Abstract:

The present progress in research on mixed rock of terrigenous clastics and carbonates is reviewed in this paper, mainly
including classification,  terminology, depositional environment, depositional modes and petroleum-gas geological significance.
It  is proposed by a comprehensive analysis  that  the depositional  facies  favorable  for  the mixed deposition mainly cover coastal
and shallow-lake  faicies,  following by shallow-sea shelf, shore-shallow  lacustrine and delta  facies. The study on  the depositional
environment  implies  that  the  factors controlling  the development of coastal mixed-rocks  include  tidal effect,  relatively strong
hydrodynamic condition and a shallow sea environment favorable for the living of lower organisms. In contrast, with respect to the
shore-shallow  lacustrine  rocks,  the  factors are  frequent  lake-level and climate changes. Consequently, a deep discussion on  the
depositional micro-facies and associated environmental  factors may be an effective way  to  improve and better  the classification
and  terminology of  the mixed  rocks. Furthermore, a synthetic depositional model  for  the marine and  lacustrine environment  is
suggested based on above-mentioned analyses, combined with case studies in Paleogene and Neogene middle-deep mixed rocks in
the northwestern Qaidam Basin. In addition, the shore-shallow sea and lake areas of mixed deposition can form high-quality targets of

reservoir and source rocks, based on factual research data on source and reservoir sequences associated with mixed rocks.

Key words: mixed , rocks of , terrigenous clastics and carbonates, sedimentary , facies, depositional environment; , facies model；high-quality reservoir