Data mining of petrophysical and lithogeochemical borehole data to elucidate the origin of seismic reflectivity within the Kevitsa Ni-Cu-PGE -bearing intrusion, northern Finland

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Junno , N M , Koivisto , E A-L , Kukkonen , I T , Malehmir , A , Wijns , C & Montonen , M 2020 , ' Data mining of petrophysical and lithogeochemical borehole data to elucidate the origin of seismic reflectivity within the Kevitsa Ni-Cu-PGE -bearing intrusion, northern Finland ' , Geophysical Prospecting , vol. 68 , no. 1 , pp. 82-102 . https://doi.org/10.1111/1365-2478.12907

Title: Data mining of petrophysical and lithogeochemical borehole data to elucidate the origin of seismic reflectivity within the Kevitsa Ni-Cu-PGE -bearing intrusion, northern Finland
Author: Junno, Niina Marjut; Koivisto, Emilia Anna-Liisa; Kukkonen, Ilmo Tapio; Malehmir, Alireza; Wijns, Chris; Montonen, Markku
Contributor organization: Institute of Seismology
Department of Geosciences and Geography
Division of Geology and Geochemistry
Department of Physics
Date: 2020-01-01
Language: eng
Number of pages: 21
Belongs to series: Geophysical Prospecting
ISSN: 0016-8025
DOI: https://doi.org/10.1111/1365-2478.12907
URI: http://hdl.handle.net/10138/310104
Abstract: The Kevitsa mafic-ultramafic intrusion, located within the Central Lapland Greenstone Belt in northern Finland, hosts a large, disseminated Ni-Cu-PGE sulphide deposit. A three-dimensional seismic reflection survey was conducted over the Kevitsa intrusion in 2010 primarily for open-pit mine planning and for deep mineral exploration purposes. In the Kevitsa three-dimensional seismic data, laterally continuous reflections are observed within a constrained region within the intrusion. In earlier studies, it has been suggested that this internal reflectivity mainly originates from contacts between the tops and more sulphide-rich bottoms of smaller scale, internally differentiated magma layers that represent a spectrum of olivine pyroxenites. However, this interpretation is not unequivocally supported by the borehole data. In this study, data mining, namely the Self-Organizing Map analysis, of extensive Kevitsa borehole data is used to investigate the possible causes for the observed internal reflectivity within the Kevitsa intrusion. Modelling of the effect of mineralization and alteration on the reflectivity properties of Kevitsa rock types, based on average modal compositions of the rock types, is presented to support the results of the Self-Organizing Map analysis. Based on the results, we suggest that the seismic reflectivity observed within the Kevitsa intrusion can possibly be attributed to alteration, and may also be linked to the presence of sulphide minerals.
Subject: 114 Physical sciences
1171 Geosciences
Borehole geophysics
Petrophysics
Seismics
Interpretation
MASSIVE SULFIDE DEPOSITS
SELF-ORGANIZING MAPS
WHOLE-ROCK
EXPLORATION
MINE
Peer reviewed: Yes
Rights: cc_by
Usage restriction: openAccess
Self-archived version: publishedVersion


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