Geological research object: composition, structure, occurrence, origin and distribution of lithosphere. Study the crustal movement and its various structural changes and development laws. Study the history of the earth and the laws of biological evolution.
Geomorphology: the study of the morphological characteristics, structure, causes, occurrence, development and distribution of the earth's surface. The characteristic time-space scale span is large, the time is infinite, the change is complex, and the geological process is irreversible.
Research methods: Discuss the present from the past (reason: the nature and intensity of natural forces that changed the face of the earth are the same in all geological history. Although the effect is slow, the accumulation of these forces has never stopped, leading to great changes in the face of the earth. )
The above is the equalization theory (not a sudden change from quantitative change to qualitative change)
Corresponding to this is catastrophe theory (sudden extinction of dinosaurs)
Since the formation of the earth, it has experienced long and complicated changes, and the surface morphology, internal structure and material composition of the earth's crust are constantly changing, all because of geological processes.
Olivine+silica ... pyrite+amphibole
Pyrite+silica ... amphibole+biotite.
Hornblende+silica ... biotite.
The content of original silica determines the mineral assemblage.
Minerals that are close together can grow * * *, but minerals that are far away can't grow * * *, such as olivine, which can't grow with time.
Generally speaking, minerals with early crystallization have a good degree of automorphism, while minerals with late crystallization have a poor degree of automorphism.
Refers to the crystallization degree, particle size, shape and relative size of minerals in rocks and the characteristics of the relationship between particles. Divided into:
The glass structure consists of amorphous volcanic glass.
Cryptomeric structure mineral particles
The crystal structure can distinguish mineral crystal particles with naked eyes.
The porphyritic structure is that rocks are composed of some large mineral crystals (porphyritic crystals) and some aphanitic mineral crystals or glassy components (matrix).
Mainly based on chemical composition, formation depth and mineral composition.
Firstly, according to the content of Si02 (Wt%), magmatic rocks can be divided into ultrabasic rocks, basic rocks, intermediate rocks and acid rocks.
Secondly, according to the formation depth, it can be divided into plutonic rock, shallow rock and extrusive rock.
Secondly, according to the main mineral composition.
Rock formed by weathering and denudation products of original rock in situ or after treatment, deposition and compaction under surface and near-surface conditions.
Clastic minerals, also known as inherited minerals, refer to the minerals that have strong weathering resistance and are preserved after mechanical crushing of parent rocks such as Yingshi, feldspar and muscovite.
Supergene minerals include clay minerals (kaolinite, montmorillonite, illite, etc. ) and oxide minerals, which can be transformed from primary minerals or crystallized from colloidal solutions.
Refers to the size, shape and arrangement of sedimentary rocks, and its structural type depends on the formation of rocks.
The rock cemented by mechanical crushing products of parent rock has clastic structure.
In the process of chemical decomposition of parent rock, the newly formed rocks mainly composed of clay minerals have argillaceous structure.
The rocks formed by chemical deposition have chemical structure.
Rocks composed of biological remains or biological debris have biological structures.
Refers to the rock appearance characteristics reflected by the spatial distribution and arrangement of various components of sedimentary rocks.
Bedding structure The bedding phenomenon shown by the change of material composition, color and structure of sedimentary rocks along the direction perpendicular to the bedding plane is called bedding structure.
Bedding structure is one of the most important characteristics of sedimentary rocks, and it is also the most important sign that field sedimentary rocks are different from magmatic rocks and some metamorphic rocks.
Mechanical movement or biological activities leave traces on the surface of unconsolidated sediments, which are covered by later sediments and remain on the plane.
(1) ripple mark
(2) Biological traces
(3) mud cracking