Burning Coal and the Permo-Triassic extinction

Geological map of the Mesozoic igneous and sedimentary rocks in the Korean Peninsula sh owingthe ov erall distributions of the Mesozoic volcanic and plutonic rocks. The developments of the Bohaiwan ca. Because the Korean Peninsula geographically located between the mainland China and the Japanese Islands, the geochemistry and geochro- nology of the Cretaceous plutonic rocks in the Korean Peninsula hence play a key role in the evaluation of the Cretaceous tectonomagmatic evo- lution in northeast Asia. Here, we report geochemistry and SHRIMP zircon U—Pb ages of the Cretaceous plutonic rocks in the Korean Peninsula to- gether with the published data to seek the insights into the temporal and spatial distributions of the Cretaceous plutonic rocks. The Korean Peninsula, located at the northeastern margin of the Asian continent, consists of three Paleoproterozoic massifs viz. Nangnim, Gyeonggi, and Yeongnam , two Neoproterozoic to Paleozoic mobile belts viz. The massifs consist mainly of 1. ThemobilebeltsarecomposedofMiddlePaleozoicsedimentary rocks underlain by metamorphosed Neoproterozoic plutonic and volcanic rocks Kim et al. The Pyeongnam basin consists of Paleozoic sedimentary rocks, including platformal carbonates with minor siliciclastic rocks Lee and Lee,

History of Earth

Our discussions are based on both palaeomagnetic constraints and on geological correlations of basement provinces, orogenic histories, sedimentary provenance, the development of continental rifts and passive margins, and the record of mantle plume events. In our preferred Rodinia model, the assembly process features the accretion or collision of continental blocks around the margin of Laurentia.

Like the supercontinent Pangaea, Rodinia lasted about million years after complete assembly. Mantle avalanches, caused by the sinking of stagnated slabs accumulated at the mantle transition zone surrounding the supercontinent, plus thermal insulation by the supercontinent, led to the formation of a mantle superswell or superplume beneath Rodinia 40—60 million years after the completion of its assembly.

As a result, widespread continental rifting occurred between ca. Like its assembly, the break-up of Rodinia occurred diachronously.

四国中央部三波川変成岩上昇時の変形構造 Exhumation-related deformation structures of the Sambagawa metamorphic rocks, central Shikoku,Japan.

Planetary differentiation An artist’s rendering of a protoplanetary disk The standard model for the formation of the Solar System including the Earth is the solar nebula hypothesis. It was composed of hydrogen and helium created shortly after the Big Bang As the cloud began to accelerate, its angular momentum , gravity , and inertia flattened it into a protoplanetary disk perpendicular to its axis of rotation.

Small perturbations due to collisions and the angular momentum of other large debris created the means by which kilometer-sized protoplanets began to form, orbiting the nebular center. After more contraction, a T Tauri star ignited and evolved into the Sun. Meanwhile, in the outer part of the nebula gravity caused matter to condense around density perturbations and dust particles, and the rest of the protoplanetary disk began separating into rings.

In a process known as runaway accretion , successively larger fragments of dust and debris clumped together to form planets. The same process is expected to produce accretion disks around virtually all newly forming stars in the universe, some of which yield planets.

Radiometric dating

These results indicate that protolith of the marbles is a kind of limestone that was synchronously deposited with volcaniclastic rocks in the mid-Neoproterozoic rift basin of continental margin. Like the UHP metamorphic rocks in the Dabie-Sulu orogenic belt, both mid-Neoproterozoic magmatism and Triassic metamorphism are recorded in the impure marbles. Therefore, protolith of the impure marbles corresponds to the sedimentary limestone of rift basin developed during the mid-Neoproterozoic breakup of supercontinent Rodinia, but it was the sedimentary cover along the northern margin of the South China Block prior to its Triassic subduction.

The occurrence of the mid-Neoproterozoic limestone with the Triassic metamorphism in the southern margin of the North China Block thus indicates tectonic overthrust by a crustal detachment between the sedimentary cover and the Precambrian basement during the continent subduction. As a result, the marbles in affinity to the South China Block were northward thrusted over the basement of the North China Block.

Previous article in issue.

Der Zuckerhut, portugiesisch Pão de Açúcar („Zuckerbrot“), ist ein Meter hoher, steilwandiger, durch schalenartige Abschuppung des groben Gneises im feuchtheißen Klima entstandener Glockenberg auf der Halbinsel Urca am westlichen Eingang zur der gleichnamigen Felsengruppe gehören außer dem Pão de Açúcar die Felsen Morro da Urca und Morro da Babilônia.

Il decadimento radioattivo[ modifica modifica wikitesto ] Esempio di un decadimento radioattivo , dal Piombo Pb al Piombo Pb. Alcuni nuclidi sono instabili: Molte sostanze radioattive decadono da un isotopo fino ad un isotopo stabile figlio attraverso una serie di passaggi conosciuta come catena di decadimento. Gli isotopi utili per la datazione radiometrica sono quelli con vita media da poche migliaia di anni fino a miliardi di anni.

Precondizioni[ modifica modifica wikitesto ] Spettrometro di massa utilizzato nella datazione radiometrica. Quando un materiale incorpora sia i nuclidi genitori sia i figli nel momento della sua formazione, bisogna assumere che l’iniziale rapporto tra una sostanza radioattiva e suoi prodotti di decadimento sia conosciuto.

Datazione radiometrica

It is composed of pre-rift basement rocks that underwent little stretching during Cretaceous rifting. It is thinly mantled by a few hundred metres of mainly Cenozoic siliceous and carbonate oozes and Cretaceous—Cenozoic volcanic rocks. Its boundary with the Fairway, New Caledonia and Aotea basins to the east is marked by a scarp and an abrupt deepening of the basement surface. The Central Rift Province, west of the Lord Howe Platform, consists of basement blocks and normally faulted basin depocentres with up to 4km of Cretaceous to Cenozoic syn- and post-rift sediments.

The underlying continental crust is moderately extended about 20km thickness. This province includes the Faust Basin in the north and the Moore Basin in the south.

La datazione radiometrica (o radiodatazione) è uno dei metodi per determinare l’età di oggetti si basa sul raffronto tra le abbondanze osservate di un opportuno isotopo radioattivo e dei suoi prodotti di decadimento (noto il tempo di dimezzamento, ed è la principale fonte di informazioni sull’età della Terra e sulla velocità dell’evoluzione delle specie viventi).

Triggers on sulfide saturation in Fe-Ti oxide-bearing, mafic-ultramafic layered intrusions in the Tarim large igneous province, NW China. The provenance of late Permian karstic bauxite deposits in SW China, constrained by the geochemistry of interbedded clastic rocks, and U—Pb—Hf—O isotopes of detrital zircons. Lithos, , Hong LB; Y.

Hydrous orthopyroxene-rich pyroxenite source of the Xinkailing high magnesium andesites, Western Liaoning: Implication for the subduction-modified lithosphere mantle and destruction mechanism of the North China Craton. Lithos, , Li, H. Evolution of the mantle beneath the eastern North China Craton during the Cenozoic: Linking geochemical and geophysical observations. Phanerozoic crust growth by magma underplating in the North China Craton. Terra Nova, 29, , Primary magmas and mantle sources of Emeishan basalts constrained from major element, trace element and Pb isotope compositions of olivine-hosted melt inclusions.

Datazione radiometrica

Bill Compston , [1] trying to build an ion microprobe at the Research School of Earth Sciences of the Australian National University that exceeded the sensitivity and resolution of ion probes available at the time in order to analyse individual mineral grains. The first successful geological applications occurred in Narryer in Western Australia [5] and then later at the nearby Jack Hills.

The standard model for the formation of the Solar System (including the Earth) is the solar nebula hypothesis. In this model, the Solar System formed from a large, rotating cloud of interstellar dust and gas called the solar was composed of hydrogen and helium created shortly after the Big Bang Ga (billion years ago) and heavier elements ejected by supernovae.

History[ edit ] Estimated size of juvenile South Dakota specimen blue and the Stokesosaurus holotype orange , compared to a human. Life reconstruction of Stokesosaurus clevelandi. During the early seventies Madsen began to catalogue these finds in detail, discovering that some remains represented species new to science. In Madsen named and described the type species Stokesosaurus clevelandi.

Its generic name honours Stokes. The specific name refers to the town of Cleveland, Utah.

Lord Howe Rise

Hydrodynamics of coastal areas and current systems along continental margins The new undergraduate degree in meteorology and oceanography means that my teaching duties are being shuffled. Introduction to Oceanography and a series of graduate oceanography classes that attracted mostly students pursuing the MS in Marine Biology. With the new degree I will start teaching more majors classes.

La datazione radiometrica (o radiodatazione) è uno dei metodi per determinare l’età di oggetti si basa sul raffronto tra le abbondanze osservate di un opportuno isotopo radioattivo e dei suoi prodotti di decadimento (noto il tempo di dimezzamento, ed è la principale fonte di informazioni sull’età della Terra e sulla velocità dell’evoluzione delle specie viventi).

Posted on March 21, by Roger Andrews Having worked as a geologist I know that geologists are among the most imaginative of people when it comes to thinking up exotic theories. But the theory featured in the Guardian article in Blowout Week — that CO2 and other noxious gases emitted from coal seams ignited by lava caused the Permo-Triassic PT extinction million years ago, is among the most imaginative yet.

In this post I look into this burning in every sense of the word — the article prompted a number of comments question. As usually happens, the issues become more complicated when you start looking into them in detail, but in this particular case the data speak for themselves. Coal seam fire in Kentucky. We begin with a summary of how coal is formed.

Figure 1 gives details: The processes of coal formation Missing from Figure 1, however, is any information on how long the conversion process takes. I looked for specific numbers but was unable to find any, so from a variety of sources I put together the data shown in Figure 2: Coal and lignite ages by country In four of the cases China, South Africa, the UK and Australia there is no coal younger than million years and no lignite older than 80 million years.

Overall, these results suggest that in most cases it takes at least million years to convert a swamp into coal. The exception is Colombia. Coal deposits of similar age and origin are present in Indonesia and probably also in other tectonically-active environments, but they are not widespread.

Zuckerhut (Felsen)

Researchers mostly interpret variation in the preserved zircon age distribution as representing periods of enhanced production of continental crust coupled with recycling of older crust. Yet, estimates from several global databases show considerable variation, which suggests the need for standardizing sampling and statistical analysis methods. Grid-area sampling and modern sediment sampling are proposed for future database development with the goal of producing statistically consistent estimates of zircon age distributions at four scales — global, continental, regional, and intra-basin.

Roger, thank you for debunking the burning coal idea. I am sure that you know that it was based on the fallacious belief in academic circles that CO2 is the fount of all evil, causing global warming and ocean acidification, often at the same time.

Radioactive decay[ edit ] Example of a radioactive decay chain from lead Pb to lead Pb. The final decay product, lead Pb , is stable and can no longer undergo spontaneous radioactive decay. All ordinary matter is made up of combinations of chemical elements , each with its own atomic number , indicating the number of protons in the atomic nucleus. Additionally, elements may exist in different isotopes , with each isotope of an element differing in the number of neutrons in the nucleus.

A particular isotope of a particular element is called a nuclide. Some nuclides are inherently unstable. That is, at some point in time, an atom of such a nuclide will undergo radioactive decay and spontaneously transform into a different nuclide. This transformation may be accomplished in a number of different ways, including alpha decay emission of alpha particles and beta decay electron emission, positron emission, or electron capture.

Another possibility is spontaneous fission into two or more nuclides. While the moment in time at which a particular nucleus decays is unpredictable, a collection of atoms of a radioactive nuclide decays exponentially at a rate described by a parameter known as the half-life , usually given in units of years when discussing dating techniques. After one half-life has elapsed, one half of the atoms of the nuclide in question will have decayed into a “daughter” nuclide or decay product.

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Pb isotope intensity of zircon during O- ion bombardement is significantly enhanced if the sample surface is saturated with regard to oxygen. During zircon analysis, oxygen gas is leaked through a valve into the ims sample chamber. Energy Scan and Offset At the beginning of an analytical session or when analytical parameters such as primary beam intensity or spot size were changed, energy offsets for all measured ion species must be determined. Centering the ion image in the field aperature Centering the secondary ion image in the center of the field aperture FA is necessary for each new analysis spot because primary beam paths and conditions of secondary ion extraction vary over the area of the sample surface,in particular when spot-to-spot movements over large distances few mm are required.

The SHRIMP U-Pb age places Tieling Formation near the end of the Calymmian Period of the early Mesoproterozoic Era. In addition, a SHRIMP U-Pb zircon date of ±18 Ma was acquired for K-bentonite beds in the overlying, dark-shale-dominated Xiamaling Formation from the same location northeast of Beijing.

The results indicate that the Wenyu and Niangniangshan biotite monzogranites belong to the I-type granite, which are the products of partial melting of high-grade metamorphic rocks of the Archean Taihua Group,and their ages are of The age data are slightly older than the time of detachment extension in this area, implying that the Xiaoqinling metamorphic core complex is resulted from the formation of magma thermal dome within middle-lower crust, and the upwelling and emplacement of granitic magma within upper crust.

The age data are also older than the gold ore-forming time,showing there is no direct relationship between the granitic magmatism and large-scale gold mineralization in the Xiaoqinling area. Do you want to read the rest of this article? The conundrum regarding the petrogenesis of the ore-related Mesozoic granites and source of molybdenum for the ore mineralization have drawn attentions of many geoscientists, and numerous studies have been carried out in the last two decades e.

Some researchers proposed that these granites were derived from partial melting of the lower crust with input of a juvenile mantle component e.

Decay scheme of K-Ar, U-Pb, Rb-Sr and Sm-Nd isotopic systems