Continental faciessedimentary faciesAndmarine faciesRelativity refers to the sedimentation formed in the land area.The land is mainly denuded, but it can accept sedimentation in relatively low-lying areas.
Compared with marine deposits, the types of continental deposits are diverse, with significant lateral changes,stratumYes, it is difficult.The sediments are mainly composed of detritus (gravel, sand, mud), and sometimes contain terrestrial animals and plantsFossil。[1]
The eluvial facies is one of the continental sedimentary typesBedrockthroughPhysical weatheringandChemical weatheringAfter that, the weathering products remained in place.Along the profile, it gradually transits to bedrock.It is mainly composed of bedrock debris and iron, lateritic (ferruginous) and clayey sediments.No sorting, and the bedding is not clear.Because the eluvial facies are often scoured and generally distributed in a small area, the ancient eluvial facies are rare.[2]
Residual facies refers to the deposits left in place after physical damage and chemical composition change of surface rocks due to weathering.
Deluvial facies
Slope wash facilities is one of the continental sedimentary types, which is the weathering product of highland bedrock. Due to the action of rain and snow, it rolls along the slope with the help of gravity and accumulates on the slope to form sediment.The deluvial facies is mainly composed ofSandy conglomerate、SiltstoneThe debris is poorly sorted, angular, and often has bedding parallel to the slope.
Proluvial facies
Pluvial fan factorsalluvial fanAlluvial fan factors is one of the continental sedimentary types.Intermittent torrents in mountain areas carry the weathered products of bedrock to the sediment formed at the outlet of the valley.
It is most developed in dry and semi dry areas.Usually, there is no water in the valleys and rivers in these areas, and the valleys and slopes on both banks are full of weathering and erosion products of the mountains on both sides.In the rainy season, mountain torrents break out, the river water in the valley rises sharply, carrying a large amount of debris materials downward. At the valley mouth, the river channel becomes wider, the slope decreases, and the water flow carrying capacity is weakened. A large number of flowing gravels and mud sands rapidly deposit to form a fan shaped accumulation body inclined from mountain to plain, calledProluvial fan。
The conglomerate deposited in the proluvial fan is called fan conglomerate.Its composition is slightly sorted and has unclear bedding.The grain size of the sediment has obvious gradual change on the plane. The coarsest debris is distributed in the inner fan, mainly gravel, with large thickness. The grain size of the middle fan and the outer fan gradually decreases, from gravel to sand, silt and argillaceous materials, with gradually smaller thickness, and various cross bedding developed.Deposited at a position similar to the diluvial fanRoundnessTerrestrial debris with good sorting property is called dryDeltaDry delta.
Alluvial facies
Alluvial faciesFluvial facies(fluvial factors), one of the continental sedimentary types, refers to a set of sediments andsedimentary rock。The debris of rock weathering and denudation is composed of river or othersurface runoffSediment deposited on land due to transportation.Along with the distance from the debris source supply area, the constituent materials include boulder, gravel, gravel, sand, silt, clay, etcnoble metalOr precious stones.
Continental strata
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There are great differences between continental sequence stratigraphy and marine sequence stratigraphy of passive continental margin.The sedimentation of continental basins is controlled by many factors, and the main controlling factors of different types of basins are different, resulting in many types of continental basin sedimentation, fast phase transformation, poor horizontal continuity, large changes in the thickness of vertical upper sequence, and frequent lake transgression and regression make the vertical rhythm of lake basin sedimentation change quickly;Therefore, the formation, structure and model of continental sequence stratigraphy are more complex and difficult to study.
In research and practice, Chinese scholars have established the sequence stratigraphic framework and model of depression basin and fault basin in line with the sedimentary reality of China's basins according to the boundary characteristics of continental basins, boundary characteristics of system tracts, initial flooding surface and maximum flooding surface, whether there is slope break zone and other factors.
The main factors controlling the development of continental stratigraphic sequence are lake level change, structure, climateDatum planeThe change of water level and the supply of material sources, especially the structure and climate, are very important. They directly control the change of lake level.
