What are the enigmatic "coffee bean"-like globules and bullets in the deposits of the delta ?

-- An attempt at an explanation --

 

Spherical to ellipsoidal objects can be found both in the layered deposits of ash and in larger form as conglomerate. They are often distinguished by a side seam where they have sometimes been split in half. Close-ups show that there are some bright mineral bands and an outer ring arranged equartorially in the interior.

If we assume that the objects is volcanic ejecta, the question of these puzzling characteristics remains open. The mineral-separations probably took place in the molten state. The rounded shape suggests a rotation of the object. But why the ribbons and the outer ring appear to be arranged equatorially I cannot explain physically.
 

  
In these splitted globules, stucking in the ash, are the bright ribbons arranged equatorial


This globules look like coffee beans stuck in the ash layer

 

    
Hidden globules in the ash layer

 

    

Larger accumulation of globules in layered ash deposit


In the upper slope an accumulation of larger volcanic bullets that were not formed by running water


The bullets with their characteristic marks


Slipped ash deposits filled with volcanic bullets. In close-ups, the characteristic equatorial marks on the bullets can also be seen here


This shared object, found outside the delta, also belongs to this category