Geochemistry, mineralogy, and petrogenesis of basalt from the Gorda Ridge ( Pacific).

Basalt pillow lava with glossy rims was dredged from 17 sites along the Gorda Ridge between latitudes 43oN and 40.8oN. All samples are low-K2O mid-ocean ridge tholeiitic basalt having a narrow compositional range with Mg numbers clustered around 60-62; more primitive and evolved compositions are present but rare. Magma chambers under the Gorda Ridge appear to be small, discontinuous in time and space and possibly at greater depth than those beneath other Pacific spreading centers.-from Authors