Discovery of Radiolaria from the Zongzhuo Formation in Tianba,Kangmar,Tibet and its Age Implication

There is a group of variegated marine deposits, including the red beds widespread in the area of Tianba, Kangmar, southern Tibet, which previous works have contributed to Cretaceous Zongzhuo Formation by lithologic associations only, but with poor fossil evidence. Due to the absence of age dating fossils, the red bed age is obscure. Abundant Cretaceous radiolaria were discovered from the Zongzhuo Formation in the present study. In spite of the poor general preservation of some radiolarian specimens as recrystallized quartz infillings, 58 species from 46 genera of radiolaria, extracted from chert and silicous limestone of the Zongzhuo Formation in Kangmar, were identified on the basis of their shape and ornamentation. Based on the radiolaria, the age of the Zongzhuo Formation of this area has been referred to as Late Cretaceous. The new radiolarian data from the Zongzhuo Formation of Tianba area provide a local basis to correlate these deposits with other regions of the Tethyan Himalaya.