Carbon isotope fluctuations from the Cambrian Jialao formation in Jianhe County, Guizhou Province, China: Implications for stratigraphic correlation

The dolostone-dominated Cambrian Jialao Formation was deposited in the south-eastern Guizhou Province. The scarcity of fossils severely limits the use of biostratigraphy for the division and correlation of dolostone strata. The Balang and Wuhe sections were selected as the study objects, and 129 whole rock samples were collected for isotopic analyses of carbon and oxygen. The results show that: (1) The δ13Ccarb values of the Balang and Wuhe sections range from −4.77 ‰ to 0.56 ‰ and − 4.88 ‰ to 1.08 ‰, respectively. Furthermore, the DICE has been identified in the lower part of the Loushanguan Formation in the Balang section and the upper part of the Jialao Formation in the Wuhe section. (2) The sections of this study demonstrate a high degree of correlation with the contemporaneous strata of different continents. Although the amplitude of the DICE in this study is relatively weak (0.73 ‰ and 1.79 ‰, respectively), it is considered that the recognition of the DICE in this study is reliable, based on the characteristics of the DICE reported worldwide and the biostratigraphy done by predecessors in the contemporaneous strata. (3) By observing sections deposited in different sedimentary facies where the DICE has been identified, it was found that there is an ‘M'-shaped δ13Ccarb excursion under the DICE, which may be one of the pieces of evidence identifying the DICE. Furthermore, the results suggest that the Jialao Formation could be a diachronous unit from the Wuliuan to the Drumian. The identification of the DICE not only indicates that the Jialao Formation has significant value and potential for stratigraphic correlation, but also provides a reference for correlating other strata with few or no fossils from the same period. [Display omitted] •The δ13C stratigraphy of the Balang and the the Wuhe sections have good correlation with the strata of different plates at the same time.•The DICE has been identified from the lower part of the Loushanguan Formation in the Balang section and the upper part of the Jialao Formation in the Wuhe section.•The Jialao Formation could be a diachronous unit from the Wuliuan to the Drumian.•The ‘M'-shaped variation pattern was identified under the DICE in the different sedimentary facies, which may be one of the pieces of evidence identifying the DICE.