Measurements of in situ produced 14C in terrestrial rocks.

We developed and are testing a system for extracting in situ produced 14C from quartz. 14C is liberated from quartz matrix using step-wise heating during which time a spiked carrier gas consisting O2–CO–CO2–He is flowed through the high-temperature chamber continuously. The total 14C background is reproducible and typically (2.3 ± 0.2) × 106 atoms, and the recovery is consistently greater than 90%. To validate the performance of the system and determine the blank level, we are using quartz samples taken from the Homestake mine (1600 m below the surface), South Dakota. To determine the 14C release pattern and recovery, we used samples taken from the Transantarctic Mountains, Antarctica. [Copyright &y& Elsevier]