Looks like a late 40s zipper but the bust seams are on the leather. I initially thought it was a zipper front vest and 60s. Any info is appreciated. Very thin layer of leather and lining is not sewn down and feels like rayon to me.
Could it have been a dress that was cut into a top? Can't tell from your photos whether the hem and zip sewing is original. I ask because I've had a few tops that were originally dresses but someone had cut off the skirt, probably because it was a slim skirt that didn't fit. If so the zip would likely be a replacement, and someone might have used an older zipper for that.
It looks like original hem tape looks like it has original hem tape but could have also been added. Will upload some more photos.