Pollen analysis of the mid-lake Indian Cove well in the Great Salt Lake, collected by Amoco Production Co., provides a 1.5 Ma record of climatic change, correlative with the deep-sea oxygen isotope record. Chronologic control for Indian Cove is provided by the Lava Creek B (0.060 Ma). Bishop (0.76 Ma), and Huckleberry Ridge (2.06 Ma) volcanic ashes. The processing of close-interval (3 m. ca. 8 ka) samples is complete for the upper 628 m (1.5 Ma) of the Indian Cove well. During the last 750 ka. interglacial glacial cycles are expressed as the ratio of Juniperus + Ambrosia + Sarcobatus (interglacial) vs. Picea, Abies, and Pseudotsuga (glacial). Correlating the peak abundances of this ratio with the odd-numbered oxygen isotope stage has refined the time control provided by three volcanic tephra. The average Pleistocene sedimentation rate is 0.39 m ka-1 (Huckleberry Ridge, 2057 ka. 797 m). Based on the refined time scale, resulting from correlation with the marine chronology, sedimentation reached maximum values during isotope stages 11.9, and was slow between stages 13 and 11 and stages 9.7. Development of the Bonneville Pluvial cycles, from 759 to 600 ka, is recorded by changes in wetland and aquatic palynomorphs. Increased pollen concentration above 150 m (310 ka) may result from the diversion of the Bear River into the Great Salt Lake Basin.
ASJC Scopus subject areas
- Ecology, Evolution, Behavior and Systematics
- Earth-Surface Processes