Pillow Ba-salts
You can see it here, on the right side.
These salt rich Ba-salts would have had much more associated water than terrestrial extrusive or intrusive analogs. Perhaps there was abundant synchronous hydrothermal emplacements as well, and this formed the more nodular materials, and the small pillows seen here. Or perhaps there was just abundant surface water to alter the margins of these in/ex-trusions.