In my Artscroll Siddur Yitzchak Yair Hashalem, after the section called Vayiten L'cha there is a small piece of instruction:
בכמה קהילות אמרים כאן קדיש יתום
In some congregations [people] say here Mourner's Kaddish
But this section of prayer has in it both sections from Nach and from the Talmud. What determines that in this spot, one would say the Mourner's Kaddish and not the one Derobonnon which is said after reading a "non legal" section of the Talmud?