scholarly journals Diamonds in ultrabasic rock near Wawa, Ontario, Canada

2019 ◽  
Keyword(s):  
Ultrabasic Rock

XXII.—The Petrology of Picritic Rocks in Minor Intrusions—a Hebridean Group

1959 ◽  
Vol 63 (3) ◽  
pp. 459-499 ◽  
Author(s):  
H. I. Drever ◽  
R. Johnston
Keyword(s):  
Source Rock ◽  
Rock Type ◽  
Basaltic Magma ◽  
Ultrabasic Rock ◽  
Working Hypothesis ◽  
Selective Fusion ◽  
Rich Liquid ◽  
Factual Data

SynopsisThe results are presented of a detailed petrological reconnaissance of a group of picritic minor intrusions in the Hebrides. A substantial amount of new factual data is subjected to a unified treatment as a basis for reference and discussion. Olivine phenocrysts are not appreciably zoned and there is no evidence that they have a reaction relation with the liquid represented by the groundmass. Variations in the size and amount of olivine in individual intrusions are examined in detail and attributed to composite intrusion of differentiated material. A distinctive non-porphyritic facies found in several sills and in one dyke is chemically analyzed. Four analyses from widely separated localities establish this facies as a remarkably invariant, eucritic rock-type. The composition of the groundmass of the picritic rocks is variable and there is no evidence whatever of the participation of basaltic magma in their formation. Although no attempt is made to explain the new data in detail, a comprehensive working hypothesis is formulated. The origin of such picritic intrusions is believed to be due to selective fusion of pre-existing ultrabasic rock. Liquid more basic than normal basalt magmas can be formed by this process. Some re-precipitation of olivine may have preceded final emplacement of a magnesia-rich liquid which contained xenocrysts, mainly of olivine, from the source rock.

Diamonds of Russia's «midnight lands»

2021 ◽  
pp. 76-81
Author(s):  
Vladimir Karzhavin
Keyword(s):  
Kola Peninsula ◽  
Ultrabasic Rock ◽  
Geochemical Study

Carbon and carbon-rich organics were identified throughout the Kola peninsula. Based on petrological and geochemical study of basic and ultrabasic rock metamorphism, diamond occurrences are assumed in the northwestern Kola peninsula.

Preparation of An Ultrabasic Rock Standard For Analytical Use

1964 ◽  
Author(s):  
J A Maxwell ◽  
W H Champ ◽  
C H Smith
Keyword(s):  
Ultrabasic Rock
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