Faulted and tilted Pliocene olivine-tholeiite lavas near Alturas, NE California, and their bearing on the uplift of the Warner Range

2006 ◽  
Vol 118 (9-10) ◽  
pp. 1196-1211 ◽  
Author(s):  
I. S.E. Carmichael ◽  
R. A. Lange ◽  
C. M. Hall ◽  
P. R. Renne
Keyword(s):  
Olivine Tholeiite

Chemistry and Differentiation of Mafic Dikes in an area near Fiskenaesset, West Greenland

1975 ◽  
Vol 12 (5) ◽  
pp. 721-730 ◽  
Author(s):  
Giorgio Rivalenti
Keyword(s):  
Trace Element ◽  
Magma Chamber ◽  
Trace Element Geochemistry ◽  
Element Geochemistry ◽  
West Greenland ◽  
Olivine Tholeiite ◽  
Three Generations ◽  
Upward Displacement ◽  
Crustal Magma

In the Fiskenaesset region (West Greenland), there are three generations of postorogenic doleritic dikes of tholeiitic affinity. Two types of differentiation are evident: (a) laterally from the contacts to center and vertically, with the upper centres of the youngest generation of dikes attaining an andesitic or rhyolitic composition; and (b) between the different generations of dikes.Major and trace element geochemistry and calculations of the cumulus composition indicate that the differentiation within dikes is due not to flow, but to a shallow crustal fractionation of an olivine tholeiite magma. The differentiation between the various generations is attributed to fractionation of an olivine tholeiite magma during its upward displacement from a deep crustal magma chamber.

Can crystallization of olivine tholeiite give rise to potassic rhyolites?—an experimental investigation

2007 ◽  
Vol 70 (3) ◽  
pp. 417-434 ◽  
Author(s):  
Matthew L. Whitaker ◽  
Hanna Nekvasil ◽  
Donald H. Lindsley ◽  
Michael McCurry
Keyword(s):  
Experimental Investigation ◽  
Olivine Tholeiite

Low Alkali, High Calcium Olivine Tholeiite Lavas from the Isle of Skye, Scotland

1975 ◽  
Vol 16 (1) ◽  
pp. 488-497 ◽  
Author(s):  
J. ESSON ◽  
A. C. DUNHAM ◽  
R. N. THOMPSON
Keyword(s):  
Olivine Tholeiite ◽  
High Calcium ◽  
Isle Of Skye

Low Alkali, High Calcium Olivine Tholeiite Lavas from the Isle of Skye, Scotland

1975 ◽  
Vol 16 (2) ◽  
pp. 488-497 ◽  
Author(s):  
J. ESSON ◽  
A. C. DUNHAM ◽  
R. N. THOMPSON
Keyword(s):  
Olivine Tholeiite ◽  
High Calcium ◽  
Isle Of Skye

A Spinifex Rock from Munro Township, Ontario

1975 ◽  
Vol 12 (6) ◽  
pp. 928-939 ◽  
Author(s):  
M. E. Fleet ◽  
N. D. MacRae
Keyword(s):  
Thin Section ◽  
Preferred Orientation ◽  
Plateau Basalt ◽  
Composite Blade ◽  
Olivine Tholeiite ◽  
Tetrahedral Sites ◽  
Host Olivine ◽  
Growth Development ◽  
Parallel Growth

The textural and compositional characteristics of a spinifex rock (MS-1) from Munro township, Ontario have been investigated in some detail. When projected into Mg–CaO–Al2O3 and CaO–MgO–FeO space, MS-1 appears late in the fractionation trends for peridotites, associated spinifex rocks and high Mg basalts. The latter trend extrapolates almost linearly to olivine tholeiite compositions.There are two types of blade megacrysts in the rock, both apparently representing preexisting olivine: (1) an earlier phase of composite, skeletal platy crystals of clinochlore, about 10 × 10 × 0.5 mm in size, which have a preferred orientation in the rock and show pronounced parallel growth development in the plane of the blades. The clinochlore is crystallographically related to the host olivine with c* and [100] parallel to a and b axis of olivine, respectively; (2) sheafs of oriented skeletal plates about 0.1 mm in shortest dimension which are completely altered to chlorite, calcite, magnetite and amphibole. The appearance of the composite blade megacrysts varies markedly with thin section orientation and this seems to account for the various types of blade (or platey) crystals reported in the literature. The interblade areas are largely of acicular and spherulitic pyroxene and interstitial groundmass. The acicular pyroxene is augite. Its composition varies considerably, especially with the area analysed, the greatest variations being in Cr, Ti and Na. The augite is characterized by high Al contents—preferentially accommodated in tetrahedral sites—and this leads to a distinctive field in Ti, Al plots compared to those for lunar and other terrestrial pyroxene. The rock also contains a few relict rounded olivine phenocrysts, amygdules, accessory chromite octahedra with magnetite rims, pentlandite and pyrrhotite.The Mg–Fe ratios for the clinochlore, augite and interstitial groundmass do not vary greatly from that of the whole rock value in contrast to the situation in a quenched plateau basalt.

Trondhjemitic and granitic melts formed by fractional crystallization of an olivine tholeiite from Reykjanes Peninsula, Iceland

2005 ◽  
Vol 142 (6) ◽  
pp. 651-658 ◽  
Author(s):  
E. MARTIN ◽  
O. SIGMARSSON
Keyword(s):  
Continental Crust ◽  
Fractional Crystallization ◽  
Significant Role ◽  
Major Element ◽  
Low Pressure ◽  
The Other ◽  
Olivine Tholeiite ◽  
Host Lava ◽  
Reykjanes Peninsula ◽  
Silicic Magmas

A pair of samples, from host lava and an included segregation vein from the Reykjanes Peninsula, Iceland, allows the assessment of a complete fractional crystallization of an olivine tholeiite at low pressure. The final product consists of silicic glasses with bimodal composition: trondhjemitic and more rarely granitic. Compilation of data on major element compositions of Icelandic silicic rocks reveals a clear difference from those of the segregation glasses. Fractional crystallization of basalts at low pressure is therefore not the most likely mechanism for the origin of silicic magmas in Iceland. Similar conclusions have been reached in studies on O- and Th-isotope compositions. On the other hand, the trondhjemitic compositions of the glasses in the segregation vein from Reykjanes Peninsula suggest that fractional crystallization of olivine tholeiites could have played a significant role during the formation of the very early continental crust.

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