Major- and trace-element chemistry of DSDP Leg 70 Holes basalts and their alteration products

Major and trace element compositions of basalts from the lower part of Hole 504B indicate their cogenetic nature. The cored sequence of interlayered pillow lavas and massive lava flows was produced by eruption of lavas, slightly variable in composition. Plagioclase and olivine crystallization in a shallow magma chamber, followed by small-scale fractionation at higher levels, is responsible for these variations. Except in highly fractured zones within the basement, there are systematic variations in the style and degree of rock alteration with depth. Trace element characteristics of altered rocks and secondary minerals indicate that progressive changes in sea water composition occurred as it reacted with basaltic crust

Rare earth elements and some other trace elements in volcanic ashes and pelagic clays at DSDP Leg 59 Holes

Published data on trace- and dispersed-element distributions, including rare-earth elements (REE), in volcanic rocks of the Mariana island-arc system are very limited (Taylor, 1968) and are virtually unavailable for sediments. Thus determinations of trace-element abundances in the volcanic and sedimentary rocks penetrated by drilling during DSDP Leg 59 is of significant interest. Rock samples from the sedimentary sequence in the southern part of the Philippine Sea were obtained from six holes at five drill sites (the West Philippine Basin, the Palau-Kyushu Ridge, the Parece Vela Basin, and the West Mariana Ridge). The sequence is represented by vitric tuffs, volcaniclastic breccias, carbonate sediments, and pelagic clays, which vary in age from middle Oligocene to Pleistocene