A Study On The Age Of The Uranium Series Of Rock Paintings In Cangyuan, Yunnan

The rock paintings of the Cangyuan County in the southwestern of Yunnan,close to the China-Burma border,were discovered firstly in 1965 by the archaeologist Ningsheng Wang.To date,15 rock paintings sites have been found in this area.The Cangyuan rock paintings are located upon the open limestone surfaces from 1 to 8 m above the present ground level.Some paintings have faded from the walls because of rainwater erosion,but there are still more than 1100 identifiable figures,including humans,animals,houses,objects,geometric designs and hand stencil.The human figures,generally in 5 to 50 cm high,account for about 70%of the total drawings.The animal figures account for about 20%of the total,including probably buffalos,zebus,dogs,monkeys,deer,wild boar,leopards,elephants,and birds.The houses are illustrated in the type of pile dwellings and tree huts.Hand stencil is popular in rock art of many parts of the world,but only one is present in the Cangyuan rock Paintings at the Site 5.These rock paintings provide precious information about the economic,social and cultural aspects of a sedentary life in the remote mountainous area.The men probably had permanent houses,raised domestic animals?such as pigs and oxen?and also hunted wild animals?deer,monkeys and leopards?using bows,spears and chases.They probably developed agriculture,as shown by pairs of people pounding grains in mortars.The age of the Cangyuan rock paintings has been studied by different ways over the past three decades,but still remains unsettled.In order to determine precisely the age of the Cangyuan rock paintings,this study carried out a comprehensive U-series dating of the secondary carbonate deposits associated with the paintings.The ²³⁰Th/U dating results demonstrate that ages of the rock art at the site 2 can be bracketed between 3709±9 and 3847±6 yr BP corresponding to the middle of the Xia dynasty?AD 1759 to 1897?.The results imply that the rock art practices at Cangyuan probably lasted to 2567±7 yr BP which corresponds to the Zhou dynasty?AD 617?.The age distribution of the samples from the site 2 indicate that the deposition of the thin layer carbonatewere continuously deposited.The ²³⁰Th/U dating results at the site 7demonstrate that ages of the rock art can be bracketed between 3550±79 to 3673±52 yr BP comtemperary with the Site 2,implying that the rock art practices probably lasted more than 700 years and ended between 2871±18 to 2975±32 yr BP corresponding to the Western Zhou dynasty?AD 921 to 1025?.The uranium and thorium contents at the site 3 and site 5 fluctuated greatly,and their age errors were large,which should be treated with caution.Samples from the site 4 is seriously young in age,due to modern sedimentation.Samples from Cangyuan rock art in 11 and 14 sites were deposited all above the rock art.The minimum age of rock paintings at the Site 11 was about 1000years.A figure with both hands downswing at the site 14 indicates a minimum age of2692±10 yr BP.The dating results of this study provide references for the Wa people living in Cangyuan area of Yunnan province at that age for their migration,production and living conditions and archaeological research.However,due to the influence of sample quantity and sample calcite purity,the other five sites failed to obtain more accurate dating results,which required more archaeological work to further strengthen exchanges,cooperation and exploration.