皖南新元古代冰期地层再认识

A REVISIT OF THE NEOPROTEROZOIC GLACIAL DEPOSIT IN SOUTHERN ANHUI

前人认为皖南地区新元古代冰期地层存在两套冰碛岩。通过对皖南蓝田新元古界剖面和皖南地区的另外3条新元古界剖面的重新观察,发现该剖面只存在一套冰碛层和一套盖帽白云岩,均未发现间冰期地层。植被覆盖和地层错断是造成前人认为本地区新元古代冰期地层存在两套冰碛层和两套盖帽白云岩的主要原因。这一套冰碛层与中国南方扬子区南华系南沱组相当。

It has been reported that there are two Neoproterozoic tillite intervals in southern Anhui Province. Our recent field re-examination of the same outcrop in Lantian area has convinced us that there is only one tillite interval overlain by a cap carbonate. Poor exposure and repetition by fault may have lead to the previous incorrect inference in previous observation. No interglacial deposit is found in other three sections studied in southern Anhui. We thus conclude that only one interval of glacial deposit is preserved in this region,which is equivalent to the widespread Nantuo Formation diamictite in the Yangtze Platform of South China.