Paper Number: 880
The carbon and oxygen isotope excursion of the Late Neoproteroic to Early Cambrian Taozichong Formation in Qingzhen City, Guizhou Province, Southwest China: Implication for phosphorite formation
Yang, R.1, Mao, T.1 and Gao, J.1
1College of Resources and Environmental Engineering, Guizhou University, Guiyang 550025, China
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Taozichong Formation is a phosphate-bearing sedimentary sequence of the Late Neoproterozoic to Early Cambrian period in Qingzhen, Guizhou Province. Carbon and oxygen isotopic compositions of carbonate rocks in this sequence are analysed and compared with other synsedimentary carbon isotope profiles of the same time interval[1]. The results showed three negative anomalies of carbon isotopes in the Taozichong Formation (Fig.1①②③), indicating a significant temporal change in palaeo-oceanographical environment, in which there happened two times of intensive carbon isotope variation, corresponding to creature extinction[2].
Figure 1: The carbon and oxygen isotope excursion for the Taozichong Formation in Qingzhen City, Guizhou Province
1. Black shale; 2. bioclastic phospholite; 3. siliceous phospholite; 4. silicalite; 5. foliated clay stone; 6. brown weathered crust; 7. dolostone; 8. siliceous dolostone containing phosphorus; 9. brecciaous phosphorite.
References:
[1] Yang R et al. (2005) Acta Geologica Sinica 79:158−164
[2] Yang R et al. (2004) Progress in Natural Science 14(10): 898-904
[3] Chen Jiyan et al.(2012) Journal of Rare Earths 31(1): 101-111