Elfin Thyme is turning purple to brown in some areas
We planted sections of flats around our front lawn and allowed it to grow together. It grew fast and filled in nicely with small mounds forming. It is still doing well; however, we are noticing browning in some areas.
Certified GKH Gardening Expert
The thyme will turn brown if it's too dry, or can do the same if it's too wet.
Due to your location I would think it's due to drought conditions.
You can cut away dead material.
Here is a link to care of Elfin Thyme.