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Paquier Event
The Paquier Event (OAE1b) was an oceanic anoxic event (OAE) that occurred around 111 million years ago (Ma), in the Albian geologic stage, during a climatic interval of Earth's history known as the Middle Cretaceous Hothouse (MKH). Timeline OAE1b had three main subevents: the Kilian, Paquier, and Leenhardt. The Kilian subevent was defined by a negative ''δ''13C excursion from about 2-2.5% to 0.5-1.5% followed by a gradual ''δ''13C rise in the Atlantic Ocean, though the magnitude of these carbon isotope fluctuations was higher in areas like the Basque-Cantabrian Basin. The Paquier subevent was the most extreme subevent of OAE1b, exhibiting a ''δ''13C drop of ~3% in marine organic matter and of 1.5-2% in marine carbonate, which was succeeded by a gradual positive ''δ''13C excursion. The Leenhardt subevent was the last OAE1b subevent and is associated in the eastern Tethys Ocean with a negative ''δ''13C excursion of 0.09‰ to -0.48‰ followed by a positive ''δ''13C excursion t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oceanic Anoxic Event
An anoxic event describes a period wherein large expanses of Earth's oceans were depleted of dissolved Oxygen, oxygen (O2), creating toxic, Euxinia, euxinic (anoxic waters, anoxic and wikt:sulfidic, sulfidic) waters. Although anoxic events have not happened for millions of years, the geologic record shows that they happened many times in the past. Anoxic events coincided with several mass extinctions and may have contributed to them. These mass extinctions include some that geobiology, geobiologists use as Global Boundary Stratotype Section and Point, time markers in biostratigraphy, biostratigraphic dating. On the other hand, there are widespread, various Shale, black-shale beds from the mid-Cretaceous which indicate anoxic events but are not associated with mass extinctions. Many geologists believe oceanic anoxic events are strongly linked to the slowing of ocean circulation, climatic warming, and elevated levels of greenhouse gases. Researchers have proposed enhanced volcanism (t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geology (journal)
''Geology'' is a peer-reviewed publication of the Geological Society of America (GSA). GSA stated (in 2006) (ISSN 0091-7613) that it is the most widely read scientific journal in the field of earth science. It is published monthly, with each issue containing 20 or more articles. One of the goals of the journal is to provide a forum for shorter articles (four pages each) and less focus on purely academic research–type articles. According to the ''Journal Citation Reports'', the journal had a 2020 impact factor of 5.399. The journal is indexed in Scopus and SCImago The SCImago Journal Rank (SJR) indicator is a measure of the prestige of scholarly journals that accounts for both the number of citations received by a journal and the prestige of the journals where the citations come from. Etymology SCImag .... See also * List of scientific journals ** List of earth and atmospheric sciences journals References External links *Geology — Browse Issues [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Breistroffer Event
The Breistroffer Event (OAE1d) was an oceanic anoxic event (OAE) that occurred during the middle Cretaceous period, specifically in the latest Albian, around 101 million years ago (Ma). Causes A rise in carbon dioxide and consequent negative carbon isotope excursion (CIE) ensued at the start of OAE1d, causing global temperatures to rise by 2 °C. During the Breistroffer Thermal Maximum, as this climatic interval has been referred to, Earth's mean surface air temperature was 23.3 °C. Average sea surface temperatures (SSTs) were 3 to 5 °C higher than today. Mercury anomalies from the time of the event implicate large igneous province volcanism from the Kerguelen Plateau as the cause of the rise in global temperatures. An alternative hypothesis implicating enhanced monsoons forced by Milankovitch cycles rather than volcanism has also been proposed, based on the lack of unradiogenic osmium isotope ratio fluctuations observed during OAE1d. Total organic carbon values and carbon an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Toarcian Oceanic Anoxic Event
The Toarcian extinction event, also called the Pliensbachian-Toarcian extinction event, the Early Toarcian mass extinction, the Early Toarcian palaeoenvironmental crisis, or the Jenkyns Event, was an extinction event that occurred during the early part of the Toarcian age, approximately 183 million years ago, during the Early Jurassic. The extinction event had two main pulses, the first being the Pliensbachian-Toarcian boundary event (PTo-E). The second, larger pulse, the Toarcian Oceanic Anoxic Event (TOAE), was a global oceanic anoxic event, representing possibly the most extreme case of widespread ocean deoxygenation in the entire Phanerozoic eon. In addition to the PTo-E and TOAE, there were multiple other, smaller extinction pulses within this span of time. Occurring during the supergreenhouse climate of the Early Toarcian Thermal Maximum (ETTM), the Early Toarcian extinction was associated with large igneous province volcanism, which elevated global temperatures, acidified t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Earth-Science Reviews
''Earth-Science Reviews'' is a monthly peer-reviewed scientific journal published by Elsevier. It covers all aspects of Earth sciences. The editors-in-chief for this journal are A. Chin, C. Doglioni, J.L. Florsheim, M.F.J. Flower, G.R. Foulger, A. Gómez-Tuena, S. Khan, S. Marriott, A.D. Miall, G.F. Panza, J.A. Sanchez-Cabeza, M. Strecker, E.S. Takle, M. Widdowson, and P.B. Wignall. Abstracting and indexing This journal is abstracted and indexed by: According to the ''Journal Citation Reports'', the journal has a 2012 impact factor The impact factor (IF) or journal impact factor (JIF) of an academic journal is a type of journal ranking. Journals with higher impact factor values are considered more prestigious or important within their field. The Impact Factor of a journa ... of 7.339. References External links {{Authority control Earth and atmospheric sciences journals Elsevier academic journals English-language journals Monthly journals Academic journals esta ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cenomanian-Turonian Boundary Event
The Cenomanian-Turonian boundary event, also known as the Cenomanian-Turonian extinction, Cenomanian-Turonian Oceanic Anoxic Event ( OAE 2), and referred to also as the Bonarelli Event or Level, was an anoxic extinction event in the Cretaceous period. The Cenomanian-Turonian oceanic anoxic event is considered to be the most recent truly global oceanic anoxic event in Earth's geologic history. There was a large carbon cycle disturbance during this time period, signified by a large positive carbon isotope excursion. However, apart from the carbon cycle disturbance, there were also large disturbances in the ocean's nitrogen, oxygen, phosphorus, sulphur, and iron cycles. Background The Cenomanian and Turonian stages were first noted by D'Orbigny between 1843 and 1852. The global type section for this boundary is located in the Bridge Creek Limestone Member of the Greenhorn Formation near Pueblo, Colorado, which are bedded with the Milankovitch orbital signature. Here, a positi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Selli Event
The Selli Event, also known as OAE1a, was an oceanic anoxic event (OAE) of global scale that occurred during the Aptian stage of the Early Cretaceous, about 120.5 million years ago (Ma). The OAE is associated with large igneous province volcanism and an extinction event of marine organisms driven by global warming, ocean acidification, and anoxia. Timing The negative δ13C excursion representing the onset of OAE1a was rapid, taking only 22,000-47,000 years. The recovery of the global climate from the injection of large amounts of isotopically light carbon lasted for over a million years. The end of OAE1a is characterised by a positive δ13C excursion, which had a magnitude of +4 to +5%. The OAE lasted for about 1.1 to 1.3 Myr in total; one high-precision estimate put the length of OAE1a at 1.157 Myr. Causes Global warming OAE1a ensued during a hot climatic interval, with the global average temperature being around 21.5 °C. The Tethys Ocean experienced an increase in humidity at th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Negative Feedback
Negative feedback (or balancing feedback) occurs when some function (Mathematics), function of the output of a system, process, or mechanism is feedback, fed back in a manner that tends to reduce the fluctuations in the output, whether caused by changes in the input or by other disturbances. Whereas positive feedback tends to instability via exponential growth, oscillation or chaos theory, chaotic behavior, negative feedback generally promotes stability. Negative feedback tends to promote a settling to List of types of equilibrium, equilibrium, and reduces the effects of perturbations. Negative feedback loops in which just the right amount of correction is applied with optimum timing, can be very stable, accurate, and responsive. Negative feedback is widely used in Mechanical engineering, mechanical and electronic engineering, and it is observed in many other fields including biology, chemistry and economics. General negative feedback systems are studied in Control engin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nature (journal)
''Nature'' is a British weekly scientific journal founded and based in London, England. As a multidisciplinary publication, ''Nature'' features Peer review, peer-reviewed research from a variety of academic disciplines, mainly in science and technology. It has core editorial offices across the United States, continental Europe, and Asia under the international scientific publishing company Springer Nature. ''Nature'' was one of the world's most cited scientific journals by the Science Edition of the 2022 ''Journal Citation Reports'' (with an ascribed impact factor of 50.5), making it one of the world's most-read and most prestigious academic journals. , it claimed an online readership of about three million unique readers per month. Founded in the autumn of 1869, ''Nature'' was first circulated by Norman Lockyer and Alexander MacMillan (publisher), Alexander MacMillan as a public forum for scientific innovations. The mid-20th century facilitated an editorial expansion for the j ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
δ18O
In geochemistry, paleoclimatology and paleoceanography ''δ''18O or delta-O-18 is a measure of the deviation in ratio of stable isotopes oxygen-18 (18O) and oxygen-16 (16O). It is commonly used as a measure of the temperature of precipitation (meteorology), precipitation, as a measure of groundwater/mineral interactions, and as an indicator of processes that show isotope fractionation, isotopic fractionation, like methanogenesis. In paleosciences, 18O:16O data from corals, foraminifera and ice cores are used as a proxy (climate), proxy for temperature. It is defined as the deviation in "per mil" (‰, parts per thousand) between a sample and a standard: :\delta \ce = \left( \frac - 1 \right) \times 1000 ‰ where the standard has a known isotopic composition, such as Vienna Standard Mean Ocean Water (VSMOW). The fractionation can arise from Kinetic fractionation, kinetic, Equilibrium fractionation, equilibrium, or Mass-independent fractionation, mass-independent isotope fra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Global And Planetary Change
''Global and Planetary Change'' is a monthly peer-reviewed scientific journal covering research into the earth sciences, particularly pertaining to changes in aspects thereof such as sea level and the chemical composition of the atmosphere. It has been published by Elsevier since it was established in 1989. The editors-in-chief are Alan Haywood, Jed Kaplan, Trude Storelvmo, Liviu Matenco, Zhengtang Guo, Maoyan Zhu, Fabienne Marret-Davies, Howard Falcon-Lang. According to the ''Journal Citation Reports'', the journal has a 2021 impact factor The impact factor (IF) or journal impact factor (JIF) of an academic journal is a type of journal ranking. Journals with higher impact factor values are considered more prestigious or important within their field. The Impact Factor of a journa ... of 5.114. References External links * Earth and atmospheric sciences journals Planetary science journals Academic journals established in 1989 Elsevier academic journals Monthly jour ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Axial Precession
In astronomy, axial precession is a gravity-induced, slow, and continuous change in the orientation of an astronomical body's rotational axis. In the absence of precession, the astronomical body's orbit would show axial parallelism. In particular, axial precession can refer to the gradual shift in the orientation of Earth's axis of rotation in a cycle of approximately 26,000 years.Hohenkerk, C.Y., Yallop, B.D., Smith, C.A., & Sinclair, A.T. "Celestial Reference Systems" in Seidelmann, P.K. (ed.) ''Explanatory Supplement to the Astronomical Almanac''. Sausalito: University Science Books. p. 99. This is similar to the precession of a spinning top, with the axis tracing out a pair of cones joined at their apices. The term "precession" typically refers only to this largest part of the motion; other changes in the alignment of Earth's axis— nutation and polar motion—are much smaller in magnitude. Earth's precession was historically called the precession of the equinoxes, b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
