On re-look, the Jebel Shams area does look perfectly likely.
Sorry for being indecisive!
The rapelling roadblock does appear to be at Jebel Shams area. Those cliffs are to high to be an open pit mine.
"On the next leg of Prof Uraiís geological tour, the audience was introduced to geological quirks in the Jabal Akhdar and Jabal Shams areas that truly attest to Omanís spectacular geological heritage. Fossils and other geological features dating from the Cretaceous to the Jurassic periods can be found in and around Wadi Nakhr, a dramatic gorge located 3,000 metres above sea level in Jabal Akhdar.
Jabal Shams has its own share of geological wonders, according to Prof Urai. Along the rim of the canyon are Cretaceous and Jurassic era rock layers, while elsewhere can be found rock veins ó exposed fractures that have the semblance of rock art. Importantly, the study of Omanís exceptional geological heritage has benefits that go beyond the search for hydrocarbons, says Prof Urai."http://www.srikumar.com/oman/articles/oman_a_geological_wonderland.htm
The big blocky rock formation appear to be marine limestones and dolostones of the Cretaceous/Jurassic eras.. IF
they go to the open pit copper mines in the Sohar area, there is a major highway due south out of Sohar to the Nizwa/Bahla area, which are the gateways to the Wadi Nakhr/Grand Canyon region. The teams would not have to drive back to the Muttah/Muscat area. Another possible drive a box around Oman.
This article is from Oct, 2003 and could explain the use of drivers. The teams could drive themselves to the Wadi, then have drivers drive them to the top and bottom of the roadblock, then back out of the Wadi.http://www.newsbriefsoman.info/item/2006/04/jabal-shams--campers-paradise
"Walking time is around three hours one-way. At one point the road leaves the wadi and cuts a twisting swathe through the rugged terrain, skirting small hamlets en route. Work is still under way on a 10km stretch to the summit, a rocky plateau that offers unparalleled views of Wadi Nakhr and its splendid gorge."