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USGS · 70001639

The strontium isotopic composition of basalts from the Gordo and Juan de Fuca Rises, northeastern Pacific Ocean

C. E. Hedge·Z. E. Peterman
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Abstract

The strontium isotopic compositions have been determined for twelve tholeiitic basalts dredged from the Gordo and Juan de Fuca Rises. Sr 87 /Sr 86 ratios range from 0.7012 to 0.7031 and average 0.7026. These data, combined with other data from the East Pacific Rise indicate that tholeiite basalts being erupted along the active rises, in the Pacific Ocean, contain less radiogenic Sr 87 than basalts erupted on the islands. These isotopic differences between the ocean-ridge tholeiite and the more alkali island basalts indicate that variations in Rb/Sr have persisted in the mantle for billions of years. The possible origins and distribution of these heterogeneties are discussed.

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C. E. Hedge, Z. E. Peterman. 1970. The strontium isotopic composition of basalts from the Gordo and Juan de Fuca Rises, northeastern Pacific Ocean. https://doi.org/10.1007/bf00371978

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