Mineralization Characteristics and Prospecting Potential of Potash in the Qaidam Basin，Qinghai Province, China

 

Abstact：The Qaidam Basin is a large-scale Cenozoic intermontane closed fault-depression basin in the northern part of the Qinghai-Tibet Plateau. Controlled by the plateau uplift and the dry-cold, cool-humid, dry-cold climatic cycles, it has formed lithium-rich salt lakes through arid evaporation and concentration, and possesses favorable conditions for salt formation in "high mountain and deep basin" settings.

In terms of geological background, the basin is an irregular rhomboidal water-collecting graben basin extending in the NW-SE direction, covering an area of approximately 255,000 km², with 12 types of proven minerals. Regarding spatiotemporal distribution, halite and gypsum are present in the Shizuigou structural area during the Oligocene; potassium-rich deep brines developed in areas such as Nanyishan during the Pliocene; and thenardite, halite, and potassium-magnesium salts formed in the Early Pleistocene.  

In terms of mineralization units and mineral resources, the formation of the basin can be traced back to the Mesozoic Era, and it is currently divided into 5 mineralization units (e.g., the Boron-Potassium-Magnesium Salt-Oil Fault Step Zone in the Northern Margin of Qaidam). There are 33 salt lakes of varying sizes in the basin, with key development areas including Chahan, East and West Taijinar-Yiliping. The cumulative proven salt lake resources amount to approximately 400 billion tons, and 55 ore deposits (31 of which are large-scale or above) have been discovered, involving 12 types of minerals such as lithium (brine), strontium, and potash. A mineralization model has also been established.

The division of mineralization series adheres to the principles of sedimentary basin evolution, geological process correlation, and reflection of the latest exploration results. Two mineralization series and 5 sub-series have been identified, including the Paleogene-Neogene potassium-lithium-boron-strontium-gypsum ore deposit series related to deep fluid and sedimentary superposition, and the Quaternary potassium-sodium-magnesium-lithium-boron-strontium-halite-trona and clay-lithium ore deposit series related to sedimentation.

The conclusions point out that 55 ore deposits and 12 types of minerals have been discovered in the basin; the piedmont glutenite-type potassium-rich deep brines and the mid-western anticline zone fracture-cave-type lithium-rich deep brines have huge reserves and are key breakthrough areas for ore prospecting; the first division of 2 mineralization series and 5 sub-series has improved the mineralization theory and provided guidance for subsequent exploration.

Keywords：Qaidam Basin; Potash； Mineralization Characteristics;Prospecting Potential;  Salt Lakes