Geological landscape resources

There are various types of geological landscapes, the more typical ones are as follows.

(1) Volcanic landscape

There are 1,343 active volcanoes on the earth. They are mountains formed by lava passing through the earth's crust, rising to the ground or erupting from the surface." They are mainly concentrated in Distributed at the edge of the plate. When a volcano erupts, it is accompanied by earthquakes, thunderous sounds and explosions, and the billowing smoke is like a mushroom cloud rising from an atomic bomb explosion. The lava flow roars and flows, reflecting the red sky (Figure 7-32). There are many volcanoes. The Hawaiian Islands were created by volcanoes, and they are still overflowing with magma and pouring into the sea. Japan and Iceland are also volcanic countries, as well as Indonesia, the Philippines, Italy, and Antarctica.

The main forms of volcanic eruptions are central type, fissure type and mixed type. Italy is the earliest country in the world to study volcanoes. Many volcanic types are named after Italian and Mediterranean volcanoes. Volcanoes have a life span, so they are divided into active ones. Volcanoes, dormant volcanoes, and extinct volcanoes.

In general, geological processes on Earth occur very slowly, but volcanoes form quickly when underground magma rises through the crust. It mainly erupts magma, volcanic bombs, volcanic gravel, volcanic ash, water vapor, carbon dioxide, sulfur-containing gas, etc. Its ejections accumulate to form volcanic cones, lava plateaus, lava plateaus, lava barrier lakes and other landforms.

In the past hundred years, most of the news about volcanic eruptions that people have heard came from areas outside China. The most recent volcanic eruption recorded in China was in the Ashkule Basin in the West Kunlun Mountains. Ash Volcano, also known as Cardassia Volcano (Figure 7-33), suddenly heard a loud noise on May 27, 1951, and a cylindrical column of black smoke shot straight into the sky. Subsequently, many rocks were thrown from the crater... …The officers and soldiers who were building the Xinjiang Highway nearby were on the scene, and Xinjiang Daily also reported on it. Because the volcanic eruption occurred in an inaccessible mountain at an altitude of 5,000 meters, it did not cause much damage.

Picture. 7-32 Volcanic Eruptions

Figure 7-33 Caldasian Volcano

China was once a country with many volcanic eruptions. Changbai Mountain is a dormant volcano that has been dormant for a long time since 1597. During the 105 years from its awakening in 1702, there were three consecutive eruptions. In my country, clusters of volcanic areas include the Datong Volcanic Group in Shanxi (Figure 7-34), the Datun Volcanic Group in Taiwan, and the Tengchong Volcanic Group in Yunnan (Figure 7). -35), Hainan Leiqiong Volcano Group, Qinghai-Tibet Plateau Volcano Group, etc. The risk and possibility of re-eruption of dormant volcanoes still exists. Volcanic eruptions have a certain cycle, and when volcanoes wake up is an issue that volcanic geologists should pay more attention to. .

Figure 7-34 Datong Volcano, Shanxi

Figure 7-35 Tengchong Volcano, Yunnan

(2) Geothermal Landscape

Geothermal Landscape It refers to various peculiar, colorful and diverse hydrothermal activity landscapes, such as geysers, fumaroles, steam valleys, boiling fountains, boiling spring groups, hot water lakes and "hot water lakes" formed by various springs. Natural landscapes such as "Stone Mushroom", "Tiantian Bridge" and "Stone Forest" also include the magnificent scenery of steam columns with diameters of several meters and heights of tens or even hundreds of meters formed when high-temperature geothermal wells blow out (Figure 7- 36). Geothermal landscapes are formed in specific geological structural environments during a long geological history and in the process of human development. Once they are affected by natural or man-made factors such as earthquakes, well drilling, excessive mining, road construction, building construction, etc. It is almost impossible to restore the damaged or disappeared landscapes such as the hot water lake, 92°C spring and river boiling spring in the Yangpajing Geothermal Field in Tibet, which disappeared from people's sight more than ten years ago. . In recent years, with the rise of tourism geoscience and the booming development of the tourism industry, the value of geothermal landscape resources has attracted more and more attention. Some of them have been included in national nature reserves or world-class natural heritage and are protected by relevant laws and regulations. .

Figure 7-36 Geothermal landscape

(3) Earthquake relics

Various seismic geological processes and seismic effects related to strong tectonic seismic activity. called earthquake relics. Generally speaking, the relics of recent earthquakes are clear and have many points; while for earthquakes that are older in time, as time goes by, only the relics remain, which are few and blurry. Earthquake relics mainly include ground fissures, landslides, collapses, surface barrier lakes, sunken land (buildings), damage to bridges and towers, and even splitting mountains and moving rocks, bulges on the ground, spraying water and sand, and large trees torn apart by earthquakes, etc. Landscape phenomenon (Figure 7-37).

Figure 7-37 Earthquake Relics (1)

Figure 7-37 Earthquake Relics (2)

my country is a country with many earthquakes, with earthquakes across the Pacific Rim Belt and Mediterranean-Himalayan seismic zone, neotectonic movement is strong, there have been many strong earthquakes and major earthquakes in history, and there are many earthquake relics, especially in the western provinces and regions, they are more or less distributed. However, currently only the "Undersea Village" ruins in Hainan Dongzhaigang National Nature Reserve are included in nature reserves. The Qiongzhou Earthquake in 1610 AD caused 72 villages in Qiongshan County to sink, forming today's Dongzhai Port. This is the only earthquake ruin in the history of our country where land subsided and sank into the sea. It has high scientific research and tourism value.

Figure 7-38 Schematic diagram of meteor impact (Yang Shiyu et al., 2007)

(4) Crater

Meteorites are meteorites that have passed through the atmosphere but have not been completely burned And the remnants that landed on the ground. It is a precious sample that allows humans to directly understand celestial bodies. It has important scientific research value and is also a unique ornamental stone. A series of effects occurred during the meteorite falling from the sky to the ground, collectively called meteorite impact. Figure 7-38 shows the various effects that occur when meteorites fall from the sky to the ground. First, it penetrates into the ground at high speed (Figure 7-38a, b), causing downward and lateral compression to the surroundings (Figure 7-38c, d). Then the rock material crushed by the impact is sputtered high into the sky (Figure 7-38e, f), and part of the material is backfilled into the meteorite impact crater and around the crater. At the same time, an annular highland was formed around the impact crater, and the rocks at the bottom of the impact crater underwent impact metamorphism (the high-temperature mineral char quartz appeared) and fragmentation, forming impact rocks, breccias, and fissure zones. A rebound protrusion will also be formed at the center of the impact, forming a special geological structural relic landscape. Meteorites and craters are distributed around the world, such as Xinjiang, my country (Figure 7-39) and Arizona, USA (Figure 7- 40) There are very typical meteorites and crater remains.

Our country started a little late in studying the geological landscape and formation mechanism of impact craters, but it has initially gained some important understandings. The crater located in Duolun County and Zhenglan Banner, Xilingol League, Inner Mongolia Autonomous Region, is the largest crater discovered in my country so far, and it has obvious annular landform features around it. The Duolun Crater was formed between the Jurassic and Cretaceous periods, about 140 million years ago. The diameters of its inner ring, middle ring and outer ring are 8km, 82km and 170km respectively. The inner ring is 8km of andesite, and the middle ring is located on the outside of the annular water system. The geomorphology is represented by a ring of residual hills composed of Archean granite, metamorphic rock and alluvial molten rock. The crater also preserves some rare geological phenomena. Duolun Crater is one of the better-preserved craters and provides important inspiration and basis for exploring the formation mechanism of impact craters.

In 1993, while analyzing satellite-borne synthetic aperture radar images in Qixia County, Shandong Province, our country's remote sensing scientists discovered a semicircular bright ring, which was confirmed to be a meteorite impact relic after analysis and research, and was named Tangjia. Meteorite impact structure. Field inspections revealed that there are features of depressions and craters, with rebound and uplift in the central area. Impact-shattered breccias are widely distributed, and local rock formations are disordered. Molten breccias with shattered cones were also found in the center.

Figure 7-39 Xinjiang iron meteorite

Figure 7-40 Arizona meteorite crater, USA

(5) Stratigraphy and paleontological landscape

1. Typical geological (stratigraphic) section landscape

Figure 7-41 Sinian-Cambrian boundary section at Xiaowaitou Mountain in Meishu Village

Stratigraphic exposures in various eras in my country It is complete and very distinctive. Although many sections are regional, there are also many sections that are internationally representative, and many domestic and foreign experts come to investigate and study. Some sections have high ornamental value, such as the Jinshitan section in Dalian, Liaoning, which has been listed as a national scenic spot. For example, the Meishu Village section in Jinning, Yunnan (Figure 7-41) is located in Xiaowaitou Mountain near Meishu Village, Jinning, Yunnan. It is composed of dolomite, siliceous dolomite, dolomitic phosphate rock, etc. From 1984 to 1991, this section was the best candidate for the global Precambrian-Cambrian boundary stratotype section. The Meishu Village fauna is rich in small-shell animal fossils and trace fossils such as gastropods, brachiopods, and soft tongue snails. Its complete evolutionary series and fossil distribution are the basis for geological comparisons between domestic and foreign countries. More than 50,000 specimens and more than 100 animal fossils from more than 40 categories have been discovered. The Meishu Village fauna is an important fossil group before the Chengjiang fauna (the Cambrian explosion of life). It is a large classroom for studying the history of the earth 530 million years ago and exploring the origin and evolution of organisms. It has been included in the provincial natural protected area. In addition, abundant Chengjiang fauna fossils, including Haikou fish and Kunming fish fossils, were found in Haikou Ercai Village, Mafang and other places near the section.

2. Paleontology landscape

Paleontology refers to the creatures that once lived on the earth during geological history. In general concepts, organisms in the Quaternary Pleistocene and before are called ancient organisms, and organisms after the Holocene are called modern organisms. Of course, there are no strict rules for this. Most ancient organisms have become extinct, but a few ancient species have survived to this day after the mass extinction of their kind, and are called relics or living fossils, such as ginkgo, giant panda, etc. After ancient organisms died, they could only become fossils after being quickly buried by sediment and undergoing petrification (Figure 7-42). Fossils can be large or small. Fossils that can be clearly observed without a microscope are called macrofossils. Fossils that require microscopic magnification to see individual organisms and structures are called microfossils. Generally, the main things that can be preserved as fossils are the hard parts or remains (footprints, crawl marks), or relics (feces, etc.) of ancient organisms. Only under very special circumstances can the soft bodies of ancient organisms be preserved. Paleontological fossils record the history of biological evolution on earth and are extremely important evidence for studying biological evolution, determining the age of strata, and inferring paleogeographic environment and paleoclimate. The paleontological clock preserves fossils with various growth patterns that can be used to mark timing, such as tree rings, coral outer wall patterns, etc., which are of greater scientific research value.

For example, research on coral patterns from the Middle Devonian Period (about 380 million years ago) shows that at that time there were approximately 399 days and 13.04 months in a year, and the number of hours in a day at that time was 21.6 hours. This can be used to study changes in the rotation speed of the earth. The conclusion is that the earth rotated faster than it does now. Some fossils also have high ornamental value and are an important geological tourism resource and precious tourism commodity resource.

Figure 7-42 Paleontological Landscape

(1) Fossil Group of the Cambrian Explosion of Life (Chengjiang Fauna)

“The evolution of early life on Earth and "The Cambrian Explosion of Life" is one of the hot spots in contemporary scientific research and an unsolved mystery in earth science and life science. The Chengjiang fauna found in Maotian Mountain in Chengjiang, Yunnan is a witness to the "Cambrian Explosion of Life." It is widely distributed in the yellow-green shale in the middle and upper Yuganshan section of the Heilinpu Formation during the Qiongzhusi Period of the Early Cambrian in eastern Yunnan. It not only contains almost all categories of living animals, but also includes some extinct categories, and even contains very exquisite soft-bodied fossils. It is the only soft-bodied and oldest preserved animal found in the world so far (bigger than Canada). The Gies fossil group (middle Cambrian) is still early), the richest and most complete group of multicellular metazoan fossils, and has been hailed by the international scientific community as "one of the most amazing scientific discoveries of the 20th century." In addition, the "Kaili Fossil Group" (Middle Cambrian) discovered in Taijiang County, Guizhou is a subsequent fauna.

(2) Ten Thousand Volumes of Books - Shanwang Paleontological Fossils

Shanwang Village, located in the east of Linqu City, Shandong Province, is one of the national nature reserves. The exposed diatomite of the Shanwang Formation of the Tertiary Miocene has been mined for many years, and the rock formations contain a large number of precious fossils dating back 18 million years. Fossils have been discovered in more than ten categories and more than 400 species, 1/3 of which are extinct genera and species, including algae, mosses, ferns, gymnosperms and angiosperms, as well as fish, frogs, snakes, birds and angiosperms. Ancestors of extinct large mammals such as rhinoceros, tapir, and deer. These fossils are not only complete and finely preserved, but also preserve the form of animals struggling during their lifetime, which is rare in the world. These fossils are of great significance for the study of Miocene fauna, paleogeography, paleoclimate, and stratigraphic correlation in eastern North China. Because the shale composed of diatom remains and clay is as thin as paper, it will lift up layer by layer after weathering, like "book pages". There are also fine fossils preserved on the "pages", so it is called Wanjuanshu. At present, the Shanwang Fossil Museum has been established.

(3) Bird fossils

In the past half century or so, especially since the 1980s, more and more types of bird fossils have been discovered in my country. The most important source of bird fossils is the western Liaoning region. The key fossils discovered support the theory that birds evolved from small theropod dinosaurs. The evolutionary history of primitive birds is divided into four stages: the Sinosauropteryx period, the Archaeopteryx period, the Confucius bird period and the Euornis period. Representatives of the four stages are found in western Liaoning. The research results show that from the perspective of the ancient environment, in the Late Jurassic 140 million years ago, the western Liaoning area had a humid climate, undulating terrain, crisscrossing rivers and streams, and lush terrestrial organisms and aquatic plants, providing a good environment for various species including birds. species of animals create a good living environment.