The main rocks of Elephant Trunk Hill are classified according to their genesis? Metamorphic or sedi

Rocks can be divided into three categories: magmatic rocks, sedimentary rocks and metamorphic rocks according to their genesis.

1. Magmatic rocks:

Magma is a silicate substance that exists in a molten state at high temperatures and pressures beneath the earth's crust. The pressure inside the magma is very high, and it constantly moves towards the low pressure, so that it breaks through the rock layers deep in the earth's crust, rises along the cracks, and erupts out of the earth's surface. Or when the internal pressure of the magma is less than the pressure of the upper rock formation, the magma is forced to stay and condense into rock.

It can also be divided into intrusive rocks and ejective rocks (volcanic rocks). It mainly includes granite, diorite, gabbro, diabase, basalt, etc.

2. Sedimentary rocks:

Also known as aqueous rocks, they are rocks formed by the unity of loose sediments such as detritum, colloids, and organic matter that accumulate in layers on land or in the sea. At the same time, it is also one of the three main rocks that make up the Earth's lithosphere (the other two are magmatic rocks and metamorphic rocks).

On the Earth's surface, 70 percent of the rocks are sedimentary rocks, but only 5 are sedimentary rocks if you count the entire lithosphere from the Earth's surface to a depth of 16 kilometers. Sedimentary rocks mainly include limestone, sandstone, shale, etc. Sedimentary rocks contain minerals that account for 80% of the world's mineral reserves.

Sedimentary rocks mainly include limestone, sandstone, shale, etc.

3. Metamorphic rocks:

Primitive crustal rocks (including magmatic rocks, sedimentary rocks and metamorphic rocks), due to the changes in physical and chemical conditions caused by crustal movement and magmatic activity, that is, under the action of high temperature, high pressure and chemically active substances (moisture), various volatile gas infiltration and hot water solutions, the solid state changes the structure, structure and mineral composition of the rock, forming a new type of rock called metamorphic rock.

Metamorphic rocks not only have their own unique characteristics, but also retain some characteristics of the original rocks. It can be divided into normal metamorphic rocks and secondary metamorphic rocks.

Descriptions of rocks include: genesis, age, name, color, major mineral content structure, tectonic and weathering degree. on sedimentary rocks.

It is also necessary to describe the particle size, shape, cementation composition and degree of cementation of the sediment; For magmatic rocks and metamorphic rocks, it is necessary to describe the size and degree of crystallization of minerals.

The description of the rock mass should include the genesis, age, rock name, color, structural plane, and structure.

and rock thickness, etc. The description of the structural plane should include: type, nature, occurrence combination form, degree of development, degree of ductility, degree of closure, roughness, filling situation, filling properties and water-filled properties.

The description of the structure should include: type, shape, size, force of the structure in the surrounding rock, etc.

Metamorphic rocks, Guilin karst landforms, no volcanoes.

1.Magmatic rock: It is formed by the intrusion of magma rising from the earth's crust into the earth's crust or erupting from the surface of the earth, also known as igneous rock.

Magmatic rocks are common, such as granite, an intrusive rock with a medium-coarse-grained structure that is widely distributed in the earth's crust, a black and dense basalt with a developed stomatal structure, and rhyolite, an acidic ejecta rock with a significant rhyolite structure.

2.Sedimentary rock: It is formed by the deposition of ground instant rocks under the action of external forces, weathering, transportation, sedimentary consolidation, etc.

Its main characteristics are: the bedding structure is remarkable; Sedimentary rocks often contain ancient biological remains, which become fossils after petrification; Some have dry fissures, pores, nodules, etc. Common sedimentary rocks are:

Conglomerate with a diameter of more than 3 mm and rounded pebbles and conglomerates formed by cementation of other materials, sandstone cemented by sand grains with a diameter of 2 mm to millimeters, shale composed of fine-grained clay minerals, limestone with calcite as its main component, and limestone with little hardness.

3.Metamorphic rocks: It is a new type of rock formed by magmatic or sedimentary rocks under metamorphism. The main difference from the first two types of rocks is that metamorphic rocks are recrystallized rocks, with coarse grains and no vitreous and organic remains.

The most commonly used rock classification scheme is:

Igneous rocks (magmatic rocks) – as the name suggests, are rocks formed directly from magma, which are formed by the condensation of magma from deep in the earth's crust or ejection from the earth's surface. It can also be divided into intrusive rocks and ejective rocks (volcanic rocks).

Sedimentary rock, as the name suggests, is a rock formed by sedimentation, which refers to the rock exposed to the surface of the earth's crust that is damaged by various external forces during the development of the earth, and the damage products are deposited in situ or transported and deposited, and then formed by complex diagenesis. The classification of sedimentary rocks is complex, and can generally be divided into parent rock weathering deposits, volcaniclastic deposits and biological remains deposits according to sedimentary materials.

Metamorphic rock, as the name suggests, is a rock formed by metamorphism, which refers to the rock formed by the original rock in the earth's crust under the influence of internal forces such as tectonic movement, magmatic activity or heat flux change in the earth's crust, so that its mineral composition and structural structure change to varying degrees. It can be divided into positive metamorphic rocks and secondary metamorphic rocks.

The three types of rocks can be transformed into each other through various diagenesis, which also forms the cycle of crustal materials.

Title: Which of the following rocks is the main type of rock that produces karst fighting? （）

a Siliceous limestone.

b Limestone.

c Sandstone. d Tuff.

Answer: B.

There are two types of magmatic rocks: intrusive rocks (granite is a type of intrusive rock) and ejective rocks (basalt is one of them); There are two types of sedimentary rocks: limestone and conglomerate (including sandstone and phyllophyl); There are also two types of metamorphic rocks:

marble from limestone metamorphosis and slate (from phyllophyllite).

They are granite, slate, and sandstone.

Rocks are classified into magmatic rocks, metamorphic rocks, and sedimentary rocks according to their genesis.

Magmatic rocks are formed by the cooling and solidification of magma.

Metamorphic rocks are formed by the metamorphism of rocks under high temperature and high pressure conditions.

Sedimentary rocks are formed by the consolidation of sediments.

1.Magmatic rocks: granite (intrusive rock), basalt (ejecta rock), etc. 2.Sedimentary rocks: sandstone, shale, limestone, etc. 3.Metamorphic rocks: slate, marble, gneiss, etc.

Metamorphic rocks are new rocks formed after volcanic rocks, sedimentary rocks or other metamorphic rocks have changed their composition through metamorphism;

Metamorphic rocks also have a variety of components, kyanite, andalusite, sillimanite, garnet, hard chlorite, epidote, and amphibole are all characteristic minerals (note that these are components, not that kyanite and andalusite are metamorphic rocks), serpentine, gneiss are metamorphic rocks; So it's okay for you to say that metamorphic rock comes out of serpentine.

And the pebbles you mentioned are not special stones, and you can't say what kind of rock they are. Whether it is sedimentary rock, magmatic rock or metamorphic rock, it is broken from the mountain and falls into the river, washed by hydrodynamic forces, carried, and worn away to become smooth and round, which is called pebbles.

Of course, because pebbles are relatively hard, many of them are crystallized and stable magmatic rocks and metamorphic rocks, hard sedimentary rocks can also form pebbles, and mudstone in sedimentary rocks is not easy.

As for the characteristics of metamorphic rocks and sedimentary rocks, this range is too large, the common sedimentary rocks have a bedding structure, some can also see organic fossils, but metamorphic rocks do not, metamorphic rocks have metamorphosis structure, metamorphic structure, metamorphosis structure, metasomatic structure... I don't remember if there is any.

The pebbles are volcanic or metamorphic rocks that are washed and polished by rivers.

The recommended book is Comprehensive Geology, published by the Geological Press, and you will understand it when you read it.

To put it simply, it's not that simple when it comes to a specific rock:

Magmatic rocks: Divided into intrusive rocks and ejective rocks.

The inner intrusive rocks are contained below the description. Ejecta rocks are simpler: they can be caught in sedimentary rock formations and can be easily mistaken for sedimentary rocks.

However, sometimes stomata or stomata are filled (it takes experience to determine the stomata specifically), sometimes there are features of magma flow (rhyolite structure, rope lava), and sometimes there are traces of lava cooling and contraction (columnar joints); No fossils, no organic matter.

Intrusive rocks: the rocks are crystallized (the size of the mineral particles can be seen with the naked eye); not stratigraphed (although sometimes tabular intrusive rocks are present, they are not continuously stratigraphed); morphological instability in the wild; It is clearly demarcated from the surrounding rocks, and there are large fragments of the surrounding rocks (called traps) within the contact zone

Sedimentary rocks: stable stratigraphy, usually with bedding structures (layered textures) within the strata; There are fossils (containing organic matter); There are special minerals (clay minerals, glauconite, etc.); Most have a clastic structure; **More iron ions than low-cost ones.

Metamorphic rocks: sometimes also stratigraphed, but the strata are unstable and variable; Most of them have a typical sheet structure (directional arrangement of minerals); There are typical metamorphic minerals (garnet, staurite, andalusite, etc.); The rocks are composed of crystalline minerals (although sometimes indistinguishable to the naked eye); No fossils, no organic matter.

2. The following rock structures belong to metamorphic rocks: d

a. Bedding structure b. Stomata and almond structure.

c. Wave marks and mud cracks d. Gneissy structure.

3. When the geological structure of the rock layer is observed in the field, the crossing method is often used to pass through the observation along the strike route perpendicular to the rock layer, and if it is observed that the rock layer exposed on the surface is repeatedly symmetrically exposed from old to new and from new to old without interruption, this geological structure is: d

a. Anticline structure b. Monoclinic structure.

c. Fold structure d. Oblique structure.

4. The surface of a fold crankshaft is upright, the two wings tend to be opposite, and the inclination angle is roughly equal. The rock outcrops in the axial part are relatively new, and the rock layers on the two flanks are exposed in turn to the older rock formations. This fold can be determined as: c

a, anticline upright fold b, anticline oblique fold.

c. Oblique upright fold d, oblique flat horizontal fold.

5. If there is an asymmetrical repetition phenomenon in the strata, the geological structures existing here are: BA, fold B, and fault.

c. Joint d. Monoclinic structure.

Magmatic rocks are divided into intrusive rocks and ejective rocks, and the intrusive rocks are compact in structure, and the ejective rocks are loose and porous.

Most sedimentary rocks are formed by the sedimentation of weathered rocks, and sedimentary fossils are sedimentary rock formations.

Metamorphic rocks are formed by magmatic rocks and sedimentary rocks under high temperature and high pressure conditions, such as granite into schist and so on.

You should find a book to read by yourself, and you can't be lazy in studying.