DATING GLACIAL SURFACES ON BAFFIN ISLAND


We have been funded to use the cosmogenic nuclides 10Be and 26Al to determine when portions of Baffin Island were last glaciated. Two summers of field work have resulted in the collection of nearly 170 samples. P. T. Davis (PI) spent three weeks in Baffin Island during the summer of 1994 collecting about 30 samples for analysis and Kim Marsella, the Masters student supported by this grant, led a field party of 8 in the collection of 140 samples and the mapping of moraines during the summer of 1995. The dozen isotopic analyses made so far show excellent correlation of model 10Be and 26Al ages and suggest that portions of Pangnirtung fjord previously believed to be ice free since the mid-Wisconsinan were likely occupied by ice as recently as the early Holocene. Marsella has purified quartz from over half of the collected samples and has shown that stable Al can be reduced to extremely low-levels in Baffin quartz (<100 ppm) making relatively high precision measurements possible even considering the short exposure ages.


JULY 11.......


WE SAMPLED BEDROCK SURFACES AT CRATER LAKE WHICH HAD BEEN EXPOSED BY ICE RETREAT IN THE PAST 20 YEARS. 10-BE ABUNDANCES FOR SAMPLES WERE SIMILAR TO OUR PROCESS BLANKS.


KIM MARSELLA POINTS OUT THE DUVAL MORAINES OUTSIDE OF PANG


TOM DAVIS ON A DUVAL RECESSIONAL MORAINE


CHRISTINE MASSEY ON UPLAND BEDROCK TOR. SAMPLES FROM 6 SUCH TORS ALL SHOW ISOTOPIC EVIDENCE FOR BURIAL AFTER OR DURING EXPOSURE

For more information see

Marsella, K. and P. Bierman (1995). "Timing and extent of glaciation on southern Baffin Island, NWT, Canada determined using in situ produced cosmogenic isotopes 10-Be and 26-Al." Terra Nostra INQUA (Berlin, 26) 179.

Marsella, K., P. T. Davis, and Bierman, P. (1995). "Geologic test of weathering zone concept and nunatak hypothesis using cosmogenic isotope dating in Pangnirtung fjord area, Baffin Island, Nunavat Territory, Canada. Geological Society of America Abstracts with Programs 27 (6): A-59.

Davis, P. T., Marsella, K. A., Bierman, P. R., Finkel, R. C., Caffee, M., Southon, J. and Koning, J. (1995). Timing and extent of glaciation on southern Baffin Island, Nunavut Territory, arctic Canada, using in situ cosmogenic isotopes. Geological Society of America Abstracts with Programs 27 (6) A-60.

Research supported by CAMS, Livermore National Laboratory; NSF, Polar Programs.
In collaboration with Tom Davis (Bentley College), Marc Caffee and Bob Finkel (LLNL).