The Marine was identified as Lance Cpl. Jonathan S. Long, 22, of Barboursville, W.Va., the Marine Corps Times reported.
"The cause of death is still under investigation, but it does not appear to have been training related," Marine officials said.
Marine officials said in a release Long collapsed Saturday night following daylong training in improvised explosive detection methods, the newspaper said. He was flown from the base to Desert Regional Medical Center in Palm Sprigs where he was pronounced dead.
Long had enlisted in 2010 and had served a deployment to Afghanistan last year. He was assigned to the 8th Engineer Support Battalion, based at Camp Lejeune, N.C.
The bulk fuel specialist was at the Marine Corps Air Ground Combat Center in Twentynine Palms for Enhanced Mojave Viper exercises.