Sr and Nd isotopic relationships in the Oka carbonatite complex, Canada
A detailed isotopic study on separated minerals and whole-rock samples from the Oka complex, which intrudes rocks of Grenville age near Montreal, Quebec, shows that the complex had a very small variation in initial isotopic composition for both Sr and Nd. Apatite, calcite, garnet, melilite, olivine, and pyroxene separates give a range for initial /sup 87/Sr//sup 86/Sr of 0.70323 - 0.70334; and for initial /sup 143/Nd//sup 144/Nd of 0.51281 - 0.51271 (/epsilon//sub Sr/ =-16.2 to -14.2; /epsilon//sub Nd/=6.1 to 4.1). The negative /epsilon//sub Sr/ and positive /epsilon//sub Nd/ values indicate derivation of the Sr and Nd from a source with a time-integrated depletion in the large-ion lithophile (LIL) elements. This find in is consistent with some of the Pb isotope data from Oka. A well-defined Rb-Sr isochron obtained from biotites gives an age of 109/plus minus/2 Ma, indicating that the Oka complex is the youngest intrusion of the Monteregian Hills igneous province, and one of the youngest carbonatites in Canada. Isotopic data from carbonatites that intrude other parts of the Canadian Shield have shown that a large part of the Shield is underlain by a source region depleted in the LIL elements. The new data from Oka indicate that the same source has remained coupled to the continental crust until recent time.
- Research Organization:
- Carleton Univ., Ottawa, Ontario (Canada)
- OSTI ID:
- 6032200
- Report Number(s):
- CONF-8510489-
- Journal Information:
- Geol. Soc. Am., Abstr. Programs; (United States), Vol. 17; Conference: 98. annual meeting of the Geological Society of America, Orlando, FL, USA, 28-31 Oct 1985
- Country of Publication:
- United States
- Language:
- English
Similar Records
Pb-Sr-Nd isotope study of the 100- to 2700-Ma old alkalic rock-carbonatite complexes in the Canadian shield: inferences on the geochemical and structural evolution of the mantle
Late Precambrian (740 Ma) charnockite, enderbite, and granite from Jebel Moya, Sudan: A link between the Mozambique Belt and the Arabian-Nubian Shield
Related Subjects
PLUTONIC ROCKS
GEOCHEMISTRY
ISOTOPE DATING
BIOTITE
CARBONATE ROCKS
CHEMICAL COMPOSITION
ISOTOPE RATIO
NEODYMIUM ISOTOPES
ORIGIN
PETROGENESIS
QUEBEC
STRONTIUM ISOTOPES
AGE ESTIMATION
ALKALINE EARTH ISOTOPES
CANADA
CHEMISTRY
IGNEOUS ROCKS
ISOTOPES
MICA
MINERALS
NORTH AMERICA
ROCKS
SEDIMENTARY ROCKS
SILICATE MINERALS
580100* - Geology & Hydrology- (-1989)
580400 - Geochemistry- (-1989)
580300 - Mineralogy
Petrology
& Rock Mechanics- (-1989)