A resin nodule in the Cretaceous Garschella Formation from Langer Kochel (Bavaria, S Germany): possible origin and palaeogeographic provenance

作者：Engelbrecht Hubert^*; Foellmi Karl B; Baumer Ursula; Koller Johann

来源：Swiss Journal of Geosciences, 2010, 103(1): 3-13.

DOI：10.1007/s00015-010-0003-7

• Resin nodule
• Amber
• Garschella formation
• Cretaceous
• Agathalene
• Palaeogeography

A resin nodule was found in glauconite-rich detrital sediments of the Cretaceous Garschella Formation (Aptian to Albian) outcropping at Langer Kochel (Bavaria, S Germany). Gas chromatographic and mass spectrometric analyses of the fossil resin revealed dealkylation and the total defunctionalisation of its polycyclic constituents. Besides many unspecific components a specific one, agathalene, has survived. Agathalene also presents a strongly degraded product, but may have been derived from its natural precursor agathic acid, which is a very specific constituent (biomarker) of recent and fossil kauri resin. Although agathalene is a far less specific secondary biomarker, it indicates the botanic origin of the fossil resin nodule. Besides other potential producers of agathic acid, precursors of the present-day conifer species Agathis dammara and A. australis were distributed in a wider palaeophytogeographic range than today and might have been the botanical source of kauri resin. In view of the east-west directed Early Cretaceous surface current system of the Tethys ocean, the palaeogeographic provenance of the Werdenfels resin nodule probably was a mainland positioned further to the east or southeast of the Helvetic shelf, to where it was transported probably by driftwood of the resin-producing Agathis sp.

• 出版日期2010-7