Seizures Were Major Factor in Brandon Blackstock's Death Amid Melanoma Battle

Brandon Blackstock’s death certificate is revealing more about his passing from melanoma -- showing that seizures played a major role in his death.

According to the death certificate from the Butte-Silver Bow County Clerk and Recorder’s Office in Montana, first obtained by People -- Brandon died at 11:13 AM on August 7 -- with seizures listed as a "significant condition contributing to death but not resulting in the underlying cause."

The death certificate reveals no autopsy was performed, and Brandon was cremated.

Brandon’s family announced the tragedy the same day of his death, and sources with direct knowledge tell us Brandon died of melanoma -- a form of skin cancer -- after fighting it for more than three and a half years.

His ex-wife, Kelly Clarkson, had postponed her Las Vegas residency ahead of his death ... telling fans he was very ill and she needed to step back to be with their kids.

Brandon was 48.