[meteorite-list] Ureilite Formation

From: Abdelfattah Gharrad <life19maroc_at_meteoritecentral.com>
Date: Tue, 7 Oct 2014 02:31:06 +0100
Message-ID: <1412645466.39988.YahooMailBasic_at_web171202.mail.ir2.yahoo.com>

Thanks Bernd for your answer.

I was thinking about this type of meteorites and I think they are unique and it's like a kind of transition from a kind of chondrite-rich of carbon to primitive achondrite with absence of chondrules and high magnetism (pressure and temperature) . what let me to post this question on the list so I find that ureilites are typical.

this my opinion. I am not graduated on this field but always we want to learn as everytime some thing new appear and also we want really know about the meteorites.

I thank all the people whom writed me to guide me and share with me their information.

Thanks again,
Abdelfattah.

--------------------------------------------
En date de?: Lun 6.10.14, Bernd V. Pauli via Meteorite-list <meteorite-list at meteoritecentral.com> a ?crit?:

 Objet: [meteorite-list] Ureilite Formation
 ?: meteorite-list at meteoritecentral.com
 Date: Lundi 6 octobre 2014, 23h13
 
 Hello Abdelfattah and List,
 
 In 1992, C.A. Goodrich wrote a very comprehensive paper
 about ureilite
 formation. If you have access to this invited review, I
 strongly advise you
 read it:
 
 GOODRICH C.A. (1992) Invited Review - Ureilites: A critical
 review
 (Meteoritics 27-4, 1992, pp. 327-352).
 
 It is almost impossible to explain in just a few words how
 these coarse-grained, ultramafic, highly fractionated,
 igneous rocks were formed. Mrs. Goodrich was
 well aware that ureilites have some primitive
 characteristics that are difficult to
 reconcile with extensive igneous processing. Among these
 are:
 
 1) metal with high abundances of trace siderophile
 elements,
 2) carbon which contains planetary-type noble gases;
 3) the oxygen isotopic signature of?
 primitive/unequilibrated
 ? ? solar system materials.
 
 Both (1) and (2) are typical of undifferentiated, chondritic
 (!) materials but in
 terms of mineralogy and lithophile element chemistry
 ureilites are absolutely non-chondritic. They rather
 resemble ultramafic rocks from the Earth and Moon.
 
 Moreover, the presence of noble gases in near-chondritic
 abundances is difficult
 to explain because gases are expected to be lost at high
 temperature. This is
 especially difficult to explain because none of the other
 major achondrite types
 contain noble gases in chondritic or near-chondritic
 abundances.
 
 So you probably understand that there is no easy answer to
 your question
 but I am sure Mrs. Goodrich?s Review will ?emlighten?
 you!
 
 Best regards,
 
 Bernd
 
 
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Received on Mon 06 Oct 2014 09:31:06 PM PDT