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The Super Carbon-Rich Magic Age: Do you know how the LJE affected Earth's oxygen levels?
In the Paleoproterozoic about two billion years ago, an important carbon isotope event occurred, called the Lomagundi-Jatuli carbon isotope event (LJE). This event is not only the largest positive δ13C carbon isotope shift in Earth's history, but also one of the longest-lasting carbon isotope events, which has aroused great interest among researchers in the life and environmental changes during that period.
According to geoscience research, δ13C values during the LJE ranged from +5 to +30‰, which indicates significant marine carbonate deposition at that time.
Scientists are able to better understand Earth's ancient carbon cycle by measuring δ13C values in ocean carbonate rocks. The "flow" of the carbon cycle is the transfer of carbon from the atmosphere, oceans, and terrestrial biosphere to various carbon reservoirs in the Earth's superposition. From photosynthesis to respiration, changes in these processes are directly related to the concentration of carbon dioxide in the Earth's atmosphere, which in turn affects the global climate.
In the context of the LJE, scientists initially thought that carbonate rocks with high δ13C values only reflected local increases in organic carbon. Over time, this phenomenon was found to occur all over the world, indicating that the LJE is a A global change in the carbon cycle.
The continuation of LJE and its influence
It is generally believed in the scientific community that the LJE began about 2.3 billion years ago and ended 2.1 billion years ago, lasting for 249 ± 9 million years. The effects of this event were felt on every continent around the world, with all but Antarctica showing similarly high carbon isotope values. In addition, significant geological changes were discovered during this period, indicating dramatic changes in global climate and ecosystems.
According to geologists' observations, the thickness of these carbonate rocks ranges from several meters to more than ten meters, highlighting the changes in the sedimentary environment at that time.
Development of research methods
Studying carbon isotopes in these ancient rocks is not easy. Scientists often use a variety of techniques to determine the age of rocks, such as thermal ionization mass spectrometry (TIMS) and isotope dilution thermal ionization mass spectrometry (ID-TIMS). These technologies can detect changes in carbon isotopes with high precision, thereby inferring the carbon dioxide concentration and ecological environment at that time.
Causes of LJE
The cause of LJE is still under debate. One leading theory is that this event is related to the Great Oxidation Event (GOE). Scientists speculate that the LJE caused a large deviation in global carbon storage, especially the oxidation process of iron carbonates, which may have produced a large amount of carbon dioxide. Such changes in turn promoted the release of oxygen and facilitated the evolution of ancient organisms.
"The global changes in the LJE not only altered the ecosystem at the time, but also may have paved the way for later biological evolution to some extent."
Future Research Directions
As Earth science research advances, our understanding of LJE continues to deepen. Future research will help us better understand Earth's carbon cycle and its implications for current climate change. Even in modern society, the impacts of LJE may still have a profound impact on our ecosystems and environmental decision-making.
Human behavior has left its mark on the changing carbon cycle, and we should ask: In this context, can we gain insights into the future from the past carbon cycle?
