Page 257 - Geochemical Remote Sensing of The Sub-Surface

230 T. Ruan and Q. Fei
~ \ "~\ "-.:. ~i/" / " t ~-~
) ~] ~:~ \16,0, -x' Uv- ~/" '-- 1600

\ /I I - :-~
\ .i I / / f \
..~/ ./ /q.,~/ \N
0, 1, / / / (lalk g-1 ) \ ""
km /

[----7] Cz +
L~ Fault bF i,hydrocarbonsL.__~ ] T9 depth (m)
Fig. 6-11. Contour map of C2+ in soils determined by acid treatment method, Lixian Depression
(from Ruan and Cheng, 1991 ).

-" @

R_ing ~Hydrogen stipping C,
~ anomaly
Fig. 6-12. Contour map of C 4 in soils determined by hydrogen stripping, Lixian Depression (from
Ruan and Cheng, 1991 ).

Ruan and Cheng (1991) describe two gas geochemical surveys in the region. In the
first survey, a pronounced C2+ anomaly was found in soils analysed by the acid treatment
method (Fig. 6-11). In a subsequent survey at a higher sampling density, soil samples
were analysed for hydrocarbon gases by the hydrogen stripping method. The results for
C4, shown in Fig. 6-12, confirm the general patterns of the earlier survey and