Rock chemical database of Finland

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This text is taken from Geological survey of Finland, Report of Investigation 171/2008: Chemical Characteristics of Finnish Bedrock]

Introduction

The purpose of this paper is to summarize the chemical composition of Finnish bedrock using analytically consistent data. The summary data presented here is based on the geochemical data set termed the Rock Geochemical Database of Finland (Geological Survey of Finland 2007) and described by Rasilainen et al. (2007). The database contains whole-rock geochemical data for 6544 bedrock samples from throughout Finland. This data enables the estimation of the chemical composition of major units of Finnish bedrock as presented on the 1:1 000 000 scale Bedrock Map of Finland (Korsman et al. 1997). The estimated average compositions of bedrock units and their combinations are tabulated in the Appendix of this report. The tables are available in Microsoft Excel 2003 format at: http://www.gtk.fi/publ/RGDB/Mapunitsummaries/.

Bedrock of Finland

Outline of the Finnish bedrock

The bedrock of Finland is composed mainly of Precambrian crystalline rocks and it forms a central part of the Fennoscandian shield. Korsman et al. (1997) divided the bedrock of Finland into the Karelian, Svecofennian and Caledonian domains and a northeastern area composed of the Lapland Granulite Belt and the Inari Complex. The Karelian domain is composed of Archean rocks, Paleoproterozoic cover and Paleoproterozoic plutonic rocks. The Svecofennian domain consists of Paleoproterozoic rocks. The Caledonian domain includes a small area of Caledonian allochthons in the north-western corner of Finland. The Lapland Granulite Belt is Paleoproterozoic in age and the Inari complex includes both Archean and Paleoproterozoic rocks. Postorogenic small intrusions (c 1.8 Ga) occur in southern and northern Finland and 1.65 – 1.54 Ga rapakivi granites have intruded along the southern and south-western coast. Small areas of Mesoproterozoic and Neoproterozoic metasedimentary rocks are also found along the western coast and some Precambrian and Phanerozoic alkaline rocks and carbonatites occur in eastern Finland. The latest comprehensive description of the bedrock of Finland is found in Lehtinen et al. (2005) and references therein.

Map units on the 1:1 000 000 scale

Bedrock Map of Finland The Finnish bedrock is divided into domains on the 1:1 000 000 scale bedrock map of Finland (Korsman et al. 1997). The domains are divided into complexes, sequences and intrusions and these are further divided into map units. This division is dominantly based on the interpreted tectonic history of the rocks, but many map units are described only with an age interval and rock type. A map unit may consist of a single rock type or many rock types of either similar origin (e.g., intrusive rocks) or different origin. For example, map unit 56 includes carbonate and calc-silicate rocks, black schists, metavolcanic rocks and banded iron formations.

Each sample in the Rock Geochemical Database of Finland is assigned to one of the map units shown on the 1:1 000 000 scale bedrock map. The assignment is based on the location of the sampling point when plotted on the digitized map using GIS software. The scale of the bedrock map prohibits fine details to be shown. Hence, samples that fall within a certain map unit on the map may actually belong to another unit due to simplifications that are a necessary part of creating the 1:1 000 000 scale map. Samples near lithologic contacts or with rock names not suitable for the particular map unit were investigated, and, when appropriate, reassigned to the correct map unit (Rasilainen et al. 2007).

During the compilation of the database, some changes were made in the configuration of map units. These changes are partly based on updated knowledge concerning the geology of certain areas and partly they reflect features that are marked as overprints on the bedrock map. Map unit 28 on the 1:1 000 000 scale bedrock map is composed of mica gneisses and mica schists with black schist intercalations. On the west coast of Finland, in the area between Vaasa and Kokkola, the central part of this unit consists mostly of granitic and granodioritic rocks that have formed by melting of the sedimentary mica gneisses (Sipilä et al. 2008). The area containing the granitoid samples was digitized as a separate map unit, 281, using GIS software.

Map unit 39 on the 1:1 000 000 scale bedrock map is composed of granite and granodiorite with gneissic inclusions. Mica gneisses occur along the margins of the large granitic area composed of this unit north of Rovaniemi in northern Finland. Within this area, the small tracts defined by the mica gneiss samples were separated as map unit 391 using GIS software.

Fourteen granitic samples in north-western Lapland plotting on or near the Archean gneissic map unit 76 or the granitic map unit 84 on the bedrock map were reclassified as belonging to map unit 39 based on the data in Koistinen et al. (2001).

The area covered by each map unit on the 1:1 000 000 scale bedrock map was measured using GIS software. Diabase dykes are expressed on the 1:1 000 000 scale bedrock map as line features and for this reason their surface area could not be calculated from the map. The area covered by diabase dykes was estimated based on studies at two tracts within the Archean bedrock in eastern Finland, at Romuvaara and Veitsivaara. The detailed bedrock maps covering about 26 km2 at Romuvaara (Saksa et al. 1992) and 30 km2 at Veitsivaara (Saksa et al. 1993) were digitized and the area of diabases was calculated using GIS software. Diabase dykes covered 4.7 % of the map area at Romuvaara and 5.3 % at Veitsivaara (H. Salmirinne, pers. comm. 2006). Based on these figures, diabase dykes were estimated to cover five percent of the surface area of the Archean bedrock in Finland. Consequently, the estimated area covered by each Archean map unit (units 66–76) was decreased by five percent to acquire the area covered by Archean rocks only.

Rock chemical database of Finland(-)
ObsDomainAgeSequenceMap.unitNRock.typesDescription
1PaleozoicCambrian sedimentary sequences14Sandstone and shale
2NeoproterozoicVendian sedimentary sequences20Siltstone and shale
3NeoproterozoicVendian sedimentary sequences31Sandstone and conglomerate
4MesoproterozoicInteracratonic sedimentary sequences and intruisition41Slitstone ans Shale
5MesoproterozoicInteracratonic sedimentary sequences and intruisition518Olivine diabase
6MesoproterozoicInteracratonic sedimentary sequences and intruisition65Sandstone and conglomerate
7MesoproterozoicAnorogenic or postogenic bimodal intrusive complexes73Quartz porphyry (1.65-1.62 Ga)
8MesoproterozoicAnorogenic or postogenic bimodal intrusive complexes895Rapakivi granite (1.65-1.63 Ga)
9MesoproterozoicAnorogenic or postogenic bimodal intrusive complexes949Rapakivi granite (1.59-1.57 Ga)
10MesoproterozoicAnorogenic or postogenic bimodal intrusive complexes109Gabbro-anorthosite (1.65-1.62 Ga)
11MesoproterozoicAnorogenic or postogenic bimodal intrusive complexes111Gabbro-anorthosite (1.59-1.57 Ga)
12PaleoproterozoicPostorogenic intrusions1229Granite; norther Finland (1.80-1.77 Ga)
13PaleoproterozoicPostorogenic intrusions133Granite and associated rocks; southern Finland (1.81–1.77 Ga)
14Svecoffenian domain APaleoproterozoicIntrusions post-dating the main stage of crustal thickening14209Microline granite (1.84-1.82 Ga)
15Svecoffenian domain APaleoproterozoicCollision-related intrusions15SA236Granodiorite, tonalite and quartz diorite (1.89-1.87 Ga)
16Svecoffenian domain APaleoproterozoicCollision-related intrusions16SA72Gabbro and diorite (1.89.1-87 Ga)
17Svecoffenian domain APaleoproterozoicSupracrustal sequences (1.90-1.88 Ga)172Quartzite
18Svecoffenian domain APaleoproterozoicSupracrustal sequences (1.90-1.88 Ga)18348Mica schist and mica gneiss
19Svecoffenian domain APaleoproterozoicSupracrustal sequences (1.90-1.88 Ga)1985Indermetiate and felsic metavolcanic rock and metasediments
20Svecoffenian domain APaleoproterozoicSupracrustal sequences (1.90-1.88 Ga)20178Mafic metavolcanic rocks
21Svecoffenian domain APaleoproterozoicSupracrustal sequences (1.90-1.88 Ga)213Ultramafic metavolcanic rocks
22Svecoffenian domain BPaleoproterozoicIntrusions post-dating main stage of crustal thickening2213Pyroxene grantoid (1.88-1.87 Ga)
23Svecoffenian domain BPaleoproterozoicIntrusions post-dating main stage of crustal thickening2326Granite (1.88-1.87 Ga)
24Svecoffenian domain BPaleoproterozoicIntrusions post-dating main stage of crustal thickening24SB205Granite (~1.88 Ga)
25Svecoffenian domain BPaleoproterozoicCollision-related intrusions15SB485Granodiorite, tonalite and quartz diorite (1.89-1.88 Ga)
26Svecoffenian domain BPaleoproterozoicCollision-related intrusions16SB137Gabbro, diorite and peridotite (1.89-1.88 Ga)
27Svecoffenian domain BPaleoproterozoicSupracrustal sequences2547Mica schists, intercalated arkosites and conglomerates
28Svecoffenian domain BPaleoproterozoicSupracrustal sequences2681Indermetiate and felsic metavolcanic rocks with metasedimentary intercalations (1.89-1.88 Ga)
29Svecoffenian domain BPaleoproterozoicSupracrustal sequences27107Mafic metavolcanic rocks (1.89–1.88 Ga)
30Svecoffenian domain BPaleoproterozoicSupracrustal sequences28319Mica gneisses and mica schists with black schist intercalations
31Svecoffenian domain BPaleoproterozoicSupracrustal sequences28171Granitic and granodioritic rocks formed by melting of unit 28 sedimentary rocks
32Svecoffenian domain BPaleoproterozoicSupracrustal sequences290Felsic to intermediate metavolcanic and metasedimentary rocks (~1.90 Ga)
33Svecoffenian domain BPaleoproterozoicSupracrustal sequences3041Mafic metavolcanic rocks (~1.90 Ga)
34Svecoffenian domain BPaleoproterozoicSupracrustal sequences310Ultramafic metavolcanic rocks (~1.90 Ga)
35Svecoffenian domain CPaleoproterozoicIntrusions post-dating main stage of crustal thickening24SC39Granite (~1.88 Ga)
36Svecoffenian domain CPaleoproterozoicIntrusions post-dating main stage of crustal thickening3220Pyroxene granitoid and mafic dykes (1.885 Ga)
37Svecoffenian domain CPaleoproterozoicCollision-related intrusions15SC74Granodiorite, tonalite and quartz diorite (1.89-1.87 Ga)
38Svecoffenian domain CPaleoproterozoicCollision-relates intrusions16SC31Gabbro, diorite and peridotite (1.89-1.87 Ga)
39Svecoffenian domain CPaleoproterozoicSupracrustal sequences331Intermediate and felsic metavolcanic rocks with metasedimentary intercalations (1.90–1.88 Ga)
40Svecoffenian domain CPaleoproterozoicSupracrustal sequences342Mafic metavolcanic rocks (1.90–1.88 Ga)
41Svecoffenian domain CPaleoproterozoicSupracrustal sequences35113Mica gneiss and mica schist with intercalated carbonate rocks
42Svecoffenian domain CPaleoproterozoicSupracrustal sequences3616Felsic and intermediate metavolcanic rocks (~1.92 Ga)
43Svecoffenian domain CPaleoproterozoicSupracrustal sequences3756Mafic metavolcanic rocks (~1.92 Ga)
44Svecoffenian domain CPaleoproterozoicPre-collisional intrusions3819Gneissic tonalite and granodiorite (1.93–1.91 Ga)
45Karelian domainPaleoproterozoicIntrisions post-dating crustal thickening in northern Finland (~1.8 Ga)39277Granite and granodiorite with gneissic inclusions
46Karelian domainPaleoproterozoicSupracrustial unit39142Mica gneisses and migmatites intruded by unit 39
47Karelian domainPaleoproterozoicPost-collasional foreland sequence, molasse4010Quartzite and conglomerate
48Karelian domainPaleoproterozoicPost-collisional intrusions in southeastern Finland4137Granite and granodiorite (~1.86 Ga)
49Karelian domainPaleoproterozoicPost-collasional intrusions in southeastern Finland24K16Granite (~1.88 Ga)
50Karelian domainPaleoproterozoicEarly foreland sequences426Quartzite and conglomerate
51Karelian domainPaleoproterozoicEarly foreland sequences433Mafic and felsic metavolcanic rocks (~1.88 Ga)
52Karelian domainPaleoproterozoicCollision-related intrusions448Granite (1.89–1.88 Ga)
53Karelian domainPaleoproterozoicCollision-related intrusions4516Quartzmonzodiorite, quartz monzonite and granodiorite (1.90-1.86 Ga)
54Karelian domainPaleoproterozoicCollision-related intrusions4614Gabbro
55Karelian domainPaleoproterozoicAllochthonous sequences emplaced onto the craton margin47116Mica schists and intercalated black schists
56Karelian domainPaleoproterozoicAllochthonous sequences emplaced onto the craton margin481Banded iron formations (BIF)
57Karelian domainPaleoproterozoicAllochthonous sequences emplaces onto the craton margin4934Mafic metavolcanic rocks with metasedimentary intercalations
58Karelian domainPaleoproterozoicOphiolites and related tectonic complexes (1.96-1.95 Ga)506Gneissic alkaline granite
59Karelian domainPaleoproterozoicOphiolites and related tectonic complexes (1.96-1.95 Ga)5116Serpentinites and other rocks of ophiolitic origin
60Karelian domainPaleoproterozoicInteracratonic to craton margin sequences and mafic intrusions5219Gabbro (2.15–2.00 Ga)
61Karelian domainPaleoproterozoicInteracratonic to craton margin sequences and mafic intrusions53173Mica schist, black schist, conglomerate and arkosite
62Karelian domainPaleoproterozoicInteracratonic to craton margin sequences and mafic intrusions5427Ultramafic metavolcanic rocks
63Karelian domainPaleoproterozoicInteracratonic to craton margin sequences and mafic intrusions559Arkosite, mica schist and conglomerate
64Karelian domainPaleoproterozoicInteracratonic to craton margin sequences and mafic intrusions5678Carbonate- and calc-silicate rocks, black schists and metavolcanic rocks, BIF
65Karelian domainPaleoproterozoicInteracratonic to craton margin sequences and mafic intrusions57144Mafic and felsic metavolcanic rocks
66Karelian domainPaleoproterozoicInteracratonic to craton margin sequences and mafic intrusions5871Quartzite
67Karelian domainPaleoproterozoicInteracratonic sequences and mafic intrusions5926Gabbro (2.2 Ga)
68Karelian domainPaleoproterozoicInteracratonic sequences and mafic intrusions60243Quartzite, arkosite and mica schist
69Karelian domainPaleoproterozoicInteracratonic sequences and mafic intrusions613Conglomerate, arkosite and diamictite
70Karelian domainPaleoproterozoicInteracratonic sequences and mafic intrusions6288Mafic and ultramafic metavolcanic rocks
71Karelian domainPaleoproterozoicLayered intrusions and other intracratonic igneous complexes (2.5-2.3 Ga)635Granite (2.45–2.3 Ga)
72Karelian domainPaleoproterozoicLayered intrusions and other intracratonic igneous complexes (2.5-2.3 Ga)6434Gabbro and peridotite (2.44 Ga)
73Karelian domainPaleoproterozoicLayered intrusions and other intracratonic igneous complexes (2.5-2.3 Ga)6514Intermediate and felsic metavolcanic rocks
74Karelian domainArcheanSyn- to late orogenic intrusive complexes (2.74-2.65 Ga)661Orthopyroxene diorite
75Karelian domainArcheanSyn- to late orogenic intrusive complexes (2.74-2.65 Ga)67124Granodiorite, tonalite, quartz diorite, granite and syenite
76Karelian domainArcheanSyn- to late orogenic intrusive complexes (2.74-2.65 Ga)6835Leucocratic granite and granodiorite
77Karelian domainArcheanGreenstone belts (3.0-2.7 Ga)694Gabbro
78Karelian domainArcheanGreenstone belts (3.0-2.7 Ga)707Metaperidotite, serpentinite and soapstone
79Karelian domainArcheanGreenstone belts (3.0-2.7 Ga)7112Ultramafic metavolcanic rocks
80Karelian domainArcheanGreenstone belts (3.0-2.7 Ga)72133Mafic metavolcanic rocks
81Karelian domainArcheanGreenstone belts (3.0-2.7 Ga)7315Intermediate and felsic metavolcanic rocks
82Karelian domainArcheanGreenstone belts (3.0-2.7 Ga)7459Metasedimentary rocks
83Karelian domainArcheanGneiss complexes (3.1-2.6 Ga)7553Paragneiss
84Karelian domainArcheanGneiss complexes (3.1-2.6 Ga)76735Tonalite-trondhjemite-granodioritic gneiss and migmatite
85Lapland granulite belt and Inari complexPaleoproterozoic77168Garnet-bearing paragneiss
86Lapland granulite belt and Inari complexPaleoproterozoic78168Orthopyroxene diorite
87Lapland granulite belt and Inari complexPaleoproterozoic7934Anorthosite
88Lapland granulite belt and Inari complexPaleoproterozoic8032Gneissic granite, granite gneiss and hornblende gneiss
89Lapland granulite belt and Inari complexPaleoproterozoic8124Foliated gabbro and granodiorite (1.95–1.93 Ga)
90Lapland granulite belt and Inari complexPaleoproterozoic8238Paleoproterozoic mafic and felsic metavolcanic rocks
91Lapland granulite belt and Inari complexPaleoproterozoic8331Paleoproterozoic metasedimentary rocks
92Lapland granulite belt and Inari complexPaleoproterozoic849Granite (2.6–2.5 Ga)
93Lapland granulite belt and Inari complexArchean8558Gneisses and migmatites
94Caleconian domainPaleozonic862Ordovician mafic-ultramafic complex of the Upper Allochthon
95Caleconian domainPaleozonic874Metamorphic rocks of the Middle Allochthon
96Caleconian domainPaleozonic886Cambrian sedimentary rocks of the Lower Allochthon
97Paleozoic892Alkaline intrusions: Iivaara (365 Ma)
98Paleozoic-Archean904Carbonatite: Sokli (365 Ma), Halpanen (1.8 Ga), Laivajoki, Kortejärvi (2.0 Ga), Siilinjärvi (2.61 Ga)
99Mesozoic-Proterozoic911Impact melt rocks
100Mesozoic-Proterozoic920Suevite
101Paleoproterozoic-98Diabase dykes (2.50 – 1.97 Ga)
Svecofennian domain A: Arceretionary arc complex of southern Finland (1.90-1.82 Ga)
Svecofennian domain B: Accrentionary arc complex of central and western Finland (1.90-1.87 Ga)
Svecofennian domain C: Primitive arc complex of central Finland (1.93-1.87 Ga)
Table moodified from Rasilainen et al. 2008

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