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Steinar Ellefmo
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Master thesis
(2025)
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A.P. Kollamparambil, M.W.N. Buxton, R.L.J. Helmons, Steinar Ellefmo, K. Pashna
The global transition to green energy has intensified demand for critical raw materials, increasing interest in deep-sea mineral resources such as cobalt-rich ferromanganese (Fe-Mn) crusts on seamounts like Tropic Seamount in the NE Atlantic. This thesis investigates the relationship between water depth and Fe-Mn crust composition and evaluates whether incorporating this relationship through Co-kriging (CK) improves resource estimation compared to Ordinary Kriging (OK). Geochemical and bathymetric data were analyzed using exploratory data analysis. The estimation workflow included block model generation, isometric log-ratio (ILR) transformation, Landmark-ISOMAP embedding for locally varying anisotropy, variogram modeling, and geostatistical estimation with Ordinary Kriging, Simple Co-Kriging (SCK) and Intrinsic Collocated Co-Kriging (ICCK) as well as Inverse Distance Weighted (IDW) Estimation. Model performance was assessed using Quantitative Kriging Neighborhood Analysis (QKNA) metrics and leave-one-out cross-validation (LOOCV), with a critical evaluation of LOOCV’s limitations.
Results demonstrate a significant relationship between water depth and Fe-Mn crust composition, with a significant improvement in estimation accuracy and confidence when water depth is used as the secondary variable in Co-Kriging, with SCK and ICCK providing more accurate and confident resource estimates than OK. ICCK also performed better than IDW. For the first time, tonnage calculations for metals in Fe-Mn crusts based on a 3D block model and real geochemical data are presented, highlighting Tropic Seamount’s potential as a substantial mineral resource for Europe. The workflow developed in this study, including ILR transformation and L-ISOMAP embedding, proved effective for handling compositional data and spatial anisotropy. The study also identifies methodological limitations, such as the need for improved variography, better sampling distribution, consideration of non-metallic elements, and more advanced cross-validation techniques. The assumption that the top 1 cm of crust represents the entire deposit is noted as a simplification, and future research should address vertical stratigraphy and sampling distribution.
The findings indicate that integrating ILR transformation and Landmark-ISOMAP embedding with Co-Kriging leads to better resource estimation for Fe-Mn crusts, enabling more confident and accurate assessments. This methodology offers significant potential for mineral resource exploration and future research in both marine and terrestrial environments. ...
Results demonstrate a significant relationship between water depth and Fe-Mn crust composition, with a significant improvement in estimation accuracy and confidence when water depth is used as the secondary variable in Co-Kriging, with SCK and ICCK providing more accurate and confident resource estimates than OK. ICCK also performed better than IDW. For the first time, tonnage calculations for metals in Fe-Mn crusts based on a 3D block model and real geochemical data are presented, highlighting Tropic Seamount’s potential as a substantial mineral resource for Europe. The workflow developed in this study, including ILR transformation and L-ISOMAP embedding, proved effective for handling compositional data and spatial anisotropy. The study also identifies methodological limitations, such as the need for improved variography, better sampling distribution, consideration of non-metallic elements, and more advanced cross-validation techniques. The assumption that the top 1 cm of crust represents the entire deposit is noted as a simplification, and future research should address vertical stratigraphy and sampling distribution.
The findings indicate that integrating ILR transformation and Landmark-ISOMAP embedding with Co-Kriging leads to better resource estimation for Fe-Mn crusts, enabling more confident and accurate assessments. This methodology offers significant potential for mineral resource exploration and future research in both marine and terrestrial environments. ...
The global transition to green energy has intensified demand for critical raw materials, increasing interest in deep-sea mineral resources such as cobalt-rich ferromanganese (Fe-Mn) crusts on seamounts like Tropic Seamount in the NE Atlantic. This thesis investigates the relationship between water depth and Fe-Mn crust composition and evaluates whether incorporating this relationship through Co-kriging (CK) improves resource estimation compared to Ordinary Kriging (OK). Geochemical and bathymetric data were analyzed using exploratory data analysis. The estimation workflow included block model generation, isometric log-ratio (ILR) transformation, Landmark-ISOMAP embedding for locally varying anisotropy, variogram modeling, and geostatistical estimation with Ordinary Kriging, Simple Co-Kriging (SCK) and Intrinsic Collocated Co-Kriging (ICCK) as well as Inverse Distance Weighted (IDW) Estimation. Model performance was assessed using Quantitative Kriging Neighborhood Analysis (QKNA) metrics and leave-one-out cross-validation (LOOCV), with a critical evaluation of LOOCV’s limitations.
Results demonstrate a significant relationship between water depth and Fe-Mn crust composition, with a significant improvement in estimation accuracy and confidence when water depth is used as the secondary variable in Co-Kriging, with SCK and ICCK providing more accurate and confident resource estimates than OK. ICCK also performed better than IDW. For the first time, tonnage calculations for metals in Fe-Mn crusts based on a 3D block model and real geochemical data are presented, highlighting Tropic Seamount’s potential as a substantial mineral resource for Europe. The workflow developed in this study, including ILR transformation and L-ISOMAP embedding, proved effective for handling compositional data and spatial anisotropy. The study also identifies methodological limitations, such as the need for improved variography, better sampling distribution, consideration of non-metallic elements, and more advanced cross-validation techniques. The assumption that the top 1 cm of crust represents the entire deposit is noted as a simplification, and future research should address vertical stratigraphy and sampling distribution.
The findings indicate that integrating ILR transformation and Landmark-ISOMAP embedding with Co-Kriging leads to better resource estimation for Fe-Mn crusts, enabling more confident and accurate assessments. This methodology offers significant potential for mineral resource exploration and future research in both marine and terrestrial environments.
Results demonstrate a significant relationship between water depth and Fe-Mn crust composition, with a significant improvement in estimation accuracy and confidence when water depth is used as the secondary variable in Co-Kriging, with SCK and ICCK providing more accurate and confident resource estimates than OK. ICCK also performed better than IDW. For the first time, tonnage calculations for metals in Fe-Mn crusts based on a 3D block model and real geochemical data are presented, highlighting Tropic Seamount’s potential as a substantial mineral resource for Europe. The workflow developed in this study, including ILR transformation and L-ISOMAP embedding, proved effective for handling compositional data and spatial anisotropy. The study also identifies methodological limitations, such as the need for improved variography, better sampling distribution, consideration of non-metallic elements, and more advanced cross-validation techniques. The assumption that the top 1 cm of crust represents the entire deposit is noted as a simplification, and future research should address vertical stratigraphy and sampling distribution.
The findings indicate that integrating ILR transformation and Landmark-ISOMAP embedding with Co-Kriging leads to better resource estimation for Fe-Mn crusts, enabling more confident and accurate assessments. This methodology offers significant potential for mineral resource exploration and future research in both marine and terrestrial environments.