From what i have read from this paper I understand that a role based access control system is one where users can be assigned to roles where roles specify permissions to perform operations on objects But in asp.net we do not specify "Operations on objects", what i mean here is that how can we specify "All users in Role R can perform a delete on object O" Where is the Object Part in ASP.Net
The security model is asp.net is pretty limited. In essence you only have control at the Role level. Which means that for any operation you have to test to see if the user is any of the roles that you want to allow that operation to be performed.
We took the path of defining our own model that gives much more granularity. Basically we define operations and assign those operations to various roles. This way we can test if they have a "delete account" right versus testing if they are in "Admin", "Account Admin", or any number of other roles. It's very similar to how Active Directory works. Further it allows us to reconfigure roles as needed.
There is a piece called Authorization Manager (AzMan) that ships with windows. It can work with your membership provider to provide operation level control. Some people have had success with it, but others have complained that it's difficult to get working. We used it about 5 years ago on a project and at that time it worked about 95% of the time. The other 5% it had communications issues with our AD controller.
Which leads us to your question: Is the built in ASP.Net membership provider a true role based access control system? No. It allows you to define Roles, not operations.