GEOMORPHOLOGY REPORT - CRC LEME

when sampling. This is also reflected in the higher pH of the Terrace and Uplands units
(Table 3).
The K, U, and Th concentrations generally reflect that seen in airborne gamma ray
radiometric data illustrated in Appendix 4, with higher concentrations of the three
radioelements in the units found within the Murray River Trench, and lower concentrations in
the Uplands.
6.4 XRD mineralogy
6.4.1 Methods
X-Ray defraction is an effective way of accurately determining mineralogy. Mineralogy is
important to the study the mineral suite can influence conductivity and clay types effect
porosity and permeability and surface recharge behaviour.
Samples were analysed using both semi-quantitative XRD and qualitative PIMA methods.
Samples for XRD were scanned on a Siemens D500 Diffractometer, from 2° to 70° 2θ, in 1°
increments, 2 seconds per degree, using a Cu anode X-ray tube. Minerals were identified
using Bruker Diffrac plus and Siroquant V3 was used to quantify minerals. The samples are
characterised by simple scans, containing predominant Quartz peaks with accessory mica
(probably Muscovite), feldspar and clay (probably Kaolin). Specific feldspars have been
identified according to best-fit of peaks. Further petrological work would be required to
conclusively identify feldspars.
6.4.2 Results
XRD shows that the samples all contain quartz, muscovite, and microcline. Kaolinite and
albite are present in almost all. These results are consistent with the samples being composed
of two sediment types, a slightly feldspathic micaceous quartz sand and kaolinitic quartz silt
with very fine-grained detrital muscovite.
The relationship between distribution of clay species and provenance would be worth further
investigation (c.f. Ginegle and de Deckker 2004). However it is beyond the scope of this
investigation as it would require clay-specific mineral separates to be prepared.
Table 3. Mean values of selected XRF analyses
Geomorphic
Unit
Fm1
Fm2
Fm3
T
U
Depth Al2O CaO Cl Fe2O3 K2O Na2O S (%) SiO2 Th (%) U (%)
(m) 3 (%) (%) (%) (%) (%) (%)
(%)
0.0-0.1 10.75 0.44 0.548 3.24 2.07 0.46 0.460 72.26 0.01960 0.00722
0.1-0.2 10.13 0.38 0.367 2.83 2.09 0.49 0.281 76.99 0.01160 0.00410
0.2-0.3 9.60 0.36 0.361 2.66 1.97 0.50 0.195 78.64 0.01320 0.00494
0.0-0.1 14.31 0.47 1.296 4.74 2.22 0.50 0.283 64.75 0.01400 0.00670
0.1-0.2 13.91 0.45 0.955 4.51 2.19 0.57 0.206 66.91 0.02050 0.00535
0.2-0.3 14.10 0.45 0.822 4.59 2.18 0.58 0.199 66.44 0.02000 0.00540
0.0-0.1 10.36 0.49 0.172 2.93 2.20 0.58 0.160 75.47 0.01925 0.00708
0.1-0.2 11.02 0.50 0.371 3.23 2.21 0.58 0.151 74.62 0.01325 0.00565
0.2-0.3 11.52 0.53 0.639 3.45 2.24 0.61 0.163 73.54 0.01750 0.00465
0.0-0.1 12.64 1.81 2.440 4.63 1.99 0.51 0.329 66.52 0.01460 0.00084
0.1-0.2 10.99 1.83 2.303 3.98 1.77 0.51 0.300 70.38 0.01720 0.00556
0.2-0.3 10.63 1.67 3.319 3.85 1.74 0.62 0.280 71.86 0.01140 0.00292
0.0-0.1 5.23 3.48 0.082 1.92 0.99 0.00 0.244 79.92 0.01025 0.00243
0.1-0.2 4.97 3.71 0.473 1.81 0.93 0.07 0.209 81.08 0.01375 0.00388
0.2-0.3 4.91 5.65 0.532 1.80 0.87 0.07 0.296 76.15 0.00650 0.00213
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