Current theory is that the big bang only produced Hydrogen atoms. Heavier elements could only form inside the cores of Hydrogen rich stars.
Oh, and the explosion of a supernova produces nothing; the pressure of gravity against the core of a start is enough to cause lighter atoms to fuse into heavier atoms, thus hydrogen becoming helium, and so on. The nova occurs when the core can no longer fuse beyond iron, causing the explosive forces of the fusion process (heat and radiation) to overcome the gravity and blow away the layers above the core. Fusion is already over when this occurs.