Question 1 a. Define the terrestrial age of a meteorite and explain, how this is determined. b. if a meteorite were to be of Martian origin, explain where the oxygen isotope

composition of this sample and other Martian samples would appear with respect to the terrestrial fractionation line (TFL) on a plot of 170 versus 180 using figure 9.16 Figure 9.16 A plot of 80 and 8¹% for whole-rock meteorites is shown in Figure 9.16. Compare the scales of this plot with those of Figure 9.15; while astronomical entities display vast variations in oxygen isotopic compositions, those of materials formed within the solar nebula are much less variable (although the small differences which can be measured are of immense importance). Note the line of slope 0.5 representing the TFL. 870% 2 terrestrial fractionation line 17 calcium-aluminium- rich inclusions 2 8180/% bulk meteorites Figure 9.16 Plot of 6¹70 and 5180 for whole-rock meteorite samples. Each different coloured field represents a different type of meteorite group (included on the plot are fields for different groups of carbonaceous chondrites, different types of ordinary chondrites, Martian meteorites, HEDs, and so on). The inset shows the range in oxygen isotopic composition of all bulk meteorite samples and covers a range in 8¹O values from -40 to +20% and in 8¹70 values from -40 to +30%. The region of the main graph is 10 shown by the shaded box in the inset. (Franchi et al., 2001)