4 Ga 附近的缺氧到好氧的大气过渡一致，而没有减少氧汇，尽管这些可能有所贡献。此外，我们的逆分析表明，太古宙绝对有机埋藏通量与现代相当，这意味着有机埋藏效率高，排除了太古宙初级生产力非常低的可能性。