KENIEBA
SUD DIAMOND CONCESSION
Diamond & Indicator Mineral Anomalies
Upper
Doundi
Diamonds and indicator minerals have been reported from the upper reaches
of the Doundi River, extending from immediately upstream of Kenieba
village to above the Tambaoura
escarpment. The BRGM recorded three diamonds (1.25ct, 1ct and 0.5ct)
found by local gold miners in alluvium in the Doundi valley below the
escarpment. Picroilmenite and chromite (possibly kimberlitic) have been
recovered along a 10km stretch of the Doundi River within the Kenieba
Sud concession. The indicator trail extends above the escarpment but
appears to be closed off a further 3km upstream, albeit by relatively
sparse sampling. The poorly tested Sounkorou pipe is located within
the upper Doundi catchment and may have contributed to at least some
of the diamonds and indicator minerals in the area. MADE reported that
no diamonds or indicator minerals were recovered from an 87kg drill
core sample from Sounkorou. The Sounkorou pipe was found in 1998 solely
by geophysical methods and has only been tested by a single drill hole.
Samples collected by MADE in upper Doundi area contained picroilmenite
and chromite. Some of the picroilmenite grains were reported to be fresh
and are probably quite close to their source. Some of the chromite grains
show classic kimberlitic morphology whereas others are less diagnostic
but are still considered of interest. The chromite grains are also considered
interesting on the basis of their chemistry with reasonably high Cr2O3
levels and several that have similar chemistry to chromite inclusions
found in diamonds. Some of the MADE samples contain equal or greater
abundance of chromite relative to
picroilmenite, indicating potential for a different source.
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Sanoukou
Diamond and indicator minerals have been recovered from alluvial samples
in the Sanoukou area, 5km southwest of Kenieba. The anomalous streams
drain an outlier of Infracambrian sandstone that forms a prominent topographic
feature to the south of Kenieba. Limited alluvial sampling by MADE in
this area returned very encouraging results that included the recovery
of a diamond, pyrope, chromite, picroilmenite and kimberlitic zircon.
The high indicator counts, presence of pyrope and relative freshness
of some of the chromite grains implies a proximal source. As with the
Upper Doundi, the Sanoukou area represents a chromite-rich, picroilmenite-poor
anomaly that contrasts withmost other occurrences in the region and
is considered to be of great interest. Some of these samples were collected
from palaeogravel around gold diggings in the Doundi valley and so the
kimberlitic minerals may well be sourced from the Upper Doundi area.
Fambina
On the south of the Infracambrian outlier to the Sanoukou anomaly and
approximately 10km south-southwest of Kenieba, alluvial sampling by
MADE recovered picroilmenite and chromite. The chromite grains are of
possible kimberlitic affinity. The anomaly is of lower priority because
of the prevalence of picroilmenite. No analytical data is available
for the indicator minerals from this area. The Selou anomaly is located
4km downstream in the same drainage. [top]
Selou
The Selou diamond and indicator mineral anomaly is located 15km southwest
of Kenieba and 4km north of the Bilali pipes. A small, 0.5ct diamond
was reportedly recovered from alluvium by local gold miners and a +0.5mm
diamond was recovered in a 40kg alluvial sample by MADE 4km further
north. Limited sampling by MADE around the site of the first diamond
returned very high picroilmenite counts with minor chromite of probably
kimberlitic affinity.The indicator mineral anomaly at Selou is downstream
of other occurrences at Fambina and the lack of infill sampling between
the two means that a continuous dispersion train cannot be ruled out.
Disse
River
The Disse River diamond and indicator mineral anomaly is located 30km
southeast of Kenieba in an area of no known kimberlite occurrences.
Alluvial diamonds have been recovered by local gold miners along the
Disse River. Nine diamond finds were recorded by previous explorers
and during a 1996 visit to the area, MADE geologists confirmed the continued
regular recovery of small diamonds by local gold miners. The diamonds
and indicator minerals are dispersed within a 150km2 catchment area
and only limited followup
work has been conducted. Picroilmenite is the dominant indicator mineral
and has been recovered from several sites proximal to where diamonds
have been reported along the Disse River and similarly, further north
where a tributary drains from the Infracambrian plateau. Chromite is
present in low numbers in several samples and most of these do not exhibit
diagnostic kimberlitic morphology. One MADE sample contained chromite
grains with typical kimberlitic morphologies and chemical properties
similar to diamond inclusion chromite. Other less diagnostic chromite
grains in the same sample had similar favourable chemistry. It should
be noted that this sample was spiked with 4 kimberlitic chromites as
part of routine laboratory quality control. It is not certain that the
spike (foreign) chromites were removed from the sample. The sample should
be repeated to confirm these results. The area was covered by the 1997
aeromagnetic survey and there appear to be several anomalies within
the catchment that are worthy of investigation. To my knowledge, none
of these anomalies have been investigated.
Bokolobi
The Bokolobi indicator mineral anomaly is located 10km southwest of
the Bilali pipes and downstream of the village of Bokolobi. Indicator
minerals were first described from the area by Selection Trust in the
1960’s. Follow-up alluvial sampling by MADE confirmed the anomaly
but no further work was undertaken.
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