Aluminum‐26, sodium‐22 and cobalt‐60 in two drill cores and some other samples of the Jilin chondrite

Two drill cores have been taken from the main mass of the Jilin chondrite, Jilin I. One was bored perpendicular to the 2π surface of the first exposure stage, the other parallel to this surface, and both intersected at the presumed 4π center of Jilin's second exposure stage. The probed depths were 65 cm and 105 cm, respectively, with a diameter of 26.5 mm. Fifteen drill core samples, 2 documented samples and 14 strewn field samples have been analysed for 26Al, 60Co and 22Na. The reconstruction of the preatmospheric Jilin via 60Co resulted in slight deviations for the center position and for the radius (now R = 80+10−5 cm) compared to an earlier study in 1985. The 60Co production rate profile is now almost completely reproduced. A constant production rate of 22Na and of 26Al during the 4π irradiation is confirmed also for the center region. The good linear correlation of 26Al and 21Ne yields slightly revised irradiation ages for both stages of t1 = 7 ± 1 Ma and t2 = 0.32+0.06‐0.03 Ma.