Loading ...
Sorry, an error occurred while loading the content.

AI-GEOSTATS: Indicato Kriging

Expand Messages
  • Elmidio Estévez Cruz
    Dear All: I´m working with a Au gossan deposit. The data come from grade control of 8 benches in the mine. All the histograms show evidences of bimodality
    Message 1 of 2 , Jan 12, 2003
    • 0 Attachment
      Dear All:

      I´m working with a Au gossan deposit. The data come from grade control of 8 benches in the mine. All the histograms show evidences of bimodality .The presence of a complex population is geologically explained by the fact that gold is hosted by different lithological units (limonite, sandstone, clay etc.), which are mixed and it is not possible to separate at present mining scale (5m benches). The variograms of Au show a clear spatial structure with a range of around 30m in all benches. Based on this spatial correlation some people have proposed to used OK to estimate the Au grade in 5x5m block on the other hand the mixture of population indicates the violation of stationarity (homogeneity) indispensable for the application of OK. According to literature the only method that mitigate this problems is IK. I have interpolated the grade using IK but I found a high correlation between OK and IK estimates. I also crossvalidated the methods and found similar errors. What could be the reason for that? Is there any method to demonstrate which interpolation techniques works better in this situation?

      Best regards,

      MSc. Emidio Estévez Cruz

      Dpto de Geología

      Universidad de Pinar del Río



      [Non-text portions of this message have been removed]
    • Pierre Goovaerts
      Hello, You need to provide more information on your problem. For example, how many threshold values did you use for indicator kriging and did you observe large
      Message 2 of 2 , Jan 12, 2003
      • 0 Attachment
        Hello,

        You need to provide more information on your problem.
        For example, how many threshold values did you use for
        indicator kriging and did you observe large differences between
        indicator variogram models (e.g. anisotropy) for different
        thresholds. I am also assuming you are using the mean of the
        probability distribution obtained by IK (i.e. E-type estimate).
        Last how did you interpolate and extrapolate the upper and lower
        tails of your discrete distributions.
        Nevertheless I am not surprised by your findings.
        As long as you are using the same data in these
        least square interpolation techniques, you will get
        similar results.

        Regards,

        Pierre Goovaerts
        <><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><>

        Dr. Pierre Goovaerts
        Consultant in (Geo)statistics
        President of PGeostat, LLC
        and Senior Chief Scientist with Biomedware Inc.
        710 Ridgemont Lane
        Ann Arbor, Michigan, 48103-1535, U.S.A.

        E-mail: goovaert@...
        Phone: (734) 668-9900
        Fax: (734) 668-7788
        http://alumni.engin.umich.edu/~goovaert/

        <><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><>

        On Sun, 12 Jan 2003, [iso-8859-1] Elmidio Estévez Cruz wrote:

        > Dear All:
        >
        > I´m working with a Au gossan deposit. The data come from grade control of 8 benches in the mine. All the histograms show evidences of bimodality .The presence of a complex population is geologically explained by the fact that gold is hosted by different lithological units (limonite, sandstone, clay etc.), which are mixed and it is not possible to separate at present mining scale (5m benches). The variograms of Au show a clear spatial structure with a range of around 30m in all benches. Based on this spatial correlation some people have proposed to used OK to estimate the Au grade in 5x5m block on the other hand the mixture of population indicates the violation of stationarity (homogeneity) indispensable for the application of OK. According to literature the only method that mitigate this problems is IK. I have interpolated the grade using IK but I found a high correlation between OK and IK estimates. I also crossvalidated the methods and found similar errors. What could be the reason for that? Is there any method to demonstrate which interpolation techniques works better in this situation?
        >
        > Best regards,
        >
        > MSc. Emidio Estévez Cruz
        >
        > Dpto de Geología
        >
        > Universidad de Pinar del Río
        >
        >


        --
        * To post a message to the list, send it to ai-geostats@...
        * As a general service to the users, please remember to post a summary of any useful responses to your questions.
        * To unsubscribe, send an email to majordomo@... with no subject and "unsubscribe ai-geostats" followed by "end" on the next line in the message body. DO NOT SEND Subscribe/Unsubscribe requests to the list
        * Support to the list is provided at http://www.ai-geostats.org
      Your message has been successfully submitted and would be delivered to recipients shortly.