Abstract

The carbon-isotope composition of fossil wood fragments, collected through a biostratigraphically well-constrained Aptian (Lower Cretaceous) shallow-marine siliciclastic succession on the Isle of Wight, southern Britain, shows distinct variations with time. The results indicate that the stratigraphic signature of δ13Cwood through the Aptian was influenced primarily by fluctuations in the isotopic composition of CO2 in the global ocean-atmosphere system, as registered in marine carbonates elsewhere, and was not governed by local paleoenvironmental and/or paleoecological factors. Negative and positive excursions in δ13Cwood through the lower Aptian occur in phase with inferred transgressions and regressions, respectively—a pattern that contrasts with that observed in many previous studies for different time intervals. The relationship between δ13C variations and relative sea-level change is tentatively interpreted as a response to various climatic and eustatic factors, relating to rapid sea-floor spreading, thermal uplift of ocean floor, emplacement of plateaus, volcanic CO2 emissions, weathering, and sedimentary rate.

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