What are the strange phenomena in Lop Nur?

Lop Nur is located in the east of Tarim Basin in Xinjiang. Like the lost ancient city of Loulan, Lop Nur is a place full of mystery. The debate about whether Lop Nur is a wandering lake in the past hundred years has touched the heartstrings of so many people in the geological field, making it a fascinating natural mystery.

Extreme heat, drought, sandstorm, Ya Dan (steep cliff) and salt crust prevent people from approaching Lop Nur, which has been called "the road to death" for many years. Historically, many Chinese and foreign scholars have tried to break through obstacles and cross the desert to complete their investigation of Lop Nur, but not many have succeeded. Even if there are only a few successful visits, there are great differences on the exact location of Lop Nur.

Russian explorer H·M· Poole Geval first put forward the argument that Lop Nur is a lake tour. He visited Lop Nur in A.D. 1876. He found that Lop Nur is located in KalaHeshun, the mouth of Tarim River, which is farther south than the location recorded on the map of our country, and the latitude difference is about 1 degree. Moreover, the lake he saw was a freshwater lake, a swamp full of reeds, and thousands of birds gathered together. Lop Nur (Lop Nur recorded in China's geographical documents) has dried up and turned into a salt flat, which is very desolate.

After the publication of Pule Geval's opinion, it caused a controversy in the international earth science community.

German Richthofen disagreed. He thinks that what Purgwar-Ski visited may not be Lop Nur on the map of China in Qing Dynasty, but the real Lop Nur is still in the north of Platts' investigation.

Later, Stein of Britain and Sven Hedin of Sweden visited Lop Nur successively, and both sides of the dispute were right, but Lop Nur swam to Kara smoothly. Since then, Lop Nur has been described as a wandering lake. Sven Hedin also speculated that the reason of drifting in Lop Nur was that the river water (Tarim River) entering the lake carried a lot of sediment and deposited it in the lake basin, which made the lake bottom rise and led to the lake moving to a lower place. After a period of time, the bottom of the lake exposed by sediments was eroded by the wind, and then the lake returned to its original lake basin. Lop Nur drifts from north to south like a pendulum, and the drift period may be 1500 years.

1923, lop Nur discovered by Poole Geval and Sven Hedin suddenly disappeared and became a desert. Birds flew away, reeds died, and fishermen and residents who made a living by fishing left their huts made of reeds and moved to other places. It turned out that Lop Nur dramatically returned to its former old place, which was marked on the ancient map.

In 1930 and 193 1 year, survey teams from Sweden and China came to Lop Nur marked on the map of China, and found that the water surface there was about188km long, 50km wide and 5m deep, about 2,000km2. 1945, the water surface of lop Nur was expanded to 3000 square kilometers. During the period of 1959, when the Xinjiang comprehensive investigation team of China Academy of Sciences visited the north bank of Lop Nur, it also saw the sight of vast smoke waves and flocks of waterfowl. They also rowed on the lake and even caught a big fish.

But in 1964, Lop Nur began to dry up. In 1973, Landsat photographed the area and confirmed that Lop Nur had completely dried up.

However, geologists in China believe that the reason why Lop Nur dried up is the result of the redistribution of water bodies in human economic activities, that is, land reclamation and diversion irrigation in the upper reaches of the river led to the exhaustion of water sources in Lop Nur, rather than Lop Nur wandering elsewhere.

During the period of 1980, the scientific expedition of China crossed Lop Nur twice, and made a detailed investigation on the landform and ancient water system there. Xia, the captain of the expedition team, wrote in the investigation report: "The lowest point of Lop Nur is 778 meters, and the lowest point of Kara Heshun is 788 meters, with a difference of 10 meters. It is impossible to reverse the kalashun phenomenon in Lop Nur if the water flows downwards. At the mouth of the lower reaches of Tarim River and Peacock River, the sediment content of the river is less, and a large amount of sediment will not be accumulated in a short time, which raises the bottom topography of the lake and makes the water flow to a lower place. During this investigation, we saw that the dry lake bottom was full of hard salt shells, which were difficult to break with steel hammers and wind erosion, making the lake bottom lower again. We also drilled samples in the dry Lop Nur basin. The results of sporopollen and dating of these samples show that there are sporopollen distribution of aquatic plants such as Typha Typha and Sedge in different layers of lake bottom sediments, which indicates that Lop Nur has been stagnant with water in history and the lake has never left Lop Nur. According to the results of carbon 14 dating, the depth of sediments at the bottom of the lake is 1.5 m, about 3600 years ago. It shows that the sedimentation of the lake has been going on since 3600, and unlike Sven Hedin's prediction, the sediment exceeding1500m will be formed around1500m. Field investigation and modern aerial survey data prove that the statement that Lop Nur is a lake tour is not in line with the actual situation, and the water body of Lop Nur has never been refluxed into Kalashun. "