新的模型表明，我们对地球上第一次大规模的氧气爆发的认识可能是错误的

These days, Earth's atmosphere is perfectly suited for us to breathe - but the air on our planet wasn't always this way.

如今，地球的大气层非常适合我们呼吸，但地球上的空气并不总是这样。

Now, researchers have put forward a new explanation for the events that dramatically shifted that crucial composition of gasses.

现在，研究人员提出了一种新的解释，来解释那些剧烈改变气体关键成分的事件。

According to the new study, a critical event in Earth's atmospheric history may have come in the form of volcanic eruptions, caused by shifting tectonic plates.

根据这项新的研究，地球大气史上的一个关键事件可能以火山爆发的形式出现，这是由移动的构造板块引起的。

The planet's crust and mantle moved in a way that set off particular chemical reactions, resulting in a spike in oxygen production and laying the foundation for complex life on our planet.

地球的地壳和地幔以一种引发特殊化学反应的方式移动，导致氧气产量激增，为我们星球上复杂的生命奠定了基础。

The new model put forward by a Rice University-led team could help to explain not one, but two long-standing geological mysteries.

由莱斯大学领导的研究小组提出的新模型有助于解释两个长期存在的地质谜团，而不是一个。

First, there's the Great Oxidation Event (GOE) of around 2.4 billion years ago, where oxygen levels rose sharply; then, the Lomagundi event, a significant shift in carbon isotope balances that happened about 100 million years later.

首先是大约24亿年前的大氧化事件(GOE)，当时氧含量急剧上升;然后是Lomagundi事件，大约1亿年后，碳同位素平衡发生了重大变化。

Carbon has three naturally occurring isotopes - variants that can be distinguished based on the number of neutrons they contain. The ratio of carbon-12 and carbon-13 isotopes is a useful tool for studying natural systems and the atmosphere, since the two variants tend to come from different sources.

碳有三种天然存在的同位素——根据它们所含的中子数可以区分它们的变体。碳-12和碳-13同位素的比例是研究自然系统和大气的有用工具，因为这两种同位素往往来自不同的来源。

The vast majority of carbon on Earth is carbon-12, but during the Lomagundi event there was a sudden spike in carbon-13 isotopes. Before now, researchers have found it tricky to fit the GOE and the Lomagundi event together in one coherent hypothesis.

地球上绝大多数的碳是碳12，但是在Lomagundi事件中，碳13的同位素突然激增。在此之前，研究人员发现很难把GOE和Lomagundi事件放在一个连贯的假设中。

What makes this unique is that it's not just trying to explain the rise of oxygen, says geoscientist James Eguchi, from the University of California, Riverside.

来自加州大学河滨分校的地球科学家James Eguchi说:“这一发现的独特之处在于，它不仅试图解释氧气的产生。”

It's also trying to explain some closely associated surface geochemistry, a change in the composition of carbon isotopes, that is observed in the carbonate rock record a relatively short time after the oxidation event.

“它还试图解释一些密切相关的表面地球化学，即碳同位素组成的变化，这是在氧化事件发生后较短时间内从碳酸盐岩记录中观察到的。”

We're trying to explain each of those with a single mechanism that involves the deep Earth interior, tectonics and enhanced degassing of carbon dioxide from volcanoes."

“我们试图用一种单一的机制来解释每一种机制，它涉及到地球深处的内部构造和火山释放的二氧化碳。”

Before now, photosynthesis was thought to be the main driver of the GOE, as cyanobacteria pumped oxygen out as a waste product of just being alive. That still played a big part, the new research suggests, but much more was going on in our planet's interior.

在此之前，光合作用被认为是GOE的主要驱动力，因为蓝藻细菌把氧气作为活着的废物排出体外。新的研究表明，这仍然发挥了很大的作用，但更多的是在我们星球的内部。

Based on detailed modelling, the scientists think that increased tectonic activity produced hundreds of new volcanoes ahead of the GOE, pumping masses of CO2 into the air. This warmed the climate, increasing rainfall and subsequent weathering, leading to more minerals being washed off rocks and into the ocean.

基于详细的模型，科学家们认为，构造活动的增加在GOE之前产生了数百座新火山，将大量的二氧化碳排放到空气中。这使得气候变暖，增加了降雨量和随后的风化，导致更多的矿物质从岩石中被冲刷到海洋中。

In turn, this triggered a boom in cyanobacteria and carbonates, with this extra organic and inorganic carbon getting recycled from the ocean floor into Earth's mantle. The rise in oxygen is accounted for in both the growth of cyanobacteria numbers (therefore increasing photosynthesis) and in the carbon being taken out of the atmosphere as it gets buried deep underground.

反过来，这引发了蓝藻和碳酸盐的繁荣，这些额外的有机和无机碳从海底回收到地球的地幔。氧气的增加既可以解释蓝藻数量的增长(因此增加了光合作用)，也可以解释碳被从大气中抽出并深埋地下的过程。

It's kind of a big cyclic process, says Eguchi.

“这是一个大的循环过程，”Eguchi说。

Crucially for the Lomagundi event calculations, the different chemical make-up of organic and inorganic carbon means they reappeared at different times, explaining the increase in carbon-13 with a 100-million-year gap.

对Lomagundi事件的计算至关重要的是，有机碳和无机碳的不同化学组成意味着它们会在不同的时间重新出现，这解释了碳13的增加与1亿年的时间差距。

The research has been published in Nature Geoscience.

这项研究发表在《自然地球科学》杂志上。