Continental Crust, Crustal Underplating, and Low-
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              <i>Q</i>
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            Upper Mantle Beneath an Oceanic Island Arc

Suyehiro, Kiyoshi; Takahashi, Narumi; Ariie, Yoshiro; Yokoi, Yasutaka; Hino, Ryota; Shinohara, Masanao; Kanazawa, Toshihiko; Hirata, Naoshi; Tokuyama, Hidekazu; Taira, Asahiko

doi:10.1126/science.272.5260.390

Cited by 324 publications

(298 citation statements)

References 14 publications

(7 reference statements)

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“…Pressure and temperature were estimated from the inferred position of the silicic plutons in the Talkeetna section and data from modern arcs. Hacker et al [2008] calculated pressures of 0.13-0.27 GPa for four tonalite and quartz diorite samples from the Chugach section, consistent with an estimated ∼7 km thickness for the overlying volcanic section [Clift et al, 2005a], and the ∼5-12 km depth of low-velocity (V p = 6.0-6.5 km/s) zones in modern arcs [Suyehiro et al, 1996;Kodaira et al, 2007aKodaira et al, , 2007bTakahashi et al, 2007;Calvert et al, 2008]. Proposed temperatures at these depths in modern arcs range from 100 to 700°C [Kelemen et al, 2003b].…”

Section: Felsic Magmatism In Intraoceanic Arcsmentioning

confidence: 69%

“…Data from the Aleutian arc are interpreted to reflect a basaltic crust built around an existing oceanic plate [Holbrook et al, 1999;Lizarralde et al, 2002;Shillington et al, 2004;Van Avendonk et al, 2004]. In contrast, studies of the Izu-Bonin [Suyehiro et al, 1996;Takahashi et al, 1998;Kodaira et al, 2007aKodaira et al, , 2007b, Mariana [Takahashi et al, 2007;Calvert et al, 2008], Tonga [Crawford et al, 2003], and South Sandwich [Larter et al, 2001;Leat et al, 2003] arcs have all documented thick (∼2-8 km), low-velocity (V p = 6.0-6.5 km/s) midcrustal layers that are interpreted to represent intermediate to felsic plutonic rocks. This interpretation is corroborated by the presence of extensive tonalitic plutons in exposed middle crust from the Izu-Bonin arc, preserved in the Tanzawa plutonic complex, Japan [Kawate and Arima, 1998].…”

Section: Introductionmentioning

confidence: 99%

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Intermediate to felsic middle crust in the accreted Talkeetna arc, the Alaska Peninsula and Kodiak Island, Alaska: An analogue for low‐velocity middle crust in modern arcs

et al. 2010

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Seismic profiles of several modern arcs have identified thick, low‐velocity midcrustal layers (Vp = 6.0–6.5 km/s) that are interpreted to represent intermediate to felsic plutonic crust. The presence of this silicic crust is surprising given the mafic composition of most primitive mantle melts and could have important implications for the chemical evolution and bulk composition of arcs. However, direct studies of the middle crust are limited by the restricted plutonic exposures in modern arcs. The accreted Talkeetna arc, south central Alaska, exposes a faulted crustal section from residual subarc mantle to subaerial volcanic rocks of a Jurassic intraoceanic arc and is an ideal place to study the intrusive middle crust. Previous research on the arc, which has provided insight into a range of arc processes, has principally focused on western exposures of the arc in the Chugach Mountains. We present new U‐Pb zircon dates, radiogenic isotope data, and whole‐rock geochemical analyses that provide the first high‐precision data on large intermediate to felsic plutonic exposures on Kodiak Island and the Alaska Peninsula. A single chemical abrasion–thermal ionization mass spectrometry analysis from the Afognak pluton yielded an age of 212.87 ± 0.19 Ma, indicating that the plutonic exposures on Kodiak Island represent the earliest preserved record of Talkeetna arc magmatism. Nine new dates from the extensive Jurassic batholith on the Alaska Peninsula range from 183.5 to 164.1 Ma and require a northward shift in the Talkeetna arc magmatic axis following initial emplacement of the Kodiak plutons, paralleling the development of arc magmatism in the Chugach and Talkeetna mountains. Radiogenic isotope data from the Alaska Peninsula and the Kodiak archipelago range from ɛNd(t) = 5.2 to 9.0 and 87Sr/86Srint = 0.703515 to 0.703947 and are similar to age‐corrected data from modern intraoceanic arcs, suggesting that the evolved Alaska Peninsula plutons formed by extensive differentiation of arc basalts with little or no involvement of preexisting crustal material. The whole‐rock geochemical data and calculated seismic velocities suggest that the Alaska Peninsula represents an analogue for the low‐velocity middle crust observed in modern arcs. The continuous temporal record and extensive exposure of intermediate to felsic plutonic rocks in the Talkeetna arc indicate that evolved magmas are generated by repetitive or steady state processes and play a fundamental role in the growth and evolution of intraoceanic arcs.

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Section: Felsic Magmatism In Intraoceanic Arcsmentioning

confidence: 69%

Section: Introductionmentioning

confidence: 99%

Intermediate to felsic middle crust in the accreted Talkeetna arc, the Alaska Peninsula and Kodiak Island, Alaska: An analogue for low‐velocity middle crust in modern arcs

et al. 2010

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“…Globally the average arc production rate needed to balance the "steady state" subducted losses of 3.0 km 3 /a is 94 km 3 /Ma/km (see below), yet oceanic arcs average rates of 125 km 3 /Ma/km compared to 81 km 3 /Ma/km for the continental arcs (Table 1). If the oceanic arcs are not efficiently accreted to continental margins then the continental arcs would have to generate melt at an average rate of 133 km 3 /Ma/km, which is somewhat higher than seismically-derived melting rates for even the supposed more productive oceanic arcs (Suyehiro et al, 1996;Holbrook et al, 1999;Takahashi et al, 2007). In its most basic form arc-continent collision can be envisaged as a process in which an oceanic arc collides with a passive continental margin resulting in orogeny, followed by subduction polarity reversal and establishment of an active continental margin (Fig.…”

Section: Crustal Losses and Gains During Arc-continent Collisionmentioning

confidence: 99%

“…If the age of subduction initiation is known then an average rate of net melt production can be calculated. Holbrook et al (1999) estimated long-term magmatic growth rates of 55-82 km 3 /Ma/km for the Aleutians, while Suyehiro et al (1996) indicated long-term average accretion rates of 66 km 3 /Ma/km in the Izu Arc. However, a true magmatic production rate requires that these estimates account for the loss of crust by subduction erosion, because the present crustal volume divided by age only provides the net production rate, meaning that the true estimates of magmatic output for these arcs would be higher.…”

Section: Tablementioning

confidence: 99%

Crustal redistribution, crust–mantle recycling and Phanerozoic evolution of the continental crust

Clift

Vannucchi

Morgan

2009

Earth-Science Reviews

199

151

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“…Continuing arc magmatism causes anatexis and differentiation of the arc crust, along with transformation of mafic crustal component into the mantle through the Moho, finally creating mature arc crust with an intermediate composition similar to the average continental crust. (B) Generalized seismic velocity structure in the IzuBonin-Mariana arc after Suyehiro et al (1996), Takahashi et al (2007), and Kodaira et al (2007). Because the amphibolite is derived from volcanic rifted margin mafic magmas at depth, these felsic melts are juvenile additions to the continental crust.…”

Section: Additions (Au)mentioning

confidence: 99%

Yin and yang of continental crust creation and destruction by plate tectonic processes

Stern

Scholl

2010

International Geology Review

202

107

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Earth's continental crust today is both created and destroyed by plate tectonic processes, a balance that is encapsulated by the traditional Chinese concept of yin-yang, whereby dualities act in concert as well as in opposition. Yin-yang conceptualizations of crustal growth and destruction are mostly related to plate tectonics; both occur mostly at subduction zones, by arc magmatic creation and by subduction removal. Crust is also created and destroyed by processes unrelated to plate tectonics, including losses by lower crust foundering and additions at hotspots. At present, creation and destruction of continental crust is either in balance (∼3.2 km 3 /year, or 3.2 AU) or more crust is being destroyed than created; the uncertainty comes from unknown deep losses of continental crust at collision zones and due to lower crustal foundering. The yinyang creation-destruction balance changes over a supercontinent cycle, with crustal growth being greatest during supercontinent break-up due to high magmatic flux at new arcs and crustal destruction being greatest during supercontinent amalgamation due to subduction of continental material and increased sediment flux due to orogenic uplift. These conclusions challenge the widely held view that continental crust volume has increased over time due to plate tectonic activity; it is just as likely that this volume has decreased.

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Continental Crust, Crustal Underplating, and Low- Q Upper Mantle Beneath an Oceanic Island Arc

Cited by 324 publications

References 14 publications

Intermediate to felsic middle crust in the accreted Talkeetna arc, the Alaska Peninsula and Kodiak Island, Alaska: An analogue for low‐velocity middle crust in modern arcs

Intermediate to felsic middle crust in the accreted Talkeetna arc, the Alaska Peninsula and Kodiak Island, Alaska: An analogue for low‐velocity middle crust in modern arcs

Crustal redistribution, crust–mantle recycling and Phanerozoic evolution of the continental crust

Yin and yang of continental crust creation and destruction by plate tectonic processes

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