Geochemistry at DSDP Leg 73 Holes@en

Basalt was encountered under sediments in four holes (519A, 520, 522B, and 524) on Leg 73. The rocks in three holes (519A, 520, and 522B) are typical somewhat evolved mid-ocean-ridge basalt (MORB) tholeiites that occur as pillows, flows, and sills. In Hole 524 there occur (1) an upper alkalic sequence of pillows and a sill enclosed in Cretaceous volcaniclastic sedimentary rocks and (2) a lower, moderately evolved, slightly alkalic tholeiite in a multiple sill, also injected into Cretaceous volcaniclastic rocks. […]