Archaeocyathan zonation of the Yangtze Platform: Implications for regional and global correlation of lower Cambrian stages

Abstract

AbstractDetailed analysis of the distribution of archaeocyaths in five lower Cambrian sections in South China has resulted in the erection of four new archaeocyathan zones and one new archaeocyathan bed. Listed in order of ascending age, these are: theDailycyathus xiuqiensisZone; theDictyocyathus shaanxiensisZone; theSpirillicyathus duplexRange Zone; theSibirecyathus meitanensisRange Zone; and theArchaeocyathus yanjiaoensisbeds. These new subdivisions permit a correlation of lower Cambrian strata both within the area of the Yangtze Platform (South China) as well as between this region and Siberia, Australia, Western Europe and North America. Within the Yangtze Platform area, archaeocyaths of theDailycyathus xiuqiensisandDictyocyathus shaanxiensiszones co-occur with trilobites of the middle and upperEoredlichiaTrilobite Zone of the Qiongzhusian Stage. TheSpirillicyathus duplexand theSibirecyathus meitanensisRange Zone correspond to theMalungia, Yiliangella–YunnanaspisandDrepanuroidesTrilobite zones of the basal and middle Canglangpuan Stage, respectively. Finally, theArchaeocyathus yanjiaoensisbeds belong to thePalaeolenus fengyangensisTrilobite Zone of the upper Canglangpuan Stage. Global correlations based on archaeocyath assemblage zones suggest that: (1) the middle–upper Qiongzhusian of South China correlates with the middle Atdabanian Stage of the Siberian Platform, theWarriootacyathus wilkawillinensisArchaeocyath Zone in South Australia, the middle Issendalenian Stage of Morocco and the lower Ovetian Stage in Spain; (2) the lowermost Canglangpuan Stage of South China correlates with the uppermost Atdabanian of the Siberian Platform, theSpirillicyathus tenuis – Jugalicyathus tardusarchaeocyath zones in South Australia, the uppermost Issendalenian – lower Banian stages of Morocco, the middle Ovetian Stage of Spain and the middle Montezuman Stage of North America; (3) the middle Canglangpuan Stage approximates the lowermost Botoman Stage of the Siberian Platform, middle Banian Stage of Morocco, the uppermost Ovetian – lowermost Marianian stages of Spain and the upper Montezuman Stage of North America; (4) the uppermost Canglangpuan Stage is equivalent of the middle Toyonian Stage of the Siberian Platform,Archaeocyathus abacusbeds in Australia, the middle Bilbilian Stage in Spain and the middle Dyeran Stage (Bolbolenellus eurypariaTrilobite Zone) in North America.