Mineralogic and stable isotopic characteristics of select Great Basin speleothems
Abstracts with Programs - Geological Society of America
The mineralogy and stable isotopic chemistry of stalagmites from three caves in east-central Nevada, Lehman Caves, Great Basin National Park, Mineral Hill Cave, and Goshute Mountain Cavern, have been investigated in an attempt to constrain the exact timing of late Quaternary climatic and vegetation shifts in the Great Basin. 238U-234U-230Th alpha spectrometry dating of these samples demonstrates that the majority of the speleothems have not been active for >350,000 years. A small number have been dated to the middle Holocene (6 ka) and the last interglacial (approx. 120 ka). Each of these samples is characterized by similar alternating layers of brown, dense calcite and white, fibrous calcite and aragonite. Both carbon and oxygen isotopic values remain largely consistent (vary to less than 1) within individual stalagmites, even between dense and fibrous layers. Oxygen isotopic values are low, ranging from -8 to -14 PDB, suggesting that speleogenesis is sustained predominantly by infiltrating snow melt delivered to high elevations. These preliminary data suggest that speleothem growth was more active during warm-wet interglacial periods than during glacials.
Published Article/Book Citation
Abstracts with Programs - Geological Society of America, 32:4 (2000) pp.11.