Progress,Controversies and Challenge of Studies on South Altyn Tagh-North Qaidam HP/UHP Metamorphic Belt

The South Altyn Tagh (SAT)-North Qaidam (NQD) HP/UHP metamorphic belt extends approximately 1000 km along the northern margin of the Tibetan Plateau,and is truncated by the Altyn Tagh sinistral strike- slip fault and splitted into two parts: the South Altyn Tagh region and the North Qaidam region. Based on rock associations, petrologic criteria and the field relationships, six HP/UHP metamorphic units can be distinguished in the South Altyn Tagh(SAT)-North Qaidam (NQD) region (Fig. 1A). From west to east, they are: the Jianggalesayi eclogite-gneiss unit (JSU), the Bashiwake garnet peridotite-high pressure granulite unit (BWU), the Yuka eclogite- gneiss (schist) unit (YLU), the Luliangshan garnet peridotite-gneiss unit (LLU), the Xitieshan eclogite-gneiss unit (XTU) and the Dulan eclogite-gneiss unit (DLU). The geological relationship, petrology and geochronology indicate that these six HP/UHP metamorphic units have different rock associations, and underwent different p-T conditions and metamorphic histories. Geochronologyical dating for these eclogite-facies metamorphics yields ages between 500 and 420 Ma. This implies that a possible multiple or disachronous subduction took place along the SAT-NQD HP/ UHP metamorphic belt.