Mat_M, Your wrong.
First, in the 70's there was 4-channel LP's where the 2 "surround" channels was in the 30-40KHz range on the vinyl.
Second, according to
Kevin Grey (that cut vinyl's daily) his cutting system;
With frequency response from 7 Hz to 25kHz (I think his laters measuring was at 27KHz. Taken from:
http://www.recordtech.com/prodsounds.htm
David Judah, Well, according to
Kevin Grey again, vinyl has;
over 75 dB dynamic range possible.
The reason he say over is because you can with good gear "hear thru the noise floor".