Change search
Link to record
Permanent link

Direct link
BETA
Berggren, Robert
Publications (4 of 4) Show all publications
Sandrin, A., Edfelt, Å., Waight, T. E., Berggren, R. & Elming, S.-å. (2009). Physical properties and petrologic description of rock samples from an IOCG mineralized area in the northern Fennoscandian Shield, Sweden (ed.). Journal of Geochemical Exploration, 103(2-3), 80-96
Open this publication in new window or tab >>Physical properties and petrologic description of rock samples from an IOCG mineralized area in the northern Fennoscandian Shield, Sweden
Show others...
2009 (English)In: Journal of Geochemical Exploration, ISSN 0375-6742, E-ISSN 1879-1689, Vol. 103, no 2-3, p. 80-96Article in journal (Refereed) Published
Abstract [en]

The Tjårrojåkka Fe-Cu prospect in northern Sweden is considered an example of a Fe-oxide Cu-Au (IOCG) deposit and is hosted in metamorphosed Paleoproterozoic volcanic and intrusive rocks. Rock samples from 24 outcrops were collected for petrophysical analysis (magnetic susceptibility, remanent magnetization, variation of magnetic susceptibility with temperature, Curie temperature and density). The major Cu-prospect in the area has been studied by magnetic and electron microprobe analyses of four selected rock samples. The samples are from an exploration well that intersects the main Cu-mineralized body.The magnetic analyses show that magnetite is the dominant magnetic mineral, while hematite and other Fe-minerals are present in minor amounts. The electron microprobe observations confirm the presence of magnetite and further indicate that hematite is an alteration product of magnetite. Moreover, microprobe observations indicate that Fe-sulfides are present in negligible amounts in the samples from the Tjårrojåkka area. The strong spatial relationship of Cu-minerals (e.g., chalcopyrite) and the oxidation of magnetite to hematite suggest that the presence of rocks with low magnetic susceptibility in areas dominated by high susceptibility rocks may be a signal of related Cu-prospects.

National Category
Geology Geophysics
Research subject
Ore Geology; Applied Geophysics
Identifiers
urn:nbn:se:ltu:diva-9276 (URN)10.1016/j.gexplo.2009.07.002 (DOI)000271542100003 ()2-s2.0-70349969976 (Scopus ID)7de31ae0-9317-11de-8da0-000ea68e967b (Local ID)7de31ae0-9317-11de-8da0-000ea68e967b (Archive number)7de31ae0-9317-11de-8da0-000ea68e967b (OAI)
Note

Validerad; 2009; 20090827 (ysko)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Sandrin, A., Elming, S.-å. & Berggren, R. (2008). Geophysical and petrophysical characterisation of IOCG prospects in northern Sweden (ed.). In: (Ed.), : . Paper presented at International Geological Congress : 06/08/2008 - 14/08/2008.
Open this publication in new window or tab >>Geophysical and petrophysical characterisation of IOCG prospects in northern Sweden
2008 (English)Conference paper, Oral presentation only (Other academic)
Abstract [en]

In the last decade the importance of Fe-oxide Cu-Au deposits has been increasing constantly and a relevant effort was put on the creation of efficient exploration models. Among the other disciplines, geophysics is a vital tool for the first definition of IOCG leads. Airborne/field geophysical surveys are widely used fro preliminary exploration and they can be further exploited to characterise mineral alterations and to indicate the presence of magnetic or density anomalies. The link between the geophysical signature of altered or mineralised rocks and the alterations/mineralisations themselves is given by the physical properties of rocks. In this study we review this link by investigating in very detail the petrophysical (i.e. magnetic and density) properties of the Tjårroåkka IOCG prospect together with its geophysical expression at the surface. Moreover, we put this prospect in a more regional context with a study that makes use of available airborne magnetic and radiometric data, coupled with ground gravity measurements and petrophysical databeses.Our study suggests that, at semi-regional scale, the Fe-Cu prospects are located at major gravity highs that bound granitic intrusions. The prospects appear to be linked to main faulting and to positive magnetic anomalies caused by magnetite enrichment. At prospect scale, the magnetic print of IOCG deposits may be subdivided as follows: the Fe-prospect is characterised by high magnetic anomalies due to a high content of magnetite, whereas the Cu-mineralised rocks show hematitisation of magnetite, which causes a decrease in magnetic susceptibility. The occurrence of IOCG mineralised rocks is also indicated by the associated potassic alteration, which can be mapped through analysis of airborne radiometric data. In this case, the potassium/thorium ratio has been proven to be a viable attribute to locate K-altered zones.

National Category
Geophysics
Research subject
Applied Geophysics
Identifiers
urn:nbn:se:ltu:diva-34238 (URN)85fc5530-b0c7-11dd-9c9d-000ea68e967b (Local ID)85fc5530-b0c7-11dd-9c9d-000ea68e967b (Archive number)85fc5530-b0c7-11dd-9c9d-000ea68e967b (OAI)
Conference
International Geological Congress : 06/08/2008 - 14/08/2008
Note

Godkänd; 2008; 20081112 (ysko)

Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2018-06-04Bibliographically approved
Sandrin, A., Berggren, R. & Elming, S.-å. (2007). Geophysical targeting of Fe-oxide Cu-(Au) deposits west of Kiruna, Sweden (ed.). Journal of Applied Geophysics, 61(2), 92-101
Open this publication in new window or tab >>Geophysical targeting of Fe-oxide Cu-(Au) deposits west of Kiruna, Sweden
2007 (English)In: Journal of Applied Geophysics, ISSN 0926-9851, E-ISSN 1879-1859, Vol. 61, no 2, p. 92-101Article in journal (Refereed) Published
Abstract [en]

Ore deposits are frequently associated with various types of rock alteration that may affect the physical properties of rocks, and result in a characteristic signature of the deposits. The present work focuses on the use of geophysical data in targeting areas hosting Fe-oxide Cu-Au (IOCG) deposits west of the Kiruna mining district, northern Sweden. It is noted that IOCG deposits in different areas worldwide (e.g., Australia, Canada) are preferentially located in proximity to faults associated with deformation zones of regional relevance, and that the deposits are hosted in areas affected by potassic to sodic alteration. This study shows that at a semi-regional scale IOCG deposits occur within areas of high positive gravity anomalies, high values of estimated potassium content and high K/Th ratios, which is an expression of potassic alteration. High magnetic anomalies are associated with magnetite occurrences, while low linear magnetic anomalies mark fault/shear zones, in proximity of which the majority of the IOCG deposits occur.

National Category
Geology Geophysics
Research subject
Ore Geology; Applied Geophysics
Identifiers
urn:nbn:se:ltu:diva-5587 (URN)10.1016/j.jappgeo.2006.05.002 (DOI)000246503600002 ()2-s2.0-33845884098 (Scopus ID)3b870f80-d479-11db-8550-000ea68e967b (Local ID)3b870f80-d479-11db-8550-000ea68e967b (Archive number)3b870f80-d479-11db-8550-000ea68e967b (OAI)
Note

Validerad; 2007; 20070317 (ysko)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Berggren, R., Sandrin, A. & Elming, S.-å. (2004). Physical properties of rocks and geophysical data as tools for targeting Fe-oxide Cu-Au mineralisations in northern Sweden (ed.). Paper presented at American Geophysical Union 2004 fall meeting : 13/12/2004 - 17/12/2004. EOS: Transactions, 85(47)
Open this publication in new window or tab >>Physical properties of rocks and geophysical data as tools for targeting Fe-oxide Cu-Au mineralisations in northern Sweden
2004 (English)In: EOS: Transactions, ISSN 0096-3941, E-ISSN 2324-9250, Vol. 85, no 47Article in journal, Meeting abstract (Other academic) Published
National Category
Geology Geophysics
Research subject
Ore Geology; Applied Geophysics
Identifiers
urn:nbn:se:ltu:diva-28145 (URN)1d8055e0-e487-11dc-b4b0-000ea68e967b (Local ID)1d8055e0-e487-11dc-b4b0-000ea68e967b (Archive number)1d8055e0-e487-11dc-b4b0-000ea68e967b (OAI)
Conference
American Geophysical Union 2004 fall meeting : 13/12/2004 - 17/12/2004
Note

Godkänd; 2004; Bibliografisk uppgift: Abstract MR11A-0933; 20080226 (ysko)

Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2018-06-04Bibliographically approved

Search in DiVA

Show all publications