Origin of Archean lamprophyre dykes, Superior Province, Canada: rare earth element and Nd?Sr isotopic evidence

1992 ◽  
Vol 111 (4) ◽  
pp. 515-526 ◽  
Author(s):  
Richard A. Stern ◽  
Gilbert N. Hanson
Keyword(s):  
Rare Earth ◽  
Rare Earth Element ◽  
Earth Element ◽  
Superior Province ◽  
Isotopic Evidence

Geochemical evolution in the Blake River Group, Abitibi Greenstone Belt, Superior Province

1980 ◽  
Vol 17 (9) ◽  
pp. 1292-1299 ◽  
Author(s):  
I. E. M. Smith
Keyword(s):  
Rare Earth ◽  
Volcanic Rock ◽  
Rare Earth Element ◽  
Greenstone Belt ◽  
Earth Element ◽  
Superior Province ◽  
Calc Alkaline ◽  
Abitibi Greenstone Belt ◽  
Rock Types ◽  
Element Fractionation

In well exposed, well developed greenstone belts of the Superior Province there is a clear progression from stratigraphically lower, geochemically primitive volcanic rock types (komatiites, tholeiites) to overlying geochemically evolved calc-alkaline volcanic rock types. In the western Blake River Group of the Abitibi Greenstone Belt the change from tholeiitic to calc-alkaline volcanics represents a geochemical discontinuity defined by an increase in incompatible elements and light/heavy rare-earth element fractionation in the overlying rocks. Quantitative modelling of the parameters of the discontinuity indicates that it can be explained by a change to very small amounts of melting of unmodified mantle lherzolite, although this is not a unique solution. In calc-alkaline suites showing high degrees of rare-earth element fractionation the calculated melt fraction required of unmodified mantle becomes unrealistically low and models involving a geochemically evolved source may have to be considered.

Petrogenesis of mantle-derived, LILE-enriched Archean monzodiorites and trachyandesites (sanukitoids) in southwestern Superior Province

1989 ◽  
Vol 26 (9) ◽  
pp. 1688-1712 ◽  
Author(s):  
Richard A. Stern ◽  
Gilbert N. Hanson ◽  
Steven B. Shirey
Keyword(s):  
Rare Earth ◽  
Rare Earth Element ◽  
Mantle Source ◽  
Earth Element ◽  
Crustal Contamination ◽  
Mantle Peridotite ◽  
Superior Province ◽  
Source Regions ◽  
Enriched Mantle ◽  
Ree Patterns

In southwestern Superior Province, diorite, monzodiorite, and trachyandesite ("sanukitoids") occurring within syn- to post-tectonic intrusive complexes and within greenstone belts have the following chemical characteristics: 55–60 wt.% SiO2, MgO > 6 wt.%, Mg# > 0.60, Ni and Cr both > 100 ppm, Na2O + K2O = 6 wt.%, Sr and Ba both 600–1800 ppm, and rare-earth-element (REE) patterns that are strongly light rare-earth-element (LREE) enriched (Cen = 80–250, Ybn = 4 – 10) and show no Eu anomalies. Sanukitoids and their granodioritic derivatives constitute at least 5% of the exposed crust in the study area. The sanukitoids cannot be derived by melting, fractionation, or crustal contamination of basalts or lamprophyres that are coeval with the sanukitoids. Crustal contamination of komatiites fails to explain the high large-ion-lithophile-element (LILE) contents of the sanukitoids. Rather, we suggest that the sanukitoids were derived by hydrous melting of LILE-enriched mantle peridotite at pressures between 10 and 15 kbar. The sanukitoids with steepest REE patterns have the lowest FeO contents, indicating that the part of the mantle source with the highest Mg# had the most fractionated REE pattern prior to melting. Mantle source regions to the sanukitoids had different Mg#'s and were enriched in LILE's (metasomatized) to varying extents by fluids of crustal or mantle origin prior to melting.

RARE EARTH ELEMENT AND THORIUM ASSAYING IN PARTS OF THE EAST COAST, INDIA

2016 ◽  
Author(s):  
Shayantani Ghosal ◽  
◽  
Sudha Agrahari ◽  
Debashish Sengupta
Keyword(s):  
Rare Earth ◽  
Rare Earth Element ◽  
Earth Element ◽  
East Coast
Sign in / Sign up

Export Citation Format

Share Document