30:, a geologic eon extending from 4.0-2.5 billion years ago. Until recently there was little evidence unequivocally supporting one side over the other, and in the past many scientists either believed in shallow subduction or its complete non-existence. However, the past two decades have witnessed the potential beginning of a change in geologic understanding as new evidence is increasingly indicative of episodic, non-shallow subduction.
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of early-Earth materials should be emphasized in future research as it is not well understood, and therefore subduction dynamics are poorly constrained. Moreover, the paucity of
Archean data requires an even better understanding of the links between the Earth's interior and its surface processes if
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Though the subject of
Archean subduction has long been controversial, the emergence of innovative modelling and geologic evidence has begun to sway some of the scientific community toward favouring the existence of non-shallow, episodic subduction. Moving forward, the
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likely formed via subduction to an extent, it does not require that subduction was the only way to form continental crust. Thus the continued debate over the origin of continental crust cannot be fully resolved by subduction arguments alone.
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and thicker regions of underlying depleted lithospheric mantle. As such, the density of the lithosphere was reduced due to both differentiation of the crust from the mantle and the ensuing relative depletion of the residual mantle in
155:
Those who favour
Archean subduction claim that recent modelling has elucidated the following fundamental features of the Archean, which they argue can be used to describe why subduction was occurring:
78:
Those who favour non-existent subduction in the
Archean point to the well-established model that the Archean Earth was significantly hotter than it is today, which would have affected lithospheric
135:. These expected properties have led to suggestions that oceanic lithosphere was so light that it subducted very shallowly or not at all. Scientists who favour this hypothesis argue that
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Mathematical reasoning based on these constraints led to the conclusion that cooling was sufficient to provide a driving force for subduction. In fact, it is thought that the low
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formation, another process of modern Earth that has a mysterious past. Furthermore, subduction is the main mechanism by which surface materials enter the deep
421:
Bierlein, FP; Groves DI; Cawood PA (2009). "Metallogeny of accretionary orogens – the connection between lithospheric processes and metal endowment".
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transition. In addition to modelling, geologic evidence has been discovered that further supports the existence of
Archean subduction. Many Archean
70:
processes, it is clear that studying its past and present nature is essential to developing our understanding of the Earth as a dynamic system.
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of
Archean plates perhaps made subduction initiation easier than it is today. On one hand, the lower density of oceanic plates reduced
51:
371:
Davidson, JP; Arculus, RJ (2006). "The significance of
Phanerozoic arc magmatism in generating continental crust".
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and building its compositional structure. In particular, subduction zones are the primary sites of present-day
202:(LILE) over high-field-strength elements (HFSE), which is a classic subduction signature commonly observed in
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Subduction is the density-driven process by which one tectonic plate moves under another and sinks into the
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Jaupart, C; Labrosse S; Mareschal J-C (2007). "Temperatures, heat and energy in the mantle of the Earth".
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R̈upke, LH; Morgan JP; Hort M; Connolly JAD (2004). "Serpentine and the subduction zone water cycle".
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4) Heat flow into the base of the tectonic plates was 1.3-2.0 times higher than it is today.
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2) The oceanic crust was approximately 21 km thick, compared to 7 km thick today.
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47:
46:. Gravitational pull from dense slabs provides approximately 90% of the driving force for
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Condie, KC (2011). "Did early
Archean continental crust form without plate tectonics?".
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487:
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Abbott, DH; Drury R; Smith WHF (1994). "Flat to steep transition in subduction style".
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belts are also hallmarks of subduction dynamics and subsequent environmental changes.
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of mantle material rising at oceanic spreading centres. This in turn produced thicker
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503:
474:
Sleep, NH; Windley BF (1982). "Archean plate tectonics: constraints and inferences".
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50:, and consequently subduction is crucial in changing the Earth's layout, guiding its
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110:, led to the Earth being 200 K hotter in the Archean than it is today. Assuming
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of the
Archean Earth can be attributed to the release of tremendous amounts of
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Van Hunen, J; Moyen JF (2012). "Archean
Subductionl: Fact or Fiction?".
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106:. This energy, coupled with a greater concentration of heat-producing
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is a contentious topic involving the possible existence and nature of
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1) Mantle temperatures were indeed 200 K hotter than they are today.
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306:"On the relative importance of the driving forces of plate motion"
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Hynes, A (2014). "How feasible was subduction in the Archean?".
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we plan on gaining additional insight into Archean subduction.
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in such a way as to perhaps prohibit subduction. The higher
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10.1130/0091-7613(1994)022<0937:ftstis>2.3.co;2
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Possible existence and nature of subduction in the Archean
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While the existence of Archean subduction implies that
147:, and not from subduction zones as generally believed.
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Geophysical Journal of the Royal Astronomical Society
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and is also largely responsible for the formation of
118:in the Archean, higher temperatures led to greater
66:. Considering the importance of subduction in many
373:Evolution and Differentiation of Continental Crust
190:as well as the passage of thick crust through the
143:of thickened oceanic crust in the root zones of
168:was 114 km, compared to 54 km today.
456:Leitch, AM (2004). "Archean Plate Tectonics".
271:Annual Review of Earth and Planetary Sciences
98:material and subsequent differentiation into
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604:Geological Society of America Fall Meeting
458:American Geophysical Union, Spring Meeting
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164:3) The depth to which the mantle was
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34:The importance of Archean subduction
388:Earth and Planetary Science Letters
291:10.1146/annurev-earth-042711-105255
74:The case against Archean subduction
534:Canadian Journal of Earth Sciences
331:10.1111/j.1365-246X.1975.tb00631.x
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229:Conclusion and future directions
443:10.1016/j.oregeorev.2009.04.002
151:The case for Archean subduction
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304:Forsyth, D; Uyeda, S (1975).
200:large-ion lithophile elements
139:material formed from hydrous
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408:10.1016/j.epsl.2004.04.018
400:2004E&PSL.223...17R
554:10.1139/cjes-2013-0111
350:Treatise on Geophysics
581:1994Geo....22..937A
546:2014CaJES..51..286H
488:1982JG.....90..363S
435:2009OGRv...36..282B
423:Ore Geology Reviews
358:2007mady.book..253J
322:1975GeoJ...43..163F
283:2012AREPS..40..195V
198:show enrichment of
44:convergent boundary
476:Journal of Geology
114:generated oceanic
112:seafloor spreading
20:Archean subduction
222:continental crust
176:flexural rigidity
56:continental crust
52:thermal evolution
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96:Solar System
84:temperatures
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352:: 253–303.
215:metamorphic
213:and paired
116:lithosphere
628:Subduction
622:Categories
375:: 135–172.
243:References
68:geological
24:subduction
504:129466505
180:slab pull
92:accretion
90:from the
236:rheology
192:eclogite
108:elements
577:Bibcode
569:Geology
542:Bibcode
484:Bibcode
431:Bibcode
396:Bibcode
354:Bibcode
318:Bibcode
279:Bibcode
120:melting
80:density
28:Archean
26:in the
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137:felsic
104:mantle
88:energy
40:mantle
500:S2CID
207:rocks
188:crust
60:Earth
42:at a
610:(5).
131:and
102:and
100:core
64:ores
585:doi
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94:of
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133:Al
129:Fe
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