Infatuated stone

After leaving Hongmen palace cave in the north, the scenery of the mountain suddenly changes. The sound of water in the middle stream on the right side of the mountain road is tinkling, and the "little cave" of Mount Tai is hidden in the valley. Turn right from the circle road, and go along the path to the northeast. Not far away is xiaodongtian, where the grass is as green as grass, the cypress is as green as cover, and the water is murmuring. Down to the bottom of the valley, there is a huge stone flat with 12 square meters in width and 1.5 meters in thickness. To the south, there is the Ming Dynasty; On the left side of shiganyingjiati and fan Guangshu's "xiaodongtian" in Tai'an Prefecture is a stone stream. The rocks in the stream are jagged and of different shapes. The cliffs at the bottom of the valley are stacked and the horizontal waterfalls are flying. During the rainy season, the clear water of Zhongxi will flow out from the crevices of the rocks. Over time, it rushes out of three bays: liutiaowan, Yinma Bay and Shixia Bay. Every night when the moon is full, the moon is reflected in the Bay, leaving three reflections, which is very poetic.

There is also a rare geological landscape of Mount Tai - "enchanting stone". Zuixin stone, named "diabase porphyrite vortex column structure", is a lot of round bodies with east-west orientation and different sizes lying at the bottom of the valley. There is a stone core in the center of the cross section of these cylinders, which cracks to the outer ring around the stone core. This peculiar rock shape has long attracted the attention and interest of the ancients. Mei Cheng, a scholar of Han Dynasty, called it "the slip through stone of Mount Tai", commonly known as heishibu. It is a ring jointed diabase porphyrite, which is rare at home and abroad. Some people have engraved the word "intoxicated" on the cross section of a stone column, which is exactly the feeling of the ancients for the amazing craftsmanship of Taishan stone. Up to now, there is no definite theory about the origin of zuixin stone. It attracts many tourists and scholars to visit and investigate it every year. Here a ravine winding, Qingxi Bitan, mountains, streams grass, dense vine, unique cave.

Barrel structure

synonym

Drunk stone generally refers to barrel structure

It is commonly known as "infatuated stone"

It is a new tectonic type. It is rare at home and abroad. It was first found in Mount Tai. It occurs in the North-South diabase porphyrite dikes. The isotopic age is about 1.2 billion years. It is mainly composed of ring core, ring layer, ring and radial joints. It is formed by condensation of low viscosity magma flowing in the form of vortex street or vortex array under specific conditions. They are often exposed in groups, overlapping each other, and in peculiar shapes.

"Vortex core stone"

Vortex core stone, a geological term, describes the geological structure. Also known as barrel structure, vortex column structure. It belongs to a new tectonic type

. It is rare at home and abroad. It is the first time to find the vortex column structure of Zuixian diabase porphyrite in Taishan. It occurs in the North-South diabase porphyrite dikes. The isotopic age is about 1.2 billion years.

Taishan stone

It is mainly composed of ring core, ring layer, ring and radial joints

. It is formed by condensation of low viscosity magma flowing in the form of vortex street or vortex array under specific conditions. They are often exposed in groups, overlapping each other, and in peculiar shapes. The genesis and formation mechanism of this rare and peculiar geological structure is a rather complicated geological problem. It can not be analyzed by spherical weathering, nor can it be answered by the traditional theory of primary magmatic joints. In the past, many geologists tried to apply theories and methods from different angles to do some research work. They have been listed as National Natural Science Foundation projects and carried out special research work, and made some achievements and progress. However, the understanding of its causes is still very inconsistent, and it still needs to be further explored and studied.

Evolution history

It experienced the influence of Taishan tectonic movement about 2.5 billion years ago at the end of Archean and was subjected to intense and widespread granitization and migmatization. It belongs to medium and high grade regional metamorphism with a total thickness of more than 12000m. The fold axis and schistosity of the strata are 340 degrees due to the Taishan tectonic movement. The ancient continental core hidden under the Taishan Group is distributed in the east-west direction. Therefore, it can be inferred that the problem of stress field transformation existed in Archean, that is, from north-south to east-west. The Indosinian and Yanshanian crustal movements resulted in violent tectonic changes in the area, with widespread folding, faulting and magmatic activities. In this period, the tectonic stress field has changed to NW-SE direction. As Professor Li Siguang pointed out, "at least since Paleozoic, the whole and part of the northern and Central Eurasia has been sliding southward at the same time", that is to say, the East Asian continental plate has been sliding from north to South relative to the Pacific basement plate, resulting in NW-SE compressive stress. The change of Mesozoic tectonic stress field replaced the stress field dominated by north-south compressive stress before Paleozoic. Annular joint is the dividing surface of two adjacent annular layers, which is round or arc-shaped. The annular layer is relatively smooth, and weak scratches can be seen locally. This kind of annular joint is not clear enough in the fresh outcrop, only in the weathered outcrop. Generally, radial joints are not well developed. They radiate from the inner ring layer to the outer ring layer on the cross section, and generally terminate at the edge of the ring core. Only a few of them can penetrate all the ring layers to the ring core. The joint surface is perpendicular to the ring layer and extends stably along the strike, The joint plane is straight but not smooth, and it is often not continuous when passing through each ring layer, sometimes it cuts through the ring layer, sometimes it is interrupted due to the ring layer restriction.

Organization

There are two types of cylinder combination: "dislocation arrangement type" and "parasitic type"

. On the cross section perpendicular to the long axis of the former, the two cylinders are staggered, just like the gasoline barrels stacked upside down in a warehouse. The latter is a small cylinder parasitic between the two large cylinders. Part of the ring layer of the small cylinder transits into the ring layer of the two large cylinders, and then is wrapped by the outermost ring layer, forming a large "barrel structure".

The cylinders are hosted in the veins of the diabase porphyrite and strictly controlled by the dikes. There are more than 500 cylinders, which are perpendicular to the strike of dikes and distributed in east-west direction. The inclination angle of the long axis of the cylinder is very small, generally less than 5 ° and up to 10 ° individually. Most of the cylinders incline to the East and a few to the West. It is one of the most important characteristics of this kind of "barrel structure", which is different from other barrel structures. The development and quantity of the cylinder are closely related to the width of the vein. If the width of the vein is large, the cylinder is well developed, the quantity is large, and the scale is large. On the contrary, if the width of the vein is small, the cylinder is poorly developed, the quantity is small, and the scale is small. If the width of the vein is too small, there will be no development of the cylinder. For example, the exposed width of diabase porphyrite dikes near Hongmen is 60m, and the number of cylinders is more than 30. Generally speaking, the development of cylinders along the strike of dikes is not the same, some sections are relatively dense, and some sections are relatively sparse. In the vertical direction, the cylinder develops to a depth of about 200 meters and disappears at a certain depth, which is a shallow structure in the crust.

Mount Tai has a long history of geological evolution, complex geological structure and typical geological relics

It has always attracted the attention of geologists at home and abroad. Adjacent to "xiaodongtian", it is the rare geological landscape of Mount Tai - "zuixin stone". Its shape is like the growth rings of ancient trees, and it is very strange. In the south slope of Mount Tai, from Hongmen to the north, along Dengshan Middle Road, through wanxianlou, Doumu palace and Zhongtianmen, and to the north of Daiding, sometimes in the west of Mount Tai, sometimes in the east of Mount Tai or in its gullies, many black stones can be seen. In fact, this is the outcrop of a nearly north-south extending diabase porphyrite vein. The diabase porphyrite is dark green and turns light brown red after weathering. Its texture is very hard and its specific gravity is large. It has porphyritic structure. The main mineral components are pyroxene and basic plagioclase. The color of pyroxene is dark green, columnar, glassy luster, hardness 5-7, specific gravity 3.2-3.6. The basic plagioclase is dark gray, flat columnar, glassy luster, hardness 6-6.5, specific gravity 2.76. The microscopic observation of rock thin section shows that the basic plagioclase is obviously more automorphic than pyroxene, and the diabase structure is obvious. Plagioclase generally has wavy extinction phenomenon, and has undergone varying degrees of alteration. Diabase porphyrite is a kind of dark basic dike formed by the intrusion of basic magma along the original nearly N-S trending extensional and torsional fault, and finally condensed and crystallized, which belongs to hypabyssal intrusive rock. The surrounding rocks are Taishan complex formed in Archean. Due to the influence of contact metasomatism in the process of magmatic intrusion, slight alteration of potassic feldspar occurred in the surrounding rocks close to the two sides of the dikes, resulting in reddening of rocks in varying degrees. According to the preliminary determination of isotopic age, the age of diabase porphyrite is about 1.7 billion years, which may be the product of magma intrusion in the early Mesoproterozoic.

characteristic

Stable occurrence of diabase porphyrite dikes

Its strike is 350 ° NW and its dip angle is about 80 ° SW. Nearly erect. The length of the base is more than 5000 meters, but the width varies greatly, generally 20-60 meters. The width is about 60 meters near the Red Gate, but only about 20 meters at Doumu palace. In some areas, the bifurcation phenomenon of the vein is obvious, and the width becomes very small and even pinches out. In geomorphology, dikes often show negative topography and are mostly exposed in valleys. In the vein of this diabase porphyrite, there are many cylinders of different sizes lying horizontally, and there are many concentric circles in the cross section, which are very peculiar in shape, such as folded picture rolls or egg rolls in food stores. These cylinders appear in groups, parallel to each other, overlapping each other, cool like a pile of gasoline barrels, so

Chinese PinYin : Zui Xin Shi