New palynology-based astronomical and revised Ar-40/Ar-39 ages for the Eocene maar lake of Messel (Germany)

作者：Lenz Olaf K^*; Wilde Volker; Mertz Dieter F; Riegel Walter

来源：International Journal of Earth Sciences, 2015, 104(3): 873-889.

DOI：10.1007/s00531-014-1126-2

• Paleogene
• Maar lake
• Palynology
• Ar-40/Ar-39 age
• Astronomical tuning
• Milankovitch cycles

The annually laminated oil shale from the Eocene maar lake at Messel (Federal State of Hessen, Germany) provides unique paleoenvironmental data for a time interval of similar to 640 ka during the Paleogene greenhouse phase. As a consequence of orbitally controlled changes in the vegetation in the vicinity of the lake, the lacustrine laminites can now be astronomically tuned. Dating is based on the short eccentricity amplitude modulations of the regional pollen rain and their correlation to the astronomical La2010a/La2010d solutions in combination with a revised Ar-40/Ar-39 age of a basalt fragment from a lapilli tuff section below the first lacustrine sediments. Depending on different newly suggested ages for the Fish Canyon sanidine used as monitor for neutron irradiation, the age for the eruption at Messel is between 48.27 +/- A 0.22 and 48.11 +/- A 0.22 Ma. This allows for the first time the exact correlation of a Paleogene lacustrine sequence to the marine record in Central Europe. The Messel oil shale becomes now slightly older than previously assumed and includes the Ypresian/Lutetian boundary that moves the base of the European Land Mammal Age Geiseltalian (MP 11) into the Lower Eocene. This opens a window for establishing an independent chronostratigraphic framework for Paleogene terrestrial records and their correlation to the marine realm. Furthermore, the study reveals that higher amounts of pollen from "wet" and thermophilous plants indicate less seasonal and more balanced precipitation and slightly higher temperatures during a well-expressed eccentricity minimum.

• 出版日期2015-4