Looking northward, the southern face of the Kunlun
Mountains rises sharply above a barren plain, the
Xidatan-Tuosuohu-Maqu Fault defining its southern border (right).
Glaciers and snowfields do not extend as far down the southern
side of the mountains. 
The Tsaidam Basin is visible at the bottom of this Space
Shuttle photograph. The Kunlun Mountains cut diagonally across
the photograph from the lower left to middle right. The
snow-capped peaks in the upper left part of the picture are the
Fenghuo Shan. Golmud is at the entrance to the winding valley
through the Kunlun Shan in the lower left corner. The Fenghuo
Mouintains, comprised of Eocene and Cretaceous redbeds, are upper
left half of the image. The ruddy sedimentary rocks of this area
have been extensively thrusted and folded, but form more subdued
mountains than the crystalline rocks in the Kunlun.
The Jinsha Suture, which is the boundary between the
Songban-Ganzi and Qiangtang crustal blocks, is located within the
Fenhuo Mountains, but is covered by recent alluvium. Ophiolites
associated with this suture crop out about 50 km west of the
road. The age of closure is considered to be Late Triassic to
Early Jurassic.
The
Late Cretaceous-Eocene redbeds are strongly deformed near the
town of Erdaogou (left), just south of Fenghuoshan Pass, which is
4958 m (16,266') high according to the geological map, but 5100 m
(16,728') according to the Qinghai "traffic" map purchased in
Golmud. Prayer flags are strung around a telephone pole like
ropes off a May pole, but unlike at Kunlun Pass, there are no
fancy monuments to mark the summit. The redbeds were deposited
unconformably on Triassic-Jurassic and Paleozoic rocks of the
Qiangtang Terrane, and deformed during the Himalayan orogeny.
They are intruded by a 30 Ma trachyte/syenite stock about 15 km
northwest of Fenghuoshan Pass, indicating a pre-Oligocene age of
deformation. The frontal thrust is located about 15 km south of
Erdaogou, and the steep valley through the Fenghou Shan opens out
into a wide plain. 
The sole
claim to fame for the village of Tuotuo River is the "First
Bridge over the Yangtze." The Tuotuo River is considered the
principal source of the Yangzi River, and at an elevation of
about 4530 m (14,860'), the bridge is located closest to the
source of the Yangtze. The shallow river fills the broad plain in
a series of ever-shifting braids (right). South of Tuotuo River
is a sequence of deformed Paleozoic rocks. These are intruded by
what appears to be a young volcanic center, although on the map
it is indicated as also of Paleozoic age. 
South of Wenchuan Station, reputedly the highest village
in the world, the redbeds are faulted and tilted in a narrow zone
of deformation (left).
