1/9/2012 5:20 PM PST BY TMZ STAFF
Tyga mugshot
Rapper Tyga was locked up in Las Vegas this weekend ... after cops discovered the 22-year-old had an active warrant out for his arrest ... TMZ has learned.

Law enforcement sources tell us ... Tyga -- real name Michael Stevenson -- was initially flagged on a routine traffic violation ... but during the stop, cops discovered the warrant stemming from 4 other traffic incidents.

According to KSNV in Nevada ... Tyga's prior issues include driving without a license, registration violations and unlawful acts of financial responsibility.

The "Rack City" and "Coconut Juice" rapper was hauled to the Clark County Detention Center where he was booked and tossed behind bars. He was released the next day on his own recognizance.

Story developing ...