TABLE 3.

δ¹³C values and standard errors for spots determined by SIMS in the mat section shown in Fig. 3

Spot in mat section	Area in beta imager micrographa	δ13C	SE
A	LASL	−74.7	0.5
B	HASSL	−75.5	0.6
C	HASSL	−60.7	1.4
D	HASSL	−63.8	0.6
E	HASSL	−62.9	1.3
F	LASL	−66.2	1.5
G	LASL	−77.0	1.7
I	LASL	−66.7	0.8
J	LASL	−64.5	0.9
K	LASL	−64.3	0.5
L	LACL	−69.1	0.9
M	LACL	−72.6	0.8
N	LACL	−70.4	1.1
O	LASL	−65.3	0.8
P	LASL	−63.1	0.8
Q	LASL	−63.4	1.1
R	LASL	−63.0	0.8
S	HASSL	−76.3	0.8
T	HASSL	−75.8	0.8
U	HASSL	−72.2	1.0
V	LASL	−63.7	0.7
W	LASL	−65.3	0.9
X	LASL	−66.2	2.4
Y	HASSL	−75.0	0.9
Z	HASSL	−72.2	1.1
AA	HASSL	−65.6	0.8
BB	HASSL	−66.2	0.8
CC	LACL	−76.0	0.8
DD	LASL	−76.0	0.5
EE	LASL	−60.7	1.1
FF	LACL	−71.4	0.9
GG	LACL	−76.6	2.2
HH	HASSL	−75.7	0.9
II	HASSL	−66.8	0.8
JJ	HASSL	−77.7	0.6
KK	LACL	−73.7	0.5
LL	LACL	−74.6	0.7
1	HASSL	−57.6	1.3
2	HASSL	−60.2	1.3
3	HASSL	−60.4	1.7
4	HASSL	−56.0	2.6
5	HASSL	−39.9	4.6
6	HASSL	−31.3	5.4
7	HASSL	−67.8	2.6
8	HASSL	−68.0	2.1
9	HASSL	−73.3	1.2
10	HASSL	−68.8	1.8
11	HASSL	−68.7	1.0
12	LASL	−69.0	0.6
13	HASSL	−67.1	1.9
14	LASL	−75.4	0.9
15	HASSL	−47.3	2.3
16	LASL	−70.9	1.6
17	HASSL	−43.5	1.4
18	HASSL	−60.7	1.4
19	LASL	−67.7	0.7

^aLocations of the spots in the beta imager micrograph. The mat was divided into the less active surface layer (LASL), the highly active subsurface layer (HASSL), and the less active central layer (LACL). For further explanation see the text.