NORTHERN ENGLAND SERPUKHOVIAN (EARLY NAMURIAN) FARFIELD BRACHIOPOD AND PLANT ISOTOPE RESPONSES TO SOUTHERN HEMISPHERE GLACIATION
Altro
Data di Pubblicazione:
2010
Citazione:
NORTHERN ENGLAND SERPUKHOVIAN (EARLY NAMURIAN) FARFIELD BRACHIOPOD AND
PLANT ISOTOPE RESPONSES TO SOUTHERN HEMISPHERE GLACIATION / M.H. Stephenson, L. Angiolini, P. Cózar, F. Jadoul, J. Melanie, D. Millward. ((Intervento presentato al convegno Internation Palaeontological Congress IPC3 tenutosi a Londra nel 2010.
Abstract:
The Serpukhovian was a period of climatic change in Gondwana with glaciation being initiated in limited
areas of eastern Australia, South America and Tibet. The Serpukhovian is poorly represented by farfield
isotope studies. Previous surveys of isotope data from brachiopod carbonate have few Serpukhovian sample
points, as well as low values questioned by previous workers. Similarly organic δ 13 C which mainly tracks
terrestrial plant tissue is poorly represented in the Serpukhovian. The Woodland, Throckley and Rowlands
Gill boreholes (northern England) contain a Serpukhovian to Bashkirian farfield record newly dated by
foraminiferans. δ 18 O values from late Serpukhovian Woodland brachiopods vary between -3.4 and -6.3‰,
and δ 13 C varies between -2.0 and + 3.2‰, confirming low values recorded elsewhere and suggesting a δ 18 O
seawater (w) value of around -1.8‰ VSMOW, and therefore an absence of widespread ice-caps. The
organic carbon δ 13 C increasing trend in the Throckley Borehole (Serpukhovian to Bashkirian; c. -24 to
c. -22‰), and the Rowlands Gill Borehole (Serpukhovian; c. -24 to c. -23‰) indicates large-scale burial of
organic material, probably in burgeoning lycophyte-dominated coal forest and would imply a steady fall in
pCO
2
. Therefore these high resolution data show that at least one substantial period of the Serpukhovian
cannot have been glaciated. The steady fall in Serpukhovian pCO
2
appears not to have caused large-scale
glaciation until the early Bashkirian, but a scenario of coalescing upland icecaps through the Serpukhovian
with a background of decreasing pCO
2
, appears to be similar to the process that initiated Cenozoic Antarctic
glaciation.
Tipologia IRIS:
14 - Intervento a convegno non pubblicato
Elenco autori:
M.H. Stephenson, L. Angiolini, P. Cózar, F. Jadoul, J. Melanie, D. Millward
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