palynological evidence for pennsylvanian extra-basinal ...€¦ · в Атлантическа...

95 БЪЛГАРСКО ГЕОЛОГИЧЕСКО ДРУЖЕСТВО, Национална конференция с международно участие „ГЕОНАУКИ 2010“ BULGARIAN GEOLOGICAL SOCIETY, National Conference with international participation “GEOSCIENCES 2010” Embedded within these clastic palynological data, however, is also evidence of the vegetation from areas surrounding the wetland depositional basins (extra-basinal habitats) in the form of rare “exotic” pa- lynomorphs. Although a few authors have discussed these “exotic” elements their significance has gener- ally been ignored. In this paper, we look at two sets of palynological samples from the Upper Asturian and Lower Cantabrian Substages (Moscovian Stage) of the Sydney Coalfield, Cape Breton, Atlantic Canada (Fig. 1). The evidence that these samples provide about the wetland vegetation has been described elsewhere; the present study will instead look at what they tell us about the vegetation in areas surrounding the depositional basin. Pollen preserved in Late Westphalian and Early Stephanian clastic deposits of the Sydney Coalfield suggest that there was a concentric set of vegetational habitats surrounding the wetlands where the coal- forming peat was formed. On the margins of the wet- Palynological evidence for Pennsylvanian extra-basinal vegetation in Atlantic Canada Палиноложки доказателства за околоблатната растителност в Атлантическа Канада Tatyana Dimitrova 1 , Christopher Cleal 2 , Barry Thomas 3 Татяна Димитрова 1 , Кристофър Клил 2 , Бари Томас 3 1 Geological Insititute, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 24, 1113 Sofia, Bulgaria; E-mail: [email protected] 2 Department of Biodiversity and Systematic Biology, National Museum of Wales, Cathays Park, Cardiff CF10 3NP, UK; E-mail: [email protected] 3 Institute of Rural Sciences, Aberystwyth University, Llanbadarn Fawr, Aberystwyth SY23 3AL, UK; E-mail: [email protected] Key words: Westphalian, vegetation, Cape Breton, Canada. lands was a narrow band with large cordaitanthacean trees. This was surrounded by “occasionally-dry” habitats supporting Schuetzia-plants, ruflorioid-plants and Aethophyllum-like herbaceous conifers. Around this were mesic or seasonally-dry habitats, dominated by walchian conifers, cycads and disaccates-producing peltasperms. These in turn were surrounded by xeric or seasonally-wet habitats, dominated by ullman- niacean conifers, cycads and monsaccates-producing peltasperms. During Late Westphalian and Early Stephanian times, the mesic and xeric habitats en- croached nearer to the wetlands, although the vegetation of the wetlands themselves remained essentially unaffected. This vegetation change was not a response to climate change, but probably to changing drainage patterns and topography in the surrounding hinterland. The Florinites-producing cordaitanthaceans appear not to have been upland trees, as previously suggested, but occupied mainly coastal habitats, or riparian habitats on the margins of the wetlands.

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Page 1: Palynological evidence for Pennsylvanian extra-basinal ...€¦ · в Атлантическа Канада Tatyana Dimitrova 1 , Christopher Cleal 2 , Barry Thomas 3 Татяна

БЪЛГАРСКО ГЕОЛОГИЧЕСКО ДРУЖЕСТВО, Национална конференция с международно участие „ГЕОНАУКИ 2010“BULGARIAN GEOLOGICAL SOCIETY, National Conference with international participation “GEOSCIENCES 2010”

Embedded within these clastic palynological data, however, is also evidence of the vegetation from ar-eas surrounding the wetland depositional basins (ex-tra-basinal habitats) in the form of rare “exotic” pa-lynomorphs. Although a few authors have discussed these “exotic” elements their significance has gener-ally been ignored. In this paper, we look at two sets of palynological samples from the Upper Asturian and Lower Cantabrian Substages (Moscovian Stage) of the Sydney Coalfield, Cape Breton, Atlantic Canada (Fig. 1). The evidence that these samples provide about the wetland vegetation has been described elsewhere; the present study will instead look at what they tell us about the vegetation in areas surrounding the depositional basin.

Pollen preserved in Late Westphalian and Early Stephanian clastic deposits of the Sydney Coalfield suggest that there was a concentric set of vegetational habitats surrounding the wetlands where the coal-forming peat was formed. On the margins of the wet-

Palynological evidence for Pennsylvanian extra-basinal vegetation in Atlantic CanadaПалиноложки доказателства за околоблатната растителност в Атлантическа КанадаTatyana Dimitrova1, Christopher Cleal2, Barry Thomas3

Татяна Димитрова1, Кристофър Клил2, Бари Томас3

1 Geological Insititute, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 24, 1113 Sofia, Bulgaria; E-mail: [email protected] Department of Biodiversity and Systematic Biology, National Museum of Wales, Cathays Park, Cardiff CF10 3NP, UK; E-mail: [email protected] Institute of Rural Sciences, Aberystwyth University, Llanbadarn Fawr, Aberystwyth SY23 3AL, UK; E-mail: [email protected]

Key words: Westphalian, vegetation, Cape Breton, Canada.

lands was a narrow band with large cordaitanthacean trees. This was surrounded by “occasionally-dry” habitats supporting Schuetzia-plants, ruflorioid-plants and Aethophyllum-like herbaceous conifers. Around this were mesic or seasonally-dry habitats, dominated by walchian conifers, cycads and disaccates-produc-ing peltasperms. These in turn were surrounded by xe-ric or seasonally-wet habitats, dominated by ullman-niacean conifers, cycads and monsaccates-producing peltasperms. During Late Westphalian and Early Stephanian times, the mesic and xeric habitats en-croached nearer to the wetlands, although the vegeta-tion of the wetlands themselves remained essentially unaffected. This vegetation change was not a response to climate change, but probably to changing drainage patterns and topography in the surrounding hinterland. The Florinites-producing cordaitanthaceans appear not to have been upland trees, as previously suggested, but occupied mainly coastal habitats, or riparian habitats on the margins of the wetlands.