Alteration Zone Mapping with field portable SWIR
The presence of alteration in drill core or field mapping can point exploration geologists to mineralization zones. Alteration enriches ore bodies or expands their footprint, which makes their discovery easier to find. Understanding ore deposits and exploring them requires a comprehensive understanding of alteration mineral assemblages. Tools used for conventional mapping may not be able to identify fine-grained minerals that are not immediately noticeable or define important compositional variations. Some of these problems are addressed by field portable shortwave infrared (SWIR) spectrometers, which provide an important tool for assessing change assemblages.
Common alteration applications seen with field portable SWIR are:
- Micas: muscovite-paragonite, biotite, phlogopite
- Chlorites: variations in iron-magnesium chlorite
- Amphiboles: tremolite, hornblende, actinolite
- Sulfates: jarosite, gypsum
- Tourmaline: Fe-tourmaline, tourmaline
- Clays: illite, illite-smectite, kaolinite, dickite
- Carbonates: calcite, dolomite, ankerite, and siderite
Spectroscopy provides an invaluable tool for geologists to track mineral assemblage and composition. As they explore a new region, an oreXpress™, oreXplorer™, or oreXpert™ NIR spectrometer with EZ-ID™ can help them to detect alteration minerals and chemical/crystalline variations that are not immediately noticeable. These field portable spectrometers are rugged and reliable and have been used for important deposits such as volcanogenic massive sulfide (VMS), high-sulfidation epithermal, low-sulfidation epithermal, intrusion-relation environments, and important hydrothermal ore deposits. Figure 1 shows the spectral data of key alteration minerals used as vectoring tools in these deposits, where the wavelength shape and position change, leading to the identification and discrimination of alteration minerals.
Figure 1: Spectral data of key alteration minerals
The table above shows an example of the alteration and application of key minerals found within alteration zones. Figure 1 shows the spectral data of these minerals with ultra-high spectral resolution from the oreXpert.
With Spectral Evolution field portable UV-Vis-NIR spectrometers and EZ-ID™ mineral identification software, geologists can measure and identify minerals within seconds and cover more ground than by using traditional methods. They can identify different mineral phases, create mineral alteration maps and more accurately identify mineral pathfinders for vectoring to ore deposits. Spectral Evolution’s field portable, battery-operated oreXpress™, oreXplorer™ and oreXpert™ ultra-high resolution UV-Vis-NIR spectrometers provide quick payback with faster, more accurate mineral identification in exploration for gold, silver, diamonds, iron, nickel, copper, uranium, aluminum – in the field, core shack, or in the lab.