Hi,
A data mart is a subset of you data warehouse. SSAS and data marts / data warehouse are not nessasary for each other.
As they are only loose concept, SSAS can build your data mart as well as your data house. You could also add tables into your project and enrich you data warehouse or creat/ add new data mart.
Please also see this thread, which clarifies the relation between them : What is the difference between SSAS & Data Mart?
Regards,
Lukas