Lop Nur, once the largest saltwater lake in China, did not possess as much salt as it does today about 1,800,000 to 2,500,000 years ago, scientists concluded from a core sample drilled from deep in the lake site.
The discovery was made when the deep-drilling research program, funded by the Ministry of Science and Technology and the Chinese Academy of Sciences, was performed in Ruoqiang, a county in northwest China's Xinjiang Uygur Autonomous Region.
The research program, which is still going on, is the first systematic deep-drilling project in environmental science at Lop Nur aiming to find the relationship between the drought of Lop Nur and the aridity of west China.
Lop Nur was once the largest lake in arid northwest China, but dried up in 1972 as a result of environmental deterioration.
The first drilling position is fixed at the center of ancient Lop Nur, where a continual core sampling down to as deep as 800 meters will be made.
As the drilling reached 160-250 meters, some caesious silt and powder sand were collected.
"Little salt crystal was separated out from the sample and the deeper the bit went down the less salt we got," said Fang Xiaomin, who is in charge of the program. "It shows that the lake possessed some salt but not as much as today. So, Lop Nur could not be defined as a saltwater lake about 1,800,000 to 2,500,000 years ago, but a semi-saltwater lake at most."
"And Lop Nur must have been a deep lake about 2 million years ago, because only when the lake is deep enough so there is no oxygen at the bottom will the silt become caesious", added Fang.
A shallow drilling up to 50 meters deep will be performed parallel at other spots of Lop Nur to confirm findings at the first position.
(Xinhua News Agency October 21, 2003)
