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Archean felsic volcanic rocks (or Archean felsic volcanics, AFVs) are volcanic rocks that were formed during explosive eruption in the Archean Eon from 4 to 2.5 billion years ago. AFVs are rarer because they were formed in the early Earth and only contribute 10–20% in the Archean greenstone belt rock units^[1]. Crucial AFVs are distributed only in the preserved Archean volcano-sedimentary sequences, which are known as greenstone belts^[1]^[2]^[3].

Archean felsic volcanic activities commonly occur in submarine environments, which are different from modern eruptions. There are two types of volcanic rocks in AFVs: dacite and rhyolite^[3]. They can be distinguished by their mineral assemblages, rock chemistry and rock layer relationship in the sequences.

AFVs are the key to reconstruct Archean geological environments^[4]^[5].

Tonalite-Trondhjemite-Granodiorite (TTG) is a felsic plutonic association. It is the most prevalent rock type in Archean terranes. Whether TTG granitoids are the plutonic equivalents of AFVs^[1]^[6] is still uncertain. Hence relationship exhibits between TTG and AFVs^[7]^[8] remains controversial.

Occurrence

Felsic volcanic rocks are rare in Archean cratons^[2]. Dacites and rhyolites on average only contribute ~15-20% in volcanic rocks of greenstone belts^[1]. See Figure 2 and Table 1 for AFVs occurrence examples.

Stable Archean cratons survived from tectonic destruction. A lot of Archean cratons have a dome-and-keel geometry. Keels structure represent the greenstone belt that are intruded by domal batholith (magma chamber) of the TTG suites^[9]. In such context, greenstone belts resemble the supracrustal rock and it is dominated by volcano-sedimentary units^[5]^[7]^[10]^[11]. Some volcanic sequences can be several kilometers thick, such as the Warrawoona Group of Eastern Pibara Craton^[12]^[13]. However, ultramafic and mafic units make up substantial volume of the volcanic units. The remaining volcanic units are extensive but thin felsic volcanic layers, such as Duffer Formation of the Warrawoona Group^[12].

Modern volcanic processes along with its products are observed and recorded^[14]. Yet, erosion, constantly removing surface materials from the source, leads to sampling bias when studying the Archean supracrustal rocks back in deep time^[1].

Table 1. Examples of AFVs occurrence in greenstone belts
AFVs units/localities	Age (Ma)	Greenstone belt	Craton	Country/Region
Duffer Formation^[5]^[4]	3468 ± 2^[15]	Warrawoona	Eastern Pilbara Craton	Australia
Marda Tank^[16]	2734 ± 3^[17]	Marda Volcanic Complex	Yilgarn Craton	Australia
Kallehadlu Felsic volcanics^[10]	2677 ± 2^[18]	Gadag-Chitradurga	Dharwar Craton	India
Kovero schist belt^[19]	2754 ± 6^[19]	Ilomantsi	Baltic Shield	Finland
Sample SM/GR/93/57^[20]	3710 ± 4^[21]	Isua	North Atlantic Craton	Greenland
Musk massive sulphide deposit^[22]	2689.3 +2.4/-1.8^[22]	Yellowknife	Slave Province	Canada
Blake River Group^[6]^[23]	2694.1±4.5^[24]	Abitibi	Superior Province	Canada
Upper Michipicoten volcanic sequences^[25]	2696 ± 2^[26]	Wawa	Superior Province	Canada
Bulawayan Group^[27]	2615 ± 28^[27]	Harare	Zimbabwean Craton	Zimbabwe
Onverwacht Group^[28]	3445 ± 3^[28]	Barberton	Kaapvaal Craton	South Africa

Characteristics

Mineralogy and texture

By meaning "felsic", the volcanic rocks are rich in quartz and feldspars. A typical mineral assemblage is quartz + feldspar (albite/oligoclase) + amphibole (chlorite) + micas (biotite and/or muscovite)^[29]. The mineralogy seems similar with modern rhyolites and dacites. Volcanics are aphanitic, whereas some exhibits porphyritic texture that certain larger minerals (phenocrysts) are visible by eyes.

AFVs also include felsic tuff that was formed when tephra was consolidated. It is composed of volcanic ash, glass shards and lithic fragments. Reported eutaxitic tuff from Superior Province, Canada (Figure 3)^[31], contains lenticular fiamme. When hot pumice deposits rapidly, it is recrystallised and welded into quartz with flame-like ending tips. This texture represents a hot vapour-phase emplacement of the fragmented volcanic materials on the Earth's surface.

Flow bands are present in massive, uniform dacitic flow during the movement of lava^[29]. When the viscous lava flow encounters a surface, friction drags the mobile lava and forms internal banding.

Structureless hyaloclastite is commonly found in AFVs^[12]^[29]^[30]^[32]. In submarine environments, water quenches and cools lava rapidly during volcanic eruption. The flow is fragmented and form glassy volcanic breccia.

Geochemistry

The assemblages of AFVs are calc-alkaline in the whole-rock composition^[25]. Such magmatic series indicates fractional crystallisation of magma leading to low magnesium and iron content in the rock and forms dacite or rhyolite. Magma is a mixture of various minerals. When minerals crystallise from the molten magma, they are progressively removed and dissociated from the melt. The last proportion of the melt is strongly fractionated, causing richness in quartz and feldspars that make AFVs felsic.

Dacite and rhyolite are characterised by high silica (SiO₂) content from 62 to 78 wt%^[33]. The average composition of AFVs in greenstone belts is between dacite to rhyolite (Table 2)^[1]^[33]. In comparison, the average composition after Archean (<2.5 Ga) is alike rhyolite, indicating a more felsic shift in felsic volcanism^[1]. However, this average may be biased because of weathering right after deposition or metamorphism during later stages of deformation^[7].

Table 2. Average composition of felsic volcanics^[1]
Time	SiO₂ (wt%)	Na₂O+K₂O (wt%)	Rock Classification^[33]
Archean	72.2–73.0	6.4–6.8	Dacite–Rhyolite
Post-Archean	73.0–73.6	7.0–8.0	Rhyolite

In addition, AFVs have high zircon abundance. Incompatible elements, like zirconium, are reluctant to substitute into early-forming crystals. So, they tend to remain in the melt. In strongly fractionated felsic magma, zircon is easily saturated. As a result, zircom is common in felsic rocks^[34]. Timing of felsic volcanism and tectonic constraints can be identified by radiometric dating and isotopic analysis.

AFVs show a different trend in rare-earth elements (REE). They are depleted in Light REE but enriched in Heavy REE compared to post-Archean felsic volcanics^[1].

Archean Felsic Volcanism

Eruption style

In Archean, underwater felsic eruptions were common^[29]^[32]^[35]. It is evident by coarse volcanic breccia formed in situ, hyaloclastite or underwater pyroclastic deposits (clastic rock, composed of tephra only). Since felsic magma is viscous, volcanic eruptions that form dacite or rhyolite are explosive and violent. The Archean felsic eruption may be assigned to Vesuvius eruption type in the present day^[29].

Rhyolitic flows are not uncommon in Archean but it is less common in the modern volcanic environment^[35]. It is predicted that viscous felsic eruption often causes pyroclastic flow (hot, dense gas with volcanic fragments) instead of fluid lava flow. However, if the rhyolitic lava is is still molten during extrusion, it can behave and flow like fluid flow^[32]^[36].

Subaqueous deposits

Felsic lava flow and lava dome are the two common types of underwater deposits formed by AFVs (Fig. 4)^[32]. Documented Archean lava structures are distinct from post-Archean felsic lava because of underwater eruption^[32]. The dacitic or rhyolitic lava flows are quenches right afterwards their eruption^[12]^[32]. When water is in touch with the flow, it quickly cools the lava down^[36]. This causes the lava to solidify, break up as clasts and accumulate on the flow fronts to form breccia^[29].

Lava flow

Effusive felsic lava flows elongate several kilometres long. During an eruption, lava continuously wells out from the vent, then starts to flow outward on the sea floor. Due to quenching, lava is rapidly fragmented to form breccia^[36]. A new lobe of lava is injected inside the breccia but it is cooled down slower and push the flow further outwards^[32].

Lava dome

Short, stocky dome with subsequent pyroclastic deposits extend less than few kilometres long. When explosion eruption occurs, volcanic fragments would be deposited by violent pyroclastic flows. Coarse breccia would be formed as a result^[37]. Submarine sediments would subsequently be deposited along the steep flank of the volcano^[37]. Submarine landslides would occur to form turbidites^[37].

Stratigraphic significance

AFVs is important to deduce absolute age of the rock units in greenstone belts^[38]. Felsic eruptions are episodic so that the felsic volcanic layers are distinctive stratigraphic units^[5]. Also, AFVs are distributed vastly across long distances because of its extensive deposition^[12]^[13]^[32]^[37]. However, the rock sequences of greenstone belts are commonly disputed by later deformation, such as regional folding or intrusion of granitoids^[12]. By identifying these felsic sequences and dating their time of formation, stratigraphic units of different locations can be correlated despite the obstacles or discontinuity in between AFVs^[12]^[37].

Timing of volcanism

The geochronology of Archean events strongly relies on U-Pb dating^[5]^[20] or Lu-Hf dating^[39]. Since mafic rocks, such as basalt, is lack of zircon, only the age of felsic rocks can be dated among the volcanic rocks in greenstone belts^[38]. As AFVs are episodically deposited in between mafic layers, the age range of a particular mafic layer can be constrained by the upper and lower felsic volcanic layers^[5].

In addition, because of absolute dating, by determining the specific ages of the rocks, the episodic occurrence and the duration of felsic volcanism are revealed^[12].

Relationships between Archean felsic volcanics and granitoids

TTG and GMS granitoids

Two plutonic, igneous rock suites forms 50% of Archean cratons^[1]. They are (1) Tonalite-Trondhjemite-Granodiorite (TTG) suites and (2) Granite-Monzonite-Syenite (GMS) suites in chronological order. They are the batholith that formed the volcanics on the Earth's surface^[23]. Later they intruded the supracrustal rocks of similar age and composition in Archean^[9]. The uprising magma bodies deformed the surface greenstone belt in a cratonic scale^[3].

Table 3. Comparison between 2 common Archean Granitoids^[7]^[40]
Relative age	Granitoid	Important mineral present	Magma origin
Older (1^st granitoid)	Tonalite-Trondhjemite-Granodiorite (TTG)	Na-rich plagioclase + garnet + amphibole	hydrated mafic crust
Younger (2^nd granitoid)	Granite-Monzonite-Syenite (GMS)	K-feldspar	felsic crust

The two kinds of granitoids are the product of progressive chemical changes of the Earth's crust^[7]. They have different magma origins: melting of water-rich mafic materials formed older TTG and felsic materials (e.g. TTG and/or sediments^[41]) formed younger GMS (see Table 3)^[7]^[40].

Connections between felsic volcanics and granitoids

The volcanic and plutonic types have similar age and geochemistry, but there is a lack of equivalents in the opposite of extrusive or intrusive rocks. Some plutons contain tonalites that are more silicic than andesites, the dominant intermediate volcanic rock in the belt^[42]. Conversely, for example, no plutonic equivalents are found for the heavy REE-enriched rhyolite of the Superior Province^[42].

References

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[:3-1] ^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j Condie, Kent C. (1993). "Chemical composition and evolution of the upper continental crust: Contrasting results from surface samples and shales". Chemical Geology. 104 (1–4): 1–37. doi:10.1016/0009-2541(93)90140-e. ISSN 0009-2541.

[:25-2] Szilas, Kristoffer (2018). "A Geochemical Overview of Mid-Archaean Metavolcanic Rocks from Southwest Greenland". Geosciences. 8 (7): 266. doi:10.3390/geosciences8070266. ISSN 2076-3263.{{cite journal}}: CS1 maint: unflagged free DOI (link)

[:26-3] Halla, J; Whitehouse, M. J.; Ahmad, T.; Bagai, Z. (2017). "Archaean granitoids: an overview and significance from a tectonic perspective". Geological Society, London, Special Publications. 449 (1): 1–18. doi:10.1144/SP449.10. ISSN 0305-8719.

[:5-4] Van Kranendonk, Martin J.; Hugh Smithies, R.; Hickman, Arthur H.; Wingate, Michael T.D.; Bodorkos, Simon (2010). "Evidence for Mesoarchean (∼3.2Ga) rifting of the Pilbara Craton: The missing link in an early Precambrian Wilson cycle". Precambrian Research. 177 (1–2): 145–161. doi:10.1016/j.precamres.2009.11.007. ISSN 0301-9268.

[:6-5] ^ ^a ^b ^c ^d ^e ^f Thorpe, R.I.; Hickman, A.H.; Davis, D.W.; Mortensen, J.K.; Trendall, A.F. (1992). "U-Pb zircon geochronology of Archaean felsic units in the Marble Bar region, Pilbara Craton, Western Australia". Precambrian Research. 56 (3–4): 169–189. doi:10.1016/0301-9268(92)90100-3. ISSN 0301-9268.

[:9-6] Goodwin, A.M.; Smith, I.E.M. (1980). "Chemical discontinuities in Archean metavolcanic terrains and the development of Archean crust". Precambrian Research. 10 (3–4): 301–311. doi:10.1016/0301-9268(80)90016-9. ISSN 0301-9268.

[:7-7] ^ ^a ^b ^c ^d ^e ^f Agangi, Andrea; Hofmann, Axel; Elburg, Marlina A. (2018). "A review of Palaeoarchaean felsic volcanism in the eastern Kaapvaal craton: Linking plutonic and volcanic records". Geoscience Frontiers. 9 (3): 667–688. doi:10.1016/j.gsf.2017.08.003. ISSN 1674-9871.

[:21-8] Paradis, Suzanne; Ludden, John; Gélinas, Léopold (1988). "Evidence for contrasting compositional spectra in comagmatic intrusive and extrusive rocks of the late Archean Blake River Group, Abitibi, Quebec". Canadian Journal of Earth Sciences. 25 (1): 134–144. doi:10.1139/e88-013. ISSN 0008-4077.

[:1-9] Kerrich, Robert; Polat, Ali (2006). "Archean greenstone-tonalite duality: Thermochemical mantle convection models or plate tectonics in the early Earth global dynamics?". Tectonophysics. 415 (1–4): 141–165. doi:10.1016/j.tecto.2005.12.004. ISSN 0040-1951.

[:2-10] Manikyamba, C.; Ganguly, Sohini; Santosh, M.; Subramanyam, K.S.V. (2017). "Volcano-sedimentary and metallogenic records of the Dharwar greenstone terranes, India: Window to Archean plate tectonics, continent growth, and mineral endowment". Gondwana Research. 50: 38–66. doi:10.1016/j.gr.2017.06.005. ISSN 1342-937X.

[11] Johnson, Tim E.; Brown, Michael; Goodenough, Kathryn M.; Clark, Chris; Kinny, Peter D.; White, Richard W. (2016). "Subduction or sagduction? Ambiguity in constraining the origin of ultramafic–mafic bodies in the Archean crust of NW Scotland". Precambrian Research. 283: 89–105. doi:10.1016/j.precamres.2016.07.013. ISSN 0301-9268.

[:0-12] ^ ^a ^b ^c ^d ^e ^f ^g ^h DiMarco, Michael J.; Lowe, Donald R. (1989). "Stratigraphy and sedimentology of an early Archean felsic volcanic sequence, eastern Pilbara Block, Western Australia, with special reference to the Duffer Formation and implications for crustal evolution". Precambrian Research. 44 (2): 147–169. doi:10.1016/0301-9268(89)90080-6. ISSN 0301-9268.

[:10-13] Barley, M.E. (1993). "Volcanic, sedimentary and tectonostratigraphic environments of the ∼3.46 Ga Warrawoona Megasequence: a review". Precambrian Research. 60 (1–4): 47–67. doi:10.1016/0301-9268(93)90044-3. ISSN 0301-9268.

[14] V., Cas, R. A.F Wright, J. (1996). Volcanic successions modern and ancient: a geological approach to processes, products and successions. Chapman and Hall. ISBN 0412446405. OCLC 961300385.{{cite book}}: CS1 maint: multiple names: authors list (link)

[15] Nelson, David R. (2001). "An assessment of the determination of depositional ages for precambrian clastic sedimentary rocks by U–Pb dating of detrital zircons". Sedimentary Geology. 141–142: 37–60. doi:10.1016/s0037-0738(01)00067-7. ISSN 0037-0738.

[:8-16] Hallberg, J.A.; Johnston, C.; Bye, S.M. (1976). "The Archaean Marda igneous complex, Western Australia". Precambrian Research. 3 (2): 111–136. doi:10.1016/0301-9268(76)90029-2. ISSN 0301-9268.

[17] Nelson, D. R. (2001). 168961: welded tuffaceous rhyolite, Marda Tank. Geochronology Record, 195. Geological Survey of Western Australia.

[18] Jayananda, M.; Peucat, J.-J.; Chardon, D.; Rao, B. Krishna; Fanning, C.M.; Corfu, F. (2013). "Neoarchean greenstone volcanism and continental growth, Dharwar craton, southern India: Constraints from SIMS U–Pb zircon geochronology and Nd isotopes". Precambrian Research. 227: 55–76. doi:10.1016/j.precamres.2012.05.002. ISSN 0301-9268.

[:11-19] Vaasjoki, M., Sorjonen-Ward, P. and Lavikainen, S. (1993). U-Pb age delerminations and sulfide Pb-Pb Characteristics from the late Archean Hattu Schist Belt, Ilomantsi, eastern Finland. Geological Survev of Finland, Special Paper 17, 103-131

[:12-20] KAMBER, B; WHITEHOUSE, M; BOLHAR, R; MOORBATH, S (2005). "Volcanic resurfacing and the early terrestrial crust: Zircon U–Pb and REE constraints from the Isua Greenstone Belt, southern West Greenland". Earth and Planetary Science Letters. 240 (2): 276–290. doi:10.1016/j.epsl.2005.09.037. ISSN 0012-821X.

[21] Nutman, Allen P.; Bennett, Vickie C.; Friend, Clark R.L.; Rosing, Minik T. (1997). "∼ 3710 and ⪖ 3790 Ma volcanic sequences in the Isua (Greenland) supracrustal belt; structural and Nd isotope implications". Chemical Geology. 141 (3–4): 271–287. doi:10.1016/s0009-2541(97)00084-3. ISSN 0009-2541.

[:13-22] Mortensen, J. K.; Thorpe, R. I.; Padgham, W. A.; Keng, J. E.; Davis, W. J. (1988). "U-Pb zircon ages for felsic volcanism in Slave Porvince, N.W.T." Radiogenic age and isotopic studies: Report 2. Paper No. 88-2: 85–95 – via Geological Survey of Canada.

[:28-23] Lesher, C. M.; Goodwin, A. M.; Campbell, I. H.; Gorton, M. P. (1986). "Trace-element geochemistry of ore-associated and barren, felsic metavolcanic rocks in the Superior Province, Canada". Canadian Journal of Earth Sciences. 23 (2): 222–237. doi:10.1139/e86-025. ISSN 0008-4077.

[24] Ayer, J.; Amelin, Y.; Corfu, F.; Kamo, S.; Ketchum, J.; Kwok, K.; Trowell, N. (2002). "Evolution of the southern Abitibi greenstone belt based on U–Pb geochronology: autochthonous volcanic construction followed by plutonism, regional deformation and sedimentation". Precambrian Research. 115 (1–4): 63–95. doi:10.1016/s0301-9268(02)00006-2. ISSN 0301-9268.

[:4-25] Sylvester, Paul J.; Attoh, Kodjo; Schulz, Klaus J. (1987). "Tectonic setting of late Archean bimodal volcanism in the Michipicoten (Wawa) greenstone belt, Ontario". Canadian Journal of Earth Sciences. 24 (6): 1120–1134. doi:10.1139/e87-109. ISSN 0008-4077.

[26] Turek, A.; Smith, Patrick E.; Schmus, W. R. Van (1982). "Rb–Sr and U–Pb ages of volcanism and granite emplacement in the Michipicoten belt—Wawa, Ontario". Canadian Journal of Earth Sciences. 19 (8): 1608–1626. doi:10.1139/e82-138. ISSN 0008-4077.

[:27-27] Baldock, J.W.; Evans, J.A. (1988). "Constraints on the age of the Bulawayan group metavolcanic sequence, Harare Greenstone Belt, Zimbabwe". Journal of African Earth Sciences (and the Middle East). 7 (5–6): 795–804. doi:10.1016/0899-5362(88)90022-x. ISSN 0899-5362.

[:14-28] Krüner, Alfred; Byerly, Gary R.; Lowe, Donald R. (1991). "Chronology of early Archaean granite-greenstone evolution in the Barberton Mountain Land, South Africa, based on precise dating by single zircon evaporation". Earth and Planetary Science Letters. 103 (1–4): 41–54. doi:10.1016/0012-821x(91)90148-b. ISSN 0012-821X.

[:16-29] ^ ^a ^b ^c ^d ^e ^f Morris, P. A.; Barnes, S. J.; Hill, R. E. T. (1993). Eruptive environment and geochemistry of Archaean ultramafic, mafic and felsic volcanic rocks of the eastern Yilgarn Craton : IAVCEI, Canberra 1993 : excursion guide. Australia: Australian Geological Survey Organisation. p. 6. ISBN 064219663X. OCLC 221544061.

[:17-30] Thurston, P. C. (1980). "Subaerial volcanism in the Archean Uchi-Confederation volcanic belt". Precambrian Research. 12 (1–4): 79–98. doi:10.1016/0301-9268(80)90024-8. ISSN 0301-9268.

[31] Thurston, P. C. (1980). "Subaerial volcanism in the Archean Uchi-Confederation volcanic belt". Precambrian Research. 12 (1–4): 79–98. doi:10.1016/0301-9268(80)90024-8. ISSN 0301-9268.

[:18-32] ^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ de Rosen-Spence, Andrée F.; Provost, Gilles; Dimroth, Erich; Gochnauer, Karen; Owen, Victor (1980). "Archean subaqueous felsic flows, Rouyn-Noranda, Quebec, Canada, and their Quarternary equivalents". Precambrian Research. 12 (1–4): 43–77. doi:10.1016/0301-9268(80)90023-6. ISSN 0301-9268.

[:15-33] Le Bas, M. J.; Le Maitre, R. W.; Streckeisen, A.; Zanettin, B. (1986). "A Chemical Classification of Volcanic Rocks Based on the Total Alkali-Silica Diagram". Journal of Petrology. 27 (3): 745–750. doi:10.1093/petrology/27.3.745. ISSN 0022-3530.

[:22-34] Watson, E. Bruce (1979). "Zircon saturation in felsic liquids: Experimental results and applications to trace element geochemistry". Contributions to Mineralogy and Petrology. 70 (4): 407–419. doi:10.1007/bf00371047. ISSN 0010-7999.

[:23-35] Mueller, Wulf; White, James D.L. (1992). "Felsic fire-fountaining beneath Archean seas: pyroclastic deposits of the 2730 Ma Hunter Mine Group, Quebec, Canada". Journal of Volcanology and Geothermal Research. 54 (1–2): 117–134. doi:10.1016/0377-0273(92)90118-w. ISSN 0377-0273.

[:24-36] Yamagishi, Hiromitsu; Dimroth, Erich (1985). "A comparison of Miocene and Archean rhyolite hyaloclastites: Evidence for a hot and fluid rhyolite lava". Journal of Volcanology and Geothermal Research. 23 (3–4): 337–355. doi:10.1016/0377-0273(85)90040-x. ISSN 0377-0273.

[:19-37] ^ ^a ^b ^c ^d ^e ^f Lambert, M B; Burbidge, G; Jefferson, C W; Beaumont-smith, C; Lustwerk, R (1990). "Stratigraphy, Facies and Structure in Volcanic and Sedimentary Rocks of the Archean Back River Volcanic Complex, N.w.t." Current Research, Part C, Geological Survey of Canada, Paper 90-IC: 151–165.

[:20-38] Sylvester, P. J.; Harper, G. D.; Byerly, G. R.; Thurston, P. C. (1997). "Volcanic Aspects". In De Wit, Maarten J.; Ashwal, Lewis D. (eds.). Greenstone belts. Oxford: Clarendon Press. pp. 55–90. ISBN 0198540566. OCLC 33104147.

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[:29-40] Lowe, Donald R.; Byerly, Gary R. (2007), "Chapter 5.3 An Overview of the Geology of the Barberton Greenstone Belt and Vicinity: Implications for Early Crustal Development", Earth's Oldest Rocks, Elsevier, pp. 481–526, ISBN 9780444528100, retrieved 2018-10-12

[41] Watkins, J. M.; Clemens, J. D.; Treloar, P. J. (2007-03-06). "Archaean TTGs as sources of younger granitic magmas: melting of sodic metatonalites at 0.6–1.2 GPa". Contributions to Mineralogy and Petrology. 154 (1): 91–110. doi:10.1007/s00410-007-0181-0. ISSN 0010-7999. {{cite journal}}: no-break space character in |title= at position 95 (help)

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@@ Line 8: / Line 8: @@
 == Occurrence ==
-[[File:AFVs Distribution.png|thumb|450x450px|A map showing examples greenstone belts with documented Archean Felsic Volcanics localities. See citations in the table. |alt=]]Felsic volcanic rocks are rare in Archean [[Craton|cratons]]<ref name=":25">{{Cite journal|last=Szilas|first=Kristoffer|date=2018|title=A Geochemical Overview of Mid-Archaean Metavolcanic Rocks from Southwest Greenland|url=http://dx.doi.org/10.3390/geosciences8070266|journal=Geosciences|volume=8|issue=7|pages=266|doi=10.3390/geosciences8070266|issn=2076-3263|via=}}</ref>. Dacites and rhyolites on average only contribute ~15-20% in volcanic rocks of greenstone belts<ref name=":3" />.
+[[File:AFVs Distribution.png|thumb|450x450px|Fig. 2. A map showing examples greenstone belts with documented Archean Felsic Volcanics localities. See citations in the table. |alt=]]Felsic volcanic rocks are rare in Archean [[Craton|cratons]]<ref name=":25">{{Cite journal|last=Szilas|first=Kristoffer|date=2018|title=A Geochemical Overview of Mid-Archaean Metavolcanic Rocks from Southwest Greenland|url=http://dx.doi.org/10.3390/geosciences8070266|journal=Geosciences|volume=8|issue=7|pages=266|doi=10.3390/geosciences8070266|issn=2076-3263|via=}}</ref>. Dacites and rhyolites on average only contribute ~15-20% in volcanic rocks of greenstone belts<ref name=":3" />. ''See Figure 2 and Table 1 for AFVs occurrence examples.''
 Stable Archean [[Craton|cratons]] survived from tectonic destruction. A lot of Archean cratons have a dome-and-keel geometry. Keels structure represent the [[greenstone belt]] that are intruded by [[Dome (geology)|domal]] [[batholith]] (magma chamber) of the TTG suites<ref name=":1">{{Cite journal|last=Kerrich|first=Robert|last2=Polat|first2=Ali|date=2006|title=Archean greenstone-tonalite duality: Thermochemical mantle convection models or plate tectonics in the early Earth global dynamics?|url=https://linkinghub.elsevier.com/retrieve/pii/S0040195105006323|journal=Tectonophysics|volume=415|issue=1-4|pages=141–165|doi=10.1016/j.tecto.2005.12.004|issn=0040-1951|via=}}</ref>. In such context, greenstone belts resemble the [[supracrustal rock]] and it is dominated by volcano-sedimentary units<ref name=":6">{{Cite journal|last=Thorpe|first=R.I.|last2=Hickman|first2=A.H.|last3=Davis|first3=D.W.|last4=Mortensen|first4=J.K.|last5=Trendall|first5=A.F.|date=1992|title=U-Pb zircon geochronology of Archaean felsic units in the Marble Bar region, Pilbara Craton, Western Australia|url=http://dx.doi.org/10.1016/0301-9268(92)90100-3|journal=Precambrian Research|volume=56|issue=3-4|pages=169–189|doi=10.1016/0301-9268(92)90100-3|issn=0301-9268|via=}}</ref><ref name=":7">{{Cite journal|last=Agangi|first=Andrea|last2=Hofmann|first2=Axel|last3=Elburg|first3=Marlina A.|date=2018|title=A review of Palaeoarchaean felsic volcanism in the eastern Kaapvaal craton: Linking plutonic and volcanic records|url=http://dx.doi.org/10.1016/j.gsf.2017.08.003|journal=Geoscience Frontiers|volume=9|issue=3|pages=667–688|doi=10.1016/j.gsf.2017.08.003|issn=1674-9871|via=}}</ref><ref name=":2">{{Cite journal|last=Manikyamba|first=C.|last2=Ganguly|first2=Sohini|last3=Santosh|first3=M.|last4=Subramanyam|first4=K.S.V.|date=2017|title=Volcano-sedimentary and metallogenic records of the Dharwar greenstone terranes, India: Window to Archean plate tectonics, continent growth, and mineral endowment|url=https://linkinghub.elsevier.com/retrieve/pii/S1342937X17300412|journal=Gondwana Research|volume=50|pages=38–66|doi=10.1016/j.gr.2017.06.005|issn=1342-937X|via=}}</ref><ref>{{Cite journal|last=Johnson|first=Tim E.|last2=Brown|first2=Michael|last3=Goodenough|first3=Kathryn M.|last4=Clark|first4=Chris|last5=Kinny|first5=Peter D.|last6=White|first6=Richard W.|date=2016|title=Subduction or sagduction? Ambiguity in constraining the origin of ultramafic–mafic bodies in the Archean crust of NW Scotland|url=https://linkinghub.elsevier.com/retrieve/pii/S0301926816302844|journal=Precambrian Research|volume=283|pages=89–105|doi=10.1016/j.precamres.2016.07.013|issn=0301-9268|via=}}</ref>. Some volcanic sequences can be several kilometers thick, such as the Warrawoona Group of [[Eastern Pilbara Craton|Eastern Pibara Craton]]<ref name=":0">{{Cite journal|last=DiMarco|first=Michael J.|last2=Lowe|first2=Donald R.|date=1989|title=Stratigraphy and sedimentology of an early Archean felsic volcanic sequence, eastern Pilbara Block, Western Australia, with special reference to the Duffer Formation and implications for crustal evolution|url=http://dx.doi.org/10.1016/0301-9268(89)90080-6|journal=Precambrian Research|volume=44|issue=2|pages=147–169|doi=10.1016/0301-9268(89)90080-6|issn=0301-9268|via=}}</ref><ref name=":10">{{Cite journal|last=Barley|first=M.E.|date=1993|title=Volcanic, sedimentary and tectonostratigraphic environments of the ∼3.46 Ga Warrawoona Megasequence: a review|url=https://linkinghub.elsevier.com/retrieve/pii/0301926893900443|journal=Precambrian Research|volume=60|issue=1-4|pages=47–67|doi=10.1016/0301-9268(93)90044-3|issn=0301-9268|via=}}</ref>. However, [[Ultramafic rock|ultramafic]] and [[mafic]] units make up substantial volume of the volcanic units. The remaining volcanic units are extensive but thin felsic volcanic layers, such as Duffer Formation of the [[Warrawoona Group]]<ref name=":0" />.
@@ Line 14: / Line 14: @@
 Modern volcanic processes along with its products are observed and recorded<ref>{{Cite book|url=http://worldcat.org/oclc/961300385|title=Volcanic successions modern and ancient: a geological approach to processes, products and successions|last=V.|first=Cas, R. A.F Wright, J.|date=1996|publisher=Chapman and Hall|year=|isbn=0412446405|location=|pages=|oclc=961300385}}</ref>. Yet, erosion, constantly removing surface materials from the source, leads to sampling bias when studying the Archean supracrustal rocks back in deep time<ref name=":3" />.
 {| class="wikitable sortable"
-|+Examples of AFVs occurrence in greenstone belts
+|+Table 1. Examples of AFVs occurrence in greenstone belts
-!AFVs Units/Localities
+!AFVs units/localities
 !Age (Ma)
-!Greenstone Belt
+!Greenstone belt
 !Craton
 !Country/Region
@@ Line 57: / Line 57: @@
 |Canada
 |-
+|Blake River Group<ref name=":9" /><ref name=":28">{{Cite journal|last=Lesher|first=C. M.|last2=Goodwin|first2=A. M.|last3=Campbell|first3=I. H.|last4=Gorton|first4=M. P.|date=1986|title=Trace-element geochemistry of ore-associated and barren, felsic metavolcanic rocks in the Superior Province, Canada|url=http://dx.doi.org/10.1139/e86-025|journal=Canadian Journal of Earth Sciences|volume=23|issue=2|pages=222–237|doi=10.1139/e86-025|issn=0008-4077|via=}}</ref>
-|Blake River Group<ref name=":9" />
 |2694.1±4.5<ref>{{Cite journal|last=Ayer|first=J.|last2=Amelin|first2=Y.|last3=Corfu|first3=F.|last4=Kamo|first4=S.|last5=Ketchum|first5=J.|last6=Kwok|first6=K.|last7=Trowell|first7=N.|date=2002|title=Evolution of the southern Abitibi greenstone belt based on U–Pb geochronology: autochthonous volcanic construction followed by plutonism, regional deformation and sedimentation|url=https://doi.org/10.1016/S0301-9268(02)00006-2|journal=Precambrian Research|volume=115|issue=1-4|pages=63–95|doi=10.1016/s0301-9268(02)00006-2|issn=0301-9268|via=}}</ref>
 |Abitibi
@@ Line 85: / Line 85: @@
 === Mineralogy and texture ===
 By meaning "[[felsic]]", the volcanic rocks are rich in quartz and feldspars. A typical mineral assemblage is [[quartz]] + [[feldspar]] ([[albite]]/[[oligoclase]]) + [[amphibole]] ([[Chlorite group|chlorite]]) + [[Mica|micas]] ([[biotite]] and/or [[muscovite]])<ref name=":16">{{Cite book|url=http://worldcat.org/oclc/221544061|title=Eruptive environment and geochemistry of Archaean ultramafic, mafic and felsic volcanic rocks of the eastern Yilgarn Craton : IAVCEI, Canberra 1993 : excursion guide|last=Morris|first=P. A.|last2=Barnes|first2=S. J.|last3=Hill|first3=R. E. T.|publisher=Australian Geological Survey Organisation|year=1993|isbn=064219663X|location=Australia|pages=6|oclc=221544061}}</ref>. The mineralogy seems similar with modern rhyolites and dacites. Volcanics are [[Aphanite|aphanitic]], whereas some exhibits [[porphyritic]] texture that certain larger minerals ([[Phenocryst|phenocrysts]]) are visible by eyes.
-[[File:Archean Fiamme.png|thumb|272x272px|Illustrated sketch of fiamme - recrystalised quartz with flame-like ending points, in Archean Woman Lake rhyolitic tuff, Uchi, Superior Craton,Canada. Adopted and modified from photograph of Thurston (1980)<ref name=":17">{{Cite journal|last=Thurston|first=P. C.|date=1980|title=Subaerial volcanism in the Archean Uchi-Confederation volcanic belt|url=https://doi.org/10.1016/0301-9268(80)90024-8|journal=Precambrian Research|volume=12|issue=1-4|pages=79–98|doi=10.1016/0301-9268(80)90024-8|issn=0301-9268|via=}}</ref>. ]]
+[[File:Archean Fiamme.png|thumb|272x272px|Fig. 3. Illustrated sketch of fiamme - recrystalised quartz with flame-like ending points, in Archean Woman Lake rhyolitic tuff, Superior Province, Canada. Adopted and modified from photograph of Thurston (1980)<ref name=":17">{{Cite journal|last=Thurston|first=P. C.|date=1980|title=Subaerial volcanism in the Archean Uchi-Confederation volcanic belt|url=https://doi.org/10.1016/0301-9268(80)90024-8|journal=Precambrian Research|volume=12|issue=1-4|pages=79–98|doi=10.1016/0301-9268(80)90024-8|issn=0301-9268|via=}}</ref>. ]]
-AFVs also include felsic [[tuff]] that was formed when [[tephra]] was consolidated. It is composed of [[volcanic ash]], [[Volcanic glass|glass shards]] and [[Lithic fragment (geology)|lithic fragments]]. Reported [[Eutaxitic texture|eutaxitic]] tuff from Superior Province, Canada<ref>{{Cite journal|last=Thurston|first=P. C.|date=1980|title=Subaerial volcanism in the Archean Uchi-Confederation volcanic belt|url=https://doi.org/10.1016/0301-9268(80)90024-8|journal=Precambrian Research|volume=12|issue=1-4|pages=79–98|doi=10.1016/0301-9268(80)90024-8|issn=0301-9268|via=}}</ref>, contains lenticular [[fiamme]]. When hot [[pumice]] deposits rapidly, it is [[Recrystallization (geology)|recrystallised]] and [[Welding (geology)|welded]] into quartz with flame-like ending tips. This texture represents a hot vapour-phase emplacement of the fragmented volcanic materials on the Earth's surface.
+AFVs also include felsic [[tuff]] that was formed when [[tephra]] was consolidated. It is composed of [[volcanic ash]], [[Volcanic glass|glass shards]] and [[Lithic fragment (geology)|lithic fragments]]. Reported [[Eutaxitic texture|eutaxitic]] tuff from Superior Province, Canada (Figure 3)<ref>{{Cite journal|last=Thurston|first=P. C.|date=1980|title=Subaerial volcanism in the Archean Uchi-Confederation volcanic belt|url=https://doi.org/10.1016/0301-9268(80)90024-8|journal=Precambrian Research|volume=12|issue=1-4|pages=79–98|doi=10.1016/0301-9268(80)90024-8|issn=0301-9268|via=}}</ref>, contains lenticular [[fiamme]]. When hot [[pumice]] deposits rapidly, it is [[Recrystallization (geology)|recrystallised]] and [[Welding (geology)|welded]] into quartz with flame-like ending tips. This texture represents a hot vapour-phase emplacement of the fragmented volcanic materials on the Earth's surface.
 [[Flow banding|Flow bands]] are present in massive, uniform dacitic flow during the movement of lava<ref name=":16" />. When the viscous lava flow encounters a surface, friction drags the mobile lava and forms internal banding.
@@ Line 95: / Line 95: @@
 The assemblages of AFVs are [[Calc-alkaline magma series|calc-alkaline]] in the whole-rock composition<ref name=":4">{{Cite journal|last=Sylvester|first=Paul J.|last2=Attoh|first2=Kodjo|last3=Schulz|first3=Klaus J.|date=1987|title=Tectonic setting of late Archean bimodal volcanism in the Michipicoten (Wawa) greenstone belt, Ontario|url=http://dx.doi.org/10.1139/e87-109|journal=Canadian Journal of Earth Sciences|volume=24|issue=6|pages=1120–1134|doi=10.1139/e87-109|issn=0008-4077|via=}}</ref>. Such magmatic series indicates [[Fractional crystallization (geology)|fractional crystallisation]] of [[magma]] leading to low [[magnesium]] and [[iron]] content in the rock and forms dacite or rhyolite. Magma is a mixture of various minerals. When minerals crystallise from the molten magma, they are progressively removed and dissociated from the melt. The last proportion of the melt is strongly fractionated, causing richness in quartz and feldspars that make AFVs felsic.
-Dacite and rhyolite are characterised by high [[Silicon dioxide|silica]] (SiO<sub>2</sub>) content from 62 to 78 wt%<ref name=":15" />. The average composition of AFVs in greenstone belts is between dacite to rhyolite<ref name=":3" /><ref name=":15" />. In comparison, the average composition after Archean (<2.5 Ga) is alike rhyolite, indicating a more felsic shift in felsic volcanism<ref name=":3" />. However, this average may be biased because of weathering right after [[Deposition (geology)|deposition]] or [[metamorphism]] during later stages of [[Deformation (geology)|deformation]]<ref name=":7" />.
+Dacite and rhyolite are characterised by high [[Silicon dioxide|silica]] (SiO<sub>2</sub>) content from 62 to 78 wt%<ref name=":15" />. The average composition of AFVs in greenstone belts is between dacite to rhyolite (Table 2)<ref name=":3" /><ref name=":15" />. In comparison, the average composition after Archean (<2.5 Ga) is alike rhyolite, indicating a more felsic shift in felsic volcanism<ref name=":3" />. However, this average may be biased because of weathering right after [[Deposition (geology)|deposition]] or [[metamorphism]] during later stages of [[Deformation (geology)|deformation]]<ref name=":7" />.
 {| class="wikitable"
-|+Average composition of felsic volcanics from Condie (1993)<ref name=":3" />
+|+Table 2. Average composition of felsic volcanics<ref name=":3" />
 !Time
 !SiO<sub>2</sub> (wt%)
 !Na<sub>2</sub>O+K<sub>2</sub>O (wt%)
-![[TAS classification|TAS Classification]]<ref name=":15">{{Cite journal|last=Le Bas|first=M. J.|last2=Le Maitre|first2=R. W.|last3=Streckeisen|first3=A.|last4=Zanettin|first4=B.|date=1986|title=A Chemical Classification of Volcanic Rocks Based on the Total Alkali-Silica Diagram|url=http://dx.doi.org/10.1093/petrology/27.3.745|journal=Journal of Petrology|volume=27|issue=3|pages=745–750|doi=10.1093/petrology/27.3.745|issn=0022-3530|via=}}</ref>
+![[TAS classification|Rock Classification]]<ref name=":15">{{Cite journal|last=Le Bas|first=M. J.|last2=Le Maitre|first2=R. W.|last3=Streckeisen|first3=A.|last4=Zanettin|first4=B.|date=1986|title=A Chemical Classification of Volcanic Rocks Based on the Total Alkali-Silica Diagram|url=http://dx.doi.org/10.1093/petrology/27.3.745|journal=Journal of Petrology|volume=27|issue=3|pages=745–750|doi=10.1093/petrology/27.3.745|issn=0022-3530|via=}}</ref>
 |-
 |Archean
@@ Line 124: / Line 124: @@
 === Subaqueous deposits ===
-[[File:Archean Felsic lava structures.png|thumb|318x318px|Schematic illustration of documented subaqueous felsic lava deposits. (a) Submarine lava flow, based on Héré Creek rhyolite (modified from De Rosen-Spence et al., 1980<ref name=":18">{{Cite journal|last=de Rosen-Spence|first=Andrée F.|last2=Provost|first2=Gilles|last3=Dimroth|first3=Erich|last4=Gochnauer|first4=Karen|last5=Owen|first5=Victor|date=1980|title=Archean subaqueous felsic flows, Rouyn-Noranda, Quebec, Canada, and their Quarternary equivalents|url=http://dx.doi.org/10.1016/0301-9268(80)90023-6|journal=Precambrian Research|volume=12|issue=1-4|pages=43–77|doi=10.1016/0301-9268(80)90023-6|issn=0301-9268|via=}}</ref>). (b) Submarine lava dome, based on the Gold Lake dome and flow complex (modified from Lambert et al., 1990)<ref name=":19">{{Cite journal|last=Lambert|first=M B|last2=Burbidge|first2=G|last3=Jefferson|first3=C W|last4=Beaumont-smith|first4=C|last5=Lustwerk|first5=R|date=1990|title=Stratigraphy, Facies and Structure in Volcanic and Sedimentary Rocks of the Archean Back River Volcanic Complex, N.w.t.|url=http://dx.doi.org/10.4095/131253|journal=Current Research, Part C, Geological Survey of Canada, Paper 90-IC|volume=|pages=151-165|via=}}</ref>. Illustration adopted from Sylvester et al. (1997) in de Wit & Ashwal (1997)<ref name=":20">{{Cite book|url=https://www.worldcat.org/oclc/33104147|title=Greenstone belts|last=Sylvester|first=P. J.|last2=Harper|first2=G. D.|last3=Byerly|first3=G. R.|last4=Thurston|first4=P. C.|publisher=Clarendon Press|year=1997|isbn=0198540566|editor-last=De Wit|editor-first=Maarten J.|location=Oxford|pages=55-90|chapter=Volcanic Aspects|oclc=33104147|editor-last2=Ashwal|editor-first2=Lewis D.}}</ref>.|alt=]]Felsic '''[[lava flow]]''' and '''[[lava dome]]''' are the two types of underwater deposits formed by AFVs. Documented Archean lava structures are distinct from post-Archean felsic lava because of [[Subaqueous volcano|underwater eruption]]<ref name=":18" />. The dacitic or rhyolitic lava flows are quenches right afterwards their eruption<ref name=":0" /><ref name=":18" />. When water is in touch with the flow, it quickly cools the lava down<ref name=":24" />. This causes the lava to solidify, break up as clasts and accumulate on the flow fronts to form [[breccia]]<ref name=":16" />.
+[[File:Archean Felsic lava structures.png|thumb|318x318px|Fig. 4. Schematic illustration of documented subaqueous felsic lava deposits. (a) Submarine lava flow, based on Héré Creek rhyolite (modified from De Rosen-Spence et al., 1980<ref name=":18">{{Cite journal|last=de Rosen-Spence|first=Andrée F.|last2=Provost|first2=Gilles|last3=Dimroth|first3=Erich|last4=Gochnauer|first4=Karen|last5=Owen|first5=Victor|date=1980|title=Archean subaqueous felsic flows, Rouyn-Noranda, Quebec, Canada, and their Quarternary equivalents|url=http://dx.doi.org/10.1016/0301-9268(80)90023-6|journal=Precambrian Research|volume=12|issue=1-4|pages=43–77|doi=10.1016/0301-9268(80)90023-6|issn=0301-9268|via=}}</ref>). (b) Submarine lava dome, based on the Gold Lake dome and flow complex (modified from Lambert et al., 1990)<ref name=":19">{{Cite journal|last=Lambert|first=M B|last2=Burbidge|first2=G|last3=Jefferson|first3=C W|last4=Beaumont-smith|first4=C|last5=Lustwerk|first5=R|date=1990|title=Stratigraphy, Facies and Structure in Volcanic and Sedimentary Rocks of the Archean Back River Volcanic Complex, N.w.t.|url=http://dx.doi.org/10.4095/131253|journal=Current Research, Part C, Geological Survey of Canada, Paper 90-IC|volume=|pages=151-165|via=}}</ref>. Illustration adopted from Sylvester et al. (1997) in de Wit & Ashwal (1997)<ref name=":20">{{Cite book|url=https://www.worldcat.org/oclc/33104147|title=Greenstone belts|last=Sylvester|first=P. J.|last2=Harper|first2=G. D.|last3=Byerly|first3=G. R.|last4=Thurston|first4=P. C.|publisher=Clarendon Press|year=1997|isbn=0198540566|editor-last=De Wit|editor-first=Maarten J.|location=Oxford|pages=55-90|chapter=Volcanic Aspects|oclc=33104147|editor-last2=Ashwal|editor-first2=Lewis D.}}</ref>.|alt=]]Felsic '''[[lava flow]]''' and '''[[lava dome]]''' are the two common types of underwater deposits formed by AFVs (Fig. 4)<ref name=":18" />. Documented Archean lava structures are distinct from post-Archean felsic lava because of [[Subaqueous volcano|underwater eruption]]<ref name=":18" />. The dacitic or rhyolitic lava flows are quenches right afterwards their eruption<ref name=":0" /><ref name=":18" />. When water is in touch with the flow, it quickly cools the lava down<ref name=":24" />. This causes the lava to solidify, break up as clasts and accumulate on the flow fronts to form [[breccia]]<ref name=":16" />.
 ==== Lava flow ====
@@ Line 130: / Line 130: @@
 ==== Lava dome ====
-Short, stocky dome with subsequent pyroclastic deposits extend less than few kilometres long. When explosion eruption occurs, volcanic fragments would be deposited by violent [[pyroclastic flows]]. Coarse breccia would be formed as a result. Submarine sediments would subsequently be deposited along the steep flank of the volcano. Submarine landslides would occur to form turbidites<ref name=":18" />.
+Short, stocky dome with subsequent pyroclastic deposits extend less than few kilometres long. When explosion eruption occurs, volcanic fragments would be deposited by violent [[pyroclastic flows]]. Coarse breccia would be formed as a result<ref name=":19" />. Submarine sediments would subsequently be deposited along the steep flank of the volcano<ref name=":19" />. [[Submarine landslide|Submarine landslides]] would occur to form [[Turbidite|turbidites]]<ref name=":19" />.
 === Stratigraphic significance ===
@@ Line 140: / Line 140: @@
 In addition, because of [[absolute dating]], by determining the specific ages of the rocks, the episodic occurrence and the duration of felsic volcanism are revealed<ref name=":0" />.
-== A link between felsic volcanics and granitoids ==
+== Relationships between Archean felsic volcanics and granitoids ==
-It is observed that [[Tonalite-Trondhjemite-Granodiorite|TTG]] suites intruded the [[Supracrustal rock|supracrustal volcanic rocks]] of similar age and composition in Archean cratons<ref name=":110">{{Cite journal|last=Kerrich|first=Robert|last2=Polat|first2=Ali|date=2006|title=Archean greenstone-tonalite duality: Thermochemical mantle convection models or plate tectonics in the early Earth global dynamics?|url=https://linkinghub.elsevier.com/retrieve/pii/S0040195105006323|journal=Tectonophysics|volume=415|issue=1-4|pages=141–165|doi=10.1016/j.tecto.2005.12.004|issn=0040-1951|via=}}</ref>. The pluton might represent the exposed [[batholith]] which stored felsic magma before eruption<ref>{{Cite journal|last=Lesher|first=C. M.|last2=Goodwin|first2=A. M.|last3=Campbell|first3=I. H.|last4=Gorton|first4=M. P.|date=1986|title=Trace-element geochemistry of ore-associated and barren, felsic metavolcanic rocks in the Superior Province, Canada|url=http://dx.doi.org/10.1139/e86-025|journal=Canadian Journal of Earth Sciences|volume=23|issue=2|pages=222–237|doi=10.1139/e86-025|issn=0008-4077|via=}}</ref>.
+=== TTG and GMS granitoids ===
-Although the two rock types have similar age and geochemistry, there is a lack of equivalents in the opposite of extrusive or intrusive rocks. Some plutons contain [[Tonalite|tonalites]] that are more [[silicic]] than [[Andesite|andesites]], the dominant intermediate volcanic rock in the belt<ref name=":212">{{Cite journal|last=Paradis|first=Suzanne|last2=Ludden|first2=John|last3=Gélinas|first3=Léopold|date=1988|title=Evidence for contrasting compositional spectra in comagmatic intrusive and extrusive rocks of the late Archean Blake River Group, Abitibi, Quebec|url=http://dx.doi.org/10.1139/e88-013|journal=Canadian Journal of Earth Sciences|volume=25|issue=1|pages=134–144|doi=10.1139/e88-013|issn=0008-4077|via=}}</ref>. Conversely, for example, no plutonic equivalents are found for the heavy REE-enriched rhyolite of the Superior Province<ref name=":212" />.
+Two plutonic, igneous rock suites forms 50% of Archean cratons<ref name=":3" />. They are (1) [[Tonalite-Trondhjemite-Granodiorite]] (TTG) suites and (2) [[Granite]]-[[Monzonite]]-[[Syenite]] (GMS) suites in [[Chronological Order|chronological order]]. They are the [[batholith]] that formed the volcanics on the Earth's surface<ref name=":28" />. Later they intruded the [[Supracrustal rock|supracrustal rocks]] of similar age and composition in Archean<ref name=":1" />. The uprising magma bodies deformed the surface greenstone belt in a [[Craton|cratonic]] scale<ref name=":26" />.
+{| class="wikitable"
+|+Table 3. Comparison between 2 common Archean Granitoids<ref name=":7" /><ref name=":29">{{Citation|last=Lowe|first=Donald R.|title=Chapter 5.3 An Overview of the Geology of the Barberton Greenstone Belt and Vicinity: Implications for Early Crustal Development|date=2007|url=http://dx.doi.org/10.1016/s0166-2635(07)15053-2|work=Earth's Oldest Rocks|pages=481–526|publisher=Elsevier|isbn=9780444528100|access-date=2018-10-12|last2=Byerly|first2=Gary R.}}</ref>
+!Relative age
+!Granitoid
+!Important mineral present
+!Magma origin
+|-
+|Older (1<sup>st</sup> granitoid)
+|[[Tonalite-Trondhjemite-Granodiorite]] (TTG)
+|[[Albite|Na-rich plagioclase]] + <u>[[garnet]] + [[amphibole]]</u>
+|hydrated mafic crust
+|-
+|Younger (2<sup>nd</sup> granitoid)
+|[[Granite]]-[[Monzonite]]-[[Syenite]] (GMS)
+|<u>[[K-feldspar]]</u>
+|felsic crust
+|}
+The two kinds of [[Granitoid|granitoids]] are the product of progressive chemical changes of the [[Crust (geology)|Earth's crust]]<ref name=":7" />. They have different magma origins: melting of water-rich [[mafic]] materials formed older TTG and felsic materials (e.g. TTG and/or sediments<ref>{{Cite journal|last=Watkins|first=J. M.|last2=Clemens|first2=J. D.|last3=Treloar|first3=P. J.|date=2007-03-06|title=Archaean TTGs as sources of younger granitic magmas: melting of sodic metatonalites at 0.6–1.2 GPa|url=http://dx.doi.org/10.1007/s00410-007-0181-0|journal=Contributions to Mineralogy and Petrology|volume=154|issue=1|pages=91–110|doi=10.1007/s00410-007-0181-0|issn=0010-7999}}</ref>) formed younger GMS (see Table 3)<ref name=":7" /><ref name=":29" />.
+=== Connections between felsic volcanics and granitoids ===
+The volcanic and plutonic types have similar age and geochemistry, but there is a lack of equivalents in the opposite of extrusive or intrusive rocks. Some plutons contain [[Tonalite|tonalites]] that are more [[silicic]] than [[Andesite|andesites]], the dominant intermediate volcanic rock in the belt<ref name=":212">{{Cite journal|last=Paradis|first=Suzanne|last2=Ludden|first2=John|last3=Gélinas|first3=Léopold|date=1988|title=Evidence for contrasting compositional spectra in comagmatic intrusive and extrusive rocks of the late Archean Blake River Group, Abitibi, Quebec|url=http://dx.doi.org/10.1139/e88-013|journal=Canadian Journal of Earth Sciences|volume=25|issue=1|pages=134–144|doi=10.1139/e88-013|issn=0008-4077|via=}}</ref>. Conversely, for example, no plutonic equivalents are found for the heavy REE-enriched rhyolite of the Superior Province<ref name=":212" />.
 == See Also ==
@@ Line 149: / Line 170: @@
 * [[Eoarchean geology]]
 *[[Greenstone belt]]
+*[[Tectonic evolution of the Barberton greenstone belt]]
 *[[Volcanism]]