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]
Contents
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.
Obs | Domain | Age | Sequence | Map.unit | N | Rock.types | Description |
---|---|---|---|---|---|---|---|
1 | Paleozoic | Cambrian sedimentary sequences | 1 | 4 | Sandstone and shale | ||
2 | Neoproterozoic | Vendian sedimentary sequences | 2 | 0 | Siltstone and shale | ||
3 | Neoproterozoic | Vendian sedimentary sequences | 3 | 1 | Sandstone and conglomerate | ||
4 | Mesoproterozoic | Interacratonic sedimentary sequences and intruisition | 4 | 1 | Slitstone ans Shale | ||
5 | Mesoproterozoic | Interacratonic sedimentary sequences and intruisition | 5 | 18 | Olivine diabase | ||
6 | Mesoproterozoic | Interacratonic sedimentary sequences and intruisition | 6 | 5 | Sandstone and conglomerate | ||
7 | Mesoproterozoic | Anorogenic or postogenic bimodal intrusive complexes | 7 | 3 | Quartz porphyry (1.65-1.62 Ga) | ||
8 | Mesoproterozoic | Anorogenic or postogenic bimodal intrusive complexes | 8 | 95 | Rapakivi granite (1.65-1.63 Ga) | ||
9 | Mesoproterozoic | Anorogenic or postogenic bimodal intrusive complexes | 9 | 49 | Rapakivi granite (1.59-1.57 Ga) | ||
10 | Mesoproterozoic | Anorogenic or postogenic bimodal intrusive complexes | 10 | 9 | Gabbro-anorthosite (1.65-1.62 Ga) | ||
11 | Mesoproterozoic | Anorogenic or postogenic bimodal intrusive complexes | 11 | 1 | Gabbro-anorthosite (1.59-1.57 Ga) | ||
12 | Paleoproterozoic | Postorogenic intrusions | 12 | 29 | Granite; norther Finland (1.80-1.77 Ga) | ||
13 | Paleoproterozoic | Postorogenic intrusions | 13 | 3 | Granite and associated rocks; southern Finland (1.81–1.77 Ga) | ||
14 | Svecoffenian domain A | Paleoproterozoic | Intrusions post-dating the main stage of crustal thickening | 14 | 209 | Microline granite (1.84-1.82 Ga) | |
15 | Svecoffenian domain A | Paleoproterozoic | Collision-related intrusions | 15SA | 236 | Granodiorite, tonalite and quartz diorite (1.89-1.87 Ga) | |
16 | Svecoffenian domain A | Paleoproterozoic | Collision-related intrusions | 16SA | 72 | Gabbro and diorite (1.89.1-87 Ga) | |
17 | Svecoffenian domain A | Paleoproterozoic | Supracrustal sequences (1.90-1.88 Ga) | 17 | 2 | Quartzite | |
18 | Svecoffenian domain A | Paleoproterozoic | Supracrustal sequences (1.90-1.88 Ga) | 18 | 348 | Mica schist and mica gneiss | |
19 | Svecoffenian domain A | Paleoproterozoic | Supracrustal sequences (1.90-1.88 Ga) | 19 | 85 | Indermetiate and felsic metavolcanic rock and metasediments | |
20 | Svecoffenian domain A | Paleoproterozoic | Supracrustal sequences (1.90-1.88 Ga) | 20 | 178 | Mafic metavolcanic rocks | |
21 | Svecoffenian domain A | Paleoproterozoic | Supracrustal sequences (1.90-1.88 Ga) | 21 | 3 | Ultramafic metavolcanic rocks | |
22 | Svecoffenian domain B | Paleoproterozoic | Intrusions post-dating main stage of crustal thickening | 22 | 13 | Pyroxene grantoid (1.88-1.87 Ga) | |
23 | Svecoffenian domain B | Paleoproterozoic | Intrusions post-dating main stage of crustal thickening | 23 | 26 | Granite (1.88-1.87 Ga) | |
24 | Svecoffenian domain B | Paleoproterozoic | Intrusions post-dating main stage of crustal thickening | 24SB | 205 | Granite (~1.88 Ga) | |
25 | Svecoffenian domain B | Paleoproterozoic | Collision-related intrusions | 15SB | 485 | Granodiorite, tonalite and quartz diorite (1.89-1.88 Ga) | |
26 | Svecoffenian domain B | Paleoproterozoic | Collision-related intrusions | 16SB | 137 | Gabbro, diorite and peridotite (1.89-1.88 Ga) | |
27 | Svecoffenian domain B | Paleoproterozoic | Supracrustal sequences | 25 | 47 | Mica schists, intercalated arkosites and conglomerates | |
28 | Svecoffenian domain B | Paleoproterozoic | Supracrustal sequences | 26 | 81 | Indermetiate and felsic metavolcanic rocks with metasedimentary intercalations (1.89-1.88 Ga) | |
29 | Svecoffenian domain B | Paleoproterozoic | Supracrustal sequences | 27 | 107 | Mafic metavolcanic rocks (1.89–1.88 Ga) | |
30 | Svecoffenian domain B | Paleoproterozoic | Supracrustal sequences | 28 | 319 | Mica gneisses and mica schists with black schist intercalations | |
31 | Svecoffenian domain B | Paleoproterozoic | Supracrustal sequences | 281 | 71 | Granitic and granodioritic rocks formed by melting of unit 28 sedimentary rocks | |
32 | Svecoffenian domain B | Paleoproterozoic | Supracrustal sequences | 29 | 0 | Felsic to intermediate metavolcanic and metasedimentary rocks (~1.90 Ga) | |
33 | Svecoffenian domain B | Paleoproterozoic | Supracrustal sequences | 30 | 41 | Mafic metavolcanic rocks (~1.90 Ga) | |
34 | Svecoffenian domain B | Paleoproterozoic | Supracrustal sequences | 31 | 0 | Ultramafic metavolcanic rocks (~1.90 Ga) | |
35 | Svecoffenian domain C | Paleoproterozoic | Intrusions post-dating main stage of crustal thickening | 24SC | 39 | Granite (~1.88 Ga) | |
36 | Svecoffenian domain C | Paleoproterozoic | Intrusions post-dating main stage of crustal thickening | 32 | 20 | Pyroxene granitoid and mafic dykes (1.885 Ga) | |
37 | Svecoffenian domain C | Paleoproterozoic | Collision-related intrusions | 15SC | 74 | Granodiorite, tonalite and quartz diorite (1.89-1.87 Ga) | |
38 | Svecoffenian domain C | Paleoproterozoic | Collision-relates intrusions | 16SC | 31 | Gabbro, diorite and peridotite (1.89-1.87 Ga) | |
39 | Svecoffenian domain C | Paleoproterozoic | Supracrustal sequences | 33 | 1 | Intermediate and felsic metavolcanic rocks with metasedimentary intercalations (1.90–1.88 Ga) | |
40 | Svecoffenian domain C | Paleoproterozoic | Supracrustal sequences | 34 | 2 | Mafic metavolcanic rocks (1.90–1.88 Ga) | |
41 | Svecoffenian domain C | Paleoproterozoic | Supracrustal sequences | 35 | 113 | Mica gneiss and mica schist with intercalated carbonate rocks | |
42 | Svecoffenian domain C | Paleoproterozoic | Supracrustal sequences | 36 | 16 | Felsic and intermediate metavolcanic rocks (~1.92 Ga) | |
43 | Svecoffenian domain C | Paleoproterozoic | Supracrustal sequences | 37 | 56 | Mafic metavolcanic rocks (~1.92 Ga) | |
44 | Svecoffenian domain C | Paleoproterozoic | Pre-collisional intrusions | 38 | 19 | Gneissic tonalite and granodiorite (1.93–1.91 Ga) | |
45 | Karelian domain | Paleoproterozoic | Intrisions post-dating crustal thickening in northern Finland (~1.8 Ga) | 39 | 277 | Granite and granodiorite with gneissic inclusions | |
46 | Karelian domain | Paleoproterozoic | Supracrustial unit | 391 | 42 | Mica gneisses and migmatites intruded by unit 39 | |
47 | Karelian domain | Paleoproterozoic | Post-collasional foreland sequence, molasse | 40 | 10 | Quartzite and conglomerate | |
48 | Karelian domain | Paleoproterozoic | Post-collisional intrusions in southeastern Finland | 41 | 37 | Granite and granodiorite (~1.86 Ga) | |
49 | Karelian domain | Paleoproterozoic | Post-collasional intrusions in southeastern Finland | 24K | 16 | Granite (~1.88 Ga) | |
50 | Karelian domain | Paleoproterozoic | Early foreland sequences | 42 | 6 | Quartzite and conglomerate | |
51 | Karelian domain | Paleoproterozoic | Early foreland sequences | 43 | 3 | Mafic and felsic metavolcanic rocks (~1.88 Ga) | |
52 | Karelian domain | Paleoproterozoic | Collision-related intrusions | 44 | 8 | Granite (1.89–1.88 Ga) | |
53 | Karelian domain | Paleoproterozoic | Collision-related intrusions | 45 | 16 | Quartzmonzodiorite, quartz monzonite and granodiorite (1.90-1.86 Ga) | |
54 | Karelian domain | Paleoproterozoic | Collision-related intrusions | 46 | 14 | Gabbro | |
55 | Karelian domain | Paleoproterozoic | Allochthonous sequences emplaced onto the craton margin | 47 | 116 | Mica schists and intercalated black schists | |
56 | Karelian domain | Paleoproterozoic | Allochthonous sequences emplaced onto the craton margin | 48 | 1 | Banded iron formations (BIF) | |
57 | Karelian domain | Paleoproterozoic | Allochthonous sequences emplaces onto the craton margin | 49 | 34 | Mafic metavolcanic rocks with metasedimentary intercalations | |
58 | Karelian domain | Paleoproterozoic | Ophiolites and related tectonic complexes (1.96-1.95 Ga) | 50 | 6 | Gneissic alkaline granite | |
59 | Karelian domain | Paleoproterozoic | Ophiolites and related tectonic complexes (1.96-1.95 Ga) | 51 | 16 | Serpentinites and other rocks of ophiolitic origin | |
60 | Karelian domain | Paleoproterozoic | Interacratonic to craton margin sequences and mafic intrusions | 52 | 19 | Gabbro (2.15–2.00 Ga) | |
61 | Karelian domain | Paleoproterozoic | Interacratonic to craton margin sequences and mafic intrusions | 53 | 173 | Mica schist, black schist, conglomerate and arkosite | |
62 | Karelian domain | Paleoproterozoic | Interacratonic to craton margin sequences and mafic intrusions | 54 | 27 | Ultramafic metavolcanic rocks | |
63 | Karelian domain | Paleoproterozoic | Interacratonic to craton margin sequences and mafic intrusions | 55 | 9 | Arkosite, mica schist and conglomerate | |
64 | Karelian domain | Paleoproterozoic | Interacratonic to craton margin sequences and mafic intrusions | 56 | 78 | Carbonate- and calc-silicate rocks, black schists and metavolcanic rocks, BIF | |
65 | Karelian domain | Paleoproterozoic | Interacratonic to craton margin sequences and mafic intrusions | 57 | 144 | Mafic and felsic metavolcanic rocks | |
66 | Karelian domain | Paleoproterozoic | Interacratonic to craton margin sequences and mafic intrusions | 58 | 71 | Quartzite | |
67 | Karelian domain | Paleoproterozoic | Interacratonic sequences and mafic intrusions | 59 | 26 | Gabbro (2.2 Ga) | |
68 | Karelian domain | Paleoproterozoic | Interacratonic sequences and mafic intrusions | 60 | 243 | Quartzite, arkosite and mica schist | |
69 | Karelian domain | Paleoproterozoic | Interacratonic sequences and mafic intrusions | 61 | 3 | Conglomerate, arkosite and diamictite | |
70 | Karelian domain | Paleoproterozoic | Interacratonic sequences and mafic intrusions | 62 | 88 | Mafic and ultramafic metavolcanic rocks | |
71 | Karelian domain | Paleoproterozoic | Layered intrusions and other intracratonic igneous complexes (2.5-2.3 Ga) | 63 | 5 | Granite (2.45–2.3 Ga) | |
72 | Karelian domain | Paleoproterozoic | Layered intrusions and other intracratonic igneous complexes (2.5-2.3 Ga) | 64 | 34 | Gabbro and peridotite (2.44 Ga) | |
73 | Karelian domain | Paleoproterozoic | Layered intrusions and other intracratonic igneous complexes (2.5-2.3 Ga) | 65 | 14 | Intermediate and felsic metavolcanic rocks | |
74 | Karelian domain | Archean | Syn- to late orogenic intrusive complexes (2.74-2.65 Ga) | 66 | 1 | Orthopyroxene diorite | |
75 | Karelian domain | Archean | Syn- to late orogenic intrusive complexes (2.74-2.65 Ga) | 67 | 124 | Granodiorite, tonalite, quartz diorite, granite and syenite | |
76 | Karelian domain | Archean | Syn- to late orogenic intrusive complexes (2.74-2.65 Ga) | 68 | 35 | Leucocratic granite and granodiorite | |
77 | Karelian domain | Archean | Greenstone belts (3.0-2.7 Ga) | 69 | 4 | Gabbro | |
78 | Karelian domain | Archean | Greenstone belts (3.0-2.7 Ga) | 70 | 7 | Metaperidotite, serpentinite and soapstone | |
79 | Karelian domain | Archean | Greenstone belts (3.0-2.7 Ga) | 71 | 12 | Ultramafic metavolcanic rocks | |
80 | Karelian domain | Archean | Greenstone belts (3.0-2.7 Ga) | 72 | 133 | Mafic metavolcanic rocks | |
81 | Karelian domain | Archean | Greenstone belts (3.0-2.7 Ga) | 73 | 15 | Intermediate and felsic metavolcanic rocks | |
82 | Karelian domain | Archean | Greenstone belts (3.0-2.7 Ga) | 74 | 59 | Metasedimentary rocks | |
83 | Karelian domain | Archean | Gneiss complexes (3.1-2.6 Ga) | 75 | 53 | Paragneiss | |
84 | Karelian domain | Archean | Gneiss complexes (3.1-2.6 Ga) | 76 | 735 | Tonalite-trondhjemite-granodioritic gneiss and migmatite | |
85 | Lapland granulite belt and Inari complex | Paleoproterozoic | 77 | 168 | Garnet-bearing paragneiss | ||
86 | Lapland granulite belt and Inari complex | Paleoproterozoic | 78 | 168 | Orthopyroxene diorite | ||
87 | Lapland granulite belt and Inari complex | Paleoproterozoic | 79 | 34 | Anorthosite | ||
88 | Lapland granulite belt and Inari complex | Paleoproterozoic | 80 | 32 | Gneissic granite, granite gneiss and hornblende gneiss | ||
89 | Lapland granulite belt and Inari complex | Paleoproterozoic | 81 | 24 | Foliated gabbro and granodiorite (1.95–1.93 Ga) | ||
90 | Lapland granulite belt and Inari complex | Paleoproterozoic | 82 | 38 | Paleoproterozoic mafic and felsic metavolcanic rocks | ||
91 | Lapland granulite belt and Inari complex | Paleoproterozoic | 83 | 31 | Paleoproterozoic metasedimentary rocks | ||
92 | Lapland granulite belt and Inari complex | Paleoproterozoic | 84 | 9 | Granite (2.6–2.5 Ga) | ||
93 | Lapland granulite belt and Inari complex | Archean | 85 | 58 | Gneisses and migmatites | ||
94 | Caleconian domain | Paleozonic | 86 | 2 | Ordovician mafic-ultramafic complex of the Upper Allochthon | ||
95 | Caleconian domain | Paleozonic | 87 | 4 | Metamorphic rocks of the Middle Allochthon | ||
96 | Caleconian domain | Paleozonic | 88 | 6 | Cambrian sedimentary rocks of the Lower Allochthon | ||
97 | Paleozoic | 89 | 2 | Alkaline intrusions: Iivaara (365 Ma) | |||
98 | Paleozoic-Archean | 90 | 4 | Carbonatite: Sokli (365 Ma), Halpanen (1.8 Ga), Laivajoki, Kortejärvi (2.0 Ga), Siilinjärvi (2.61 Ga) | |||
99 | Mesozoic-Proterozoic | 91 | 1 | Impact melt rocks | |||
100 | Mesozoic-Proterozoic | 92 | 0 | Suevite | |||
101 | Paleoproterozoic | - | 98 | Diabase 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