Micro- and megafloral remains of namurian H-G1 zones from Zhongwei of Ningxia, China

Abstract

Abundant micro- and megafloral remains of Namurian H-G1 zones have been studied from the Hongtuwa Formation in Zhongwei, Ningxia, China. The former consists of 80 species of 45 genera, which can be subdivided into two miospore assemblages, i.e., Lycospora subtriquetra-Gansusispora mammilla (SM) Zone and Gardenasporltes pinnatus-Microreticulatisporites concavus (PC) Zone. They are roughly correlative to the H Zone of Namurian A stage and R-G1 zones of Namurian B-C stages, respectively. The megafloral remains include 23 species of 18 genera and is known as Mesocalamites cistiformis-Paripterisgigantea assemblage. It is comparable with the Middle to Late Namurian flora of the North Qilian Mountains, China. Both micro- and megaplant fossils indicate that the Middle to Late Namurian flora in Zhongwei is dominated mainly by Filices and Pteridospermopsida, Lycopsida and Sphenopsida occupy a subdominant position, while Cordaitopsida and Coniferopsida are not significant. The present flora reflects the coastal plain and delta environments as well as a tropical-subtropical warm and humid palaeoclimate.