Zoeken
Zoeken kan via de modus 'eenvoudig zoeken' (één veld) of uitgebreid via 'geavanceerd zoeken' (meerdere velden). Zo kan je bv. zoeken op een combinatie van een auteursnaam (auteur), een jaartal (jaar) en een documenttype.
Boekenmand
Nuttige resultaten kan je aanvinken en toevoegen aan een mandje. De inhoud hiervan kan je exporteren of afdrukken (naar bv. PDF).
RSS
Op de hoogte blijven van nieuw toegevoegde publicaties binnen uw interessegebied? Dit kan door een RSS-feed (?) te maken van jouw zoekopdracht.
nieuwe zoekopdracht
| one publication added to basket [211457] |
Ground-truthing Late Ordovician climate models using the paleobiogeography of graptolites
Vandenbroucke, T.R.A.; Armstrong, H.A.; Williams, M.; Zalasiewicz, J.A.; Sabbe, K. (2009). Ground-truthing Late Ordovician climate models using the paleobiogeography of graptolites. Paleoceanography 24(4). dx.doi.org/10.1029/2008PA001720
In: Paleoceanography. American Geophysical Union: Washington, DC. ISSN 0883-8305; e-ISSN 1944-9186
|  |
| Trefwoord |
|
| Author keywords |
Sandbian; zooplankton; graptolites; faunal gradients; paleobiogeography; paleoecology |
| Auteurs | | Top |
- Vandenbroucke, T.R.A.
- Armstrong, H.A.
- Williams, M.
|
- Zalasiewicz, J.A.
- Sabbe, K.
|
|
| Abstract |
The d 18O records obtained from conodonts suggest that during the Mid-Ordovician, equatorial temperatures stabilized at close to the present day, a hypothesis broadly supported by published climate models. However, the degree to which equatorial temperatures represent global climate state and varied between different climatic modes (greenhouse/icehouse, interglacial/glacial) and to what extent Ordovician d 18O and climate models truly reflect the global climate remain to be tested. Here we present paleobiogeographical data for the planktonic graptolites, from the gracilis time slice (i.e., early Sandbian Stage) that just postdates the postulated onset of climate stabilization. TWINSPAN analysis and constrained seriation provide robust ecological groupings in paleobiogeographical presence/absence data. The highest-level groups reflect tropical-subtropical assemblages and a high–southerly latitude assemblage. Constrained seriation defines latitude-distinct biotopes that are considered equivalent to modern zooplanktonic provinces. The distribution pattern of graptolite biotopes in the gracilis time slice show (1) that models explaining local graptolite ecological assemblages using lateral differentiation (e.g., upwelling) are to be favored above those using depth stratification and (2) a steep faunal gradient from equator to pole, which is typical of a cool, nongreenhouse world and comparable to the modern situation. We therefore broadly support the climate stabilization hypothesis. Paradoxically the climate of the early Late Ordovician appears similar to that of the present day despite the higher atmospheric pCO2 levels. Graptolite species were indicative of temperature-controlled ocean water masses, in much the same way as the modern zooplankton. |
IMIS is ontwikkeld en wordt gehost door het VLIZ.
