Hi,
Seems like some thing caused at source system.
Ask basis team to find the changes on particular day.
about deltas, seems like its corrupted.
You need to delete and do the reinit.
But first find the cause why and what happen on ecc system?
Later you can go with reinit of data sources.
First try with one data source and later continue with other.
When this problem caused? Is any changes applied ecc on mar 11-14 , 2015?
Thanks