Xixi (right) and field party at 5,000 meters
on the NE Tibetan Plateau. The characters say "Source
of
the Yangtze River" (in the calligraphy of Chinese President
Jiang Zheming).
The
collision between India and Asia has uplifted the Tibetan
Plateau, well named as the "roof of the world." Although
the bounding regions of the Plateau, defined by active thrust
and strike-slip faults, have been extensively studied, the
geological history of the Tibetan interior is not yet well
established, especially the early uplift history. The hinterland
of the Tibetan Plateau contains erosional products of earlier
Tibetan uplift further to the south, and thus preserves
an important record of its tectonic evolution, but it receives
much less attention because of its remoteness and extreme
working conditions. The Hoh Xil basin, with an area of 101,000
km2 and an average elevation of over 5,000 m, is the largest
sedimentary basin in the region. Interest has increasingly
focused on whether the Hoh Xil basin was formed during the
Cretaceous or Tertiary.
