The genesis and material source of Carboniferous-Late Permian ice miscellaneous conglomerate： a case study of Gangma Co area, Qiangtang, Tibetan Plateau

In Tibetan Plateau and its adjacent areas, boulder beds, complex conglomerates and pebbly slate are widely distributed in Carboniferous-Permian strata, constituting a special type of ice marine deposit, called ice miscellaneous conglomerate. Although previous researchers have done some work on the formation environment of ice miscellaneous conglomerate, no unanimous conclusions have been reached. With the conglomerate of ice miscellaneous conglomerate in Gangmacuo area of southern Qiangtang within Tibetan Plateau as the study object, the authors observed the field and microscopic characteristics of gravels and, through the grain size analysis of quartz sandstone which is interbeded with ice miscellaneous conglomerate, revealed that the ice miscellaneous conglomerate was the deposit of ice rafting when Gondwana continental glaciar was in a state of ablation. Through a comparative study of detrital zircons and lithologic characters, the authors have reached the conclusion that the provenance of ice miscellaneous conglomerate was from Gondwana continent. On such a basis, this paper discusses the possible sources of the gravels for ice miscellaneous conglomerate. These achievements provide evidence for the sedimentary environment of Gandwana continent.