Kunlun Shan


Space Shuttle Photograph of the Kunlun Mountains

Northeast is towards the top in the Space shuttle photograph at left. The image shows the Tsaidam Basin (top left), Kunlun Mountains (snow-capped peaks diagonally across center) and part of the Tibetan Plateau (southern upper half).

The mountains are bounded by the Qaidam Basin Border thrust fault on the north, which is buried beneath the alluvial fans and young sediments of the Qaidam Basin. The North Kunlun Terrane (NKT, north of the N. Kunlun Fault System) consists of composite Plaeozoic intrusions (red) and Devonian metasediments (orange, D). These rocks are interpreted as an early Plaeozoic trench-island arc sequence. The basement of the NKT is comprised of Proterozoic rocks (Rb/Sr age of ~1990 Ma).

The N. Kunlun Fault System is a Late Devonian-Carboniferrous suture marking the accretion of the South Kunlun Terran (SKT) to the NKT. This suture has be reactivated. The SKT consists of the Ordovician to Devonian Naijtal Group, which are metasandstons, marbles, and phyllites (brown, Pz). The basement rocks are Late Proterozoic-Cambrian. The suture separating the STK from the Bayan Har Terrane (BHT) to the south, has been reactivated as the left-lateral Xidatan-Tuosuohu-Maqu strike-slip fault.

The BHT comprises trench-arc-basin rocks of Triassic age (lavender, T). Kunlun Pass Fault cuts the BHT and curves along the southern margin of the Kunlun Mountains.

Geology of the region
Terraces Along Golmud River - J.H. Wittke

 

Our route steps through the mountains, taking advantance of the major E-W valleys by following the Golmud River as it cuts across the ranges. The road emerges on the Plateau near where the XTM fault branches. Uplift of the mountains has produced valleys with multiple stranded terraces, as the Golmud River cuts rapidly downward (right). NASA's on-line geomorphology book describes the strike-slip faults of western China, including the Kunlun Fault.


XTM Fault valley in the Kunlun Mountains - J.H. Wittke

 

We stop at Naij Tal, which is at about 4000 m (c. 13,000') elevation, to view the Kunlun Mountains. We are in the Xidatan-Dongdatan valley, which follows the XTM Fault. Professor Lin tells us that the fault displays some thrust movement, but is dominantly strike-slip. Its trace is indicated by triangular facets and scarps at the base of the mountains.


Glaciers in the Kunlun Mountains - J.H. Wittke

 

Spectacular glaciers descend from the Kunlun Mountains. One particularly fine example descends from snow-capped Yuzhu Peak that is 6177 m (20,260') high. Lateral moraines embrace its long tongue of ice.

The final stretch of road up to Kunlun Pass follows a steep stream. Along it, gold miners are working the placer deposits. Their equipment consists of a few water pumps and hoses, many shovels and some sluice boxes. Judging from the places that they are concentrating their efforts, the gold is concentrated at the base of the alluvial fans along the stream.


Monument at Kunlun Pass - J.H. Wittke

 

Kunlun Pass at 4772 m (15,656') is marked by a plaque flanked by two brightly painted statues of a snowlion and an eagle. Colorful prayer flags hang in long strings from a pole behind the marble monument. The strike-slip Kunlun Pass Fault, which runs beneath the Neogene cover near the pass, marks the boundary between the Kunlun Terrane and the Songban-Ganzi Terrane. Ophiolitic material has been faulted out in this area, but it does occur to the east along the extension of the fault. The ocean between the Kunlun and Songban-Ganzi terranes closed in the Permian. Rocks of the Kunlun block include Ordovician, Devonian and Carboniferous sediments; the granites are probably Permo-Triassic. The Songban-Ganzi rocks are predominantly Triassic sediments.


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