Lower Carboniferous miospore assemblages from the Longba Formation in Gengma, West Yunnan, China and their phytogeographic significance

Yang Wei-ping, Roger Neves and Liu Ben-pei

pp. 1-19, 2 plates, in English

Abstract:

The palynology of the Lower Carboniferous succession from the Longba Formation, a new formation for the lower horizons of the original Nanpihe Formation in Gengma, West Yunnan, S.W. China is described. The miospore floras from 56 samples are discussed and tentatively correlated with those in West Europe and Australia respectively. An attempt is made to correlate these Gengma assemblages with the standard West Europe miospore zones and the LE, BP, PC (?) and Pu biozones of Higgs et al. (1998) could be found in the Longba Formation, Gengma. The discovery of a Retispora lepidophyta assemblage, a Grandispora spiculifera assemblage (originally described by Playford 1976) and a Lycospora pusilla assemblage changed these abundantly microfloral-bearing strata of the Longba Formation from upper Permian to uppermost Devonian (Strunian) and Lower Carboniferous (Tournaisian and Visean).

A tentative palynofacies analysis of the Longba Formation, in addition to the lithological and sedimentary studies, shows the original Nanpihe Formation to be a deeper marine sequence (probably slope) instead of a coal-bearing, paralic environment.

The miospore similarities of West Yunnan with both West Europe and Australia indicate that West Yunnan (S.W. China) in early Carboniferous was perhaps located much further to the south than the previous continent reconstruction suggested. This conclusion also modified the fundamental phytogeography in this Changning-Menglian Belt from solely Cathaysian (Lobatannularia ? sp.) to a mixture of Gondwana and Laurasian floras.

Keywords: Miospore, Lower Carboniferous, Longba Formation, West Yunnan