Jurassic

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Jurassic Period
201.3–145 million years ago
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O
S
D
C
P
T
J
K
Pg
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Mean atmospheric O
2
content over period duration
c. 26 vol %
(130 % of modern level)
Mean atmospheric CO
2
content over period duration
c. 1950 ppm
(7 times pre-industrial level)
Mean surface temperature over period durationc. 16.5 °C
(3 °C above modern level)
Key events in the Jurassic
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An approximate timescale of key Jurassic events.
Vertical axis: millions of years ago.

The Jurassic period ( /ʊəˈræsɪk/ ; from Jura Mountains) is a geologic period and system that spanned 56 million years from the end of the Triassic Period 201.3 million years ago (Mya) to the beginning of the Cretaceous Period 145 Mya. [note 1] The Jurassic constitutes the middle period of the Mesozoic Era, also known as the Age of Reptiles. The start of the period was marked by the major Triassic–Jurassic extinction event. Two other extinction events occurred during the period: the Pliensbachian-Toarcian extinction in the Early Jurassic, and the Tithonian event at the end [3] ; neither event ranks among the "Big Five" mass extinctions, however.

Jura Mountains mountain chain in Switzerland

The Jura Mountains are a sub-alpine mountain range located north of the Western Alps, mainly following the course of the France–Switzerland border. The Jura separates the Rhine and Rhône basins, forming part of the watershed of each.

The Triassic is a geologic period and system which spans 50.6 million years from the end of the Permian Period 251.9 million years ago (Mya), to the beginning of the Jurassic Period 201.3 Mya. The Triassic is the first and shortest period of the Mesozoic Era. Both the start and end of the period are marked by major extinction events.

The Cretaceous is a geologic period and system that spans 79 million years from the end of the Jurassic Period 145 million years ago (mya) to the beginning of the Paleogene Period 66 mya. It is the last period of the Mesozoic Era, and the longest period of the Phanerozoic Eon. The Cretaceous Period is usually abbreviated K, for its German translation Kreide.

Contents

The Jurassic period is divided into three epochs: Early, Middle, and Late. Similarly, in stratigraphy, the Jurassic is divided into the Lower Jurassic, Middle Jurassic, and Upper Jurassic series of rock formations.

In geochronology, an epoch is a subdivision of the geologic timescale that is longer than an age but shorter than a period. The current epoch is the Holocene Epoch of the Quaternary Period. Rock layers deposited during an epoch are called a series. Series are subdivisions of the stratigraphic column that, like epochs, are subdivisions of the geologic timescale. Like other geochronological divisions, epochs are normally separated by significant changes in the rock layers to which they correspond.

Stratigraphy The study of rock layers and their formation

Stratigraphy is a branch of geology concerned with the study of rock layers (strata) and layering (stratification). It is primarily used in the study of sedimentary and layered volcanic rocks. Stratigraphy has two related subfields: lithostratigraphy and biostratigraphy.

The Middle Jurassic is the second epoch of the Jurassic Period. It lasted from about 174 to 163 million years ago. Fossil-bearing rocks from the Middle Jurassic are relatively rare, but some important formations include the Forest Marble Formation in England, the Kilmaluag Formation in Scotland, the Daohugou Beds in China, Itat Formation in Russia, and the Isalo III Formation of western Madagascar.

The Jurassic is named after the Jura Mountains within the European Alps, where limestone strata from the period were first identified. By the beginning of the Jurassic, the supercontinent Pangaea had begun rifting into two landmasses: Laurasia to the north, and Gondwana to the south. This created more coastlines and shifted the continental climate from dry to humid, and many of the arid deserts of the Triassic were replaced by lush rainforests.

Limestone Sedimentary rocks made of calcium carbonate

Limestone is a carbonate sedimentary rock that is often composed of the skeletal fragments of marine organisms such as coral, foraminifera, and molluscs. Its major materials are the minerals calcite and aragonite, which are different crystal forms of calcium carbonate (CaCO3). A closely related rock is dolomite, which contains a high percentage of the mineral dolomite, CaMg(CO3)2. In fact, in old USGS publications, dolomite was referred to as magnesian limestone, a term now reserved for magnesium-deficient dolomites or magnesium-rich limestones.

Supercontinent Landmass comprising more than one continental core, or craton

In geology, a supercontinent is the assembly of most or all of Earth's continental blocks or cratons to form a single large landmass. However, many earth scientists use a different definition: "a clustering of nearly all continents", which leaves room for interpretation and is easier to apply to Precambrian times.

Pangaea Supercontinent from the late Paleozoic to early Mesozoic eras

Pangaea or Pangea was a supercontinent that existed during the late Paleozoic and early Mesozoic eras. It assembled from earlier continental units approximately 335 million years ago, and it began to break apart about 175 million years ago. In contrast to the present Earth and its distribution of continental mass, much of Pangaea was in the southern hemisphere and surrounded by a superocean, Panthalassa. Pangaea was the most recent supercontinent to have existed and the first to be reconstructed by geologists.

On land, the fauna transitioned from the Triassic fauna, dominated by both dinosauromorph and crocodylomorph archosaurs, to one dominated by dinosaurs alone. The first birds also appeared during the Jurassic, having evolved from a branch of theropod dinosaurs. Other major events include the appearance of the earliest lizards, and the evolution of therian mammals, including primitive placentals. Crocodilians made the transition from a terrestrial to an aquatic mode of life. The oceans were inhabited by marine reptiles such as ichthyosaurs and plesiosaurs, while pterosaurs were the dominant flying vertebrates.

Dinosauromorpha clade of reptiles (fossil)

Dinosauromorpha is a clade of archosaurs that includes the clade Dinosauria (dinosaurs), and all animals more closely related to dinosaurs than to pterosaurs. Birds are the only surviving dinosauromorphs.

Crocodylomorpha superorder of reptiles

Crocodylomorpha is a group of archosaurs that includes the crocodilians and their extinct relatives.

Archosaur group of reptiles

Archosaurs are a group of diapsid amniotes whose living representatives consist of birds and crocodilians. This group also includes all extinct dinosaurs, extinct crocodilian relatives, and pterosaurs. Archosauria, the archosaur clade, is a crown group that includes the most recent common ancestor of living birds and crocodilians and all of its descendants. It includes two main clades: Pseudosuchia, which includes crocodilians and their extinct relatives, and Avemetatarsalia, which includes birds and their extinct relatives.

History of term

The chronostratigraphic term "Jurassic" is directly linked to the Jura Mountains, a mountain range mainly following the course of the France–Switzerland border. During a tour of the region in 1795, [note 2] Alexander von Humboldt recognized the mainly limestone dominated mountain range of the Jura Mountains as a separate formation that had not been included in the established stratigraphic system defined by Abraham Gottlob Werner, and he named it "Jura-Kalkstein" ('Jura limestone') in 1799. [note 3] [6] [7] [8]

Chronostratigraphy is the branch of stratigraphy that studies the age of rock strata in relation to time.

Mountain range A geographic area containing several geologically related mountains

A mountain range or hill range is a series of mountains or hills ranged in a line and connected by high ground. A mountain system or mountain belt is a group of mountain ranges with similarity in form, structure, and alignment that have arisen from the same cause, usually an orogeny. Mountain ranges are formed by a variety of geological processes, but most of the significant ones on Earth are the result of plate tectonics. Mountain ranges are also found on many planetary mass objects in the Solar System and are likely a feature of most terrestrial planets.

France–Switzerland border international border between France and Switzerland

The French–Swiss border is 572 km (355 mi) long. Its modern boundaries are mostly the product of the Congress of Vienna of 1815, with the accession of Geneva, Neuchâtel, and Valais to the Swiss Confederation, but it has since been modified in detail, the last time being in 2002.

Thirty years later, in 1829, the French naturalist Alexandre Brongniart published a survey on the different terrains that constitute the crust of the Earth. [note 4] In this book, Brongniart referred to the terrains of the Jura Mountains as terrains jurassiques, thus coining and publishing the term for the first time. [9]

Alexandre Brongniart French chemist, mineralogist, and zoologist (1770–1847)

Alexandre Brongniart was a French chemist, mineralogist, and zoologist, who collaborated with Georges Cuvier on a study of the geology of the region around Paris.

Etymology

The name "Jura" is derived from the Celtic root *jor via Gaulish *iuris "wooded mountain", which, borrowed into Latin as a place name, evolved into Juria and finally Jura. [6] [7] [10]

Divisions

The Jurassic period is divided into three epochs: Early, Middle, and Late. Similarly, in stratigraphy, the Jurassic is divided into the Lower Jurassic, Middle Jurassic, and Upper Jurassic series of rock formations, also known as Lias, Dogger and Malm in Europe. [11] The separation of the term Jurassic into three sections originated with Leopold von Buch. [8] The faunal stages from youngest to oldest are:

Upper/Late Jurassic
Tithonian (152.1± 4145± 4 Mya)
Kimmeridgian (157.3± 4152.1± 4 Mya)
Oxfordian (163.5± 4157.3± 4 Mya)
Middle Jurassic
Callovian (166.1± 4163.5± 4 Mya)
Bathonian (168.3± 3.5166.1± 4 Mya)
Bajocian (170.3± 3168.3± 3.5 Mya)
Aalenian (174.1± 2170.3± 3 Mya)
Lower/Early Jurassic
Toarcian (182.7± 1.5174.1± 2 Mya)
Pliensbachian (190.8± 1.5182.7± 1.5 Mya)
Sinemurian (199.3± 1190.8± 1.5 Mya)
Hettangian (201.3± 0.6199.3± 1 Mya)

Paleogeography and tectonics

Depiction of Early Jurassic environment preserved at the St. George Dinosaur Discovery Site at Johnson Farm, with Dilophosaurus wetherilli in bird-like resting pose Dilophosaurus wetherilli.jpg
Depiction of Early Jurassic environment preserved at the St. George Dinosaur Discovery Site at Johnson Farm, with Dilophosaurus wetherilli in bird-like resting pose

During the early Jurassic period, the supercontinent Pangaea broke up into the northern supercontinent Laurasia and the southern supercontinent Gondwana; the Gulf of Mexico opened in the new rift between North America and what is now Mexico's Yucatan Peninsula. The Jurassic North Atlantic Ocean was relatively narrow, while the South Atlantic did not open until the following Cretaceous period, when Gondwana itself rifted apart. [12] The Tethys Sea closed, and the Neotethys basin appeared. Climates were warm, with no evidence of a glacier having appeared. As in the Triassic, there was apparently no land over either pole, and no extensive ice caps existed.

The Jurassic geological record is good in western Europe, where extensive marine sequences indicate a time when much of that future landmass was submerged under shallow tropical seas; famous locales include the Jurassic Coast World Heritage Site in southern England and the renowned late Jurassic lagerstätten of Holzmaden and Solnhofen in Germany. [13] In contrast, the North American Jurassic record is the poorest of the Mesozoic, with few outcrops at the surface. [14] Though the epicontinental Sundance Sea left marine deposits in parts of the northern plains of the United States and Canada during the late Jurassic, most exposed sediments from this period are continental, such as the alluvial deposits of the Morrison Formation.

The Jurassic was a time of calcite sea geochemistry in which low-magnesium calcite was the primary inorganic marine precipitate of calcium carbonate. Carbonate hardgrounds were thus very common, along with calcitic ooids, calcitic cements, and invertebrate faunas with dominantly calcitic skeletons. [15]

The first of several massive batholiths were emplaced in the northern American cordillera beginning in the mid-Jurassic, marking the Nevadan orogeny. [16] Important Jurassic exposures are also found in Russia, India, South America, Japan, Australasia and the United Kingdom.

In Africa, Early Jurassic strata are distributed in a similar fashion to Late Triassic beds, with more common outcrops in the south and less common fossil beds which are predominated by tracks to the north. [17] As the Jurassic proceeded, larger and more iconic groups of dinosaurs like sauropods and ornithopods proliferated in Africa. [17] Middle Jurassic strata are neither well represented nor well studied in Africa. [17] Late Jurassic strata are also poorly represented apart from the spectacular Tendaguru fauna in Tanzania. [17] The Late Jurassic life of Tendaguru is very similar to that found in western North America's Morrison Formation. [17]

Fauna

Aquatic and marine

During the Jurassic period, the primary vertebrates living in the sea were fish and marine reptiles. The latter include ichthyosaurs, which were at the peak of their diversity, plesiosaurs, pliosaurs, and marine crocodiles of the families Teleosauridae and Metriorhynchidae. [18] Numerous turtles could be found in lakes and rivers. [19] [20]

In the invertebrate world, several new groups appeared, including rudists (a reef-forming variety of bivalves) and belemnites. Calcareous sabellids ( Glomerula ) appeared in the Early Jurassic. [21] [22] The Jurassic also had diverse encrusting and boring (sclerobiont) communities, and it saw a significant rise in the bioerosion of carbonate shells and hardgrounds. Especially common is the ichnogenus (trace fossil) Gastrochaenolites . [23]

During the Jurassic period, about four or five of the twelve clades of planktonic organisms that exist in the fossil record either experienced a massive evolutionary radiation or appeared for the first time. [11]

Terrestrial

Example of Rare Early Jurassic (Pliensbachian) Ecosystem, the Drzewica Formation of Szydlowiec, Poland. This zone was characterised by a very damp ecosystem populated by dinosaur megafauna, more related in several aspects to Middle or Late Jurassic dinosaurs Drzewica Formation Reconstruction.jpg
Example of Rare Early Jurassic (Pliensbachian) Ecosystem, the Drzewica Formation of Szydłowiec, Poland. This zone was characterised by a very damp ecosystem populated by dinosaur megafauna, more related in several aspects to Middle or Late Jurassic dinosaurs

On land, various archosaurian reptiles remained dominant. The Jurassic was a golden age for the large herbivorous dinosaurs known as the sauropods Camarasaurus , Apatosaurus , Diplodocus , Brachiosaurus , and many others—that roamed the land late in the period; their foraging grounds were either the prairies of ferns, palm-like cycads and bennettitales, or the higher coniferous growth, according to their adaptations. The smaller Ornithischian herbivore dinosaurs, like stegosaurs and small ornithopods were less predominant, but played important roles. They were preyed upon by large theropods, such as Ceratosaurus , Megalosaurus , Torvosaurus and Allosaurus . All these belong to the 'lizard hipped' or saurischian branch of the dinosaurs. [24] During the Late Jurassic, the first avialans, like Archaeopteryx , evolved from small coelurosaurian dinosaurs. In the air, pterosaurs were common; they ruled the skies, filling many ecological roles now taken by birds, [25] and may have already produced some of the largest flying animals of all time. [26] [27] Within the undergrowth were various types of early mammals, as well as tritylodonts , lizard-like sphenodonts, and early lissamphibians. The rest of the Lissamphibia evolved in this period, introducing the first salamanders and caecilians. [28]

Flora

Conifers were the dominant land plants of the Jurassic Douglas fir leaves and bud.jpg
Conifers were the dominant land plants of the Jurassic
Various dinosaurs roamed forests of similarly large conifers during the Jurassic period. Europasaurus holgeri Scene 2.jpg
Various dinosaurs roamed forests of similarly large conifers during the Jurassic period.

The arid, continental conditions characteristic of the Triassic steadily eased during the Jurassic period, especially at higher latitudes; the warm, humid climate allowed lush jungles to cover much of the landscape. [29] Gymnosperms were relatively diverse during the Jurassic period. [11] The Conifers in particular dominated the flora, as during the Triassic; they were the most diverse group and constituted the majority of large trees.

Extant conifer families that flourished during the Jurassic included the Araucariaceae, Cephalotaxaceae, Pinaceae, Podocarpaceae, Taxaceae and Taxodiaceae. [30] The extinct Mesozoic conifer family Cheirolepidiaceae dominated low latitude vegetation, as did the shrubby Bennettitales. [31] Cycads, similar to palm trees, were also common, as were ginkgos and Dicksoniaceous tree ferns in the forest. [11] Smaller ferns were probably the dominant undergrowth. Caytoniaceous seed ferns were another group of important plants during this time and are thought to have been shrub to small-tree sized. [32] Ginkgo plants were particularly common in the mid- to high northern latitudes. [11] In the Southern Hemisphere, podocarps were especially successful, while Ginkgos and Czekanowskiales were rare. [29] [31]

In the oceans, modern coralline algae appeared for the first time. [11] However, they were a part of another major extinction that happened within the next major time period.

Since the early 1990s, the term Jurassic has been popularised by the Jurassic Park franchise, which started in 1990 with Michael Crichton's novel of the same title and its film adaptation, first released in 1993. In fact, in the franchise's science-fiction scenario, the term Jurassic is only used as a brand name for a fictional park that is intended to exhibit living cloned dinosaurs. But in any way the dinosaurs appearing in the franchise's novels or films are strictly found in Jurassic strata. Brachiosaurus and Dilophosaurus , for example, indeed belong to Jurassic stratigraphic ranges, but not Triceratops or Tyrannosaurus , nor Velociraptor , which all three are only found in the next period, the Cretaceous. For further information, see "List of cloned animals in the Jurassic Park series".

See also

Notes

  1. A 140 Ma age for the Jurassic-Cretaceous instead of the usually accepted 145 Ma was proposed in 2014 based on a stratigraphic study of Vaca Muerta Formation in Neuquén Basin, Argentina. [1] Víctor Ramos, one of the authors of the study proposing the 140 Ma boundary age, sees the study as a "first step" toward formally changing the age in the International Union of Geological Sciences. [2]
  2. "Ich hatte mich auf einer geognostischen Reise, die ich 1795 durch das südliche Franken, die westliche Schweiz und Ober-Italien machte, davon überzeugt, daß der Jura-Kalkstein, welchen Werner zu seinem Muschelkalk rechnete, eine eigne Formation bildete. In meiner Schrift über die unterirdischen Gasarten, welche mein Bruder Wilhelm von Humboldt 1799 während meines Aufenthalts in Südamerika herausgab, wird der Formation, die ich vorläufig mit dem Namen Jura-Kalkstein bezeichnete, zuerst gedacht." ('On a geological tour that I made in 1795 through southern France, western Switzerland and upper Italy, I convinced myself that the Jura limestone, which Werner included in his shell limestone, constituted a separate formation. In my paper about subterranean types of gases, which my brother Wilhelm von Humboldt published in 1799 during my stay in South America, the formation, which I provisionally designated with the name "Jura limestone", is first conceived.') [4]
  3. "[…] die ausgebreitete Formation, welche zwischen dem alten Gips und neueren Sandstein liegt, und welchen ich vorläufig mit dem Nahmen Jura-Kalkstein bezeichne." '… the widespread formation which lies between the old gypsum and the more recent sandstone and which I provisionally designate with the name "Jura limestone".' [5]
  4. That book is titled in French Tableau des terrains qui composent l'écorce du globe ou essai sur la structure de la partie connue de la terre (literally: Description of the Terrains that Constitute the Crust of the Earth or Essay on the Structure of the Known Lands of the Earth)

Related Research Articles

The Mesozoic Era is an interval of geological time from about 252 to 66 million years ago. It is also called the Age of Reptiles and the Age of Conifers.

The Permian is a geologic period and system which spans 47 million years from the end of the Carboniferous Period 298.9 million years ago (Mya), to the beginning of the Triassic period 251.902 Mya. It is the last period of the Paleozoic era; the following Triassic period belongs to the Mesozoic era. The concept of the Permian was introduced in 1841 by geologist Sir Roderick Murchison, who named it after the city of Perm.

The Phanerozoic Eon is the current geologic eon in the geologic time scale, and the one during which abundant animal and plant life has existed. It covers 541 million years to the present, and began with the Cambrian Period when animals first developed hard shells preserved in the fossil record. Its name was derived from the Ancient Greek words φανερός and ζωή, meaning visible life, since it was once believed that life began in the Cambrian, the first period of this eon. The term "Phanerozoic" was coined in 1930 by the American geologist George Halcott Chadwick (1876–1953). The time before the Phanerozoic, called the Precambrian, is now divided into the Hadean, Archaean and Proterozoic eons.

Panthalassa Prehistoric superocean that surrounded Pangaea

Panthalassa, also known as the Panthalassic Ocean or Panthalassan Ocean, was the superocean that surrounded the supercontinent Pangaea. During the Paleozoic–Mesozoic transition c. 250 Ma it occupied almost 70% of Earth's surface. Its ocean floor has completely disappeared because of the continuous subduction along the continental margins on its circumference. Panthalassa is also referred to as the Paleo-Pacific or Proto-Pacific because the Pacific Ocean developed from its centre in the Mesozoic to the present.

The Late Triassic is the third and final of three epochs of the Triassic Period in the geologic timescale. The Triassic-Jurassic extinction event began during this epoch and is one of the five major mass extinction events of the Earth. The corresponding series is known as the Upper Triassic. In Europe the epoch was called the Keuper, after a German lithostratigraphic group that has a roughly corresponding age. The Late Triassic spans the time between 237 Ma and 201.3 Ma. The Late Triassic is divided into the Carnian, Norian and Rhaetian ages.

Geology of Texas

Texas contains a great variety of geologic settings. The state's stratigraphy has been largely influenced by marine transgressive-regressive cycles during the Phanerozoic, with a lesser but still significant contribution from late Cenozoic tectonic activity, as well as the remnants of a Paleozoic mountain range.

Karoo Supergroup Widespread Mesozoic stratigraphic unit in southern Africa

The Karoo Supergroup is the most widespread stratigraphic unit in Africa south of the Kalahari Desert. The supergroup consists of a sequence of units, mostly of nonmarine origin, deposited between the Late Carboniferous and Early Jurassic, a period of about 120 million years.

Geological history of Earth The sequence of major geological events in Earths past

The geological history of Earth follows the major events in Earth's past based on the geological time scale, a system of chronological measurement based on the study of the planet's rock layers (stratigraphy). Earth formed about 4.54 billion years ago by accretion from the solar nebula, a disk-shaped mass of dust and gas left over from the formation of the Sun, which also created the rest of the Solar System.

Gondwana Neoproterozoic to Carboniferous supercontinent

Gondwana, , was a supercontinent that existed from the Neoproterozoic until the Jurassic.

A paleocontinent or palaeocontinent is a distinct area of continental crust that existed as a major landmass in the geological past. There have been many different landmasses throughout Earth's time. They range in sizes, some are just a collection of small microcontinents while others are large conglomerates of crust. As time progresses and sea levels rise and fall more crust can be exposed making way for larger landmasses. The continents of the past shaped the evolution of organisms on Earth and contributed to the climate of the globe as well. As land masses break apart, species are separated and those that were once the same now have evolved to their new climate. The constant movement of these landmasses greatly determines the distribution of organisms on the Earth's surface. This is evident with how similar fossils are found on completely separate continents. Also, as continents move, mountain building events (orogenies) occur, causing a shift in the global climate as new rock is exposed and then there is more exposed rock at higher elevations. This causes glacial ice expansion and an overall cooler global climate. Which effects the overall global climate trend of the Earth. The movement of the continents greatly affects the overall dispersal of organisms throughout the world and the trend in climate throughout the Earth's history. Examples include Laurentia, Baltica and Avalonia, which collided together during the Caledonian orogeny to form the Old Red Sandstone paleocontinent of Laurussia. Another example includes a collision that occurred during the late Pennsylvanian and early Permian time when there was a collision between the two continents of Tarimsky and Kirghiz-Kazakh. This collision was caused because of their askew convergence when the paleoceanic basin closed.

Jurassic Museum of Asturias paleontological museum

The Jurassic Museum of Asturias is located in the area of Rasa de San Telmo near the parish of Llastres in the municipality of Colunga, Asturias, Spain. Though the municipality of Ribadesella was initially proposed, Colunga was chosen for the building site in the late 1990s. Several landmarks are visible from the museum including the Bay of Biscay, the Sierra del Sueve, and the Picos de Europa. Strategically located over a mount on the Rasa de San Temo, the museum is in the midst the Jurassic Asturias.

The main points that are discussed in the geology of Iran include the study of the geological and structural units or zones; stratigraphy; magmatism and igneous rocks; ophiolite series and ultramafic rocks; and orogenic events in Iran.

Lhasa terrane A fragment of crustal material, sutured to the Eurasian Plate during the Cretaceous that forms present-day southern Tibet

The Lhasa terrane is a terrane, or fragment of crustal material, sutured to the Eurasian Plate during the Cretaceous that forms present-day southern Tibet. It takes its name from the city of Lhasa in the Tibet Autonomous Region, China. The northern part may have originated in the East African Orogeny, while the southern part appears to have once been part of Australia. The two parts joined, were later attached to Asia, and then were impacted by the collision of the Indian Plate that formed the Himalayas.

One of the major depositional strata in the Himalaya is the Lesser Himalayan Strata from the Paleozoic to Mesozoic eras. It had a quite different marine succession during the Paleozoic, as most parts of it are sparsely fossiliferous or even devoid of any well-defined fossils. Moreover, it consists of many varied lithofacies, making correlation work more difficult. This article describes the major formations of the Paleozoic – Mesozoic Lesser Himalayan Strata, including the Tal Formation, Gondwana Strata, Singtali Formation and Subathu Formation.

Huangling Complex

Huangling Complex represents a group of rock units appear in the middle of Yangtze Block in South China, distributed across Yixingshan, Zigui, Huangling and Yichang counties. The group of rock involves nonconformity that sedimentary rocks overlie the metamorphic basement. It is a 73-km long, asymmetrical dome-shaped anticline with axial plane orientating in north-south direction. It has a steeper west flank and a gentler east flank. Basically, there are three tectonic units from the anticline core to the rim, including Archean to Paleoproterozoic metamorphic basement, Neoproterozoic to Jurassic sedimentary rocks and Cretaceous fluvial deposit sedimentary cover. The northern part of the core is mainly tonalite-trondhjemite-gneiss (TTG) and Cretaceous sedimentary rock, it is called the Archean Kongling Complex. The middle of the core is mainly the Neoproterozoic granitoid. The southern part of the core is the Neoproterozoic potassium granite. Two basins are situated on the western and eastern flanks of the core respectively, including the Zigui basin and Dangyang basin. Both basins are synforms while Zigui basin has a larger extent of folding. Yuanan Graben and Jingmen Graben are found within Dangyang Basin area. Huangling Complex is an important area that helps unravel the tectonic history of South China Craton because it has well-exposed layers of rock units from Archean basement rock to Cretaceous sedimentary rock cover due to the erosion of the anticline.

The geology of Morocco formed beginning up to two billion years ago, in the Paleoproterozoic and potentially even earlier. It was affected by the Pan-African orogeny, although the later Hercynian orogeny produced fewer changes and left the Maseta Domain, a large area of remnant Paleozoic massifs. During the Paleozoic, extensive sedimentary deposits preserved marine fossils. Throughout the Mesozoic, the rifting apart of Pangaea to form the Atlantic Ocean created basins and fault blocks, which were blanketed in terrestrial and marine sediments—particularly as a major marine transgression flooded much of the region. In the Cenozoic, a microcontinent covered in sedimentary rocks from the Triassic and Cretaceous collided with northern Morocco, forming the Rif region. Morocco has extensive phosphate and salt reserves, as well as resources such as lead, zinc, copper and silver.

References

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  2. Jaramillo, Jessica (March–April 2014). "Entrevista al Dr. Víctor Alberto Ramos, Premio México Ciencia y Tecnología 2013" (in Spanish). Vol. 17 no. 66. Si logramos publicar esos nuevos resultados, sería el primer paso para cambiar formalmente la edad del Jurásico-Cretácico. A partir de ahí, la Unión Internacional de la Ciencias Geológicas y la Comisión Internacional de Estratigrafía certificaría o no, depende de los resultados, ese cambio.CS1 maint: Date format (link)
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  5. von Humboldt, Alexander (1799). Ueber die unterirdischen Gasarten und die Mittel, ihren Nachteil zu vermindern, ein Beitrag zur Physik der praktischen Bergbaukunde [On the types of subterranean gases and means of minimizing their harm, a contribution to the physics of practical mining] (in German). Braunschweig: Vieweg. p. 39.
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Other sources