In 1910, Wegener, a famous German meteorologist and geophysicist, discovered that the shapes of the two sides of the Atlantic Ocean could complement each other, thus germinating the idea of continental drift. He believes that the land of the world was still connected to each other as a whole 200 million years ago, and then it was separated and drifted to the current position due to the force of the earth’s rotation.
Scientists have found a lot of evidence to support the “continental drift theory”, one of the most convincing evidence is the fossil of the water dragon. Water dragon beast is a kind of mammal-like reptile that lived about 200 million years ago. It mainly lived on land and could not migrate across the sea. However, their fossils are widely distributed in the late Permian-early Triassic strata in Xinjiang, southern Africa, India, Antarctica and other places, and their wide distribution pattern across oceans strongly suggests that these fossil sites may have been in the same period at that time. One United Continent – Gondwana. Evidence from paleontological fossils has played a key role in proving the continental drift hypothesis.
The distribution of Yangtze Sea and ancient fish fossil origins (red represents shallow sea red bed deposition area)
The current fossil record shows that the same group of armored fish lived in the Tarim Basin and South China in the early Silurian period (438 million years ago).
In addition to water dragons, there are some fish that also play a similar role, such as armored fish with limited migration and diffusion capabilities. Armored fishes also play an important role in proving the theory of plate drift. It can even tell us that the Tarim Basin “drifted” slowly from the equator.
Armored fishes are a type of bottom-dwelling filter-feeding fish. The main living environment is the shallow sea near the edge of ancient continents. Armored fishes have flat heads and lack pairs of paired fins, indicating that their swimming ability is weak and their diffusion , The ability to migrate is limited, and the vast land and wide ocean have become obstacles to its diffusion and migration. The current fossil records show that the Tarim Basin and South China lived in the same group of armored fishes in the early Silurian Period (438 million years ago), and they covered the ancestral types of armored fishes and multibranched fishes, which shows that there is a gap between them today. The two blocks of 4,000 kilometers were probably connected together at that time and were in the same sea area.
Representative fish fossils from Tata Ertage Formation, Xinjiang
Paleogeographical location of the Tarim Basin during the Silurian period reconstructed from ancient fish fossils
In addition to the evidence of ancient fish fossils, the study of invertebrate fossils also shows that the two plates of South China and Tarim belonged to the same zoogeographical group during the Silurian period. In addition, the sedimentary environments of the two in the early Silurian period were basically the same, and the types of sedimentary rocks were both represented by red clastic rock series formed in shallow seas in arid environments. The Silurian stratigraphic structures of the two are also basically the same, that is, the age of the bottom layer and cover layer of the Silurian system and the contact relationship between them are roughly the same.
During this period, the Silurian strata on both plates covered the Late Ordovician strata, which were covered by the Middle-Late Devonian strata. According to paleomagnetic studies, as early as the Silurian period (440-420 million years ago), the Tarim plate was located approximately south of 15° north latitude, that is, near the equator, and its position was eastward. During the Silurian period, the Tarim plate should have been connected with the South China plate, which is called the Tarim-South China joint plate.
So why did the Tarim plate (equivalent to the current Tarim Basin) run from near the equator to the western border four thousand kilometers away? Different scholars have given different explanations according to the materials they have in hand, and there is still no unified view so far. At present, based on the study of paleontological fossil materials combined with comprehensive analysis of paleomagnetism, stratigraphy and paleoenvironment, the following is a more reasonable point of view: the Tarim-South China joint plate was formed in the late Silurian period (420 million years ago) began to disintegrate. The main reason for the disintegration may be that the Qiangtang and Qamdo land masses in the south rushed over with huge energy and knocked the combined plate away. After the disintegration of the joint plate, the Tarim plate began to drift slowly to the northwest in a clockwise direction, and it reached its current position in the late Permian (250 million years ago), while the South China plate moved eastward for 800 kilometers . In other words, the Tarim Basin was not where it is now 400 million years ago. After a long geological process, it drifted here slowly from South China. As the Indian plate continues to subduct northward, it remains to be seen whether it will drift northward as well.