A chondrite 'kQndrait is a stony (non-metallic) meteorite that has not been modified, by either melting or differentiation of the parent body. They are formed when various types of dust and small grains in the early Solar System accreted to form primitive asteroids. Some such bodies that are captured in the planet's gravity well become the most common type of meteorite by (whether quickly, or after many orbits) arriving on a trajectory toward the planet's surface. Estimates for their contribution to the total meteorite population vary between 85.7% and 86.2%.
Their study provides important clues for understanding the origin and age of the Solar System, the synthesis of organic compounds, the origin of life and the presence of water on Earth. One of their characteristics is the presence of chondrules (from the Ancient Greek χόνδρος chondros, grain), which are round grains formed as molten, or partially molten droplets, in the space by distinct minerals, that normally constitute between 20% and 80% of a chondrite by volume.
Chondrites can be distinguished from iron meteorites due to their low iron and nickel content. Other non-metallic meteorites, achondrites, which lack chondrules, were formed more recently. There are currently over 27,000 chondrites in the world's collections. The largest individual stone ever recovered, weighing 1770 kg, was part of the Jilin meteorite shower of 1976. Chondrite falls range from single stones to extraordinary showers consisting of thousands of individual stones. An instance of the latter occurred in the Holbrook fall of 1912, in which an estimated 14,000 stones grounded in northern Arizona.
Chondrites were formed by the accretion of particles of dust and grit present in the primitive Solar System which gave rise to asteroids over 4.54 billion years ago. These asteroid parent bodies of chondrites are (or were) small to medium-sized asteroids that were never part of any body large enough to undergo melting and planetary differentiation. Dating using 206Pb/204Pb gives an estimated age of 4,566.
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Mars is the fourth planet and the furthest terrestrial planet from the Sun. The reddish color of its surface is due to finely grained iron(III) oxide dust in the soil, giving it the nickname "the Red Planet". Mars's radius is second smallest among the planets in the Solar System at . The Martian dichotomy is visible on the surface: on average, the terrain on Mars's northern hemisphere is flatter and lower than its southern hemisphere. Mars has a thin atmosphere made primarily of carbon dioxide and two irregularly shaped natural satellites: Phobos and Deimos.
A chondrule (from Ancient Greek χόνδρος chondros, grain) is a round grain found in a chondrite. Chondrules form as molten or partially molten droplets in space before being accreted to their parent asteroids. Because chondrites represent one of the oldest solid materials within the Solar System and are believed to be the building blocks of the planetary system, it follows that an understanding of the formation of chondrules is important to understand the initial development of the planetary system.
In astrophysics, accretion is the accumulation of particles into a massive object by gravitationally attracting more matter, typically gaseous matter, in an accretion disk. Most astronomical objects, such as galaxies, stars, and planets, are formed by accretion processes. The accretion model that Earth and the other terrestrial planets formed from meteoric material was proposed in 1944 by Otto Schmidt, followed by the protoplanet theory of William McCrea (1960) and finally the capture theory of Michael Woolfson.
The responses of uranium-bearing accessory minerals to shock metamorphism have received growing interest, because under extreme pressure and temperature conditions, these phases can form unique microstructures and/or polymorphs and their radiometric ages c ...
GEOLOGICAL SOC AMER, INC2019
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Antarctica has unique areas that expose blue ice, which contrast to most of the continent (~98%) that is covered by snow. Some of these blue ice areas (BIAs) contain meteorite concentrations and (very) old ice, making them very valuable for understanding o ...
GFZ German Research Centre for Geosciences2023
Identifying extant materials that act as compositional proxies for Earth is key to understanding its accretion. Copper and sulfur are both moderately volatile elements; however, they display different geochemical behavior (e.g., phase affinities). Thus, in ...