Shulou(Shulou.com)11/24 Report--

To put it bluntly, with everyone's ingenuity, we must be no stranger to the real objects in the picture. These tree-like jade materials have a good name-tree jade, or the more professional term "silicified wood". Today, let's talk about how the two seemingly unrelated substances, "tree" and "silicon", are integrated.

There are many theories about the formation time of silicified wood, some say that "silicified wood" was formed in the Carboniferous period 300 million years ago, some say that "silicified wood" was formed in the early Triassic, and some say that "silicified wood" was formed in Jurassic / Jurassic-Cretaceous and Miocene. In view of the fact that plants have a long history on earth, their "love history" cannot be traced back to its roots, but in any case, it is a "love story" that spans at least thousands of years, and the truth is stronger than gold.

Although the formation time of silicified wood is varied, most of the studies on the causes of silicified wood tend to be discussed and studied by geological methods. To sum up, most of the causes are as follows: before the formation of ① "silicified wood", this area was once a tropical or subtropical rain forest with luxuriant plant growth. The formation of ② "silicified wood" is mostly related to a series of geological events caused by plate crustal activity, such as volcanic activity, basin differential rise and fall, earthquake, flood, volcanic eruption and debris flow. The formation of ③ "silicified wood" is influenced by a large amount of silicon-bearing hydrothermal solution (silicon-rich groundwater) (related to geological activities such as more silicon-bearing hydrothermal solution than volcanic activity). After a long geological history, the fossilization transformed into silicified wood. [1]

1. There is no doubt that there are numerous trees and luxuriant grass. Without abundant tree resources, silicified wood will lose its "flesh", and the growth of silicified wood is closely related to the climate and environment at that time. Generally speaking, before the silicified wood was formed, the region was mostly tropical or subtropical climate, the temperature was suitable, Rain Water was abundant, sunny, and the land was fertile, so tall green trees thrived and developed here, and produced a relatively complete ecosystem. Take Myanmar, which produces silicified wood at present, as an example, in the Miocene Myanmar region, the Indo-Burmese mountains folded into mountains along the Naga Mountains due to plate collision, while the sea water in the central lowlands of Myanmar retreated from the central part to the south and gradually turned into land, accompanied by the formation of a monsoon climate environment, which created conditions for the formation of a tropical rain forest ecological environment, which laid the foundation for the vigorous growth of plants. [2]

In addition to Myanmar, in the study of the Lesworth silicified forest in Greece, scientists inferred that the Miocene plant characteristics in this region are similar to those in Southeast Asia and the Americas, indicating that the Aegean region had a subtropical climate in the early Miocene, and the Lesworth silicified forest was a mixed subtropical forest before silicification. There are more than 46 plant species, mainly conifers and angiosperms, including pine, yew, cypress, laurel, beech, all kinds of palms and occasional ferns.

Lesworth silicified Forest Nature Reserve (green part) 32. The frequent geological activities of orogeny and volcanism caused by various geological activities can not only provide suitable conditions for plant growth, but also an indispensable step in the formation of silicified wood. Take Myanmar silicified wood as an example, its original surface is covered with a layer of gray-white, yellowish-brown and other grayish soil formed by volcanic ash condensation. This is an example of tropical Yusen experiencing intense volcanic magma eruptions, while western Myanmar happens to be on the Neo-Tethyan orogenic belt on the edge of plate convergence. The Neo-Tethys died out in the Cenozoic era, and it was inherited by the Alps-Himalayan orogenic belt, which has the most intense geological movement in the world and has a global scale.

In addition to Myanmar, the silicified wood skin of the Lesworth silicified forest in Greece also shows this characteristic. During the period from Eocene to Oligocene, about 45 million to 35 million years ago, the two lithospheric plates of the northern Eurasian continent and the southern African continent converged in the Kikraze area, and the African plate subducted northward under the Eurasian plate, which triggered strong volcanic activity in the northeast of the Aegean Sea. Volcanic eruptions do not necessarily burn up everything nearby. Take Mount Vesuvius and the ancient city of Pompeii as an example, after excavation, it is found that the ancient city of Pompeii and its people and things seem to be frozen in that moment by the flow of volcanic debris, and it is the same for trees. Sudden geological events make plants buried quickly and are in a hypoxia environment for a long time. Here it will quietly wait for its destiny son-silicon hydrothermal.

Geomorphological map of Lesworth Island and major silicified forests and craters and interpreted volcanic geological sites 3

Lesworth silicified forest upright silicified metasequoia trunk 33, silicon hydrothermal silicon! If the tree structure in the silicified wood is the "flesh", then the silicon in the silicified wood is the "soul", and the uncorroded organic matter in the tree is constantly replaced by a high concentration of silica hydrothermal solution. After cooling, the silicon dioxide is deposited in the form of opal or gel-like silica, making it fossilized and retaining the original internal structure of the tree. After a long period of geological history, the tree is finally silicified to form silicified wood [4]. This is why the rings and even fibrous tissue of some silicified wood are clearly visible. [5]

So the question is, where does the high concentration of silica hydrothermal come from when the solubility of silicon in water at room temperature is very low? This is also related to the frequent geological activities we mentioned earlier: first, in the process of lithospheric plate aggregation, it will carry a large amount of silicon when it rises toward the earth's crust, and second, the siliceous solution will be provided in the process of volcanic magmatism. as a result, the silicon content in this area is higher than that in other places.

The subtropical monsoon climate and tropical monsoon climate are warm and humid, it is rainy all the year round, and groundwater is very abundant. Lakes and rivers seep down along cracks produced by geological processes, while frequent geological activities such as volcanoes provide heat sources for hydrothermal fluids. Circulation and upwelling occurs after heating by geothermal or volcanism at a certain depth, and hot water leaches through rocks and strata and extracts large amounts of silicon dioxide and other minerals. Finally, a high concentration of hydrothermal solution containing soluble silica was formed. [6]

The formation of surface hot spring 3 silicified wood in Lesworth silicified forest area is the result of the joint action of climatic environment, geological environment and geological activities. it is precisely the ingenious resonance of these factors at the same frequency, after the old plants suddenly fell apart, slowly transformed into minerals, gained a new life, time flies, time is gone, after the veil of history has been lifted, it has a good name-silicified wood.

reference

[1] Dong Chuanwan. Zhu Guoqiang. Yu Zhonghui et al. Study on petrology and paleoecological environment of silicified wood in Xinchang, Zhejiang [J]. Journal of Zhejiang University. 2002. 29 (2): 202-208.

[2] Wang Yizhao. The cause of formation of Myanmar silicified wood ("tree jade") [J]. Geological bulletin. 2011 Jol 30 (10): 628-1637.

[3] Zeng Yuxin. Analysis on the characteristics and causes of silicified forest in Lesworth, Greece [J]. Journal of Changjiang University (self-Science Edition), 2018 15 (14): 48-52.

Zhu Guoqiang, Dong Chuanwan, Yinwei. Siliceous source of silicified wood in Xinchang, Zhejiang [J]. Report of Chengdu University of Technology. 2003 30 (1): 35-39.

Duan Shuying, Dong Chuanwan, Pan Jiang, et al. Study on fossil wood in Xinchang, China [J]. Botany Bulletin, 2002 pr 19 (1): 78-86.

Zheng Yuan, Zhou Jiayun, Zhu Chuang, Li Tongzhu. Landscape characteristics and Genesis of Shehong silicified Wood National Geopark in Sichuan [J]. Resource development and market. 2006, (03): 286,288

This article comes from the official account of Wechat: stone popular Science Studio (ID:Dr__Stone), author: Bian Zhou, American editor: Qiega cc

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.