| Autor: |
L. D. Ashwal, W. C. Phinney, D. A. Morrison, D.D. Bogard, D. E. MacZuga, Donald W. Davis, J.L. Wooden |
| Rok vydání: |
1985 |
| Předmět: |
|
| Zdroj: |
Earth and Planetary Science Letters. 73:306-316 |
| ISSN: |
0012-821X |
| DOI: |
10.1016/0012-821x(85)90079-2 |
| Popis: |
An investigation of zircon data from the Mulcahy Lake gabbro, a 63 sq km layered mafic intrusion in the Wabigoon subprovince of Ontario, which show that the gabbro crystallized at 2733.2 +1.0, -0.9 Ma, is considered. It is shown that the gabbro intrudes tholeiites of the Crow Lake-Savant Lake greenstone belt. Whole rock samples and mineral separates from the Mulcahy Lake intrusion are dated by Rb-Sr, Sm-Nd, and Ar-30-Ar-40 techniques. Disturbances in the system are revealed by the Rb-Sr data and an initial Sr ratio of 0.7007 for an age of 2733 Ma is indicated by samples with low Rb/Sr ratios. The age determined for the Sm-Nd data is 2744 + or 55 Ma with an epsilon Nd value of +2.6 + or - 1.2 which indicates a source region depleted in a light rare earth element. Primary hornblende is analyzed for Ar-40/Ar-39 and an age of 2703 + or - 20 is obtained. Some implications for the development of greenstone-granite belts are discussed. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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