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Topic Review
Volcanology of Mars
Volcanic activity, or volcanism, has played a significant role in the geologic evolution of Mars. Scientists have known since the Mariner 9 mission in 1972 that volcanic features cover large portions of the Martian surface. These features include extensive lava flows, vast lava plains, and the largest known volcanoes in the Solar System. Martian volcanic features range in age from Noachian (>3.7 billion years) to late Amazonian (< 500 million years), indicating that the planet has been volcanically active throughout its history, and some speculate it probably still is so today. Both Earth and Mars are large, differentiated planets built from similar chondritic materials. Many of the same magmatic processes that occur on Earth also occurred on Mars, and both planets are similar enough compositionally that the same names can be applied to their igneous rocks and minerals. Volcanism is a process in which magma from a planet's interior rises through the crust and erupts on the surface. The erupted materials consist of molten rock (lava), hot fragmental debris (tephra or ash), and gases. Volcanism is a principal way that planets release their internal heat. Volcanic eruptions produce distinctive landforms, rock types, and terrains that provide a window on the chemical composition, thermal state, and history of a planet's interior. Magma is a complex, high-temperature mixture of molten silicates, suspended crystals, and dissolved gases. Magma on Mars likely ascends in a similar manner to that on Earth. It rises through the lower crust in diapiric bodies that are less dense than the surrounding material. As the magma rises, it eventually reaches regions of lower density. When the magma density matches that of the host rock, buoyancy is neutralized and the magma body stalls. At this point, it may form a magma chamber and spread out laterally into a network of dikes and sills. Subsequently, the magma may cool and solidify to form intrusive igneous bodies (plutons). Geologists estimate that about 80% of the magma generated on Earth stalls in the crust and never reaches the surface. As magma rises and cools, it undergoes many complex and dynamic compositional changes. Heavier minerals may crystallize and settle to the bottom of the magma chamber. The magma may also assimilate portions of host rock or mix with other batches of magma. These processes alter the composition of the remaining melt, so that any magma reaching the surface may be chemically quite different from its parent melt. Magmas that have been so altered are said to be "evolved" to distinguish them from "primitive" magmas that more closely resemble the composition of their mantle source. (See igneous differentiation and fractional crystallization.) More highly evolved magmas are usually felsic, that is enriched in silica, volatiles, and other light elements compared to iron- and magnesium-rich (mafic) primitive magmas. The degree and extent to which magmas evolve over time is an indication of a planet's level of internal heat and tectonic activity. The Earth's continental crust is made up of evolved granitic rocks that developed through many episodes of magmatic reprocessing. Evolved igneous rocks are much less common on cold, dead bodies such as the Moon. Mars, being intermediate in size between the Earth and the Moon, is thought to be intermediate in its level of magmatic activity. At shallower depths in the crust, the lithostatic pressure on the magma body decreases. The reduced pressure can cause gases (volatiles), such as carbon dioxide and water vapor, to exsolve from the melt into a froth of gas bubbles. The nucleation of bubbles causes a rapid expansion and cooling of the surrounding melt, producing glassy shards that may erupt explosively as tephra (also called pyroclastics). Fine-grained tephra is commonly referred to as volcanic ash. Whether a volcano erupts explosively or effusively as fluid lava depends on the composition of the melt. Felsic magmas of andesitic and rhyolitic composition tend to erupt explosively. They are very viscous (thick and sticky) and rich in dissolved gases. Mafic magmas, on the other hand, are low in volatiles and commonly erupt effusively as basaltic lava flows. However, these are only generalizations. For example, magma that comes into sudden contact with groundwater or surface water may erupt violently in steam explosions called hydromagmatic (phreatomagmatic or phreatic) eruptions. Erupting magmas may also behave differently on planets with different interior compositions, atmospheres, and gravitational fields.
  • 766
  • 23 Nov 2022
Topic Review
Volcanism and Submarine Sedimentation around Alps during Eo-Oligocene
Different magmatic systems developed during the Eo-Oligocene on and around the Alpine Belt, favouring the accumulation of thick volcanogenic submarine sedimentary sequences in the coveal foreland and foredeep basins. 
  • 632
  • 22 Nov 2021
Topic Review
Volcanic Eruptions
Volcanic eruptions are considered major (very large) when the Volcanic Explosivity Index (VEI) ≥ 5. The nature of the impacts of a VEI ≥ 5 eruption ranges from the destruction of a city, an entire region, climate disturbances as well as to air travel. Even an eruption with VEI < 5 may also have the potential to modify the environment and landscape particularly in proximal and medial facies, as well as surrounding human societies. The variety of environmental destructions due to volcanic eruption differs from primary (e.g., summit collapse, vegetation burning, death), secondary (e.g., atmospheric cooling, global warming), and tertiary (e.g., flood, famine, disease) effects. It is mostly generated by gas emissions, ashes, lava flow, pyroclastic flow, lahar, debris flow, and landslide which results in local and global impacts.
  • 2.3K
  • 14 Apr 2021
Topic Review
Volatilomics in Prostate Cancer
The lack of highly specific and sensitive biomarkers for the early detection of prostate cancer (PCa) is a major barrier to its management. Volatilomics emerged as a non-invasive, simple, inexpensive, and easy-to-use approach for cancer screening, characterization of disease progression, and follow-up of the treatment’s success.
  • 548
  • 24 Aug 2022
Topic Review
Volatility and Risk-Adjusted Returns of ESG Indices
The importance of Environmental, Social, and Governance (ESG) aspects in investment decisions has grown significantly in today’s volatile financial market. Environmental, Social, and Governance (ESG) investing has emerged as a prominent investment strategy, garnering widespread attention. 
  • 322
  • 27 Oct 2023
Topic Review
Volatility
In finance, volatility (usually denoted by σ) is the degree of variation of a trading price series over time, usually measured by the standard deviation of logarithmic returns. Historic volatility measures a time series of past market prices. Implied volatility looks forward in time, being derived from the market price of a market-traded derivative (in particular, an option).
  • 1.1K
  • 28 Oct 2022
Topic Review
Volatiles in Food Products
The evaluation of volatiles in food is an important aspect of food production. It gives knowledge about the quality of foods and their relationship to consumers’ choices. Alcohols, aldehydes, acids, esters, terpenes, pyrazines, and furans are the main chemical groups that are involved in aroma formation. They are products of food processing: thermal treatment, fermentation, storage, etc. Food aroma is a mixture of varied molecules. Because of this, the analysis of aroma composition can be challenging. 
  • 6.3K
  • 27 Sep 2021
Topic Review
Volatile Profile of Nuts
Nuts are indehiscent dry fruits with one seed and a thick, hard pericarp. The presence of nuts in diets has notably increased due to their composition, and the presence of antioxidants and their unsaturated fatty acid profile has led to a considerable increase in their consumption. The volatile profile of nuts is important from different points of view. It affects consumer’s selection, influences raw material selection for the production of composite foods, dictates variety selection in breeding programs, and, from a quality perspective, its changes can indicate food degradation or alteration.
  • 790
  • 03 Nov 2021
Topic Review
Volatile Organic Compounds Evolution
Volatile organic compounds (VOCs) are emitted by plants as a consequence of biotic and abiotic interaction which often change rapidly over time. Epigenetic factors, such as DNA methylation and histone modification, might trigger adaptive responses to these evolutionary pressures regulating both genes and transcription factors, as well as the rhythmic emission of VOCs through circadian clock regulation. In addition, transgenerational epigenetic effects and polyploidy could modify the generation of VOCs’ profiles of offspring, contributing to long-term evolutionary shifts.
  • 728
  • 14 Jan 2021
Topic Review
Volatile Organic Compounds
Volatile organic compounds (VOCs) are promising alternatives to synthetic pesticides in pest and disease management. VOCs are gaining interest due to the various advantages of their application, such as the reduction in residuals in the environment and their ease of application in different agricultural systems. 
  • 1.3K
  • 18 Apr 2023
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