Spectral Mapping of Alteration Minerals (SMAM)
Why do spectral mapping?
The idea of spectral mapping is to get a better understanding of the geology and alteration systems in your project areas. Although mineral zoning patterns are not uncommon, they are not always obvious. By measuring e.g. rock chips, pulp or diamond drill core from a target area, it is possible to detect these zones of alteration. The SMAM service can be of great help for both exploration and mining companies; e.g. detect the system before you find the deposit, navigate your way in the alteration system, save time and money on future exploration, plan your drilling based on alteration patterns etc.
Introduction
Infrared spectrometry is a well-established method for identifying different hydrous and carbonate minerals as well as detecting chemical variations and trends in crystallinity within these minerals. These techniques have been successfully used by both mining and exploration companies in many different geological environments. Infrared spectrometry is an important tool for mapping alteration, and can aid for example in the development of 2D- and 3D-alteration models. Spectral mapping is fast, objective and accurate, and since we are able to measure 1500-2000 meters of core per day, consequently also very cost effective (click here fore more information about infrared active minerals).
Scandinavian GeoPool uses an ASD TerraSpec VNIR-SWIR spectrometer for various geological applications. The spectrometer is field portable and the measurements can be made on almost any kind of sample, e.g. powders, rock chips, drill core or directly on outcrops. To optimize our service in spectral mapping we use The Spectral Geologist (TSG) and ioGAS software for interpretations of spectral data. For TerraSpec and TSG product specifications click here. The raw data from a SMAM project can always be used in your own GIS and 3D software.
For further information on the spectral mapping service see:
Alteration mapping
In many deposits, the alteration minerals are typically fine-grained and may be difficult to differentiate in the field. Also, minor chemical and/or crystalline variations within mineral species cannot be detected. With VNIR-SWIR spectroscopy we can help you to solve these problems and detect alteration minerals and chemical/crystalline variations, in other words things that the human eye can´t observe. Spectral alteration mapping allows us for example to distinguish between Fe- and Mg-rich biotites and determine the kaolinite crystallinity (click here to see how, 2 pages).
Spectral mapping of alteration minerals is applicable to a variety of deposit environments including e.g. high- and low-sulfidation epithermal, porphyry, mesothermal, intrusive hosted gold deposits, sediment-hosted gold and copper, uranium, VMS, kimberlites, skarns, IOCG and carbonate deposits. For further information on SMAM in epithermal and porphyry copper systems click here
VNIR-SWIR spectrometers fill an important gap in exploration data by helping to map alteration rapidly and systematically throughout a mineralized system. The interpretations can be applied in real time to guide drilling and exploration. Example: “use broad-spaced drilling, and by spectral mapping you can define the footprint of the hydrothermal system and reduce the search area”.
Methodology
The TerraSpec visible-near infrared (VNIR) – short-wave infrared (SWIR) spectrometer is created specifically for determining the mineralogy of rocks and soils. Mineral identification is based on the interpretation of absorption features, i.e. wavelength positions, width and depth of the features and the overall shape of the spectrum. The positions of the spectrum features and their characteristic shapes are a function of the molecular bonds present in a mineral. Variations in chemical composition may be detected as the wavelength positions of features shift consistently with elemental substitution. SWIR spectroscopy is also sensitive to variations in crystallinity.
What are the demands?
The only demand we have for measuring a sample is that the sample is dry.
For a detailed description of the Spectral Mapping of Alteration Minerals service provided by GeoPool, please read the following presentation (click here PDF 7,4 MB).
For a printable version with most important information please click here: Spectral Mapping of Alteration Minerals Information
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