Sediments intercalated with the lowermost flow top breccia suggest that the lava intruded wet sediment. With the exception of this lowermost unit, the flows show oxidation zones and morphologies consistent with subaerial emplacement. Consequently, Site 1137 basalts form a distinct geochemical group that may reflect a relatively lower extent of melting. Lava flow interiors at Site 1137, as at Site 1136, are relatively unaltered compared to Cretaceous basement lavas previously recovered from the Kerguelen Plateau. Many beds are normally graded and others show parallel laminations.
Clasts range from well rounded granules to small boulders.
The depositional environment of Basement Units 5 and 6 appears fluvial, perhaps associated with a braided river. Furthermore, fluvial facies of Units 5 and 6 corroborates our interpretation of subaerial lava flow effusion. We also find single grains of garnet and perthitic alkali feldspar, presumably weathered from sources similar to those of the gneiss and granitoid cobbles, in the sand fraction of Unit 5 and as xenocrysts in parts of the Unit 9 crystal-vitric tuff. It is difficult to imagine anything but an originally continental source for such material. 3.The seven basement lava flows are tholeiitic to transitional basalts, as are other Cretaceous igneous basement rocks of the Kerguelen Plateau.