Geophysical characterization of the Orijärvi-Aijala VMS...

GEOLOGICAL SURVEY OF FINLAND Unit Espoo 28.8.2019 GTK Open File Work Report 102/2019

Geophysical characterization of the Orijärvi-Aijala VMS belt based on archived reports, geophysical and

petrophysical data

Elina Koskela, Viveka Laakso & Keith Galvin

GEOLOGICAL SURVEY OF FINLAND 28.8.2019

GEOLOGICAL SURVEY OF FINLAND DOCUMENTATION PAGE

28.8.2019 / Dnro

Authors

Viveka Laakso, Elina Koskela, Keith Galvin

Type of report

GTK Open File Work Report

Commission by

GTK

Title of report

Geophysical characterization of the Orijärvi-Aijala VMS belt based on archived reports, geophysical and petrophysical data

Abstract

Archived reports, geophysical and petrophysical data were reviewed to create an understanding of the geophysical characteristics of the Aijala-Orijärvi VMS area. The study area contains the Kuovila, Aijala, Aijala-Aurums, Metsämonttu, Liipola-S, Liipola-N, Iiljärvi, Orijärvi mine site and Paavonholma deposits which are located within the Orijärvi formation. East from the Orijärvi formation are located Nyckeln, Fiskars, Bäckgränd, Tolvmans, Karhuniemi, Paavola, Hermala, Jänisjärvi, Särkjärvi-Karjalohja and Puujärvi deposits. The geology of the study site is characterized overall by granite and metamorphic rocks as well as felsic to mafic volcanic rocks. Geophysical surveys carried out in the area result in distinct anomalies from which some authors identify the deposits. The main methods applied are magnetic, gravimetric, electric and electromagnetic methods. Regional geophysical characterization proves to be challenging due to the heterogeneous geology. More detailed characterization can be achieved by examining the deposits individually or in smaller groups.

All of the available geophysical data for each location were brought into a Geosoft Oasis Montaj, where the data were visualized and interpreted. All of the available drill core petrophysical data were visualized by creating strip logs containing resistivity and susceptibility data. A preliminary inversion was carried out for the Metsämonttu and Aijala deposits using aeromagnetic and borehole susceptibility data. The preliminary inversion shows the possibilities of magnetic interpretation for deposit modelling.

A coordinate transformation, from mining coordinates to KKJ2 was carried out so the mining benchmark locations could be transformed into modern coordinate systems and this transformation possibly used for the wider area. The transformation was done by defining a set of equations using mining coordinates and newly surveyed coordinates from the same locations. It was found that the tested transformation only works well on a local scale.

Keywords

Aijala, Metsämonttu, Orijärvi, geophysics, petrophysics

Geographical area

Map sheet

Other information

Report serial

GTK Open File Work Report Archive code

102/2019

GEOLOGICAL SURVEY OF FINLAND 28.8.2019

Total pages

30 p. + 1 appendix

Language

English Price

- Confidentiality

public

Unit and section

Project code

50402-2009023

Signature/name

Signature/name

GEOLOGICAL SURVEY OF FINLAND 28.8.2019 1 Open File Work Report 102/2019

Contents 1 Introduction 2

2 Study area 2

3 Geophysical characterization of the study area 5

3.1 Mineral deposits 5

3.1.1 Aijala and Aurums Aijala 5

3.1.2 Metsämonttu 7

3.1.3 Orijärvi mine site 8

3.1.4 Iiljärvi 9

3.1.5 Liipola-N and Liipola-S 11

3.1.6 Paavonholma 11

3.1.7 Paavola 11

3.1.8 Puujärvi 12

3.1.9 Särkjärvi-Karjalohja and Jänisjärvi 12

3.1.10 Hermala 13

3.1.11 Karhuniemi 13

3.1.12 Tolvmans 13

3.1.13 Bäckgränd 13

3.1.14 Fiskars 13

3.1.15 Nyckeln 14

3.1.16 Kuovila 14

3.2 Regional overview 16

4 Available numerical datasets 16

4.1 Aijala-Metsämonttu inversion 19

5 Coordinate transformation 20

5.1 Metsämonttu-Aijala coordinate transformation 20

5.2 Methodology 21

5.3 Results 24

5.4 Discussion 26

6 Conclusions 26

7 References 27

Appendix 1. Strip logs of the drill hole petrophysical data.


1 INTRODUCTION

The aim of this study is to investigate and summarize available historical geophysical and petrophysical data from Aijala-Orijärvi VMS belt, located in SW Finland, as a part of the Aijala-Metsämonttu brownfield site investigations in the GTK’s battery minerals project, WP3 (project number 50402-2009023).The review is mainly based on historical reports.

Several geophysical surveys have been carried out in the study location starting from the early 1900’s mainly by Outokumpu Oy and GTK. In order to create an understanding for the extent of the data sets available, all the reports for the study area were reviewed. Data stored in GTK and Outokumpu databases (now also stored at GTK) were retrieved and plotted in Oasis Montaj. In order to project old regional maps with local mining coordinates, a coordinate transformation from the old mining coordinates to KKJ2, and ultimately to any modern coordinate system, was created.

For the Aijala and Metsämonttu deposits a preliminary unconstrained inversion model was created by using aerogeophysical magnetic data and drillhole susceptibility data with 100 m x 100 m resolution.

2 STUDY AREA

The study area, Aijala-Orijärvi VMS belt, is located in SW Finland in the Uusimaa region between the cities of Turku and Helsinki and includes 19 separate mineral occurrences / deposits (Figure 1). Geology of these deposits, in large scale, is characterized by felsic to mafic volcanic rocks (Figure 2). The Aijala-Orijärvi area is part of the Uusimaa belt which forms the Kisko group. The Kisko group consist of Orijärvi, Kisko, Toijala and Salittu formations (Nironen and Luukas, 2017). Out of these the Orijärvi formation is the lowermost formation and is bound by the Kisko and Jyly shear zones (Figure 3).

Kuovila, Aijala, Aijala-Aurums, Metsämonttu, Liipola-S, Liipola-N, Iiljärvi, and Orijärvi mine sites and the Paavonholma deposits are located within the Orijärvi formation. The Nyckeln, Fiskars, Bäckgränd, Tolvmans, Karhuniemi, Paavola, Hermala, Jänisjärvi, Särkjärvi-Karjalohja and Puujärvi deposits are located sporadically east from the Orijärvi formation and are in large scale mainly characterized by granite and metamorphic rocks (Figure 2). In this report, due to their location and amount of available data and reports, Aijala and Aurums Aijala deposits, Särkijärvi-Karjalohja and Jänisjärvi deposits, and Liipola-S and Liipola-N deposits are paired together.


Figure 1. Topographic map of the study area with mineral occurrences / deposits.

Figure 2. Geology of the study area.


Figure 3. Formation of the Kisko group defined by Väisänen and Mänttäri (2002) (from Nironen and Luukas (2017)). The entire study site is covered with GTK’s aerogeophysical data. The aeromagnetic data show clear anomalies throughout the study area (Figure 4). All of the deposit located at the Orijärvi formation, such as Aijala and Metsämonttu, are located in the vicinity of distinct continuous anomalies. The aeromagnetic data follow the large scale geological variations and no details and can be observed with such scale.


Figure 4. Aerogeophysical magnetic data over the study area.

3 GEOPHYSICAL CHARACTERIZATION OF THE STUDY AREA

3.1 Mineral deposits

In the following subsection each deposit are considered based on historical archived reports, which can be retrieved from the GTK Hakku service (https://hakku.gtk.fi/fi/reports). The reports date back from the late 1800’s until the present day. Only reports with comprehensible and substantial content are described here.

3.1.1 Aijala and Aurums Aijala

Geology of Aijala deposit

The Aijala deposit is located within the Aijala member part of the Orijärvi formation (Nironen and Luukas, 2017). Mica gneiss, sericite-cordierite gneiss and sulphide ore are the main lithologies in the member. The Aijala area is deformed by NE-SW oriented Kisko shear zone. The Cu-Zn Ore of the Aijala deposit occurs as disseminated vertical cluster cut by faults in skarn carbonate rocks and associated schists (Parkkinen, 1975a). The elongated ore cluster has a maximum length of 500 m and 80 m width, and is known to continue to 600 m in depth. The width of individual ore formations varies from centimetres to meters with maximum width of 10 m.

GEOLOGICAL SURVEY OF FINLAND 28.8.2019 6 Open File Work Report 102/2019 Measured geophysical data

Suomen Malmi Oy (1945) carried out electric measurements (kaksikkokehämenetelmä) for prospecting purposes at the old mining sites in the Aijala area and to the south and east of the Aijala mining area in 1945. The weakest conductivity readings were measured around the mine areas and in outcrop areas. Strong conductors were observed in the Metsämonttu area and from drillings these were shown to be caused by pyrite and pyrrhotite. To further research the Metsämonttu area, a detailed electric measurement survey was carried out in 1949 using a closed primary loop (suljettu primäärisilmukka). Based on these measurements the continuation of the ore was shown to follow results from magnetic measurements. The maps and tables referred in the text are all unavailable.

Lunberg exploration conducted an airborne gravity survey over the Aijala area in 1959 (Dahlström, 1959). The survey result is plotted on a 1:40000 map. The measurements did not indicate any new large ore deposits in the Aijala area. The most important anomalies from the gravimetric survey were highlighted and listed with interpretation by the author. The anomalies were interpreted as massive peridotite, amphibolite and faults. All of the anomalies could not be identified due to the scale of the gravity survey and would require more detailed study. None of the anomalies could be directly connected with an ore occurrence. Measurement configuration is not presented.

Five surface drillholes were drilled to the Aijala-Metsämonttu area in the period of 1975-1976 based on bedrock mapping and geophysical information (Latvalahti, 1976). The drillings focused on investigations on the continuation of the Metsämonttu deposit and Björknäs geophysical anomaly. IP and magnetic measurements were included with the drillings, with no specifics on the measurement configurations/device reported. Based on the profile values measurement ID, the data ID’s are 422 for total magnetic and 460 for IP.

The Aijala area was one of the sites for testing the EM-31 device for overburden conductivity and depth extent determinations and also to provide information for the earlier geophysical measurements done in testing areas (Liimatainen, 1977). In Aijala, the measurements specifically focused on the possibility of determining a reason for discontinuities in IP measurement done earlier. In total three profiles were measured; two position between discontinuous IP anomalies and one over a more conductive filed area. Slingram, magnetic, IP and Proxan measurements were already available from the measured lines. Apparent resistivity values (data id number 461) have been calculated from the IP measurements.

In 1981, the Aijala site was part of a mercury measurement test done with a HGG-3 device (Katajarinne, 1981). The attachments of the Aijala measurements include two IP profiles.

Valjus et al. 2017 conducted magnetic and electromagnetic GEM-2 surveys over Aijala tailings area and gravity, electrical resistivity tomography (ERT) and induced polarization tomography (IPT) profiles in the area. The geophysical measurements were used to study the inner structure and dimensions of the Aijala tailings pond.

Measured petrophysical data

There are no records on measured petrophysical data at the Aijala site.

Geophysical characterization

GEOLOGICAL SURVEY OF FINLAND 28.8.2019 7 Open File Work Report 102/2019 Multiple gravity anomalies can be distinguished in the Aijala area from airborne gravity measurements (Dahlström, 1959). None of the anomalies could be directly connected to any ore occurrences, but the Aijala-Metsämonttu area showed higher gravity readings compared to the surrounding environment. Earlier electric measurements have shown low conductivity readings within the old Aijala mine area (Suomen Malmi Oy, 1945). The best conductors in the area have been detected within areas of thicker overburden such as valleys.

3.1.2 Metsämonttu Geology of Metsämonttu deposit

The Metsämonttu Zn ore is located within the same sequence as the Aijala Cu-Zn deposit. The Metsämonttu ore is formed by clusters of parallel, vertical sulfide mineral zones (Parkkinen, 1975b). The entire ore zone is 400 m long and 70 m wide and is known to continue to over 700 m in depth. Thickness of individual mineralization vary from few centimetre to meters. Quartz-feldspar schist/ quartz-feldspar gneiss (leptiitti) amphibolite and the ore bearing skarn are the main rock types in the deposit (Parkkinen, 1974). Pyrrhotite and sphalerite are the main minerals of the disseminated ore veins (Raja-Halli, 1949). The ore zones are mainly controlled by foliation in the area (Parkkinen, 1975b).

Measured geophysical data

Suomen Malmi Oy (1945) carried out electric measurements (kaksikkokehämenetelmä) for prospecting purposes at the old mining sites in the Aijala area in 1945. Strong conductors were observed in the Metsämonttu area and from drillings these were shown to be caused by pyrite and pyrrhotite. To further research the Metsämonttu area, a detailed electric measurement was carried out in 1949 using a closed primary loop (suljettu primäärisilmukka). Based on the measurements, the continuation of the ore was shown to follow the results from magnetic measurements done in the area. Dimensions of the Metsämonttu ore can be followed in the measurement results which also reflect on the steep dip of ore lenses. One thick ore lens could not be detected with the electric measurements. The sulfur content, which is more or less proportional with conductivity, of the lens is unknown. The maps and tables referred in the text are all missing from the archived report.

Raja-Halli (1949) reports magnetic and electric measurements done in the Metsämonttu mine site in a claim report (Metsämonttu 1 Kaivospiiri, 1950). Magnetic measurements done over the Aijala-Metsämonttu area shows that Metsämonttu belongs to the same sequence as the Aijala Cu-Zn ore. In the magnetic map Metsämonttu appears as a wider and more fragmented part, there is no mention how the measurements were made. Detailed magnetic measurements in Metsämonttu site were done 1948 with an Arvela magnetometer and a point density of 10 m × 10-2 m. Based on the detailed magnetic map the main ore corresponds very well with a one magnetic maximum. The same magnetic traction continues also outside the known ore formation but as more fragmented. In addition to the main magnetic maximum there are lot of smaller magnetic anomalies north and south of the maximum. In addition to magnetic measurements Raja-Halli mentions the electric measurements done by Suomen Malmi Oy (1945). All of the geophysical maps are missing from the report.

GEOLOGICAL SURVEY OF FINLAND 28.8.2019 8 Open File Work Report 102/2019 5 surface drillholes were drilled to the Aijala-Metsämonttu area in years 1975-1976 based on bedrock mapping and geophysical information (Latvalahti 1976). Two (A-82, A-81) were drilled south of the Metsämonttu mine site, focusing on investigating the continuation of the Metsämonttu deposit. IP and magnetic measurements were included with the drillings. No specifics on the measurement configurations/device are included. Based on the profile values measurement ID 422 is total magnetic and 460 is IP.


There are no records on measured petrophysical data at the Metsämonttu site.


The Metsämonttu deposit responds well to magnetic and electric measurements. The electric and magnetic measurements correspond well with each other, especially within the main ore formation. Some individual ore lenses/zones might not be detected with the electric measurements especially if the sulfur content is low (Suomen Malmi Oy 1945). Magnetic maps inform on the position, shape, dimensions and to some extent about the quality of the Metsämonttu sphalerite deposit (Suomen Malmi Oy, 1945).

3.1.3 Orijärvi mine site Geology of Orijärvi mine area occurrence

The Orijärvi mine is located in the Orijärvi formation within the Kisko group (Nironen and Luukas, 2017). During the operational years of the mine, from 1757 to 1954, over 1 million tons of rock were quarried (Mäkelä, 1982). The Orijärvi mine site is characterized by an east-west orientated quartz-feldspar schist/quartz-feldspar gneiss (leptiitti), cordierite gneiss-, and amphibolite zones. The actual Pb-Zn-Cu ore is located within the metasomatic alteration zone, in a tremolite skarn, partly unfolding in to the adjacent cordierite-antophyllite rocks (Wennervirta, 1970). The area is possibly characterized by a NNW-SSE orientated fracture zones (Wennervirta, 1970). In larger scale the continuation of the ore critical zone in Orijärvi mine area is seen to be east orientated towards Iiljärvi area (Latvalahti, 1977). Interpretations of the stratigraphy of the Orijärvi mine area are well presented by Colley & Westra (1987), Latvalahti (1979) and Mäkelä (1989) and summarized by Nironen and Luukas (2017).


Magnetic measurements conducted at Tigerstedt (1889), however there are no maps or other records for these measurements reported.

Electric measurement survey (johtokykykerroinmittaukset) were conducted in the early days of the Orijärvi mine operation (before 1951), however the contractor is unknown and the only record of these measurements are reported in ‘Orijärven kaivoksen historiikki ja selitys’ (1902) by an unknown author. No specifics of the measurement configuration such as the measured units or instrument used are reported.

Magnetic measurements and IP-measurements were conducted in 1977, led by research geologist Ulla Mäkelä (née Latvalahti). The maps for these measurements are recorded by Latvalahti (1978). The data was re-plotted in 1979 in order to determine the relation between the magnetic map’s 0-level and the contour levels by using frequency distribution (Aarnisalo,

GEOLOGICAL SURVEY OF FINLAND 28.8.2019 9 Open File Work Report 102/2019 1978). To support the regional measurements conducted in 1977, an aerial electrical survey was carried out in Skanssi quarry, located at the immediate vicinity of the Orijärvi mine (Mäkelä, 1982).


There are no records on measured petrophysical data at the Orijärvi mineral deposit site.


The thickest parts of the ore formation are interpreted to be located on top of an anticline fault between the depths of 0 – 100 m (levels + 0 to +100 in the mine), after which the ore splits into several thinner ore formations (Mäkelä, 1982). With the IP and magnetic measurements conducted at 1977, no distinct anomalies are seen to indicate an economical ore deposit (Latvalahti, 1978). The anomalies created by the ore deposit (within metamorphic rock and cut by an amphibolite vein) at Orijärvi site, do not have a clear immediate continuity beyond the deposit, according to the geophysical data (Mäkelä, 1982). The magnetic anomalies met at the study area are interpreted to be caused partially by a fault located east from the Orijärvi mine site and more importantly by a Fe-formation located north from the ore formation (Mäkelä, 1982).

3.1.4 Iiljärvi Geology of Iiljärvi occurrence

Iiljärvi (sometimes referred as Iilijärvi) Cu-Zn-Pb-Ag-Au deposit is located approximately 1.5 km northeast from the Orijärvi Pb-Zn-Cu deposit (Mäkelä, 1983). Nickel and cobalt concentrations similar to Metsämonttu are reported by Huhma (1969). Rare mineralization of meneghinite has also been reported (Stigzelius, 1974). Earlier measurements conducted at the Orijärvi mine area indicated possible continuation of the mineralization to Iiljärvi direction, this lead to the further exploration of the Iiljärvi deposit.

Geology of Iiljärvi is characterized by several small and separate mineralization which typically are discontinuous both in lateral and vertical dimensions. The formation lies within a metamorphosed rock formation, mainly including andalusite-cordierite mica gneisses (Mäkelä, 1983). Other main rock types are cordierite-antophyllite rocks (eastern part of the ore formation) and quartzite (western part of the ore formation) (Mäkelä, 1983).


Most of the geophysical surveys conducted at the Iiljärvi site before the year 1985 are reported and described by Katajarinne (1985).

• Magnetic and electrical measurements conducted by Suomen Malmi Oy (1946 – 1947).

• Airborne measurements at 1962 with line spacing of 250 m and altitude of 80 m. Magnetic Jalander fluxgate, electrical ABEM rotary field and radiation were measured by Outokumpu Oy.

• Magnetic vertical component measurements (Askania, 20 m x 50 m) by Outokumpu Oy at 1968 in KL coordinates.


• Electromagnetic measurements (Slingram 60 m /1775 Hz, 20 m x 50 m) by Outokumpu Oy in 1968 in KL coordinates.

• Gravity measurements (20 m x 50 m) by Outokumpu Oy in 1968 in KL coordinates.

• Magnetic measurements in 1977 and IP-measurements in 1977 lead by research geologists Ulla Mäkelä (née Latvalahti). The maps for these measurements are recorded by Latvalahti (1978). The survey covered both the Orijärvi mine site and Iiljärvi deposit.

• Electrical measurements with Sirotem by Outokumpu Oy in 1982 in KL coordinates. Measurements were carried out in 600 m line and also in drillhole IL-48.

• CP measurements (latauspotentiaalimittaukset) in 1982 – 1984 by Outokumpu Oy in KL coordinates.

• EM-37 measurements in 1985 by Outokumpu Oy in KL coordinates.

• Magnetic vertical component measurements and IP (Schlumberger array) measurements in 1971 by Outokumpu Oy in XY coordinates.

• Magnetic total field measurements in 1977 by Outokumpu Oy in XY coordinates.

• Low altitude airborne measurements by GTK at 1983.

• Electromagnetic (Slingram) survey in 1996 by Australian company BHP at the Iiljärvi site, at the reservation area Ori 2 (Björklund, 1997). The survey indicated a strong anomaly on the site, however diamond drillings conducted at the anomaly showed only low mineral concentrations in the desired ore minerals (Björklund, 1997).


Specific resistance, susceptibility, density, IP and remanence (remanent magnetization) measurements have been carried out in 16 of the drillholes in Iiljärvi site. Not all of the measurements have been carried out in all of the drillholes. The actual data however, is not reported by Katajarinne (1985).


As the ore mineralization is scattered in several smaller formations and is located in metamorphosed rock (not containing magnetic components), determining the ore formation is challenging with magnetic measurements. It is interpreted that the Iiljärvi mineralization and the host rock is only weakly magnetized (susceptibility of 100 – 200 *10-5 SI) and that higher values of magnetization (susceptibility of 1000 – 1000 *10-5 SI) are caused by the amphibolite dykes cutting the ore formation and sporadically met Fe concentrations (susceptibility of 300 – 800 *10-5 SI) (Katajarinne, 1985). The measured density values seem to follow the measured susceptibility values (Katajarinne 1985).

At the location where the ore formation perforates the surface, small anomalies are detected with gravity measurements (in the Bouguer anomaly) and with electromagnetic measurements (Slingam) (Katajarinne, 1985). It is unlikely, that if there had not been knowledge of the deposit location, the deposit would have been observed with these techniques (Katajarinne, 1985).

The best results have been acquired with IP measurements. The mineralization of the area is related to 200 m thick well conductive zone and at the areas where the ore formation perforates the surface clear anomalies are recorded (Katajarinne, 1985). However, interpreting the continuation of the ore body with these geophysical methods remains challenging due the shape and character of the many small areas of mineralization.

GEOLOGICAL SURVEY OF FINLAND 28.8.2019 11 Open File Work Report 102/2019 3.1.5 Liipola-N and Liipola-S Geology of Liipola occurrence

The Liipola occurrence consists of two identified individual ore deposits; Liipola-N (Zn-Pb) and Liipola-S (Zn-Pb-Cu), which are located approximately 2.5 km from each other. Thus the close location and the unifying geology, the sites can be discussed as one ore critical zone within the Kisko ore critical formation. The main rock types at the Liipola site are felsic volcanic rocks but also intermediate volcanic rocks are present in SW parts of the area, limestone and skarn are met along the 2.5 km zone from Liipola-S to Liipola-N roughly along the Kisko-Aijala road (Latvalahti, 1980).

South from Liipola-S and from the town of Kajala a relatively small granite dome is seen (Latvalahti, 1980). The so-called Liipola boulder, a Zn-Pb-Ag rich loose rock, is located east from Liipola-S (Isomäki, 1987). The boulder has been subject of several studies but the specifics of the origin of the boulder remain unsolved.


• Magnetic measurements in 1976.

• Gravity measurements in 1976.

• IP measurements with 100 m spacing in 1977. • Total magnetic field measurements in 1982.

• Electromagnetic measurements (Slingram) in 1982. • CP measurements (latauspotentiaalimittaukset) in 1982 and 1983


Physical properties of rocks (magnetic susceptibility, density, IP and resistance) measured from some of the drillholes at the study area (ominaisvakiomääritykset) (Isomäki, 1987).


Geological studies at the site have indicated the mineralization to be a single lense with no clear continuity (Isomäki, 1984a). The areas of mineralization have been detected with the utilized geophysical techniques. However, the obtained anomalies are small and weak and thus don’t enhance the geological characterization further. The rock types of the area (non- to weakly magnetic/conductive minerals present) make it challenging to constrain the ore deposit with applied geophysical methods (Isomäki, 1989b). Continuity of the possible ore critical zone in Liipola-N and -S has mainly been studied with geological methods and therefore no clear picture of the continuity, constructed with geophysical methods exist.

3.1.6 Paavonholma There are no reports available for Paavonholma area.

3.1.7 Paavola Geology of Paavola occurrence

GEOLOGICAL SURVEY OF FINLAND 28.8.2019 12 Open File Work Report 102/2019 According to Latvalahti (1981) the Paavola Cu-Zn-Pb mineralization is connected to skarn rocks in the Lohjansaari area. Thickness of the small mineralization varies from 0.5 – 3 m. Cordierite and pyroxene-rich quartz-feldspar gneiss with limestone and skarn layers are the main rock types in the Area.


In 1977 and 1978 Outokumpu Oy carried out magnetic and CP (latauspotentiaali/Mise-à-la-masse) measurements at the Lohjansaari Paavola mineralization. The areas of mineralization were detected with both methods (Latvalahti 1981).


There are no records on measured petrophysical data at the Paavola site.


The Paavola mineralization can be detected with magnetic and electric methods (Latvalahti, 1981).

3.1.8 Puujärvi Geology of Puujärvi occurrence

Puujärvi has been studied for a skarn formation in a schist formation. The layered diopside skarn contains rusty pyrite- and pyrrhotite-rich hornblende-mice gneiss layers. (Puustjärvi, 1979)


There are no records on geophysical measurements at the Puujärvi site.


There are no records on measured petrophysical data at the Puujärvi site.

3.1.9 Särkjärvi-Karjalohja and Jänisjärvi

Geology of Särkijärvi-Karjalohja-Jänisjärvi occurrence

The Särkijärvi-Karjalohja-Jänisjärvi area is part of the eastern Uudenmaa schist zone

composed by felsic gneisses, amphibolies, granitoids and multiple carbonate rock layers

(Reinikainen et al., 2003).


Magnetic and electric (Slingram) measurements were carried out in 1980 in Karjalohja Jänisjärvi Syvänoja area (Isomäki, 1984b). An old pit/quarry in the area crates a distinct magnetic anomaly in the surveyed area. Similar result cannot be obtained from the electric survey. As the magnetic measurements were anomalous only over the old pit and the mineralization was assumed to be minor. No specifics on the measurement device/configurations are included.

GEOLOGICAL SURVEY OF FINLAND 28.8.2019 13 Open File Work Report 102/2019 Low altitude aerogeophysical magnetic and electric measurements from Karjalohja Mustanlahti are presented in the report by Lindmark (1994). The area has a long SW-NE directed aeromagnetic anomaly which was studied with till sampling. Gneiss with mica gneiss layers is the main rock type in the anomalous area.

In 1999 magnetic and electric measurements were done in the Pellonkylä Karjalohja area to study the Pellonkylä carbonate deposit (Reinikainen et al., 2003). The measurements covered a 5.5 km2 area. Despite the similar petrophysical characteristics of the carbonate rock and the host rock, the EW continuation of the carbonate deposit could be followed from the geophysical maps. Results from the electric survey are not present and no specifics on the measurement device/configurations of the magnetic or electric surveys are included.


There are no records on measured petrophysical data at the Särkijärvi-Karjalohja-Jänisjärvi site.


The iron- and magnetite-rich garnet-hornblende mica gneiss in the old pit of Jänisjärvi Syvänoja creates a distinct magnetic anomaly in the area. It is possible to follow the carbonate rock layers in the area with geophysical methods.

3.1.10 Hermala There are no reports available from Hermala area.

3.1.11 Karhuniemi There are no reports available from Karhuniemi area.

3.1.12 Tolvmans There are no reports available from Tolvmans area.

3.1.13 Bäckgränd There are no reports available from Bäckgränd area.

3.1.14 Fiskars

Geology of Fiskars occurrence

Mineralization in Fiskars is a narrow (less than 2 m width) pyrite, sphalerite and galena occurrence (Isomäki, 1981). The mineralization is connected to serisite schists, chlorite-biotite schists and skarn quartzites in acid volcanic rocks (tuffite).


Outokumpu Oy has carried out magnetic, slingram and IP measurements in the Fiskars area (Isomäki, 1981). The geophysical measurements were part researching and evaluating the ore potential of the area.

GEOLOGICAL SURVEY OF FINLAND 28.8.2019 14 Open File Work Report 102/2019 During winter 1978-1979 Suomen Malmi Oy conducted magnetic and Slingram measurements and Outokumpu Oy exploration IP and potential measurements in the Fiskars area (Mäkelä, 1981). To investigate geophysical anomalies from the measurements pits were dug in summer 1978. The magnetic and electric anomalies west of the area are caused by sulfide phase iron formation in mica gneiss. In addition, the anomalous areas contain pyrite rich sericite schist. In year 1980 eight drillholes were drilled based on the geophysical surveys. Seven of these holes were drilled along the geophysical anomaly sequence in Fiskars and one west of the sequence in a pit with sulfide records.


Report by Mäkelä (1981) includes susceptibility and density value measured from drill core samples with 1 m spacing based on the graphs presented. Units for density or susceptibility are not notified in the susceptibility and density tables included with the report, but based on the density values densities are in gcm-3. The measured densities vary approximately from 2.5-3.7 gcm-3. The measured susceptibility values are mainly under 200 despite some individual readings with a susceptibility value over 3000.


The pyrite, sphalerite and galena mineralization in the Fiskars area cause electric and magnetic anomalies.

3.1.15 Nyckeln Geology of Nyckeln occurrence

The Nyckeln Zn- and Cu-mineralization is located approximately 6 km SE from Aijala (Latvalahti, 1975). The mineralization is hosted by limestones and skarns. Sphalerite, chalcopyrite and galena are the main minerals in the Nyckeln occurrence. Quartz diorite is the most common rock type in the Nyckeln area. The quartz diorite has been intruded by intermediate dikes/veins with thickness varying from 0.2 m to 4 m (Latvalahti, 1975).


An IP map from the Nyckeln area has been attached to a geological report by Latvalahti (1975). No information about the measurement specifics are included.


There are no records on measured petrophysical data at the Nyckeln site.


The Nyckeln occurrence cannot be characterized geophysically with the current data available.

3.1.16 Kuovila Geology of Kuovila occurrence

Kuovila consist of carbonate rocks, pyroclastic, felsic and alkaline volcanic rocks and iron formations. Recent studies in the area have focused on a calcite-wollastonite marble deposit

GEOLOGICAL SURVEY OF FINLAND 28.8.2019 15 Open File Work Report 102/2019 in the area but the area has also been studied for base metals in the iron formations especially around the old Lustingulla quarries where the limestone is cut by Zn-ore veins (Isomäki, 1989a).


Report by Isomäki (1990) presents magnetic, slingram and IP measurements from the Kuovila area. The magnetic and slingram measurement were done in 1981 covering 2 km2. IP measurements were conducted in 1983 covering a 1 km2 area focusing on the most central area. The measured area is characterized by two large electric anomalies to the south and east of the area and by several smaller anomalies west of the area. An IP anomaly can be seen in the old Lustingulla mine site known of Zn-ore veins cutting the limestones. Based on drilling the IP anomaly was created by hypabyssal graphite and pyrrhotite rich mafic veins. Corresponding slingram in-phase and IP anomalies can be seen south of the area but the cause could not be identified. The IP measurements are also presented by Isomäki (1989) and Kokkola (1985).

Lohva (2000) explored carbonate rocks in the Kuovila area by conducting magnetic and electric surveys in 1999, covering a 6 km2 area with the new measurements. The magnetic measurements were made with a proton magnetometer with 50 m line spacing and 10 m station spacing. Shear zone seen in the magnetic map divides the area into two distinct parts. The nearly N-S oriented magnetic anomalies east of the shear zone are caused by magnetite-rich gabbros. The nearly E-W oriented anomalies west of the shear zone are caused by quartz banded magnetite-rich iron formations followed by carbonate rocks. The electric slingram measurements were done with 60 m coil spacing, 50 m line spacing and 20 m station spacing. Electrically the study area is relatively uniform. Low altitude airborne measurements over the area has been carried out in years 1982 and 1979. The shear zone can also be seen in the aeromagnetic map.


Report by Kokkola (1985) present measured susceptibility and density values of 68 rock samples from 5 sampling lines. The lines are located within two large IP anomalies in the area. The rock samples collected are mostly tuffite, limestone, granodiorite/mica gneiss or veins. Densities of the samples vary between 2.66-3.77 gcm-3. Susceptibility values vary from 0 to 3750.

Petrophysical measurements from drill core samples were done in the research by Lohva (2000). The result are not represented in the report but can be found from the register of GTK’s petrophysics laboratory.


In general, the Kouvila area is electrically relatively homogeneous. Around the old Lustingulla mine site the graphite pyrrhotite rich veins create electric anomalies. Some of the IP anomalies in Kuovila have not been identified. Magnetic anomalies in the area are caused by magnetite-rich gabbros in the east and by magnetite-rich iron formations in the west. A shear zone seen in the magnetic maps divides these two.

GEOLOGICAL SURVEY OF FINLAND 28.8.2019 16 Open File Work Report 102/2019 3.2 Regional overview

Overall the deposits within the Orijärvi formation have been detected with applied geophysical methods, including magnetic, gravity, electromagnetic and electric methods. However, as the study area consists of several small occurrences, it is challenging to create a uniform geophysical interpretation for the whole study area. It is ideal to consider the area in smaller scale.

Aijala, Aurums Aijala and Metsämonttu can be detected with magnetic methods. Electric methods have been utilized in the area, where the Metsämonttu deposit responded well to the method by creating a distinct anomaly. Geophysical methods applied in the area have not shown continuity between the Aijala and Liipola-S deposit, located NE of Aijala. The Liipola-S and -N deposits have been detected with applied geophysical methods, however the detected anomalies have been weak due to the structure of the deposits.

Iiljärvi deposit, located NE from the Liipola-N deposit replicates the small scatted vein like deposit style of the Liipola deposits. The best results at the Iiljärvi have been acquired with apparent resistivity surveys. Some continuity towards the Liipola deposit has been obtained with geophysical methods applied in the area.

The Orijärvi mine site, located SE from the Iiljärvi deposit, has mainly been detected due the physical properties of the surrounding bedrock. The ore deposit itself does not create clear direct magnetic or electric anomalies.

Kuovila, the southernmost deposit in the Orijärvi formation, has been detected with magnetic methods. Kuovila, just like the Orijärvi deposit, is a good example of an area characterized by multiple magnetic anomalies from which only some are caused by the desired ore formations. For example in Kuovila half of the magnetic anomalies are caused by magnetite-rich gabbros and the other half by magnetite-rich iron formations.

The Nyckeln, Fiskars, Bäckgränd, Tolvmans, Karhuniemi, Paavola, Hermala, Särkjärvi-Karjalohja-Jänisjärvi and Puujärvi occurrences located outside the Orijärvi formations are mostly separate and distinct occurrences, related to carbonate rocks and skarns. The Fiskars, Paavola and Särkijärvi-Karjalohja-Jänisjärvi occurrences create magnetic and electric anomalies due the physical properties of the mineralizations. Most of the geophysical surveys carried out in the locations have focused on the carbonate rock formations. There are no records for rest of the occurrences thus leaving the geophysical characterization deficient.

4 AVAILABLE NUMERICAL DATASETS

GTK has inherited the old databases of Outokumpu Oy which include geophysical data from the Aijala-Orijärvi study site. In addition, the GTK databases include geophysical data surveyed by GTK. All geophysical data available, including petrophysical drillhole data, was downloaded and organized for each deposit. A Geosoft Oasis Montaj project was created for each of the deposits to inspect the old data. The geophysical data includes mostly magnetic total, Slingram, gravity and IP measurements. The drillhole petrophysical data contain susceptibility and resistivity values measured from drillholes located at the study site. The data were plotted using Geosoft Oasis Montaj and the results can be observed from the attached strip logs (Appendix 1).

GEOLOGICAL SURVEY OF FINLAND 28.8.2019 17 Open File Work Report 102/2019 The following maps present examples of the methods which were used and which revealed occurrences in the Aijala-Orijärvi study site. Figure 5 shows apparent resistivity at the Iiljärvi deposit surveyed by Outokumpu Oy in 1977. A W-E oriented anomaly can be detected, but no clear continuity caused by the occurrence can be constrained. Figure 6 presents gravity surveyed by Outokumpu Oy in 1986 and GTK in 2000. A Distinct W-E orientated anomaly high continuing east from Iiljärvi deposit to Liipola-N occurrence can be observed. Figure 7 shows results of a systematic magnetic total field survey by GTK in 1999 in Kuovila area. The nearly N-S oriented magnetic anomalies east of the area are caused by magnetite-rich gabbro and the nearly E-W oriented anomalies west of the area are caused by quartz banded magnetite-rich iron formations. The area is divided by approximately N-S oriented shear zone seen as a magnetic low in the data.

Figure 5. Apparent resistivity surveyed by Outokumpu Oy in 1977. Clear WE orientated anomaly can be detected at the Iiljärvi deposit site.


Figure 6. Combined Gravity results surveyed by GTK in 2000 and Outokumpu Oy in 1986. Distinct WE orientated anomaly high continuing east from Iiljärvi deposit to Liipola-N occurrence.

Figure 7. Results of a systematic magnetic total field survey by GTK in 1999. The nearly NS oriented magnetic anomalies east of the area are caused by magnetite-rich gabbro and the nearly EW oriented anomalies west of the area are caused by quartz banded magnetite-rich iron formations. The area is divided by approximately a NS oriented shear zone seen as a magnetic low in the data.

GEOLOGICAL SURVEY OF FINLAND 28.8.2019 19 Open File Work Report 102/2019 4.1 Aijala-Metsämonttu inversion

A preliminary inversion modelling (with Geosoft Oasis Montaj’s VOXI) was done over the Aijala-Metsämonttu area using aerogeophysical magnetic data and drillhole susceptibility data to model the susceptibility and continuation of the deposits with depth. The Aijala and Metsämonttu deposits are located within an elongated NE-SW oriented magnetic anomaly seen in the aeromagnetic map (Figure 8). Both deposits are part of the same sequence deformed by a shear zone. The unconstrained inversion was carried out with a 100 m x 100 m cell resolution, depth limit of 600 m and susceptibility limited to positive values. Figures 9 and 10 show the inversion result, the aeromagnetic data used for the inversion and the drillhole locations. The model visualization has been limited to show only the areas with highest susceptibility values (>0.04 SI) roughly representing the ore locations. Based on the inversion model the Metsämonttu deposit, known to continue at least over 700 m in depth (Parkkinen, 1975b), extends to deeper depths compared to the Aijala deposit known to continue to 600 m in depth (Parkkinen, 1975a). In general the unconstrained inversion result corresponds roughly to what is known of the geometry of these vertical deposits, indicating that further detailed modelling of magnetic data may be a useful exploration tool in this area.

Figure 8. Aerogeophysical magnetic data and locations of the Aijala and Metsämonttu deposits.


Figure 9. Result of the inversion modelling done in the Aijala and Metsämonttu deposits. The view has been limited to show only the highest susceptibility values (>0.04 SI). Coordinates in KKJ2.

Figure 10. Result of the inversion modelling done in the Aijala and Metsämonttu deposits. The view has been limited to show only the highest susceptibility values (>0.04 SI).

5 COORDINATE TRANSFORMATION

5.1 Metsämonttu-Aijala coordinate transformation

The aim of this task was to define a set of equations which would allow the transformation of local mining coordinates from the Metsämonttu-Aijala area into KKJ zone 2 coordinates (as this is the default national coordinate system for all mine material). Two reference maps were used, one with the Metsämonttu area (Outokumpu Oy, 1975, p. 2) with certain marker points’ local coordinates listed, and one with the wider Metsämonttu-Aijala area (Varma & Stenberg,

GEOLOGICAL SURVEY OF FINLAND 28.8.2019 21 Open File Work Report 102/2019 1976, p. 5), both in the same mining coordinate system. Combining these maps with a Differential GPS surveys and Georeferencing in ArcGIS we can formulate the coordinate transformation.

5.2 Methodology

The Aijala and Metsämonttu areas were surveyed with a DGPS to gain EUREF-FIN coordinates on the old mining benchmarks that appear in the mining reports and reference maps. In Metsämonttu, much of the study area was found to be forest that had been reworked recently and likely many times since the mining markers were put down, meaning many markers had been lost. The points Mp0, 26K, and 27K (Outokumpu Oy, 1975) were confidently found, 7K was also found but with a degree of uncertainty. In Aijala, all of the old markers had been lost or relocated over the years. To make up for the lack of recovered points, the corners of buildings that remained from the mining map (Varma & Stenberg, 1976) were surveyed to populate the area with points. These points have a degree of uncertainty as the very corners of the building could not be surveyed due to the flashing of the roofs covering the DGPS antenna, so the readings were taken 1-2 m off.

The points collected by the DGPS were imported to ArcGIS, along with the mining maps from the reports. Georeferencing of these images could then be done by matching up the confidently surveyed points with the points on the map, three points are needed for an accurate georeferenced image. Using the Metsämonttu area map first, points Mp0, 26K, and 27K were used, and in doing so it was found that the 7K point that was thought uncertain in the field matched up nicely on the georeferenced image. The same points (Mp0, 26K, and 27K) were used to georeferenced the Metsämonttu-Aijala area map (Figure 11), again the 7K point matched up well, but the building corner points in Aijala showed an error of ~9m. Also the S2 point previously thought found in the correct position was proven to be erroneous, being more than 150 m from the marking on the map meaning it had been moved from its original position.


Figure 11. Topographic map of the Metsämonttu-Aijala area overlain with the georeferenced mining map from the 1975 KTM report (Outokumpu, 1975). All points from the 1975 GTK Metsämonttu report areCoordinate points picked from the Metsämonttu map by Outokumpu (1975) are shown in the area to the west, with the DGPS point AH1 from Aijala also projected.

A transformation template was taken from McCoy & Robert (2010) so the transformation from mining coordinates to KKJ2 could be defined. Two methods of transformation were made:

1. Using one known point in both coordinate systems

2. Using two known points in both coordinate systems

a) Using two points from Metsämonttu

b) Using one point from Metsämonttu and one point from Aijala.

The first method uses the Mp0 point in Metsämonttu to define the transformation parameters, this point was chosen as it was confidently found and surveyed in the field. From the georeferencing in ArcGIS we found that the 21.6411° rotation angle stated in the Metsämonttu mining map (Outokumpu, 1975) may not be accurate for the transformation, so this angle was tested in a simple approximation of the transformation, it was found that a lower angle of 20.4° was optimal.

To mathematically transform a point from a local coordinate system to a standard coordinate system the following formulas are used: � = �� − �� + ��

(2.1) � = �� + �� + ��

Where, E and N are the easting and northing of the standard coordinate system, k is the scaling factor, X and Y are the known local coordinate system points, θ is the angle of rotation, and tx

GEOLOGICAL SURVEY OF FINLAND 28.8.2019 23 Open File Work Report 102/2019 and ty are the translation in the X and Y direction respectively in the local system after the scale and rotation have been applied. These equations can also be expressed as: � = �� − � + ��

(2.2) � = � + �� + �� ℎ��, � = �� = ��

In Excel, the parameters a and b are calculated easily using the rotation angle and the X and Y from the mining coordinates, which are also tabulated in the GTK mining report (Outokumpu, 1975) containing the map. The scaling factor k should be 1 as there should be no difference in scale in this instance. It was calculated for posterity however, using the distance between points 26K and 27K, which is stated on the map as 405.47 m, and from ArcGIS as 404.38, giving a k value of 1.0027. This could also be worked out from simple trigonometry which resulted in the same values, with such a small difference this was ignored and a scaling factor of 1 was used. The values for tx and ty were gained by reworking the above equations to give: �� = � − �� + �

(2.3) �� = � − � − �

Once the parameters a, b, tx, and ty are calculated using the reference point Mp0, the X and Y values for the full range of points on the mining map can be transformed into KKJ2 coordinates. This can either be done separately, or as part of a matrix, which when set up will calculate all transformations at once: � = ��

(2.4) � = ��⋮⋮�!�!

�� = �

��

−��−�1 00 11 0� �� 0 1⋮⋮�!!

⋮⋮−!�!⋮ ⋮⋮ ⋮1 00 1�

�� = $ ��$

In Microsoft Excel this multiplication is done my using the MMULT operation. To perform this first highlight the known number of cells where the resulting matrix E will be, then enter ‘+MMULT(array 1;array 2)’ and press Ctrl + Shift + Enter to initiate. Array 1 will be the matrix X, and array 2 the matrix T in this case.

The second method of transformation is using two known points, this was completed in two ways, firstly using two points in the Metsämonttu area (Mp0 and 27K), and secondly by using one point in Metsämonttu and one point in Aijala (Mp0 and AH1), the Aijala point AH1 was surveyed as the corner of a building and thus had to be scaled off the mining map to gain it’s mining coordinates. The basic calculations work the same as in the previous method where:

GEOLOGICAL SURVEY OF FINLAND 28.8.2019 24 Open File Work Report 102/2019 �� = �� − �� + ��

(2.5) �� = �� + �� + �� = �� − �� + �� = �� + �� + ��

The parameters a, b, tx and ty, are not directly calculated by reworking the equation like in the previous method as this would result in two sets of parameters. Instead these parameter are solved using matrices, where the matrix T is solved for: � = ��

(2.6)

� = �%��

� = $ ��$ � = ��

� � = ��−��−�

1 00 11 0� �� 0 1� To invert a matrix, in Microsoft Excel use the MINVERSE operation much the same as MMULT was used, but here only one array is needed. The MMULT operation can then be used the same way as previous to multiply the matrices X-1 and E, resulting in the matrix T. From the matrix T the rotation angle and scaling factor can be calculated:

� = �� %� &��' (2.7)

� = �� ; ��) � ; *�� + �� (2.8)

The transformations can then be carried out for all points using the previously stated equations for E and N with the transformation parameters calculated in the matrix T.

5.3 Results

Using one point in Metsämonttu:

Figure 12 shows the transformation for all points in the Metsämonttu area, and one in the Aijala area (AH1). All Metsämonttu stations are taken from the Metsämonttu area mining map, with the corner points listed being the extents of the grid in this map. Mine X and Y coordinates (MINE_X and MINE_Y) are the mining coordinates taken from the table within the same report, with the AH1 point being scaled off the KTM Metsämonttu-Aijala area map. The real KKJ2 coordinates are partly taken from the DGPS survey (noted with *) and partly from ArcGIS coordinates from the georeferenced map. The transformed points are shown in the KKJ2_TRANS_E and KKJ2_TRANS_N columns, with the difference between transformed and real points calculated in the E_ERROR and N_ERROR columns. Here we see that in the Metsämonttu area a very good accuracy is achieved with a maximum error of less than 4 metres, the average error for this area was calculated to be 1.263 metres with a standard deviation 1.077 metres. A rotation angle of 20.4° was used to calculate the a and b parameters.

GEOLOGICAL SURVEY OF FINLAND 28.8.2019 25 Open File Work Report 102/2019 This Metsämonttu based transformation doesn’t work so well in Aijala however, with errors of 24 metres (easting) and 29 metres (northing) for AH1. This very large error means that this transformation would not be considered for use in the Aijala area.

Figure 12. Transformation of the Metsämonttu points and 1 Aijala point.

Using two points in Metsämonttu:

The Metsämonttu points Mp0 and 27K were used for the first transformation using 2 points (Figure 13). This gave similar results as the previous transformation using one point in Metsämonttu. The maximum error for the points in the Metsämonttu area is slightly higher at just over 4 metres, with a lower average error of 0.203 metres and a higher standard deviation of 1.577 metres. The point in Aijala (AH1) still shows error in the 20s of metres. The rotation angle that is computed for this transformation is 20.64°, which is 1° lower than the angle stated in the mining map, and 0.2° higher than the angle defined in the approximate transformation. A scaling factor k of 0.996 is also worked out from the transformation parameters.

Figure 13. Transformation done with two points in Metsämonttu.

Using 2 points, one in Metsämonttu and one in Aijala:

For the second transformation using two points, the Metsämonttu point Mp0 and the Aijala point AH1 were used (Figure 4). This middle ground approach results in a high variance of errors with points closely surrounding the reference point like P 77 and P 78 (~70 to 100 metres from Mp0) being in good correlation, but as the distance from the reference point increases, so does the error. Average error of -7.187 metres is seen, with a standard deviation of 9.889 metres. The rotation angle that is computed for this transformation is 19.68°, which is just under

STATION MINE_Y MINE_X KKJ2_TRANS_E KKJ2_TRANS_N KKJ2_REAL_E KKJ2_REAL_N E_ERROR N_ERROR

SW corner 600 9200 2463506.784 6675017.392 2463508.735 6675020.546 1.951 3.154

NW corner 1000 9200 2463367.355 6675392.304 2463369.815 6675394.381 2.460 2.077

SE corner 600 10000 2464256.61 6675296.249 2464257.401 6675297.241 0.791 0.992

Mp 0* (NE corner) 1000 10000 2464117.181 6675671.162 2464117.181 6675671.162 0.000 0.000

P 77 943.33 9905.08 2464047.968 6675584.96 2464049.972 6675585.531 2.004 0.571

P 78 951.09 9941.7 2464079.586 6675604.998 2464079.281 6675604.986 -0.305 -0.012

Mp 12 757.94 10013.71 2464214.406 6675449.062 2464215.756 6675449.491 1.350 0.429

N:o 6K 955.05 9367.51 2463540.028 6675408.563 2463542.619 6675409.257 2.591 0.694

N:o 7K* 1048.51 9360.05 2463500.458 6675493.561 2463502.785 6675493.446 2.326 -0.115

N:o 26K* 676.33 10043.11 2464270.41 6675382.819 2464271.758 6675383.692 1.349 0.873

N:o 28K 735.69 9224.79 2463482.722 6675153.212 2463484.817 6675154.441 2.095 1.229

N:o 27K* 705.7 9638.71 2463881.135 6675269.384 2463883.684 6675270.014 2.549 0.629

N:o 29K 948.9 9649.05 2463806.054 6675500.936 2463809.263 6675500.883 3.209 -0.053

AH1** 988.7 11080 2465133.384 6676037.029 2465103.459 6676012.338 -29.926 -24.690


AH1 988.7 11080 2465127.91 6676039.686 2465103.459 6676012.338 -24.452 -27.348

SW corner 600 9200 2463511.822 6675017.503 2463508.735 6675020.546 -3.087 3.043

NW corner 1000 9200 2463371.43 6675390.379 2463369.815 6675394.381 -1.615 4.002

SE corner 600 10000 2464257.573 6675298.287 2464257.401 6675297.241 -0.172 -1.046

Mp 0 (NE corner) 1000 10000 2464117.181 6675671.162 2464117.181 6675671.162 0.000 0.000

P 77 943.33 9905.08 2464048.588 6675585.02 2464049.972 6675585.531 1.384 0.511

P 78 951.09 9941.7 2464080.001 6675605.107 2464079.281 6675604.986 -0.720 -0.121

Mp 12 757.94 10013.71 2464214.919 6675450.328 2464215.756 6675449.491 0.837 -0.837

N:o 6K 955.05 9367.51 2463543.358 6675407.269 2463542.619 6675409.257 -0.739 1.988

N:o 7K 1048.51 9360.05 2463503.601 6675491.773 2463502.785 6675493.446 -0.817 1.672

N:o 26K 676.33 10043.11 2464270.969 6675384.571 2464271.758 6675383.692 0.789 -0.879

N:o 28K 735.69 9224.79 2463487.307 6675152.693 2463484.817 6675154.441 -2.490 1.748

N:o 27K 705.7 9638.71 2463883.684 6675270.014 2463883.684 6675270.014 0.000 0.000

N:o 29K 948.9 9649.05 2463807.965 6675500.351 2463809.263 6675500.883 1.298 0.532

GEOLOGICAL SURVEY OF FINLAND 28.8.2019 26 Open File Work Report 102/2019 2° lower than the angle stated in the mining map, and 1.28° lower than the angle defined in the approximate transformation. A scaling factor k of 0.966 is also worked out from the transformation parameters.

Figure 14. Transformation done with two points, one in Metsämonttu and one in Aijala.

5.4 Discussion

What can be seen from the variety of transformations completed is that the transformations only work well on a local scale and do not translate well from Metsämonttu to Aijala. This could be attributed to lack of mining benchmarks found in Aijala, as the house corner coordinates surveyed are already accompanied with a degree of uncertainty. Whereas in Metsämonttu many of the original mining benchmark points were recovered. An issue could rise from the timing of the original surveys, the Aijala area was discovered before Metsämonttu so the original survey that defined the grid may not have taken place at the same time in both areas, but this reason is hard to recover from the literature however.

6 CONCLUSIONS

The Aijala-Orijärvi VMS deposit site contains several geological environments. Therefore, a comprehensive geophysical characterization of the area remains challenging. An understanding of the geophysical characteristics related to the study site can be drawn from studying the archived reports creating a good premises to the project even though it remains time consuming.

As the study site covers a relatively large and heterogeneous area it could be more beneficial to inspect the deposit individually to gain more detailed observations. There are archived data from the study sites available from both from GTK and Outokumpu Oy. The existing data has a lot of potential for future use. However, it should be treated with reservation as for most of the data there is no knowledge of the collection and processing phases.

The preliminary magnetic inversion done at the Metsämonttu deposit indicates that with combined geophysical and petrophysical datasets favourable results can be obtained. A more detailed and defined model is needed in order to withdraw more specific interpretations and conclusions.


AH1 988.7 11080 2465103.459 6676012.338 2465103.459 6676012.338 0.000 0.000

SW corner 600 9200 2463519.498 6675046.897 2463508.735 6675020.546 -10.763 -26.351

NW corner 1000 9200 2463389.329 6675410.823 2463369.815 6675394.381 -19.514 -16.442

SE corner 600 10000 2464247.35 6675307.236 2464257.401 6675297.241 10.051 -9.995

Mp 0 (NE corner) 1000 10000 2464117.181 6675671.162 2464117.181 6675671.162 0.000 0.000

P 77 943.33 9905.08 2464049.263 6675588.714 2464049.972 6675585.531 0.709 -3.183

P 78 951.09 9941.7 2464080.055 6675607.691 2464079.281 6675604.986 -0.774 -2.705

Mp 12 757.94 10013.71 2464208.427 6675455.394 2464215.756 6675449.491 7.329 -5.903

N:o 6K 955.05 9367.51 2463556.36 6675424.439 2463542.619 6675409.257 -13.741 -15.182

N:o 7K 1048.51 9360.05 2463519.159 6675507.042 2463502.785 6675493.446 -16.374 -13.597

N:o 26K 676.33 10043.11 2464261.733 6675390.711 2464271.758 6675383.692 10.025 -7.019

N:o 28K 735.69 9224.79 2463497.896 6675178.417 2463484.817 6675154.441 -13.079 -23.976

N:o 27K 705.7 9638.71 2463884.246 6675285.831 2463883.684 6675270.014 -0.562 -15.818

N:o 29K 948.9 9649.05 2463814.511 6675510.463 2463809.263 6675500.883 -5.248 -9.580


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GEOLOGICAL SURVEY OF FINLAND 28.8.2019 Open File Work Report 102/2019 Appendix 1. Appendix 1. Strip logs of petrophysical drill hole data

GEOLOGICAL SURVEY OF FINLAND 28.8.2019 Open File Work Report 102/2019 Appendix 1.

























































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Geophysical characterization of the Orijärvi-Aijala VMS...

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