More than 1,200 years ago, the poet immortal Li Bai left the admiration of "the clouds travel the letter and the long wind, and the sassy wings are born", and the poet Du Fu issued a sigh of "will be the top of the mountain, and see the mountains at a glance". As the honor of the five mountains, Mount Tai not only makes the literati and writers of the past dynasties sing the praises with the most beautiful words and sentences with its majestic mountain, but also becomes a vivid history book of the earth with its complex geological evolution process and diverse geological phenomena and landforms.
Taken by Zhao Hongshan
The majestic Dai Zong Exhibition Qilu land has 2.8 billion years of vicissitudes
Mount Tai has experienced nearly 2.8 billion years of geological evolution, and is one of the classic areas with the longest history of Precambrian geological research and the richest geological phenomena in China, as well as the standard area for establishing the framework of Precambrian geological evolution in the eastern part of the continent. According to the research results, Mount Tai has undergone four stages of geological evolution:
The evolution of Mount Tai
Gestation stage The previously formed intrusive rocks (a type of magmatic rock) and sedimentary rocks underwent intense metamorphism about 2.8 billion years ago to form the Taishan Rock Group. In the years of 2.7 billion ~ 2.5 billion years ago, it has undergone many magmatic activities, forming multi-stage rock masses with different lithologies, scales and shapes.
Subsidence stage After more than a billion years of erosion, the terrain tends to be flat. About 600 million years ago, the surface of the land began to subside, and the sea water submerged the ancient landmass, turning it into a vast ocean, and continuously deposited more than 2,000 meters of thick strata. At this time, the main rocks that make up Tarzan "sleep" deep underground.
Embryonic stage About 100 million years ago, under the influence of the Yanshan movement, a number of faults were produced at the southern foot of Mount Tai. Controlled by the southernmost Taiqian fault, Mount Tai began to rise, and the huge thick sedimentary rocks that had previously covered the ancient rocks were gradually eroded, and the Taishan rock group and other magmatic rocks in many stages were exposed to the surface, forming the prototype of today's Mount Tai.
Forming stage About 30 million years ago, the Taiqian fault continued to be active, and at the same time, the activity of the Zhongtianmen fault and the Yunbuqiao fault intensified, forming three steps that gradually decreased from north to south, thus laying the basic outline of Mount Tai. After the comprehensive action of various external forces, it was gradually carved and shaped into the majestic and magnificent Mount Tai today.
Ancient rocks
The stone of Mount Tai is simple, vigorous, hard in texture, and calm in tone. Among them, the Archean ~ Paleoproterozoic intrusive rocks are widely distributed, accounting for more than 95% of the main area of Mount Tai, and are extremely important geological bodies of Mount Tai. The intrusive rocks are dominated by medium-acid granite and diorite. In addition, banded gneiss, which has curved bands and various patterns, is also an important rock type of Mount Tai, and the so-called "Mount Tai stone" in the ornamental stone world mostly refers to this rock.
Photo courtesy of Taishan Rock Group / Jiang Haichao
According to the lithology and diagenesis time, the main rocks of Mount Taishan can be divided into five major rock masses: Wangfu Mountain period rock mass, lithology is black and white banded gneiss, the rock age is 2.72 billion years, the whole park is distributed, mainly distributed in Daiding, Taohuayu, Dajinkou Township and other areas; Mata area, the rock mass of the Aolai Mountain period, the lithology is monzogranite, the rock age is 2.51 billion ~ 2.52 billion years, mainly distributed in the main peak of Mount Tai, the north and east side of Mount Tai, the rock mass of Zhongtianmen, the lithology is quartz diorite, the rock age is 2.505 billion years, distributed in the central Zhongtianmen, Longjiao Mountain and Taohuayu and Fangjiazhuang in the northwest are distributed along the north-west direction in the form of rock plants, and the rock mass of Puzhao Temple is fine-grained diorite with a rock age of 2.46 billion years, which is mainly distributed in the area of Puzhao Temple, and is produced in the form of small rock plants and veins.
Diverse geological formations
The geological structure of Mount Tai is very complex, folds and faults and other structures are relatively developed, both formed in the Precambrian, and developed in the Middle and Cenozoic eras, they are superimposed on each other, constituting an extremely complex structural appearance of Mount Tai.
Mount Tai has three major fault zones. The Taiqian fault is a north-east-east regional fault formed by the action of horizontal compressive force in the east-west direction in the Luxi area, and it is the dividing line between the two tectonic units of the Taishan fault block bulge and the Tailai fault block sag. The Zhongtianmen fault was formed in the Mesozoic Era, from west to east through Hengling, Zhongtianmen, to Shangliyuan, forming a steep slope on the south side of Zhongtianmen, cutting through the Aolai Peak to the west, forming a large ditch. The Yunbuqiao fault was also formed in the Mesozoic, which cut the quartz diorite into plates to form a dense joint zone. There is a branch fault parallel to the south side of the main fault, forming a 4-meter-high cliff, which is the location of the Yunbuqiao Waterfall.
Barrel structure Photo courtesy of Jiang Dunguo
In addition to the fault structure, the barrel structure is also a major tectonic feature of Mount Tai. In the northeast gully of Hongmen, there is a black-green diabase porphyry exposed, the age of the rock is 1.6 billion years, it is the youngest rock in Mount Tai, and many horizontal cylinders of different sizes are developed in it. From the cross-section of the cylinder, it is composed of many concentric circles and a core, so it is called "barrel structure". The causes of the "barrel structure" are complex. Some scholars believe that it is formed during the condensation and contraction process after magma intrusion, and some scholars also propose that in the process of magma intrusion, due to the constraints of many factors such as thermal gradient, thermal field, velocity field, vortex strength and boundary conditions, multiple stress gradient domains are generated, which causes hidden fracture lines to be produced inside the rock, and the tensile stress in the later stage makes these fracture lines more obvious, and then forms a cylinder with annular joint development.
The art of nature shaped by geological processes
Mount Tai is majestic as a whole, and there is no lack of beautiful landscape. Xianren Bridge, Gongbei Stone and Fan Cliff are the famous geological relics landscape of Mount Tai, and they are also natural art shaped by geological action.
On the west side of Daiding Zhan Lutai, there are 3 huge stones hanging in the air and overlapping and coincidentally connected between two cliffs, its shape is like a bridge, the lower is a deep stream, the south is bordered by the abyss, the terrain is very dangerous, it seems that only the gods can pass from the bridge, people vividly call it "the fairy bridge". The rocks on the east and west sides of the Xianren Bridge are 2.5 billion years old monzogranite, which is the natural "bridgehead" of the bridge, and the three boulders that constitute the main body of the bridge body, one in the middle is felsic vein, and the two on its side are monzogranite. This geological relic is a strange landscape of the "Deep Stream Cliff Hanging Immortal Bridge" formed due to rock collapse.
Immortal Bridge Photo courtesy of Chen Indium
In the east of Daiding Riguan Peak, there is a huge stone quite like a sharp sword with a sheath obliquely piercing the sky, the name is called: "Gongbei Stone". It points almost due north, only 8 degrees to the west of the north, and the angle between it and the ground is 30 degrees, and the cliffs below the north and east sides of it are more magical and precipitous. Gongbei stone is monzogranite, which is the main rock type of Daiding. Due to the development of vertical joints, the Daiding rock is cut into plate-like rock blocks of different thicknesses, and in the process of weathering and denudation, due to the influence of gravity, collapse and dumping often occur. Gongbei stone is formed from a piece of dumped monzogranite after a long period of weathering.
Gongbeishi Photography / Zhao Hongshan
Fan Cliff Danbi such as cutting, shaped like a giant fan, the Qing Dynasty poet Sun Baoyu wrote in "Fan Cliff": "The sword peak is angry and pierces the sky, and the iron is pulled out by a thousand." Fan Cliff is a typical "boutique of cooperation" of internal and external dynamic geological processes, which was originally a whole with the Lion Peak on the east side and the Aolai Peak on the west side, and was later divided into three peaks by two north-west-trending faults, and the Fanzi Cliff was cut by the north-east-east faults to form a series of dense and upright plate-like blocks. In addition, the horizontal joints of monzogranite are developed, and the rock is very broken, so under the action of gravity, it continues to collapse, and gradually forms the fan cliff that is like half of the wall and shaped like a fan over time.
Photo courtesy of Fan Cliff / Chen Indium
Tarzan rock, Lupin sees. Hundreds of millions of years of geological evolution and external force have formed a unique geological relics landscape of Mount Tai, which has extremely high aesthetic value and geological value. The unique topography and geological relics characteristics of Mount Tai have an important impact on the ancient buildings of Mount Tai and the stone carvings of Mount Tai, and carry the heavy history and culture of Mount Tai. Mount Tai is a rare mountain of humanity and science that uniquely combines nature and culture so perfectly. It is a vast and profound cultural and natural museum, a historical masterpiece that is often read and always updated, and a magnificent and continuous cultural scroll.
Source: Earth Magazine
Editor: Lan Duoduo
The reprinted content represents the author's views only
It does not represent the position of the Institute of Physics of the Chinese Academy of Sciences
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