DNR Open-File Project 394: Test of SGH Soil Survey Method

Map of Rotosonic Locations

Map of Rotosonic Drill Hole and SGH Sample Locations
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SGH Soil Survey

The DNR is testing the effectiveness of a proprietary geochemical exploration technique in an area of known copper-nickel mineralization in Aitkin County, Minnesota.  In case studies outside of Minnesota, the soil gas hydrocarbon (SGH) procedure developed by Activation Laboratories, Ltd. (ActLabs) has delineated mineralized bedrock targets buried under thick layers of overburden by extracting and analyzing organic compounds trapped on surficial sediment. The goal of this MnDNR project is to test the method’s efficacy in an area of known bedrock mineralization that is overlain with layers of both saprolite and clay-rich glacial till. The project combines SGH surface soil sampling with detailed characterization of till and saprolite samples obtained from rotosonic drill cores. 

A comparison of the targeting results of this blind SGH soil survey against the known footprint of subsurface bedrock mineralization may provide useful guidance on the effectiveness of this exploration technique in other areas of underexplored State-owned or State-managed mineral rights. 

Project Manager: Don Elsenheimer


Data released on January 31, 2014

In October 2013, the DNR collected surface materials from 152 sample locations and sent them to ActLabs for SGH analysis and interpretation. The samples were located within a grid that was proximal to a previously sampled grid (see July 3, 2013 data release). ActLabs performed the analysis, and provided the DNR the results in an interpretive report dated January 27, 2014. The DNR is publically releasing the following associated documents:

  • January 27, 2014 laboratory report from Activation Laboratories, Ltd:  This is a PDF file. You will need Adobe Acrobat Reader to download it. 3D - SGH: A spatiotemporal Geochemical Hydrocarbon Interpretation, Minnesota Department of Natural Resources DNR SGH Soil Survey - Phase 2. This ActLabs laboratory report presents and interprets a large data set of SGH concentrations obtained from 152 samples, 8 duplicates, and 5 vertical test samples collected in the project area in October 2013 by MnDNR staff. This report includes supplemental documentation of the SGH methodology and separate data interpretations by ActLabs for the locations of redox zones, copper pathfinder class compounds and nickel pathfinder class compounds within the project area. Pathfinder class maps and SGH forensic signature ratings are used to identify areas with high Cu and Ni mineralization potential within the project area. This was a blind test of the technique; ActLabs identified areas with high or low mineral potential (based on SGH sampling) without knowing where areas of high-grade Cu-Ni mineralization existed (as defined by an extensive bedrock drilling program).
  • Sample Location Map This is a PDF file. You will need Adobe Acrobat Reader to download it., MnDNR SGH Soil Survey. This 1:12,000 scale map plots SGH sample locations against a 2010 air photograph of the project area, and exploratory borehole locations.
  • Sample location and field data This link leads to an Exel document., MnDNR SGH Soil Survey. This MS-Excel file provides field data for the SGH samples. UTM coordinates are provided for each sample location, as are information regarding the sample depth intervals and the type of material collected.

Data released on July 2, 2013

The MnDNR is releasing the following field and analytical data associated with the test of the Soil Gas Hydrocarbon (SGH) Soil Survey Method. A discussion and analysis of these results will be included within a future open-file report.

1. SGH Soil Survey

In May 2013, the MnDNR collected surface samples from 179 points in a grid that covered the project area with 65 meter spacing. These surface materials were submitted to ActLabs for SGH analysis. The results of this analysis were provided to MnDNR by ActLabs on June 27, 2013.

  • June 27, 2013 laboratory report from Activation Laboratories, Ltd This is a PDF file. You will need Adobe Acrobat Reader to download it.: SGH - Soil Gas Hydrocarbon Predictive Geochemistry Report for Minnesota Department of Natural Resources DNR SGH Soil Survey. This laboratory report from Activation Laboratories, Ltd (ActLabs) presents and interprets a large data set of SGH concentrations obtained from 179 samples and 9 duplicates collected in the project area in May 2013 by MnDNR staff. This report includes supplemental documentation of the SGH methodology and separate data interpretations by ActLabs for the locations of redox zones, copper pathfinder class compounds and nickel pathfinder class compounds within the project area. Pathfinder class maps and SGH forensic signature ratings are used to identify areas with high Cu and Ni mineralization potential within the project area. This was a blind test of the technique; ActLabs identified areas with high potential (based on SGH sampling) without knowing where areas of high-grade Cu-Ni mineralization existed (as defined by an extensive bedrock drilling program).
  • Sample Location Map This is a PDF file. You will need Adobe Acrobat Reader to download it., MnDNR SGH Soil Survey. This 1:5,000 scale map plots SGH sample locations against a 2010 air photograph of the project area, as well as active State mineral exploration leases and areas of delineated wetlands.
  • Sample location and field data This link leads to an Exel document., MnDNR SGH Soil Survey. This MS-Excel file provides field data for the SGH samples. UTM coordinates are provided for each sample location, as are information regarding the sample depth intervals and the type of material collected.

2. Geochemical analysis of silt+clay fraction from rotosonic drill core samples of glacial till and saprolite.

ActLabs has completed geochemical analysis of the silt+clay fraction separations from twenty-two (22) samples of saprolite and till from eleven (11) existing rotosonic drill cores (see June 18, 2013 data release for sample collection and processing data). While these samples of till and saprolite from the base of the overburden layer are not part of the SGH soil survey, the results obtained from these samples using conventional methods of analysis provide valuable background information.

  • June 27, 2013 ActLabs Laboratory Report Certificate of Analysis/Report This is a PDF file. You will need Adobe Acrobat Reader to download it.. This laboratory report provide analytical and quality control results for the multi-element analysis of the silt and clay fractions from the 22 till and saprolite samples. Analytical packages included fire assay-ICP/MS finish (Au, Pt, Pd), whole rock analysis of major elements, and ICP/MS trace element analysis. Both the laboratory report and spreadsheet file were dated and submitted by ActLabs to MnDNR on June 27, 2013.
  • ActLabs June 27, 2013 data table for analysis of 22 silt+clay fraction samples This link leads to an Excel document.. This MS-Excel spreadsheet, created by ActLabs and converted to PDF, provides the analytical and quality control results from the multi-element analysis of 22 silt+clay fraction samples in a data table format. Non-detect values and values that exceed maximum detection limits are reported as text strings (e.g. “< 5”, “> 1000”).
  • June 27, 2013 ActLabs Data Plots This is a PDF file. You will need Adobe Acrobat Reader to download it.. This PDF document displays rare-earth element (REE) distribution plots for the 22 silt+clay fractions of samples of till and saprolite.
  • Data table for silt+clay fraction samples with locations This link leads to an Excel document.. This MS-Excel spreadsheet adds sample locations as UTM coordinates to the multi-element geochemical analysis of the 22 silt+clay fraction samples. Information provided in the ActLabs data table on analyte detection limits, units of measure, and analytical methods was stripped from this data table in order to create a format suitable for import into ArcGIS. The “less than” non-detect values reported in the ActLabs data table are replaced by values that are one-half the method detection limit. “Greater than” values are replaced by values that are 1 unit greater than the maximum detection limit (i.e. “> 10000” replaced by 10001). The original ActLabs data table and QC results are archived in this file as separate sheets.

3. Geochemical analysis of heavy mineral concentrate, rotosonic drill core samples of glacial till and saprolite.

ActLabs has completed geochemical analysis of the magnetic and non-magnetic fractions of the heavy mineral concentrate (HMC) from twenty-two (22) samples of saprolite and till from eleven (11) existing rotosonic drill cores (see June 18, 2013 data release for sample collection and processing data). While these samples of till and saprolite from the base of the overburden layer are not part of the SGH soil survey, the results obtained from these samples using conventional methods of analysis provide valuable background information.

  • June 27, 2013 ActLabs Laboratory Report Certificate of Analysis/Report This is a PDF file. You will need Adobe Acrobat Reader to download it.. This laboratory report and associated spreadsheet file provide analytical and quality control results for the multi-element neutron activation analysis of 44 samples of magnetic and non-magnetic fraction HMC from till and saprolite from rotosonic drill cores. This laboratory report was submitted by ActLabs to MnDNR on June 27, 2013.
  • ActLabs June 27, 2013 data table for NAA analysis of 44 HMC samples This link leads to an Excel document.. This MS-Excel spreadsheet, created by ActLabs and converted to PDF, provides the analytical and quality control results from NAA analysis of the 44 HMC samples in a data table format. Non-detect values are reported as text strings (e.g. “< 5”).
  • Data table for HMC samples with locations This link leads to an Excel document.. This MS-Excel spreadsheet adds sample locations as UTM coordinates to the multi-element NAA analysis of the HMC from the rotosonic till and saprolite samples. Information provided in the ActLabs data table on analyte detection limits, units of measure, and analytical methods was stripped from this data table in order to create a format suitable for import into Arc-GIS. The “less than” non-detect values reported in the ActLabs data table are replaced by values that are one-half the method detection limit. “Greater than” values are replaced by values that are 1 unit greater than the maximum detection limit (i.e. “> 10000” is replaced by 10001). The original ActLabs data table and QC results are archived in this file as separate sheets.

Map of Rotosonic Locations

Map of Rotosonic Drill Hole Locations
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Data released on June 19, 2013

June 11, 2013 laboratory reports from Overburden Drilling Managent, Ltd: 

Till Samples This is a PDF file. You will need Adobe Acrobat Reader to download it.

Saprolite Samples This is a PDF file. You will need Adobe Acrobat Reader to download it.

These laboratory reports from Overburden Drilling Management, Ltd. (ODM) provide  processing data associated with the collection of silt+clay fractions and Heavy Mineral Concentrates (HMC) from twelve (12) samples of saprolite and ten (10) samples of overlying till within eleven (11) existing rotosonic drill cores.  Samples were collected by MnDNR in March, 2013. From each submitted sample, ODM isolated a <63 micron sieve fraction (silt+clay), and obtained HMC (S.G.>3.3) from a pan concentrate.  The HMC was subjected to a magnetic separation, and ODM made general identifications of the metallic minerals present within the pan concentrate. Gold grain counts were also obtained (note that gold was not a targeted mineral in this project).  The DNR has a contract with ODM to process these types of samples that it collects.   

The silt+clay fractions and magnetic/non-magnetic HMC splits from each sample were sent by ODM to Activation Laboratories, Ltd. (ActLabs) for geochemical analysis.  These analytical results are pending. 

Excel table for 22 till and saprolite samples with locations and normalized gold grain counts This link leads to an Exel document.

This excel table provides locations as UTM coordinates and normalized gold grain counts (10kg sample weight) for the 22 samples of till and saprolite identified in the ODM report.  This data is combined with the ODM processing report data in a single spreadsheet file that is formatted for import into ArcGIS.

Map of rotosonic drill hole locations This is a PDF file. You will need Adobe Acrobat Reader to download it.

This map displays the location of the eleven rotosonic drill locations that produced the core from which the 22 samples of till and saprolite were obtained.  These drill holes locations are all on actively-leased State-managed mineral rights in Section 3 of T48N R22W, Aitkin County.


For more information:

Project Leader - Don Elsenheimer, Ph.D
500 Lafayette Road
St. Paul, Minnesota 55155-4045
tel. 651-259-5433
fax 651-296-5939
donald.elsenheimer@state.mn.us

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