Dating speleothems from the Silberen Cave System and surrounding areas: Speleogenesis in the Muota Valley (Central Switzerland)

作者：Wildberger Andres^*; Geyh Mebus A; Groner Urs; Haueselmann Philipp; Heller Friedrich; Ploetze Michael

来源：Zeitschrift fur Geomorphologie, 2010, 54: 307-328.

DOI：10.1127/0372-8854/2010/0054S2-0016

• Dating of speleothems
• speleogenesis
• Axen nappe (Helvetic realm)
• Silberen cave system
• Holloch cave system
• Muota valley

Inactive stalagmites from the Silberen cave system and its surroundings (Muota Valley, Central Switzerland) have been dated by the (230)Th/U method (alpha spectrometry and TIMS). Several samples yielded ages of approximately 200 ka (MIS 7) and 320 ka (MIS 9), others were beyond the upper limit of the method (about >350 ka) or might have behaved as open systems with respect to uranium.
The following complementary dating methods were applied: (234)U/(238)U, paleomagnetism, palynology and electron spin resonance. Paleomagnetism yielded positive inclination of the natural remanent magnetization of two stalagmite samples, corresponding to the Brunhes-epoch (<780 ka) or older epochs with positive inclination (Jamarillo 970-900 ka, Olduvai 1870-1670 ka). The palynological investigations of four samples indicated no deviation to the recent vegetation; especially Pliocene and Early Pleistocene pollen and spores were absent. The combination of (230)Th/U ages, palynological analysis and paleomagnetic records provides evidence of stalagmite ages between 780 and 200 ka. (234)U/(238)U and ESR dating did not yield conclusive results.
The uplift rate of the mountains, the corrosion rate of the karstified surface and the incision of the valley bottom, suggest that karstification started 4 to 3 Ma (Middle to Upper Pliocene). The dated speleothems are therefore substantially younger than the beginning of speleogenesis.

• 出版日期2010-3