Rock density structure in Bangong-Nujiang suture zone and its significance

Bangong-Nujiang suture separates Lhasa and Qiangtang blocks in Qinghai-Tibet. The acquisition of rock samples and their analyses of physical properties in the area are very important both to the interpretation of deep geophysical data and to the understanding of convergence and collision between these two tectonic blocks. 2500 rock samples dated from Ordovician to Quaternary were acquired along 3 profiles in Coqen basin in 1995. After rock density indoor measurement, we obtained rock density dataset of these rock samples. The results demonstrate that their densities increase from Quaternary to Ordovician within the range of 2.78 similar to 2.53g/cm(2) and the density contrast between the neighboring rock ages is 0.10g/cm(3) in general, and reaches to the maximum of 0.12 similar to 0.13g/cm(3) between Cretaceous and Jurassic, Permian and Triassic. The results also showed strong lateral heterogeneity of rock density between and in tectonic elements of the studied area.