Here question ends. Beyond details exist
Do they occur on the same tectonic regime? For a start to distinguish Subalkali rocks froms Alkali rocks, my knowledge says that mantle is the source of Alkali rocks. Ocean Island Basalts are Hawaii, Reunion etc are all Alkali rocks. Large ignous provinces are also sourced from mantle by the mantle plumes. Such as Deccan, Siberian traps.
But in Robil Gill's ((Gill, R. (2010). Igneous rocks and processes: a practical guide. John Wiley & Sons.)) book on page 291, (chapter 9-Alkali rocks) says that Most of the large igneous provinces are subalkaline and they are much bigger and more frequent than the Alkaline Large igneous province. From this i derive that LIP's can be subalkaline.
So are there any difference between subalkali and alkali rock occuring tectonic environments ?