Open main menu
Home
Random
Recent changes
Special pages
Community portal
Preferences
About Wikipedia
Disclaimers
Incubator escapee wiki
Search
User menu
Talk
Dark mode
Contributions
Create account
Log in
Editing
Chondrite
(section)
Warning:
You are not logged in. Your IP address will be publicly visible if you make any edits. If you
log in
or
create an account
, your edits will be attributed to your username, along with other benefits.
Anti-spam check. Do
not
fill this in!
== Origin and history == Chondrites were formed by the [[Accretion (astrophysics)|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 [[Lead–lead dating|<sup>206</sup>Pb/<sup>204</sup>Pb]] gives an estimated age of 4,566.6 ± 1.0 [[Megaannum|Ma]],<ref>{{cite journal |title=Pb isotopic age of the Allende chondrules |last1=Amelin |first1=Yuri |last2=Krot |first2=Alexander |journal=Meteoritics & Planetary Science |volume=42 |issue=7/8 |pages=1043–1463 |year=2007 |url=http://digitalcommons.library.arizona.edu/holdings/journal/article?r=uadc%3A%2F%2Fazu_maps%2FVolume42%2FNumber7-8%2Fp1321-1335 |bibcode=2007M&PS...42.1043F |doi=10.1111/j.1945-5100.2007.tb00559.x |s2cid=247696781 |access-date=13 July 2009 |archive-date=16 August 2020 |archive-url=https://web.archive.org/web/20200816030412/http://digitalcommons.library.arizona.edu/holdings/journal/article?r=uadc%3A%2F%2Fazu_maps%2FVolume42%2FNumber7-8%2Fp1321-1335 |url-status=live }}</ref> matching ages for other chronometers. Another indication of their age is the fact that the abundance of non-[[Volatility (chemistry)|volatile]] elements in chondrites is similar to that found in the [[atmosphere]] of the [[Sun]] and other [[star]]s in the Milky Way [[galaxy]].<ref name="wood">{{cite journal| author = Wood, J.A.| title = Chondritic Meteorites and the Solar Nebula| year = 1988| journal = [[Annual Review of Earth and Planetary Sciences]]| volume = 16 | id = 0084-6597, 53–72| doi=10.1146/annurev.ea.16.050188.000413| pages=53–72|bibcode = 1988AREPS..16...53W }}</ref> Although chondritic asteroids never became hot enough to melt based upon internal temperatures, many of them reached high enough temperatures that they experienced significant thermal [[metamorphism]] in their interiors. The source of the heat was most likely energy coming from the decay of short-lived radioisotopes (half-lives less than a few million years) that were present in the newly formed Solar System, especially [[Aluminium-26|<sup>26</sup>Al]] and [[Isotopes of iron#Iron-60|<sup>60</sup>Fe]], although heating may have been caused by impacts onto the asteroids as well. Many chondritic asteroids also contained significant amounts of water, possibly due to the accretion of ice along with rocky material. As a result, many chondrites contain hydrous minerals, such as clays, that formed when the water interacted with the rock on the asteroid in a process known as '''aqueous alteration'''. In addition, all chondritic asteroids were affected by impact and shock processes due to collisions with other asteroids. These events caused a variety of effects, ranging from simple compaction to [[breccia]]tion, veining, localized melting, and formation of high-pressure minerals. The net result of these secondary thermal, aqueous, and shock processes is that only a few known chondrites preserve in pristine form the original dust, chondrules, and inclusions from which they formed. {{multiple image | direction = horizontal | align = center | total_width = 600 | image1 = The_Mysterious_Case_of_the_Disappearing_Dust.jpg | image2 = Chondrules Bjurboele.jpg | image3 = Chondrules grassland 1.jpg | caption1 = [[Protoplanetary disk]]: particles of dust and grit collide and accrete forming [[planet]]s or [[asteroid]]s | caption2 = [[Chondrule]]s in chondrite from the Bjurböle meteorite<ref>{{cite web |url=http://www.lpi.usra.edu/meteor/metbull.php?code=5064 |title=Bjurböle; Meteoritical Bulletin Database. The Meteoritical Society |access-date=6 March 2013 |archive-date=23 January 2021 |archive-url=https://web.archive.org/web/20210123184542/https://www.lpi.usra.edu/meteor/metbull.php?code=5064 |url-status=live }}</ref> | caption3 = Chondrules in chondrite from the [[Grassland]] meteor<ref>{{cite web |url=http://www.lpi.usra.edu/meteor/metbull.php?code=10959 |title=Grassland; Meteoritical Bulletin Database. The Meteoritical Society |access-date=6 March 2013 |archive-date=13 January 2021 |archive-url=https://web.archive.org/web/20210113072305/https://www.lpi.usra.edu/meteor/metbull.php?code=10959 |url-status=live }}</ref> }} {{clear}}
Edit summary
(Briefly describe your changes)
By publishing changes, you agree to the
Terms of Use
, and you irrevocably agree to release your contribution under the
CC BY-SA 4.0 License
and the
GFDL
. You agree that a hyperlink or URL is sufficient attribution under the Creative Commons license.
Cancel
Editing help
(opens in new window)