A new scientific review suggests that ancient impact craters created mineral-rich hydrothermal systems that may have served as a cradle for the development of pre-biological chemistry.
A new review study proposes a fresh look at one of the biggest questions in science: where and how life began on Earth. For decades, researchers have focused primarily on deep-ocean hydrothermal vents as the leading candidates for the birth of life, thanks to the unique chemical conditions they create. Now another possibility has emerged: asteroid and meteorite impacts on the early Earth could have created similar hydrothermal systems, perhaps even serving as a central arena for the pre-biological chemistry that led to the emergence of life.
The review, published in the journal Journal of Marine Science and Engineering, written by Shea M. Cinquemani of Rutgers University, along with oceanographer Richard Lutz. It explores the idea that the intense heat released by an asteroid impact melts rocks, and then, as the crater cools and fills with water, a hot, mineral-rich system is created—a system that in many ways resembles the familiar hydrothermal vents on the seafloor. Under such conditions, energy cascades, complex chemical reactions, and concentrations of essential materials could occur, which are considered promising conditions for the origin of life.
The main innovation in the study is not a rejection of the long-standing theory of deep-sea vents, but an extension of it. The hydrothermal vents discovered in the late 1970s had already shown that life could thrive without sunlight, relying on chemosynthesis rather than photosynthesis. Microorganisms there harness chemical energy from substances such as hydrogen sulfide in hot, mineral-rich environments. According to the new review, systems formed by asteroid impacts could have provided very similar conditions—and may have been especially common on the early Earth, when such impacts were much more common than they are today.
Three sites of impact
To substantiate the argument, the review considers three impact sites from different periods in Earth’s history: the Chicxulub crater in Mexico, which formed about 65 million years ago; the Houghton crater in the Canadian Arctic, which is about 31 million years old; and the Lunar Lake in India, which formed about 50 years ago and still contains water. According to the researchers, such hydrothermal systems may remain active for thousands to tens of thousands of years—a period of time that may be sufficient for simple compounds to undergo increasingly complex chemical processes, to the point where the initial components of life can appear.
This idea also has broad astrobiological implications. If environments created by asteroid impacts are indeed capable of promoting pre-biological chemistry, then the search for extraterrestrial life need not focus only on subsurface oceans or volcanic vents. The review notes that hydrothermal activity may also exist beneath the ice sheets of Europa and Enceladus, and may have also existed in ancient impact craters on Mars. In other words, what was once seen as a purely destructive event may also turn out to be a mechanism that creates opportunities for life.
It should be noted that this is a review article and not an experimental study that proves exactly where life first arose. However, its contribution is important because it expands the range of scientific possibilities and emphasizes that the ancient Earth was probably a much richer natural laboratory than was commonly thought. The answer to the question of the origin of life may not lie in a single site, but in a combination of several types of geological and chemical environments, including the hot, mineral lakes that formed in the heart of ancient impact craters.
Source: SciTechDaily based on a Rutgers University announcement and the article: “Deep-Sea Hydrothermal Vent and Impact-Generated Hydrothermal Vent Systems: Insights into the Origin of Life,” by Shea M. Cinquemani and Richard A. Lutz. DOI: 10.3390/jmse14050486
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