There are two stalagmites found in a Chinese cave Being St. for hard radiocarbon data



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The stalagmites from Hulu Uaimh, with sample-evaluation indicators.
Image: Hai Cheng et al., 2018 / Science

Since its inception in the 1950s, radiocarbon data is essential for archaeologists and climate scientists, which are the responsibility of the approach to the proper presence of organic compounds. But a good thing was better, as a result of finding two stalagmites in a Chinese cave containing an air recording. dating back to the last Ice Age.

A non-fragmented, definitive record of carbon-12 air and carbon-14 were found in a pair of stalagmata within Hulu Uamh near Nanjing, China, according to a new research published today in Science. As this record expands back to the last generation, to about 54,000 years ago, scientists are now equipped with a more advanced status for use in radiocarbon calibration .

There is no question that radiocarbon data on archaeological revival. In this way, scientists can produce organic mixtures such as bone, hair, wood, seeds and shells. But going back in the time we are going to; However, the carbon data will be more reliable, because the technology depends on the correct historical measurement of the shoulder of the atmosphere, especially carbon-12 carbon-14 ratio.

Carbon-14, or C14 is a rare type of carbon, which is unlike carbon-12 (currently known as "normal" carbon). It is an isotope in Q14 which is a? including six protons and eight neutrons, and is in the state of delays all the time, showing a generous half-time of 5,370 years. Like the usual carbon, C14 and # 39; Together with oxygen to create carbon dioxide, which is included with every living creature, whether they are animals or plants. As a result, the ratio of C12 to C14 in all living livelihoods is the same as the ratio in the atmosphere.

As the atmosphere levels C12 and C14 change over time, the special ratio in an organic sample (for example bones, wood) is served as a deadline for living creature. When organs die, it will stop a & # 39; get new carbon. When the time passes, the C14 will turn to; Closing as a fast, but not replaced. By calculating the amount of radioactivity reduction, scientists can verify when a previous corpse died.

But this approach is boundaries, and it must be done to life Q14. Organic subjects can only be bought around 55,000 to 60,000 years ago, and then the level of C14 in a sample will be reduced to a minimum. What's larger, calibration is essential to this way; Changes in the level of radiocarbon are over time over time that require the calibrated radiocarbon dates against a normal, calendar calendar.

It is easier to build these calendars to say what he did. Amazingly, scientists would like to record the correct and non-verbal recordings of changing C12 and C14 of anthropical collections over time. This can be done, for example, by counting the crops of trees (also known as dendrocrronology), which, as an 8 year old person tells you, is a reliable way to tree age confirmation. Unfortunately, only a few calibrated color-rich sources of carbon sampling are reintroduced later in the Holocene tree registers, about 12,600 to 14,000 years ago ( obviously, live trees are not tens of thousands of years old, but old, fossil, can use date trees by other means). Therefore radiocarbon data is limited to the ability of specific material to give full age, and also to maintain a record of changing air settings.

But now, with the discovery and analysis of two specific stalagmites in Hulu Cave, scientists have fallen on an uninterrupted record of air carbon dating back to 54,000 years. Instead of counting tree beads or herbs; Coral reef study (another method used to introduce full dates), researchers, led by Hai Cheng from the World Environment Renewable Institute, at Xi's University and Jiaotong , analysis of mineral transcription within the stalagmites. By going on hundreds of strings within these structures, made by a & # 39; Using a highly reliable isotopic approach known as thorium-230 dit, baseline researchers who have never been previously established can now be used for radiocarbon data.

"So far, their own campaigns have a variety of ways for C14 calibration," said Hai to Gizmodo. "For example, it is still difficult [to use] tree rings to repair the C14 airway beyond the limits of about 14,000 years now. Coalings are not consistently collected over thousands of years and are difficult to gather because those in the interest sector are now largely involved. Stalagmites, which can be excellent options for thorium-230 dyeing, usually include a large fraction of cereals that produce cereals.

Scientist UC Berkeley, Larry Edwards, co-author of the new survey, helped to & # 39; improving the thorium-230 method back in the late 1980s, but can not find unique cave deposits for doing so.

"As well as carbon from the atmosphere, there is carbon from the limestone around the cave," he said to Gizmodo. "So we would have to make a correction for a carbon that produced lime limbs. We found that there is little carbon; in the symbols of Hulu Cave, so it's very good for this type of scrutiny – so our ability to complete a precise calibration of the C-14 timetable, is the ultimate goal of its scientific community for the final almost seven decades. "

In the study, Hai and his colleagues exhibit around 300 motor vehicle 14 truck and thorium-230 trucks taken from the underwater calcic numbers inside the Hulu Cave stalagmites. The average time resolution between each pair is 170 years. The special stalagmites, which Hai says, are very special, with "dead carbon" that is very stable and reliable.

"Therefore, the C14 in the Hulu examples has been produced from the sources of the class, which allows us to make a milestone grant that can activate the revival of the C14 calibration curve through comparisons of C12 / C14 comparisons and age thorium-230, "said Hai, saying:" The new Hulu record is less uncertainty and has confirmed that a more well-known scale structure . "

As the researchers write in & # 39; their newspaper, the new monthly calendar represents "scientifically" scientists, and # 39; offer an up-to-date and continuous record of the C14 class class that covers the full range of the radiocarbon data method. For your archaeologists, it also means that they can now provide organic entrepreneurship between 14,000 and 54,000 years with more confidence, especially the oldest samples.

"For a sample that is just 40,000 years old, the C14 age range would be about 35,000 years, and the age you would do from the last calibration data of around 38,000 years, was uncertain, "explained Edwards. "So, between 2,000 and 5,000 years different, depending on how you chose your age, before we did work."

Interestingly, this research is also interesting for climate science scientists, who can use this data to monitor air variations over time.

It is a very cool result from a very wild and unlikely source – the slow is slow, slow; drip, silencing in a dark cave in the eastern part of China.

[Science]
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