not only is it possible to do what you want, it was standard practice for many years. AND, with the simple addition of an electrical switch, it is possibel to have EITHER of your power packs power any section of track. this is what is commonly known as block wiring.
plastic insulating rail joiners are readily available in any hobby shop, as are wiring components by atlas. the selector is the component you'd most likely want to use. atlas also offers a book on wiring your layout.
i would give you a basic diagram showing how to do this wiring, but do not have a graphics program to make the diagram. simply describing it without the diagram is confusing., but the wiring itself is easy.
plastic insulating rail joiners are readily available in any hobby shop, as are wiring components by atlas. the selector is the component you'd most likely want to use. atlas also offers a book on wiring your layout.
i would give you a basic diagram showing how to do this wiring, but do not have a graphics program to make the diagram. simply describing it without the diagram is confusing., but the wiring itself is easy.