Aspects of late devonian and early carboniferous palynology of southern Ireland. III. Palynology of devonian—carboniferous transition sequences with special reference to the bantry bay area, co. cork

Abstract

The present paper provides: (1) an analysis of the qualitative and quantitative compositional development of Late Devonian-Early Carboniferous palynological assemblages from the Bantry Bay and other sections of southern Ireland; (2) a scheme of successive phases, (inter) regionally recognizable in the gradual compositional development of Late Devonian-Early Carboniferous palynological assemblages; (3) a palynological zonation based on three successive assemblages zones (Retispora lepidophyta Assemblage Zone, Verrucosisporites nitidus Assemblage Zone, Spelaeotriletes pretiosus Assemblage Zone); and (4) two palaeogeographically related local phases, within the scheme of regional phases.

It is concluded that: (1) the scheme of regional phases, in combination with the assemblage zones recognized, provides a more realistic tool for long-range palynostratigraphical correlation than the earlier proposed schemes of concurrent range zones; (2) the assemblage zones may be used for chronostratigraphical purposes, the boundary between the Retispora lepidophyta Assemblage Zone and the Verrucosisporites nitidus Assemblage Zone approximates the conventional Devonian-Carboniferous boundary; (3) the palaeogeographically related local phases may be considered to reflect floras of the coastal and alluvial plain, and the coastal-deltaic area, respectively; (4) within southern Ireland, the palynologically determined Devonian-Carboniferous boundary lithostratigraphically correlates with a thin mudstone unit (Claystone Member, Castle Slate Member).

The taxonomical part includes: (1) an emended diagonosis of Lophozonotriletes; (2) formal proposals of new combinations of Ceratosporites delicatus, Asperispora acuta, Asperispora perlota and Diaphanospora scolecophora; and (3) the establishment of the Verrucosisporites nitidus morphon and the Dictyotriletes submarginatus morphon.