Exploration for porphyry-style copper mineralisation near Llandeloy

APPENDIX 2
GEOPHYSICAL MEASUREMENTS IN THE LLANDELOY
AREA
Line-by-line descriptions are given of pseudosections
measured along traverse lines only in the area of
detailed investigations around Treffynnon. A subjective
interpretation has been made of the pseudosections
shown in A2.1-A2.9 (see Fig. 41 for locations). Near-
surface anomalies are assigned in the text to the dipole
positions at which they are estimated to occur, while
deeper anomalies have been identified as such.
Line 2500E
Resistivity is low to moderate on most of the line, and
generally-lower at the surface than at depth. arrow
lows occur at about 720N and probably off the end of the
line at about 350s. At about 620N and 75N lie narrow
resistivity highs. Chargeabili ty is moderate on much of
the line, but the north end has a lower, and the south end
a higher IP response. A narrow maximum occurs at about
600N.
Line 2900E
Again low to moderate resistivities are seen. increasing:
generally with depth. Near surface values *are rathe;
higher between 400 and 450N, and at about 1100N. Four
narrow resistivity lows occur, at 1120N, 850N, 670N and
370N approximately, of which the last is the strongest.
Low resistivity material extends to greater depth to the
south of 370N than to the north. Chargeability is
moderate except for a high at the northern end of the
traverse. A narrow high at lOOON coincides with a road,
and a possible high lies at depth below about 150N.
Line 3100E
Low resistivity occurs to depth on the whole traverse
except the northern end, where values are moderate to
high. The two sections are separated by a narrow
minimum at 720N. Most of the line also has low
chargeability, but highs occur at 500 to 720N and north
of 1200N. The former occurs where the line passes
Tref fynnon village.
Line 3500E
Resistivity on this line is generally moderate to high,
although some surficial lows occur, notably at 300 to
600N. At the northern end of the line, however,
resistivity is low to depth. A narrow low lies at about
320N. Chargeability is high on the southern part of the
traverse, with a maximum at 720N, and a broader high
southwards from 450N.
Line 3700E
Most of this line seems to be underlain by hi h resistivity
material at shallow depth (probably