The Potassium Provenance Of Lop Nor In Tarim Basin,Xinjiang

Potash resources, one of the seven kinds of bulk shortage mineral (petroleum andnatural gas, copper, aluminum, iron, manganese, chromium, potassium salt), isshortage resources in China. In order to establish an effective guidance for judgmentand finding the Potash deposit, the surrounding granite, basin sediments and brine arestudied in Lop Nur potash deposit, located in Tarim Basin and the second largestpotassium deposits in China. The existing form of the potassium in the differentsediments is comparatively analyzed to explore the material source of the Lop Nurpotash. The new geochemical potash indicators were employed to find potash depositsin Tarim Basin. The main content in the paper can be summarized as:1. Comprehensively sum up the views of the Lop Nur potash material sources.2. The mineralization analysis of granitoids in exhumation area of Lop Nor withinthe catchment's range, the variation of potassium amount in unweathered, weaklyweathered and strongly weathered granite was studied to investigate the relationshipbetween the potassium salt in Lop Nur and granitoids.3. The decomposed granite, loose sand and soil ionic form were utilized toinvestigate the potassium water-soluble contribution to the Lop Nur potash.4. In order to know the removal capacity of surface water to soluble potassium,ochemical characteristics of natural water were studied. For finding more potashdeposits in Tarim Basin, the bromochloromethane coefficient and the potassiumcoefficient were discussed.5. The provenance model of the Lop Nur potash was established.Through above analysis shows that granitoids which are the Providers of activepotassium, in exhumation area of Lop Nor within the catchment range, includeKuruktag rock zone, Beishan rock zone,Xingxingxia rock zone and Altun rock zone;Among these rock zones, K2O was lost more than1%in granites of Kuruktag rockzone, which means granites of Kuruktag rock zone provide a greater amount ofmaterial composition to the Lop Nur potash. The content of water soluble potassiumin0-1.5m depth below surface changed significantly, and it was much higher than thewater soluble potassium in the lower sand. The result indicates that the water solublepotassium enriches in the shallow surface, and the closer to the surface, the lowercontent of the water soluble potassium in0-1.5m depth below surface. The result alsoshows that the0-0.5m depth below surface, which is the migration of potassium layer, has a severe loss of potassium ions. The surface water salinity in Tarim Basin e basinis higher than the salinity in the shallow groundwater, and the salinity level in surfacewater indicates that active potassium was leached and transported. Thebromochloromethane index at point09-16in the middle west of Tabei uplift tectonicareas has a higher value (1.7), and the water soluble potassium content (2948μg/g) ismuch higher than potassium content at other sampling points. It is noted that thepotassium deposition may be existed at or around point09-16in the middle west ofTabei uplift tectonic areas.