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| Titel |
Vegetation and climate development on the Atlantic Coastal Plain during the late Mid-Miocene Climatic Optimum (IODP Expedition 313) |
| VerfasserIn |
Sabine Prader, Ulrich Kotthoff, Francine McCarthy, David Greenwood |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250110826
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| Publikation (Nr.) |
 EGU/EGU2015-10866.pdf |
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| Zusammenfassung |
| The major aims of IODP Expedition 313 are estimating amplitudes, rates and mechanisms of
sea-level change and the evaluation of sequence stratigraphic facies models that
predict depositional environments, sediment compositions, and stratal geometries in
response to sea-level change. Cores from three Sites (313-M0027, M0028, and
M0029) from the New Jersey shallow shelf (water depth approximately 35 m) were
retrieved during May to July 2009, using an ECORD "mission-specific" jack-up
platform.
We have investigated the palynology of sediment cores from Site M0027, 45 km off
the present-day coast of New Jersey. For this study, we have focused on pollen
studies for the second half of the Mid-Miocene Climatic Optimum (MMCO) and the
subsequent transition to cooler conditions (ca. 15 to 13 million years before present).
Transport-caused bias of the pollen assemblages was identified via the analysis of the
terrestrial/marine palynomorph ratio and these results were considered when interpreting
palaeo-vegetation from the pollen data. Pollen preservation in the interval analyzed herein
was generally very good. Pollen grains were analyzed via both light and scanning electron
microscopy.
For most samples, the pollen assemblages were not highly diverse. The most abundant
taxa through all samples were Quercus (oak) and Carya (hickory). Typical wetland elements
like Cyperaceae, Taxodium (cypress), Nyssa (tupelo tree) and taxa today growing in the
tropics and subtropics like Sapotaceae, Symplocaceae, Arecaceae (palm trees) and Alangium,
which indicate particularly warm climate conditions, were only sporadically found, but
indicate warmer phases during the second half of the MMCO. Herbal pollen was generally
rare, but members of the Asteraceae, Apiaceae, and Ericaceae families, together with
infrequent occurences of Poaceae pollen indicate the presence of areas with open
vegetation.
The Mid-Miocene pollen assemblages reflect a vegetation in the hinterland of the New
Jersey shelf which was reminiscent of Oligocene and early Miocene ecosystems analyzed in
previous studies (e.g. Kotthoff et al. 2014). The ecosystem was characterized by oak-hickory
forests which probably dominated in the lowlands, while frequent occurrence of conifer
pollen (Pinus, Picea, Abies, Sciadopitys, and Tsuga canadensis) indicate that conifer forests
prevailed in higher altitudes during the MMCO. We assume that the Miocene uplift of
the Appalachian Mountains (e.g. Gallen et al., 2013) led to the proliferation of
mountainous taxa and thus to an increase of related pollen taxa in the palynological
record.
References:
Gallen, S. F., Wegmann, K. W., Bohnenstieh, D. W. R.: Miocene rejuvenation of
topographic relief in the southern Appalachians, GSA Today, 23, 4–10, 2013.
Kotthoff, U., McCarthy, F.M.G., Greenwood, D.R., Müller-Navarra, K., Prader, S.,
Hesselbo, S.P., (2014): Vegetation and climate development on the Atlantic Coastal Plain
from 33 to 13 million years ago (IODP expedition 313). Climate of the Past 10, 1523-1539. |
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