These characteristics are very beneficial to the study of Quaternary strata in North China. North China is the earliest and highest level area for Cenozoic geological research (including Quaternary stratigraphic research) in China. For decades, many geoscientists at home and abroad have done a lot of research on Quaternary strata in this area and established standard stratigraphic profiles. The study of North China has laid a good foundation for the study of Quaternary strata in China.
Pleistocene under 1.
(1) Nihewan Formation
The typical area of Nihewan Formation is located in Sanggan River Basin of Hebei Province and Nihewan Village of Yangyuan County. The Nihewan Formation is dominated by lake deposits, and the bottom and basin edge are river deposits. The thickness of sediment in the center of the basin may exceed 600 meters, and it has not been exposed to the end of the basin. Nihewan Formation is mainly composed of grayish green, grayish blue, grayish white clay, sandy clay and marl. In some places, there are mottled sand and sandy clay layers, such as light red, light yellow and grayish black. In some places, swamp peat layers are developed; There are gravel layers at the bottom and edge of the basin. The fine clay layer has complete large horizontal bedding; Gravel layer has obvious cross bedding. Freshwater mollusk fossils, fish fossils and abundant mammal fossils are abundant here. Brackish water foraminifera fossils have been found in some horizons. The above characteristics indicate that the Nihewan Formation is mainly a large freshwater lake deposit, and seawater may invade in some periods. This set of sediments is concentrated in some large rift lake basins in Fenwei Graben, such as Yanqing Huailai Basin, Yuxian Yangyuan Basin, Datong Basin, Fenhe Basin, Weihe Basin and Sanmenxia area in the middle reaches of the Yellow River.
The early Pleistocene true horse fauna with long nose and three-toed horses was found in Nihewan Formation, so it became the standard stratum of Quaternary lower Pleistocene in China and even in the world.
The main representatives of Nihewan fauna (that is, long-nosed three-toed horse-real horse fauna) are as follows:
Long-nosed three-toed wildebeest
Sanmenma China antelope
Bauhinia And the Kaili dog.
Gu Long and China Raccoon.
Paracamelus gigas is a national treasure hound (Hyaena sinensis).
Giant tooth tiger, Nihewan saber-toothed tiger.
Shi Ding Zokor (Myospalax tingi)
China ancient bison
In addition, Nihewan Formation also contains a large number of mollusk fossils, such as Limnaea, Pianorbis, Corbicula, Lamprotula and Cuneo.
There are still many problems in Nihe Formation that need further study. According to the information obtained in some recent work, it is briefly introduced as follows:
① The lower part of Nihewan Formation is directly covered on Pliocene red soil layer of Hippies. In the profile (Figure 13-6) found in Hongya Village, Yuxian County, west of Hulu River in the south of Yangyuan-Yuxian Basin, it is proposed that the bottom of the red clay gravel layer of 1.7m is moraine, which is designated as "Chibi Glaciation". Therefore, it is suggested to push the Quaternary boundary below the hippie red soil layer. This suggestion was not adopted.
② At present, the measured section of Nihewan Formation system is Haojiatai section. In fact, it is only a stratum exposed more than 100 meters above the surface, and it cannot represent all the Nihewan Formation with a thickness of more than 600 meters.
Figure 13-6 Section of Luanshi Luantagou in Hongya Village, Yuxian County, Hebei Province
1- Mesozoic volcanic rocks; 2- Lower Tertiary; 3- Upper Tertiary hippies, 4- Lower Pleistocene F (Nihewan Formation) grayish green marl and sandy clay.
Haojiatai section is located at the southeast corner of Xiaodukou, Huashaoying Township, Yangyuan County (Figure 13-7), on the lacustrine platform cut by Sanggan River and Liuhu River, which is higher than Sanggan River 147m, with a total stratum thickness of1kloc-0/3m. The upper part is mixed with grayish yellow sandy clay and variegated clayey silt; The lower part is grayish green and grayish white sandy clay, which contains more calcium or marl mixed with grayish yellow gravelly clayey silt.
③ Xiashagou section of Nihewan Village is a place rich in fossils, which contains most mammalian fossils of Nihewan fauna. Xiashagou section is equivalent to the upper part of Nihewan Formation. Nihewan period is located at the junction of lake plain and foothills, forming a set of alternating deposits of sand, gravel and sandy clay in rivers and lakes. Section * * * is 43.6m thick (Figure 13-8).
Figure 13-7 Haojiatai Road Section, Yangyuan City, Hebei Province
1-loess; 2- calcium tuberculosis; 3- sand; 4— Sandy clay; 5— Mudstone; 6— marl; 7— Gravel lens; 8- invertebrate fossils; 9- vertebrate fossils
Figure 13-8 Xiashagou section of Nihewan, Yangyuan City, Hebei Province
1-loess; 2- staggered sand layer; 3- sand; 4— Gravel; 5- clay; ⑥ Monocalcium tuberculosis; 7- invertebrate fossils; 8- vertebrate fossils
Figure 13-9 Measured profile of Quaternary marine strata in Nihewan, southeast of Dongyaozitou, Yuxian County, Hebei Province (according to Wang et al. )
④ At present, brackish foraminifera fossils have been found in hot springs in Huailai Basin, which is equivalent to this layer. The Sangyuhe fault basin is likely to be connected with seawater at some time in the early Pleistocene. At this time, seawater can invade the basin along a certain river course, bringing in some foraminifera. Under the special conditions of desalination of brackish water, a mutant foraminifera appeared and propagated for a period of time. The section where marine fossils are found is located in Lisan, southeast of Dongyaozitou in Yuxian County, and east of Yuxian-Xuanhua Highway (Figure 13-9). There is only one genus and one species of foraminifera in Shanxi, but there are many foraminifera, accounting for 90% of microfossils. The remaining 10% has 6 genera, 1 1 brackish water ostracods. There are also fish snails that can live in fresh water, brackish water and brackish water, and land snails.
(2) Sanmen Group
This is a set of lower Pleistocene river and lake sediments, which can be compared with Nihewan Formation. Sanmenxia is located in the fault basin in the middle reaches of the Yellow River, bordering Zhongtiao Mountain in the north, Qinling Mountain in the south, Weihe Valley in Linfen in the west and Sanmenxia Valley in the east. In this basin, fluvial gravel and marl layers are accumulated with a total thickness of about 200-900 meters, and many outcrops and working faces can be seen on both sides of the valley (Figure 13- 10). In the past, this class was generally referred to as the "Three Clans". 1959, according to the site meeting of quaternary geology in Sanmenxia, the original "Sanmen system" was divided into five layers. According to most people's opinions, ③ and ④ layers belong to the Lower Pleistocene series, which is called Sanmen Formation, while ① and ② belong to the upper Pliocene series, and the fifth layer is temporarily classified as the Middle Pleistocene series. Now briefly described as follows:
⑤ Sand and sandy clay layers are mixed with gravel layers, which are distributed in the lower part of the second and third terraces of the Yellow River.
Denudation discontinuity
④ The brownish red sandy clay layer is mixed with clay, sand and gravel layer. Clay content is high, containing mud snail fossils, which are often eroded after deposition and are not widely distributed. 60 meters thick
③ Gravel, gravel and sand interlayer. To the center of the basin, it becomes a fine sand and silt layer with clay. Gravel with high roundness is mainly composed of quartzite, seasonal sandstone and mammalian fossils, with obvious cross bedding and rich clam shells. 70- 100 m thick
Pliocene:
② Sandy clay layer mixed with gravel layer or clay sand layer, brownish red, with dense lithology, poor gravel sorting, and containing three-toed horse ... 200-240m thick.
① The bottom conglomerate layer is grayish white, consisting of quartzite, seasonal sandstone, limestone, schist and extrusive rock, with poor gravel sorting, slightly angular and hard calcareous cementation. Thickness 10—90m-90m
inconformity
The lower complex stratum is Paleogene Pinglu Formation.
Figure 13- 10 Third Member of Sanmenxia Area (according to Jia Fuhai)
Huangdi River in Pinglu, Shanxi; B— Dongpogou, Sanmenxia City; Section and histogram of Yaotougou in Sanmenxia
Before liberation, Yang discovered Oriental Minofish in the gravel layer below Dongyan Village, which was a European early Pleistocene fossil. Bian Meinian found the swollen jawbone of a deer on the sand surface in fenglingdu. After liberation, many mammalian fossils were found. Besides some unknown strata, Bubu deer, vole, deer, rhinoceros, hyena, etc. were also found in the sand layer of Hougou, Zhang Yu, from which Platycodon grandiflorum may have been produced. Flat-fronted elephant, three-door horse, beautiful Rusaelegans, bud deer and four-cornered antelope were collected in Linyi, Shanxi. This shows that it belongs to Nihewan fauna. Sporopollen data of turtle (Clemmys sp.) living in South Asia were also found in Sanmen Formation, which proved that it was deposited in forest and grassland environment, and the temperate climate was slightly wetter than it is now, belonging to interglacial climate.
In North China, most strata of Nihewan Formation and Sanmen Formation have undergone structural changes, strata are inclined and cracks have appeared. It can be proved that the neotectonic movement after the early Pleistocene is very strong. The tectonic movement in this period is called "Sanmen Movement" in North China.
After the "Sanmen Movement" and "Yuanmou Movement" in the early Pleistocene, most of the fault basins in the central fault depression sedimentary area no longer retain the paleogeographic characteristics of the lake basin. Except for a few basins with inherited lakes, most of them become valleys of river valleys. Alluvial deposits are developed in different periods, or there are other genetic types of deposits in between. In the central fault depression area, in addition to the alluvial layer in the valley, due to the change of climate in the direction of drought, a thick loess layer developed in the northern region. Loess can be covered on different genetic types of sediments and topography, and its distribution area is beyond the scope of the central fault depression sedimentary area, which is a sedimentary layer with the main feature of reflecting climate zoning.
2. Middle Pleistocene series
The Middle Pleistocene in North China used to be called Zhoukoudian Formation. Since the discovery of the "Lantian ape-man" fossil, the Xiehu Formation, which produced the Lantian ape-man fossil, has also become a standard site, and because the Lantian Gongwangling ape-man fossil is older than the "Peking ape-man", the age of the lower part of the Xiehu Formation may be earlier.
(1) The standard position of Xiehu Formation is on the third and fourth steps of Yuan Shang and Bahe River in Lantian, Shaanxi. There are two main types of sediments, namely gravel layer and river alluvial red soil. The former is distributed along Bahe River, especially on the right bank of Bahe River. Gravel layer is about 40 meters thick in Stinky River, Angou and Gongwangling, and gradually becomes thinner and even pinches out to the northwest. The latter is distributed in the Loess Plateau and Bahe III and VI terraces. According to vertebrates, buried soil and denudation surface, it can be divided into upper and lower parts:
The lower part of Xiehu Formation is located in loess tableland, which is yellow-brown loess sandy soil and contains a lot of calcareous nodules. The color of layers A and B of buried soil is not obvious, and the occurrence is basically the same as before Quaternary. In addition, in the lower layer of the Loess Plateau, there is a set of horizontal bedding brown sand and clay sediments, which are unconformity contact with the underlying strata, which may be the product of the ancient gullies in the Loess Plateau. There are gravel, sandy and red clay layers in Bahe terrace, which are in unconformity contact with the underlying tertiary system. The gravel layer is nearly horizontal, and displacement and fracture occur in the neotectonic failure area.
The upper layer of Xiehu Formation is brownish red or reddish brown loess sandy soil, and calcareous nodules are mostly in a complete network shape, sometimes even in strips. The buried soil in layers A and B has bright colors, undulating surface and dip angle of about 10. The lower layer is also loess-like soil, rich in calcium and plate-shaped, and the buried soil layers A and B are lighter in color. The stacking range is small.
In Lantian area, the "Lantian Ape Man" fossil was found in two places, one is Gongwangling and the other is Chenjiawo Village. They belong to the upper and lower parts of Xiehu Formation respectively (Figure 13- 1 1).
From the profile comparison of different parts of Xiehu Formation, Xiehu Formation has the following characteristics:
① The lower part of the lagoon formation is deposited by fluvial facies, and the Yuan Shang is deposited by ancient gullies; ② The upper part of Xiehu Formation is mainly soil-like deposit; ③ The buried soil in the upper part of Xiehu Formation is brightly colored with sporadic calcareous nodules; The buried soil in the lower part is light in color, and calcareous nodules are plate-shaped; ④ The occurrence of the upper and lower parts of Xiehu Formation on the Loess Plateau is inconsistent, the upper dip angle is 10- 15, and the lower part is nearly horizontal, with a denudation surface between them; ⑤ The fossils in the upper part of Xiehu Formation are close to those of Beijingers, while Gongwangling Fauna is between Nihewan Fauna and Zhoukoudian Fauna, and closer to the latter; ⑥ The age of the gravel layer in the lower part of Gongwangling may belong to Middle Pleistocene or Early Pleistocene. There are also some disputes about the genesis of gravel layer. One view is that it is ocean current deposition, and the other view is that it is moraine layer, which is called "Gongwangling Ice Age". It seems that the establishment of "Gongwangling Ice Age" still needs careful work.
Fig.13-1/Shuizigoukou profile, the origin of Lantian fossils in Gongwangling, and the columnar correlation map of Xiehu Formation in Lantian (simplified by Jia Lanpo et al., 1964).
(2) Zhoukoudian Formation Zhoukoudian Formation was once the standard site of Middle Pleistocene in North China, and it was a cave accumulation in Zhoukoudian, Fangshan District, Beijing. There are many cracks and caves in Zhoukoudian area. Zhoukoudian Formation refers to the cave accumulation in Zhoukoudian, the first place where Peking Man originated, and its sedimentary lithology is difficult to compare with that outside the cave. However, it contains extremely rich mammalian fossils. The mammal fauna of Zhoukoudian Formation is called China Ape Puffed Deer Fauna, which is the standard fauna in northern China.
List of fossils from the first site in Zhoukoudian:
Ju Weiye, a giant beaver of Stonehenge, is a.
Shi Ding zokor
Zokor cat
Bamboo rat cheetah thistle species.
Hystrix subcristata, porcupine, cologne See Synonyms at Namadicus, nama elephant.
Dog road jackal, three-door horse.
Mutant wolf
China raccoon dog
Alpine wild boar with round teeth
Ursus spelaeus, the cave bear, and Paracamelus gigas, the big camel.
Ailhuropoda sp. A sika deer.
Meles cf.leucurus, badger, bighorn deer, swollen deer.
Martes sp. German buffalo Bubalus teilhardi
China bison, China hyenas.
Cave hyenas, crocodiles, the ultimate hornhorn antelope
Toothless tiger, saber-toothed tiger, gazelle.
The characteristics of this fauna are: some residual species of Tertiary have been extinct, such as three-toed horse, but few residual species, such as saber-toothed tiger. The representative species and genera of the Middle Pleistocene appeared, such as swollen-boned deer, China hyenas and Stonehenge beavers. There are some more modern species, such as wolves, foxes, lynx, camels and so on.
The excavation of Zhoukoudian, the first site, before liberation and in 1950s after liberation showed that the stratum was 40m thick and divided into 13 layers (Figure 13- 12). The red clay gravel layer is exposed from the bottom of the exploration well, which is called "bottom gravel layer". During the period of 1978- 1979, during the comprehensive study in Zhoukoudian, the stratum with the thickness of 10m was exposed in the exploratory well, and the original thirteen layers were subdivided into fourteen to seventeen layers. Originally called "bottom gravel layer", it is the 14th layer.
The first layer of coarse breccia. About 3 meters thick
The second layer of travertine is cemented by hard pink soil and is located at the highest part of the cave. Materials containing fossils, stone tools and humans. About 1m thick.
The third layer of irregular huge breccia, which contains huge limestone blocks, is caused by the collapse of the roof, and the soft sediments in the lower part are subjected to the pressure of boulders, resulting in buckling. About 3 meters thick
The fourth layer is a thick red, yellow, purple and black fine soil layer. Black is charcoal ash. Red, yellow and purple are baked earth. Stones and fossils found on this floor have also been roasted, changing their colors and shapes. This layer of fossils is dominated by rodents. Because there are many stone tools, it is called "upper cultural layer". It is about 6 meters thick in the west and gradually tapers to the east.
The fifth layer is a black hard ash layer containing fossils, and some of it is a breccia layer or the bottom of the "upper cultural layer". The west gradually becomes a stalactite layer about one meter thick, and the east gradually becomes thinner and disappears.
The sixth layer contains fossil breccia, big stones and few stone tools.
The seventh layer is dark gray loose sand layer. Fossils are well preserved, most of them are wild boar, followed by deer, and there are fewer carnivores. Other animals, such as buffaloes and otters, are also found in this layer. This layer is thicker in the west, about one meter, and thinner in the east.
The eighth and ninth layers are irregular breccia layers with thin ash layers, which are rich in fossils and relatively complete. There are deer, pigs, horses, rhinos, wolves, foxes and hyenas. These two layers also have the most stone tools and human fossils, so they are called "lower cultural layers". About 6 meters thick
The upper part of the tenth layer is the red soil layer containing fossils, and the lower part is the ash layer. About 2m thick.
The eleventh layer is a breccia layer containing fossils. About 2m thick.
The twelfth layer of red coarse sand contains small gravel and fossil fragments, which are abraded. About 2m thick.
The thirteenth layer of red clay is sandwiched with red or gray sand lenses, and there are huge limestone blocks at the bottom. About 2m thick.
The fourteenth layer is clay gravel layer, mixed with brownish red clay sand and gravel. The lower gravel is reduced and dispersed in clay. This layer used to be called "bottom gravel layer". Because the upper part has been dug and filled, its thickness cannot be estimated correctly. It can be seen that the thickness is about 4m.
The fifteenth layer is brownish red coarse gravel layer and fine sand layer containing gravel. About 1m thick.
erosion surface
The 16 layer is a gray thin-layer silty sand layer with parallel bedding and inclined attitude, and there are obvious traces of erosion surface on the upper part of 80 (10). About 1.5m thick.
The seventeenth layer of yellow-brown coarse gravel has not yet bottomed out. The visible thickness is about1m.
According to the comprehensive study of these 17 layers, including the study of chronological sedimentary environment, paleoclimate and paleontology, the 16 th and 17 th layers below the erosion surface are classified as lower Pleistocene, and the 14 th and 15 th layers are 0.7-0.8 Ma pre-middle Pleistocene, which is equivalent to the occurrence horizon of Lantian apes in Gongwangling and named as "Longgushan Formation". Above the thirteenth floor is Zhoukoudian Group. It is divided into five parts according to the climate evolution.
Based on the comparative study of the inside and outside caves in Zhoukoudian area, the stratigraphic system (Table 13-2) in this area since the Late Cenozoic is established, which can be used as a reference for the Quaternary stratigraphic correlation in northern China.
Figure 13- 12 Profile of Zhoukoudian (according to Jia Lanpo)
1- breccia; 2- ashes; 3- travertine; 4- sand; 5- red soil, 6- mud sand; 7— Gravel; 8-Limestone
Table 13-2 Summary of Late Cenozoic Strata in Zhoukoudian Area
sequential
* According to Kong and Zhang Zibin, etc.
Figure 13- 13 Quaternary geological profile of Ding Cun in Xiangfen, Shanxi and profiles of 98 sites (according to Pei Wenzhong and Jia Lanpo).
3. Upper Pleistocene series
(1) The Ding Cun section of Dingcun Formation is located along the Fenhe River between Ding Cun and Chaizhuang in Xiangfen County. It is famous for discovering a large number of vertebrate fossils, human fossils and cultural relics in the profile. Later, a young skull was found. It provides new information for the study of ancient humans.
The deposition of Dingcun Formation belongs to fluvial facies and lacustrine facies (Figure 13- 13), which is located on the third terrace of Fenhe River Valley and covered with red loess (upper part of red soil).
There are abundant vertebrate fossils in the gravel layer of Dingcun Formation, including 24 species of Fang's zokor, wild donkey, wild horse, Nama elephant, Mei's rhinoceros, hairy rhinoceros, Koch's sika deer, primitive cattle, antelope and antelope. There are also fish and petabranchial fossils. Judging from the nature of fauna, Peking man's swollen bone deer fauna is later than Zhoukoudian's. The Dingcun people discovered are "ancient humans" evolved from Homo erectus, and the stone tools created by them have traces of secondary processing. Therefore, its age should be later than the Zhoukoudian period of the Middle Pleistocene and should be classified as the early Upper Pleistocene. This idea was made at the 1959 stratigraphic meeting, but it has always been considered that the Dingcun Formation belongs to the Middle Pleistocene.
(2) The Salawusu Formation was first discovered in Wushenqi, south of Hetao, Inner Mongolia, and Gelin, northern Shaanxi. It is a river and lake deposit, which usually constitutes secondary and tertiary terraces. Because of the discovery of "Hetao Man" fossils and abundant vertebrate fossils in this stratum, it is the standard fauna of Upper Pleistocene in northern China-Sarawusu fauna.
Each layer is continuously deposited, and abundant animal fossils are found in the layer. Sarawusu fauna is called Red Deer-the last hyena mammal fauna. The list of animals is as follows:
Wild donkey coelenterate
Mustang Platts Mustang and pronghorn spiro Serus.
Camel camel humpback gazelle gazelle Przewalski gazelle
Canadian red deer argali
Giant lizard of Ordos bighorn deer.
King Buffalo's Newly Discovered Hyenas
Primitive cattle
The profile of the Salawusu Formation was first measured by Germany and Japan. It is equivalent to the stratum of Salawusu Formation. At present, many sites have been discovered, almost all of which are distributed in the middle reaches of the Yellow River and North China.
The lithology of Salawusu Formation is yellow, grayish yellow and grayish green silty fine sand mixed with loess sandy clay and clayey sandy soil containing calcareous nodules. It has horizontal bedding and cross bedding. The profile is shown in figure 13- 14.
Fig. 13- 14 stratigraphic profile of sarawusu river (according to p. drikin)
1-aeolian sand dunes; 2- Loess; 3- fresh water deposition; 4— Sand layer; 5— Sandy clay; 6— Weathering layer; 7- vertebrate fossils; 8- stone tools; 9- Mollusca fossils; 10- denudation terrace and alluvial terrace
The bottom sand layer of Salawusu Formation contains Ordos people and a large number of vertebrate fossils. Important species are cave hyenas, hairy rhinos, wild donkeys, Mongolian wild horses, red deer, Hetao bighorn deer, Namagu elephants and ostriches. Paleolithic tools, such as pointed tools, scrapers and carving knives, were also found.
Compared with the Ding Cun fauna, some animals representing ancient times, such as the ivory elephant, Mei's rhinoceros and large horse, have become extinct. The appearance of a large number of "microlithics" in sediments marks the transition to the Middle Stone Age. Therefore, the Salawusu Formation is a Pleistocene stratum later than the Dingcun Formation. In many places, it is found that the Salawusu Formation is covered by "Malan Loess" with different thickness.
(3) The standard plot of Qian 'an Formation is Zhaocun, Qian 'an, Hebei Province, which is located on the second terrace of Luanhe River and is fluvial swamp facies deposit. Among them, a large number of vertebrate fossils have been found, which is equivalent to the Sarawusu fauna.
The stratigraphic profile of Qian 'an Formation (Figure 13- 15) is an alluvial clayey silty sand layer mixed with swamp black soil, with a thickness of 1.2-2m and rich vertebrate fossils.
The vertebrate fossils of Qian 'an Formation mainly include hairy rhinoceros, wild donkey, wild boar, red deer, wildebeest, primitive cow, NAMA elephant and so on. There are plenty of mollusks and ostracods here. The results of sporopollen analysis show that the Pleistocene Qian 'an Formation in Zhaocun village is roughly equivalent to an ice age in the Late Pleistocene. Pollen data can be divided into three areas (Table 13-3). The peak period of vertebrates is equivalent to the warmer interglacial period divided by sporopollen, and there are also rhinoceros fossils that like cold. Mammals are relatively simple and are typical northern animals.
Figure 13- 15 Profile of the terrace on the south bank of Luanhe River in Zhaocun, Qian 'an (showing mammal fossil products) (according to Pei Wenzhong et al. )
1-bedrock; 2— Alluvium (gravel and sand); 3- Alluvium (sandy); Four slope deposits; 5- swamp accumulation (black soil); 6— Alluvium (clayey silt); 7— Gravel layer at the bottom of fossil producing area; 8— Alluvium (sand); 9-Fossil Source
Table 13-3 Climate Change Reflected by Sporopollen Analysis of Qian 'an Formation in Qianzhao 'an Village
(According to Cenozoic sporopollen data of Institute of Geology and Mineral Resources, Academy of Geological Sciences)
(4) Quaternary Stratum in North China Plain According to the research results of mineralogy, petrology and Quaternary sediments in North China Plain, sediments can be divided into four glacial periods, three interglacial periods and one post-glacial period. Quaternary sediments in North China Plain mainly originate from or flow through the loess plateau and mountainous areas in the west and northwest of the plain, and are transported by the main streams and tributaries of the Yellow River, Haihe River and Luanhe River.
During the alternation of Quaternary Glacial Period and Interglacial Period, an alternating sequence of glacial deposits and interglacial deposits was formed. The main types of Quaternary deposits in North China Plain are glaciers and glacial deposits, alluvial deposits, diluvial deposits, marine deposits, lacustrine deposits and residual deposits. From Taihang Mountain and Yanshan Mountain area to plain and seashore, passing through foothills and piedmont areas, the particles of Quaternary sediments became finer from coarse to fine. Because North China Plain is a fault-subsidence accumulation plain in Quaternary, Quaternary sediments are well preserved in buried profile. The subsidence intensity of different parts of the basement in North China Plain is different. The thickness of Quaternary sediments changes with the development of fault subsidence movement in different parts of the plain basement. In places where rifting movement is strongly developed, the thickness of Quaternary sediments can reach more than 1000 meters, and the thickness in most areas is generally between 5 and 700 meters. ..
The basic sequence of Quaternary strata in North China Plain is as follows:
The foothills and piedmont plains of the first glacial deposit are mostly purple glacial mud gravel and clay; The central plains and coastal areas are mostly purple ice water gravel, sand and silt layers, containing spores and pollen of dark coniferous forest and meadow swamp vegetation. The sporopollen content of cold-loving plants spruce and cedar is as high as 565438 0%. After calculation, the average annual temperature at that time was about 10℃ lower than now, and the average annual temperature was below 0℃.
Iron, manganese and aluminum soil residues (buried weathering crust) formed by weathering at the top of the first glacial deposit; Alluvial and lacustrine deposits occur in areas where subsidence movement is developing violently and in some ancient river beds. Marine sediments appear in coastal areas. Pollen of broad-leaved forest or mixed coniferous and broad-leaved forest is as high as 15-22% in some places. Calculate the annual average temperature10-11℃.
The foothills and piedmont plains of the second glacial deposition are red glacial mud gravel and clay; Ice water gravel, sand and silt layers are buried in the central plain and coastal areas. Sporopollen in dark coniferous forests and grassland belts. The sporopollen of spruce and fir reached 47.5%.
The sediments of the second interglacial period developed from the iron and manganese residues (buried weathering crust) at the top of the sediments of the second interglacial period; Alluvial deposits, lacustrine deposits and marine deposits occur in buried ancient rivers, severely faulted areas and coastal areas. Coniferous broad-leaved forest grassland belt. It is estimated that the annual average temperature is about 65438 02℃.
The sediments in the third glacial period are brown glacial gravels and glacial gravels, sand and silt layers in hills and piedmont plains. In the central plains and coastal areas, there are ice water gravel, sand and silt layers. Mud is loess to some extent. Dark coniferous forest meadow swamp to coniferous forest meadow swamp. Spruce and fir accounted for 46.46%- 14%.
Iron, manganese and carbonate residues (ancient weathering crust) developed on the top of the third glacial deposit. Alluvial deposits, lake deposits and coastal deposits occur in places where ancient river burial and rifting movements are strongly developed. Coniferous broad-leaved forest grassland to coniferous forest grassland. The calculated annual average temperature is 8- 10℃.
In the fourth glacial period, silty sand buried in ice water sand, sand layer and sediment was micro-loess. There are abundant sporopollen and bryophytes in the Yunbin grassland belt of dark coniferous forest. The calculated annual average temperature is lower than now11-13℃.
The post-glacial deposits are mainly flood plain deposits, mainly silty sand and fine sand, and lacustrine deposits appear in some places; Coastal sediments are distributed in the coastal zone. Buried carbonate weathering crust and paleosol appeared in some areas along the river.
According to the study of marine sediments and foraminifera and ostracods in them, it can be determined that there are 6 transgressions and 1 transgression in North China Plain. They were named Bohai Sea transgression, Haixing transgression, Huanghua transgression, Qingxian transgression, Cangxi transgression, xian county transgression and Paodong Sea transgression respectively. These transgressions all occurred in interglacial period or interglacial period and post-glacial period. Among them, Cangxihai 14C age is 22,9001100a, xian county transgression age is 8,500-5,500a, and Cangdonghai transgression age is 5,000-3,500a.
There are basalts and tuffs in Quaternary sediments in North China Plain. The paleomagnetic dating results of volcanic sediments are as follows: at the beginning of Pleistocene, it was equivalent to Mammth event in paleomagnetic chronology, before 3.05-3. 15 Ma; The dividing line between the second glacial period and the second glacial period is equivalent to the Audoye-Iraq event, which was before 1.67— 1.90 Ma. The boundary between the third ice age and the third ice age is roughly equivalent to Brunhes-Matuyama Paleozoic, 0.7-0.9 Ma ago.