Cretaceous (cretaceous period 137 million years ago ~ 6700 million years ago) the early Cretaceous to nine thousand seven hundred years to one hundred forty-four million years ago, the late Cretaceous period to nine years from six thousand five hundred million Qianqi years ago. (Reptiles and gymnosperms to decline from the heyday off) English name: cretaceous period Pinyin: bái èjì
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Introduction
白垩纪 简介
Cretaceous (cretaceous period, cretaceous) Mesozoic last one century. Cretaceous (cretaceus period) is the Mesozoic last century, began 137 million years ago and ended in 6500 million years ago, during which experienced a 7000 years. Either inorganic or organic sector has experienced important changes in the Cretaceous. Located above the Jurassic, Mesozoic and Cenozoic below. Mesozoic Cretaceous is the largest degree of the earth's surface by the flood period in the Northern Hemisphere during the Cretaceous sedimentary layer of wide, in 1822 the Belgian scholar jbj Leader Croix will be named Omar Cretaceous. Chalk is a very fine layer of powder of pure limestone is biogenic marine sediments, mainly composed of coccolithophorids called the calcareous nannofossils and planktonic foraminifera composition. In this period, the continents separated by oceans, the earth has become warmer and drier. Flowering plants appeared, at the same time, many new dinosaur species began to appear, including beef cattle as food for such a large carnivorous dinosaur dragon, dragon halberd such as class members as well as a Long Long Lai plant-eating duckbill that dragons. Still rule the land with the dinosaurs, pterosaurs, as the same aircraft, such as pterosaurs Phi Plumed Serpent gliding in the sky, huge marine reptiles, such as Sea King Dragon dominated shallow sea. But the earliest snakes, moths, and bees, and many new small mammals also appeared in this period. Intense crustal movement and changes in land and sea, leading to great changes in the biosphere Cretaceous, Mesozoic and dominant in many popular categories (such as gymnosperms, reptiles, ammonites and belemnite, etc.) have been the late decline and extinction, the emerging angiosperms, birds, mammals and gastropods, bivalves, etc. had been developed, herald a new stage of biological evolution - the new generation to come. Reptiles from the Late Jurassic to Early Cretaceous reached its apogee, the continued occupation of the land, sea and air. Continued evolution of birds, characterized by constantly closer to modern birds. Slight development of mammals, there has been primitive marsupials and placental mammals true. Fish have been completely dominated by teleost fish. Cretaceous marine invertebrates is still the most important category of classes ammonite, ammonites in the shell size, shell shape, shell ornaments, and suture type diversity than the Jurassic. Marine bivalves, six fire corals, foraminifera, etc. also more prosperous. Freshwater invertebrates with bivalve mollusks, gastropods and ostracods arthropods, conchostracan class-based. Early Cretaceous in the cycads are still gymnosperms, the cycads in this category, mainly conifers, and Ginkgo biloba, ferns are still thriving. From the late Early Cretaceous rise of angiosperms to the rapid development of the Late Cretaceous, gradually replaced the gymnosperm dominance door. Cretaceous strata formed during this period called "Cretaceous." Representative symbol "k". Cretaceous to the disintegration of ancient continent south, north of ancient continental rise, climate cooling, significant seasonal variation. The beginning of this century there angiosperms, the progressive development of the future. Ammonites and dinosaurs, pterosaurs, ichthyosaurs, plesiosaurs and other gradually become extinct by the flourishing of mammals and birds into a new animal groups. Cretaceous continental distribution of the earth and the biosphere Shanghai dramatic changes in the Atlantic quickly crack and age of volcanic activity, the latter a wide range of low and flat transgression occurred. Instead of the Late Cretaceous angiosperms gymnosperms dominated the land, is a major change in the plant kingdom. Before the end of the animal kingdom in significant changes in the Cretaceous, dinosaurs, ammonites and many other biological groups extinction, indicating that the new generation is about to begin. Cause extinction of the reasons for this large-scale, international scientific community in recent years had a heated debate. Quite popular "extraterrestrial event" doctrine, in some places on the planet, Cretaceous - Tertiary boundary clay rock on the unusually high content of iridium, the universe is a giant meteor collision of the earth produces effects similar to nuclear winter results, whereby parts of the world to determine the Cretaceous - Tertiary boundary, the Ir anomaly is an important principle. However, the "extraterrestrial event" skeptical and many others who have objections, they believe that the end Cretaceous mass extinction was gradual biological, and is the result of ecological changes, and not a simple hit the Earth by extraterrestrial caused by the disaster. Mesozoic and dominant in many popular categories, such as gymnosperms, reptiles, ammonites and arrow stone, the decline or extinction of late have been, the emerging angiosperms, birds, mammals and gastropods, bivalves, etc. have development, and heralds a new generation of biological evolution to come. Vertebrates reptiles from the Late Jurassic to Early Cretaceous reached its apogee, on behalf of a tyrannosaurus rex, tyrannosaurus, pterodactyl, Qingdao Dragon and the subsequent decline. Planktonic foraminifera in marine invertebrates is a division of the Cretaceous in contrast, an important basis for the late marine strata, benthic foraminifera have also been many fossils. Ammonite and belemnite rapid evolution was widely distributed, is the traditional division of the standard order and with fossils. Freshwater invertebrates are also abundant, such as crustaceans and ostracods rapid evolution conchostracans, molluscs snails and mussels in the widely distributed, as well as insects and freshwater charophytes fossils, many of them can be the species division and correlation of continental strata of fossils. Early Cretaceous terrestrial gymnosperms and ferns on the still dominant position, pine, cycads, ginkgo, true ferns, and a section of the main flora of classes. Began to appear in the Early Cretaceous angiosperms, a significant increase in the mid to late home in the land plants in the dominant position, beech, banyan tree, magnolia, maple, oak, Yang, Zhang, walnut, sycamore, etc. are there, close to the Cenozoic flora look. End of the Cretaceous, dinosaurs, ammonites and other biological groups a large number of extinction. Mass extinction caused by the biological reasons, there are many arguments. Some people think that is a giant in the universe caused by meteoroids hitting Earth, based in the Cretaceous and Tertiary boundary clay rocks on abnormally high levels of iridium.
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Name source
Because of the formation is rich in chalk (chalk) is named. Chalk is a type of limestone, composed mainly of calcite, uniform and fine particles, can be grated by hand. "Cretaceous," a term coined by the French geologist Daluo Wa (jean baptiste julien d'omalius d'halloy) in 1822, Creative. Is called the Cretaceous formation Cretaceous strata. The name comes from the Cretaceous chalk layers cross the English Channel, by the Belgian scholar j.-b.-j. Leader Croix Omar founded 1822, English cretaceous system derives from the Latin word creta, is the meaning of chalk or lime . Chalk is a very fine layer of powder of pure limestone is biogenic marine sediments, mainly called coccolithophorids (coccoliths) of calcareous nannofossils and planktonic foraminifera constitute, in the UK, France shaped cross beautiful white cliffs. Chalk layer not only developed in the Europe, North America and Western Australia also have distribution.
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Stratum
The division of the Cretaceous marine strata in Europe, based on ammonite standard initially in 6 to 7-order (period), and later to some of the sub-order upgrades to the current 12-order (period), but some accustomed to the lower part of the Lower Cretaceous of the four bands collectively known as Neo-order can be wood (or translated Niukang Mu-order.) Upper Cretaceous of central Connie Yake, Thornton and Campanian three bands collectively known as Sennuo order. Of the 12 bands can be divided into 53 ammonite zone, in recent years, Youyi planktonic foraminifera and calcareous nannofossils in the Cretaceous as in phases, zoning, and an important basis for intercontinental comparison. Cretaceous continental hinterland is developed in East Asia, rich in oil, coal, salt and other minerals and a variety of freshwater and terrestrial plant and animal fossils. Republic of China only in Tibet, Xinjiang Kashgar region, eastern Heilongjiang Province, and Taiwan have a marine Cretaceous deposits, the rest are varying degrees of large areas of the terrestrial strata development. Activities in the eastern Pacific coast is a belt clip to red and variegated rock mainly pyroclastic rocks and lava; northwest inland basin sedimentary rock dominated by variegated; southwest and central China are mainly red rock. Northeast is the lower part of the Lower Cretaceous coal-bearing strata, the upper part of the lake sediments, clip a little oil shale; Upper Cretaceous is well-known oil shale, and the North American situation is different, coal-bearing strata few. Cretaceous biostratigraphy People's Republic of research since the 50s since the 20th century, made great progress, but mainly due to the continental strata, relatively weak research base, has not yet completed construction of a regional working group and the construction stage , has been established in various regions of the layer can not be perfectly compared with stratified marine standards. Jurassic - Cretaceous boundary problem by a long debate, it appears that in the short term is difficult to be properly addressed. Early Cretaceous terrestrial biosphere gymnosperms and ferns on the still dominant position, pine, cycads, ginkgo, true ferns, and a section of the main flora of classes. Began to appear in the Early Cretaceous angiosperms, a significant increase in the mid to late home in the land plants in the dominant position, beech, banyan tree, magnolia, maple, oak, Yang, Zhang, walnut, sycamore, etc. are there, close to the Cenozoic flora look. Began to emerge from the Jurassic nannofossils, characterized by different layers with the generation change, has important stratigraphic significance, which, among rock stars, there have been micro-cone extinction Stone (nannoconus), wedge-shaped stone ( sphenolithus) and so on. Vertebrates reptiles decline from the heyday of the main representatives of Tyrannosaurus rex, tyrannosaurus, pterodactyl, Qingdao Dragon. Jurassic previous ganoid be replaced by teleost fish. Planktonic foraminifera in marine invertebrates rise to become the division and correlation of the Cretaceous, the late marine strata of the important basis, benthic foraminifera also appeared in a number of fossils. Ammonite and belemnite rapid evolution was widely distributed, is the traditional division of the standard order and with fossils. Qun sessile benthic clams (rudistids) can form reefs, is a typical warm water fauna in southern Tibet and the People's Republic of Upper Cretaceous strata are found. Urchins in the Tethys was quite prosperous, there are a few standard species. Corals and brachiopods a minor role in the Cretaceous. Freshwater invertebrates are also abundant, such as crustaceans and ostracods rapid evolution conchostracans, molluscs snails and mussels in the widely distributed, as well as insects and freshwater charophytes fossils, many of them can be a species division and correlation of continental strata fossils, the geological mapping, petroleum and coal and other mineral resource exploration and play an important role.
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Biosphere
End of the Cretaceous land mass gradually today looks like. Crust are in constant motion, triggering a global volcanic activity. Large-scale volcanic eruptions lasted for hundreds of years, the surface is full eruption, the atmosphere is full of toxic gases and dust, dinosaurs still rule the desolate planet, they dominate the six thousand one hundred million years, but now fate is drawing near, began choking on Earth death. Dinosaurs ruled the last two years appears the most violent predators. Tyrannosaurus meat, 5 tons, 13 meters high, it is a male T. rex, which by the Food and drawn to the foot of the volcano. Covered the area of geothermal springs, the air full of sulfur gas, but there is another smell, a hill in the valley Foulest Shixiu. Tyrannosaurus oversight, naturally fall into the trap of volcano eruption poisonous carbon monoxide, carbon monoxide is heavier than air, it accumulated near the surface. Raptors down to eat the body, would be the impact of carbon monoxide. If it falls it will never fall to the ground. It was saved thanks to the tall size. Dangling from the food when it got up, just higher than the gas layer of the head. "On the extinction of dinosaurs are many reasons, one of which is very key is the large-scale volcanic eruptions, that is, 6,500 million years, dinosaurs extinct during this period, the Earth has a massive volcanic eruption, lava flow rocks distribution, for example, Deccan has a volcanic lava flow area is very large, and this time just the mass extinction of dinosaurs is consistent. " The lava flow is still barren green dotted the late Cretaceous, warm and humid climate, plants started to change, replacing softwood hardwood, the evolution of flowering plants is the hero of this quiet revolution. The key lies in the intimate relationship flowers and insects, and some flowers today to rely on pollination by insects, some insects, like butterflies rely on flowers for a living. Multiplication of birds in broad-leaved forest, forest birds, endless. These beautiful plants but it is highly likely to be the culprit killed the dinosaurs. "The emergence of broad-leaved plants may also impact on the dinosaurs, such as its plant structure has changed, the dinosaurs of the diet may not keep up with the speed of plant development may be its evolution, because evolution of dinosaurs the same as the Dragon It should be adapting to the environment, it does not keep up with it there is a lag, but also extinction. " Three days later, Triceratops had Shiguwucun. Tyrannosaurus mother began Xiazhukeling, public Tyrannosaurus sensible to leave. This scene took place late in the Cretaceous may be likely less and less chances of survival because the female dinosaurs getting smaller and smaller, which may directly lead to the demise of the dinosaurs. Gliding pterosaurs come from the coast Fengshen, to come to feed, watch that scene was extremely rare. Nearly thousands of years, pterosaurs dying, now only 13 meters long Fengshen pterosaurs survived. Volcanoes and dinosaurs Not safe here, the lake has a ton of crocodiles, pterosaurs can easily get involved Fengshen killed, will be extinct pterodactyl, the sky would fall strong birds. A few months after mating, the mother Tyrannosaurus build a new nest, hidden in the forest, the mother Tyrannosaurus time monitoring. The incubation period of up to two months, the mother dragon does not leave the nest to eat eggs is Ben Long and other scavengers favorites. Tyrannosaurus looked closer and closer to the Ben Long, Raptors forward eyes can accurately judge the range of attack. Sun_set_, the mother dragon is also facing the threat of another wave of food have become rare, mammals take the risk. Female Long View nests confirmed that no slip through the net. Then they continue to patrol. Weeks later, in a brilliant sun_set_, the sky is hidden a warning notice to the coming catastrophe, meteor showers flying, super-Deep impact is a warning. Under the stars are not aware of the dinosaur vision to continue feeding the dragon horn, David Long fear predators night attack, to seek protection from the adult dinosaur. Ben Long Chen Ye two action groups trying to disrupt the dragon horn, isolated a baby dragon. Sunrise, revealed last night's fighting, small horns Long Ben Long was killed, a serious blow to the horn dragons. Serious environmental pollution, the new generation too little. Teeth children have waited at the corpse next to the beast, speculation is probably the only children thriving animal teeth animal. Dinosaurs ruled the earth long, and now shift the subject to a series of fatal shock. Dinosaur A flock of geese long trek across the desert, gathered in the stagnant water filled lake, water for food. They have multiple _set_s of large cheek teeth, you can speed up the digestion plant. Pin a predator, should not stay for long. Goose Long was dangerous, then disperse. The end of the mother T. rex fasting, slaughter. New life to the nearby bushes, which hurry to look for food, waiting to eat three small tyrannosaurus, 12 eggs hatched only 3, they heard the mother T. rex hunt, they start to discuss food. Tyrannosaurus to bring home a big goose dragon meat. Small Tyrannosaurus was four weeks a large, less than one meter, sibling competition has already begun, a small Tyrannosaurus exclusion by the other two. They also need protection of the mother T. rex more than two months after the mother and son have grown apart, or else it will eat small things to Tyrannosaurus. I am afraid that the single small tyrannosaurus running out to Japan. Over a few days, the mother dragon in as the sun, but there is no place orders of small Tyrannosaurus in sight, it may have been brutally murdered sibling. Noisy happy to leave the mother of a small Tyrannosaurus Lung, and explore around. Tyrannosaurus accident and saw a mother dragon, a leading hard-shell capacity of the brain is small, in danger, thanks to fierce attack instinct. Tyrannosaurus usually retreat, but the mother refused to cast aside Tyrannosaurus David Long, the mother was hit Tyrannosaurus femur, visceral rupture, it is embarrassing pain away, the dragon dying mother cry at night. At dawn, it is thrown in the hot desert. Lung small beside the body of the mother T. rex stood waiting. Hours later, a small Tyrannosaurus still refused to leave, but their fate and other Cretaceous dinosaurs. A large comet crashed into the Gulf of Mexico today, impact glared, turned quiet, then came the shock. Then the wind comes up, the last lava down the dark sky, rain, the impact of the power of the equivalent of ten billion Hiroshima atomic bombs. Sudden changes in global climate, resulting in 65% of the biological extinction. The impact is today, many scholars believe that the demise of the dinosaurs is the main reason, but as we have seen, in fact, before this, the dinosaur has gone to the destruction of the road. Dinosaur egg "The extinction of the dinosaurs is now a mainstream view that it is the meteorite hit the Earth the ball, resulting in a large number of extinction on Earth, then the meteorite hit the Earth is in fact the ball is also divided into two views, a view that an asteroid collision, Another view is that a comet impact, then the asteroids and comets colliding with Earth after Earth's entire structure will lead to some changes, for example, it led to a massive volcanic eruptions, forest fires can lead to more global. " However, the early Cretaceous are also many types of biological origin, such as large aircraft like the feathered serpent Phi pterosaurs, hadrosaur class, flowering plants and more. Mesozoic third century. Said that the strata formed during the Cretaceous, is located on top of the Jurassic, Mesozoic and Cenozoic below. Mesozoic Cretaceous is the largest degree of the earth's surface by the flood period in the Northern Hemisphere during the Cretaceous sedimentary layer of wide, in 1822 the Belgian scholar jbj Leader Croix will be named Omar Cretaceous. Chalk is a very fine layer of powder of pure limestone is biogenic marine sediments, mainly composed of coccolithophorids called the calcareous nannofossils and planktonic foraminifera composition. Cretaceous, South America and the rift between the African continent, the rapid formation of the South Atlantic opening, to the end has been widened to about 3000 km. Rift Valley in the North Atlantic east of Greenland and North America, with the westward drift of North America, the rift is widening. Tethys separated the Eurasian continent and Africa, Central and Southern Europe and the Middle East are in many countries was in the transgression. Cretaceous when the weather is warm, and no sign of the polar ice caps. At that time most of rainfall, humid climate, the formation of offshore and coastal areas rich in oil, coal, natural gas and oil shale deposits, such as the United States, Texas, United States of Mexico, the Persian Gulf, North Africa and the Russian Federation, many of the largest oil field, and if Upper Cretaceous Songliao Plain People's Republic of Daqing oilfield, northeast and Inner Mongolia, Lower Cretaceous of the many big coal. Dry and hot climate in some areas, such as the People's Republic of Late Cretaceous southern southwestern lakes and river systems Yunmeng Ze, a thick sedimentary gypsum deposits. In addition, Cretaceous red beds in Yunnan, high grade copper deposits of sand, size large, easy-to-mining and smelting, copper is the People's Republic of famous township. Birds and angiosperms Mesozoic Cretaceous was the last century, is the total extinction of the dinosaurs from the peak period to period due to the large number of European marine sediments of Cretaceous and known as the "Cretaceous", hence the name Cretaceous. Stegosaurus extinct in the Cretaceous. But the duck-billed dinosaur, a dragon and the dragon in the late Cretaceous angular Shique rapid development, especially the dragon horn, although the Late Cretaceous, when the earth appeared, but in a very short period of time to evolve out of the rich variety. Cretaceous dinosaur reached its apogee, the most famous Tyrannosaurus rex is the largest land carnivores appeared. Birds are vertebrate development to achieve the greatest success of the air group. Early Cretaceous bird began to differentiate, and the ability to fly and greatly enhance arboreal capacity than Archaeopteryx. Of paleontologists discovered the famous "Confucius bird," is representative of the Early Cretaceous birds molecules. End of the Cretaceous, life on Earth has gone through another major extinction events: the ruling on the surface of reptiles living losing mass extinction of the dinosaurs complete; more than half of the plants and other land animals also disappear. What causes the sudden extinction of dinosaurs and a large number of biotechnology? This issue has always been a conundrum of geological history. We now generally accepted that meteorite impact said. Notably, the mammals are the biggest beneficiaries of this extinction event, they had a crisis and the subsequent occupation by the new generation of dinosaurs and other reptiles out of the ecological environment, the development of rapid evolution on Earth the new rulers.
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Characteristics of the geological history
People in central and western inland areas, very few Cretaceous volcanic activity, but there are underwater eruption in the Tibetan area.
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Introduction
Cretaceous abbreviation denoted K, Cretaceous from the German name (Kreidezeit) acronym. "Cretaceous," a term coined by the French geologist Daluo Wa (Jean Baptiste Julien d'Omalius d'Halloy) in 1822, Creative. Located between the Jurassic and Paleogene, about 100 million 4550 years (the error value is 400 million years) ago to 65.5 million years ago (the error is 30 years.) Mesozoic Cretaceous was the last century, up to 8000 years, is the longest Phanerozoic stage. Occurred in the late Cretaceous mass extinction events, the boundaries of the Mesozoic and Cenozoic. Very warm Cretaceous climate, sea level big changes. Survival of the dinosaurs on land, marine survival of the marine reptiles, ammonites, and the thick shell clams. New mammals, birds appear, the first flowering plants appeared. Cretaceous - Tertiary extinction event was the most serious geological events of mass extinction, including the majority of species, including the demise of the dinosaurs. Oxygen content in the atmosphere during the Cretaceous is now 150% carbon dioxide content is 6 times before the industrial age, the temperature is higher than today about 4 ℃. Cretaceous strata because of its rich chalk (chalk) is named. Chalk is a type of limestone, composed mainly of calcite, uniform and fine particles, grated by hand can be called the Cretaceous formation Cretaceous strata. Chalk is a very fine layer of powder of pure limestone is biogenic marine sediments, mainly called coccolithophorids (Coccoliths) of calcareous nannofossils and planktonic foraminifera constitute, in the UK, France shaped cross beautiful white cliffs. Chalk layer not only developed in the Europe, North America and Western Australia also have distribution. In this period, the continents separated by oceans, the earth has become warmer and drier. Flowering plants appeared, at the same time, many new dinosaur species began to appear, including beef cattle as food for such a large carnivorous dinosaur dragon, dragon halberd such as class members as well as a Long Long Lai plant-eating duckbill that dragons. Still rule the land with the dinosaurs, pterosaurs, as the same aircraft, such as pterosaurs Phi Plumed Serpent gliding in the sky, huge marine reptiles, such as Sea King Dragon dominated shallow sea. The first snakes, moths, and bees, and many new small mammals also appeared in this period.
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Geological age
Determination Divided The division of the Cretaceous marine strata in Europe, based on ammonite standard initially in 6 to 7-order (period), and later to some of the sub-order upgrades to the current 12-order (period), but some accustomed to the lower part of the Lower Cretaceous of the four bands collectively known as Neo-order can be wood (or translated Niukang Mu-order.) Upper Cretaceous of central Connie Yake, Thornton and Campanian three bands collectively known as Sennuo order. Of the 12 bands can be divided into 53 ammonite zone, in recent years, Youyi planktonic foraminifera and calcareous nannofossils in the Cretaceous as in phases, zoning, and an important basis for intercontinental comparison. Sub-system on the Cretaceous There are 2 comments ① from the Albian and the Cenomanian-order division between the Upper and Lower Cretaceous Upper Cretaceous Maastrichtian (Maastrichtian): 70.6 ± 0.6 - 65.8 ± 0.3 million years Campanian (Campanian): 83.5 ± 0.7 - 70.6 ± 0.6 million years Santos-order (Santonian): 85.8 ± 0.7 - 83.5 ± 0.7 million years Cognac stage (Coniacian): 89.3 ± 1.0 - 85.8 ± 0.7 million years Turonian (Turonian): 93.5 ± 0.8 - 89.3 ± 1.0 million years Cenomanian (Cenomanian): 99.6 ± 0.9 - 93.5 ± 0.8 million years Lower Cretaceous Albian (Albian): 112.0 ± 1.0 - 99.6 ± 0.9 million years Aptian (Aptian): 125.0 ± 1.0 - 112.0 ± 1.0 million years Balie Mu-order (Barremian): 130.0 ± 1.5 - 125.0 ± 1.0 million years Hao Terryville order (Hauterivian): 136.4 ± 2.0 - 130.0 ± 1.5 million years Where the blue this order (Valanginian): 140.2 ± 3.0 - 136.4 ± 2.0 million years Bei Liya order (Berriasian): 145.5 ± 4.0 - 140.2 ± 3.0 million years ② claim three points in the system to draw one, as in the traditional sector to determine the top and bottom, there are different opinions. 1974 to 1982, the international community has a "Cretaceous event in the" organization, activities, very active, mainly of the Cretaceous period, biostratigraphy, marine transgression, anoxic events, geomagnetic field reversal, the formation of salts and chalk , South Atlantic and Mozambique Canyon cracking, as well as the Indian plate from Gondwana separation issues. Mid-Cretaceous geological age is not an exact concept, it was counting to Thornton from the Aptian stage, most people from the Albian to Connie Yake of counting period. In addition to the Cretaceous in the Middle East division, the international community rarely used. Cretaceous dichotomy has been in decades, found a large number of publications and geologic maps, the current changes should not be in again. Cretaceous continental hinterland is developed in East Asia, rich in oil, coal, salt and other minerals and a variety of freshwater and terrestrial plant and animal fossils. Republic of China only in Tibet, Xinjiang Kashgar region, eastern Heilongjiang Province, and Taiwan have a marine Cretaceous deposits, the rest are varying degrees of large areas of the terrestrial strata development. Activities in the eastern Pacific coast is a belt clip to red and variegated rock mainly pyroclastic rocks and lava; northwest inland basin sedimentary rock dominated by variegated; southwest and central China are mainly red rock. Northeast is the lower part of the Lower Cretaceous coal-bearing strata, the upper part of the lake sediments, clip a little oil shale; Upper Cretaceous is well-known oil shale, and the North American situation is different, coal-bearing strata few. Cretaceous biostratigraphy People's Republic of research since the 50s since the 20th century, made great progress, but mainly due to the continental strata, relatively weak research base, has not yet completed construction of a regional working group and the construction stage , has been established in various regions of the layer can not be perfectly compared with stratified marine standards. Jurassic - Cretaceous boundary problem by a long debate, it appears that in the short term is difficult to be properly addressed. Rock Cretaceous sea-level changes, warm climate, show a large area of land covered by a warm shallow sea. Cretaceous chalk layer is a common name in Europe, but in the rest of the world, mainly from the marine Cretaceous strata of limestone layers, these marine limestone layer is formed in warm shallow sea. High sea levels will cause a wide range of sedimentation, thus creating a thick sedimentary layer. Thickness due to the Cretaceous, closer to the times, often found around the world Cretaceous strata outcrop. Cretaceous chalk in the common elements. Chalk is a marine coccolithophorid calcium shell particles (spherical granules) deposits formed; coccolithophorid algae are common species of the Cretaceous. In northwestern Europe, often found in the Cretaceous chalk deposits, including: the south coast of England, white cliffs of Dover, the French Normandy coast, and the Low Countries, northern Germany, Denmark coast. Chalky texture is not strong, so the texture of these sediments loose. These strata also contain limestone, sandy rock. These formations can be found in the sea urchin, belemnite, ammonite, and marine reptiles (such as mosasaurs) fossil. Cretaceous strata in southern Europe are mostly marine sediments, mainly composed of limestone, and a few mortar composition. During the Cretaceous period, the Alps orogeny has not happened, so the Cretaceous strata in southern Europe, mostly at the continental shelf around Tethys. In the Cretaceous, marine low-level flow stagnated, resulting in anoxic marine environment. Many around the world black shale, that is, anoxic environment in the formation of this period. These are important oil shale, natural gas sources, the North Sea is the case.
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Geographical Features
Terrestrial distribution of the Cretaceous period of the Cretaceous world, full of Pangaea into the present continents split, but they are all not the same here. Atlantic has also widened. Jurassic in North America since the beginning, the formation of multi-row parallel to the orogenic screen, such as Nevada mountain building, and after the Sevier orogeny, La Lami orogeny. In the early Cretaceous, Gondwana has not split, then South America, Antarctica, Australia have been from Africa, India and Madagascar in Africa, also connected on. South Atlantic and Indian oceans began to appear. The movement of tectonic plates, resulting in a large number of undersea mountains, and cause a global sea level rise. Tethys north Africa in the narrower. North American Western Interior Seaway will be divided into two things, the narrow sea lanes in the late Cretaceous period, leaving thick marine sediments, mixed with those coal beds. The highest sea level in the Cretaceous period, the surface has 1 / 3 of land immersed in the sea below. Clay layer known as the Cretaceous, the clay layer formed during the Phanerozoic than other periods. Mid-ocean ridge volcanic activity, or the flow of sea water near the volcano, the Cretaceous sea rich in calcium, close to saturation, but also makes the calcium increase in the number of micro-plankton. Widespread carbonate and other sedimentary layers, making the Cretaceous rock record is particularly high. Formation group contains the well-known in North America: Kansas, mountains and rivers of marine clay layer of smoke, late terrestrial Hell Creek group. Other well-known Cretaceous strata include: Europe Weald (Weald), Yixian Formation in Asia. The late Cretaceous to early Paleocene, India, massive volcanic eruptions, the formation of the Deccan shield now.
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Climate Change
Balie Mu-order there during the cold weather trends in the change from the Jurassic in the final phase began. Increased snowfall at high latitudes, while tropical regions than in the Triassic, Jurassic is more humid. However, the ice appears only at high latitudes in the mountains, while the low-latitude seasonal snowfall is still visible. Late stage in the Balie Mu, the temperature began to rise, continuing to the end of the Cretaceous. Temperature rise is due to intensive volcanic eruptions, make a lot of carbon dioxide into the atmosphere. Many mid-ocean ridges formed along the plume, caused by rising sea levels, many regions of continental crust were covered by a shallow sea. Located in the equatorial regions of the Tethys Ocean, help global warming. In Alaska and plant fossils found in Greenland, and from 15 degrees south latitude Cretaceous dinosaur fossils found in areas prove very warm Cretaceous temperatures. Range of tropical temperature gradient and a very flat, probably due to the flow of ocean stagnation and weakness caused by planetary wind system. Widespread oil shale, and anoxic events, confirm the flow of ocean stagnation. According to study sediments that tropical sea surface temperatures of about C 42 °, higher than the current of about C 17 °; while the global average surface temperature of the water C 37 °. The sea bottom temperature is higher than the current temperature is about at 15 到 20 °.
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Biological change
Biosphere Early Cretaceous terrestrial gymnosperms and ferns on the still dominant position, pine, cycads, ginkgo, true ferns, and a section of the main flora of classes. Began to appear in the Early Cretaceous angiosperms, a significant increase in the mid to late home in the land plants in the dominant position, beech, banyan tree, magnolia, maple, oak, Yang, Zhang, walnut, sycamore, etc. are there, close to the Cenozoic flora look. Began to emerge from the Jurassic nannofossils, characterized by different layers with the generation change, has important stratigraphic significance, which, among rock stars, there have been micro-cone extinction Stone (Nannoconus), wedge-shaped stone ( Sphenolithus) and so on. Vertebrates reptiles decline from the heyday of the main representatives of Tyrannosaurus rex, tyrannosaurus, Anhanguera, Qingdao Dragon. Jurassic previous ganoid be replaced by teleost fish. Planktonic foraminifera in marine invertebrates rise to become the division and correlation of the Cretaceous, the late marine strata of the important basis, benthic foraminifera also appeared in a number of fossils. Ammonite and belemnite rapid evolution was widely distributed, is the traditional division of the standard order and with fossils. Qun sessile benthic clams (Rudistids) can form reefs, is a typical warm water fauna in southern Tibet and the People's Republic of Upper Cretaceous strata are found. Urchins in the Tethys was quite prosperous, there are a few standard species. Corals and brachiopods a minor role in the Cretaceous. Freshwater invertebrates are also abundant, such as crustaceans and ostracods rapid evolution conchostracans, molluscs snails and mussels in the widely distributed, as well as insects and freshwater charophytes fossils, many of them can be a species division and correlation of continental strata fossils, the geological mapping, petroleum and coal and other mineral resource exploration and play an important role. Early Cretaceous of China's very obvious geographical plants, spores and pollen based on the research, at least two significant differences within the pollen flora. ① Seamless double-bag the flour - no sudden ribbed spores (Disacciatrileti-Cicatricosisporites) flora. Distributed in the northern areas, including northern regions of Northeast and North China. Here lush vegetation, especially Pinaceae, Podocarpaceae subjects such as plants and sea gold sand, forming a rich coal reserves. Also shows that there is a warm and humid climatic zones. ② shuttle carat pink - sedge fern spores (Clas-sopollis-Schizaeoisporites) flora. In the southern area, prolific salt deposits out of the red gypsum strata, reflecting the relatively hot and dry when the climate. At latitude 40 ° ~ 50 ° between the North West showed that there is a - NEE direction of the strip south transition zone, north and south of Mixed flora occurring phenomenon. From a global distribution, the People's Republic of North and South two plants in arid subtropical belt and quite wet. Plant Flowering plants (angiosperms) appeared in the Cretaceous, spreading, but did not become dominant until the Campanian plants. Bees appear to help the evolution of flowering plants; flowering plants and insects are common examples of evolution. Banyan tree, sycamore, magnolia and other large plants began to appear. Some of the early gymnosperms continues to exist, such as pine and cypress head. Araucaria pine and other prosperous and widely distributed, and this project in the late Cretaceous demise of cycads. Terrestrial animals Tyrannosaurus rex in the animal kingdom, mammals is still relatively small, only a small portion of land animals. Advantage of the land animals is still the main dragon reptiles, especially dinosaurs, a period which is more diverse than before. Flourished in the Cretaceous pterosaur in the project to the late, but they gradually adapted to face the competition of radiation of birds. In the late Cretaceous, pterosaurs head around the only remaining two sections. Birds are vertebrate development to achieve the greatest success of the air group. Early Cretaceous bird began to differentiate, and the ability to fly and greatly enhance arboreal capacity than Archaeopteryx. Of paleontologists discovered the famous "Confucius bird," is representative of the Early Cretaceous birds molecules. Insect diversity in this period began, and found the oldest ants, termites, Lepidoptera (butterflies and moths). Bud worm, Grasshoppers, gall wasps began to appear. Marine animals Cretaceous fossils, fossils of the hole is the imprint of sea pebbles, and now the skate fish, sharks, and other bony fish common. Marine reptiles includes: The survival in the early to mid ichthyosaurs, plesiosaurs as early as the late, Late Cretaceous mosasaurs. Rod with a straight ammonite shells, are daisy Danya Gang, and the reef for marine thick shell clams prosperous with the animals. Dusk the birds head is the original group of birds can not fly, can swim in the water, like modern Si. Foraminifera door cut the ball worm families (Globotruncanidae) and echinoderms (eg sea urchins, starfish) to survive. In the Cretaceous, the earliest ocean diatoms (siliceous diatoms should be, rather than calcium diatoms) appears; survive in fresh water until the Miocene diatom origin. For marine species caused by bio-erosion of the Cretaceous is the important stage in the evolution of these species. Extinction Intense crustal movement and changes in land and sea, leading to great changes in the biosphere Cretaceous, Mesozoic prevalence and dominance of many doors oyster fossil Cretaceous period (such as gymnosperms, reptiles, ammonites and arrows and stones, etc.) have been late decline and extinction, the emerging angiosperms, birds, mammals and gastropods, bivalves, etc. had been developed, herald a new stage of biological evolution - the new generation to come. Reptiles from the Late Jurassic to Early Cretaceous reached its apogee, the continued occupation of the land, sea and air. Continued evolution of birds, characterized by constantly closer to modern birds. Slight development of mammals, there has been primitive marsupials and placental mammals true. Fish have been completely dominated by teleost fish. Cretaceous marine invertebrates is still the most important category of classes ammonite, ammonites in the shell size, shell shape, shell ornaments, and suture type diversity than the Jurassic. Marine bivalves, six fire corals, foraminifera, etc. also more prosperous. Freshwater invertebrates with bivalve mollusks, gastropods and ostracods arthropods, conchostracan class-based. The ancient southern continent during the Cretaceous to the thick solution Cretaceous period fossil clam shell body, the North of ancient continental rise, climate cooling, significant seasonal variation. The beginning of this century there angiosperms, the progressive development of the future. Ammonites and dinosaurs, pterosaurs, ichthyosaurs, plesiosaurs and other gradually become extinct by the flourishing of mammals and birds into a new animal groups. Omnivorous, insectivorous, and scavengers to survive in this extinction event, possibly because their diet more varied. End of the Cretaceous did not seem completely herbivorous or carnivorous mammals. Mammals and birds by the insects, earthworms, snails ... and other animals for food, survival in the KT event, and these dead plants and animals Zeyi animals. Scientists assume that these organisms to organisms living on organic debris, was able to collapse in the extinction of flora survive. Biological communities in the river, only a small number of animals destroyed; because many biological communities to the river washed down from land-based organic chopped clams Cretaceous period fossil debris imbricate living, and less directly to the living plants for a living. Ocean had a similar situation, but more complicated. Animals live in the pelagic zone, than the impact on the survival of animals in the sea bed is also large. With the animals living in pelagic phytoplankton living almost to live, and live in the sea-bed animals, places bio-organic detritus, or can be converted to bio-organic detritus. Survived the extinction event in the species, the largest land animal is the crocodile and from Lombok, is a semi-aquatic animals, and can bioclastic living. Scavengers of modern crocodiles can be a living, and for several months without eating; young crocodile is small in size, slow growth, mostly in the first years of invertebrates, dead creatures for food. These characteristics may be the crocodile to survive through the critical end of the Cretaceous extinction event. Cretaceous continental distribution of the earth and the biosphere Shanghai dramatic changes in the Atlantic quickly crack and age of volcanic activity, the latter a wide range of low and flat transgression occurred. Instead of the Late Cretaceous angiosperms gymnosperms dominated the land, is a major change in the plant kingdom. Before the end of the animal kingdom in significant changes in the Cretaceous, dinosaurs, ammonites and many other biological groups extinction, indicating that the new generation is about to begin. Cause extinction of the reasons for this large-scale, international scientific community in recent years had a heated debate. Quite popular "extraterrestrial event" doctrine, in some places on the planet, Cretaceous - Tertiary boundary clay rock on the unusually high content of iridium, the universe is a giant meteor collision of the earth produces effects similar to nuclear winter results, whereby parts of the world to determine the Cretaceous - Tertiary boundary, the Ir anomaly is an important principle. However, the "extraterrestrial event" skeptical and many others who have objections, they believe that the end Cretaceous mass extinction was gradual biological, and is the result of ecological changes, and not a simple hit the Earth by extraterrestrial caused by the disaster.
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Encyclopedia
Baieji Cretaceous Cretaceous Period Mesozoic last century (third century). About 135 million years ago, began and ended in 065 million years ago. Is called the Cretaceous formation Cretaceous strata. The name comes from the Cretaceous chalk layers cross the English Channel, by the Belgian scholar J.-B.-J. Leader Croix Omar was founded in 1822, French is Terrains Cr □ tac □ s, Department of English derives from the Latin word Cretaceous Creta, is the meaning of chalk or lime. Chalk is a very fine layer of powder of pure limestone is biogenic marine sediments, mainly called coccolithophorids (Coccoliths) of calcareous nannofossils and planktonic foraminifera constitute, in the UK, France shaped cross beautiful white cliffs. Chalk layer not only developed in the Europe, North America and Western Australia also have distribution. Cretaceous continental distribution of the earth and the biosphere Shanghai dramatic changes in the Atlantic quickly crack and age of volcanic activity, the latter a wide range of low and flat transgression occurred. Instead of the Late Cretaceous angiosperms gymnosperms dominated the land, is a major change in the plant kingdom. Before the end of the animal kingdom in significant changes in the Cretaceous, dinosaurs, ammonites and many other biological groups extinction, indicating that the new generation is about to begin. Cause extinction of the reasons for this large-scale, international scientific community in recent years had a heated debate. Quite popular "extraterrestrial event" doctrine, in some places on the planet, Cretaceous - Tertiary boundary clay rock on the unusually high content of iridium, the universe is a giant meteor collision of the earth produces effects similar to nuclear winter results, whereby parts of the world to determine the Cretaceous - Tertiary boundary, the Ir anomaly is an important principle. However, the "extraterrestrial event" skeptical and many others who have objections, they believe that the end Cretaceous mass extinction was gradual biological, and is the result of ecological changes, and not a simple hit the Earth by extraterrestrial caused by the disaster. Cretaceous strata of the European division of marine strata, based on ammonite standard initially in 6 to 7-order (period), and later to some of the sub-order upgrades to the current 12-order (period) (see Table division and correlation of marine Cretaceous Summary), but there are still people accustomed to the lower part of the Lower Cretaceous stage 4 can be collectively called Leo Order of wood (or translated Niukang Mu-order.) Upper Cretaceous of central Connie Yake, Thornton and Campanian three bands collectively known as Sennuo order. Of the 12 bands can be divided into 53 ammonite zone, in recent years, Youyi planktonic foraminifera and calcareous nannofossils in the Cretaceous as in phases, zoning, and an important basis for intercontinental comparison. Cretaceous continental hinterland is developed in East Asia, rich in oil, coal, salt
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English Expression
: Cretaceous period
n.: cretaceous, cretaceous period [system]
adj.: Cretaceous of the geological period when chalk-rocks were formed
