A 6000-km-long Neo-Tethyan arc system with coherent magmatic flare-ups and lulls in South Asia

Zhang, Xiaoran; Chung, Sun‐Lin; Lai, Yeur‐Hur; Ghani, Azman A.; Murtadha, Sayed; Lee, Hao Yang; Hsu, Chang-Hong

doi:10.1130/g46172.1

Cited by 86 publications

(48 citation statements)

References 33 publications

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“…It means that bỹ 105 Ma, the metamorphic sole of the Andaman Islands was exhuming (Figure 7c). This is coeval with the~106 Ma Ar/Ar age on plagioclase xenocrysts of the Barren Island volcanic rocks (Ray et al, 2015) interpreted to represent the formation of the Andaman ophiolite The Woyla Arc and Western Sumatra Arc enter their final stages but are still active (Gafoer et al, 1993;Koning, 1985;Zhang et al, 2019). 4.…”

Section: Implication Of the Sole Age: Estimating The Duration Of Flipmentioning

confidence: 74%

“…This resulted in the development of the intra oceanic Woyla Arc and of the Western Sumatra Arc on Sundaland (Figure 7a). This is attested by the 122-to 105-Ma ages of the volcanic rocks in the Woyla Arc (Gafoer et al, 1993;Koning, 1985) and the assemblage of mid-Jurassic to Upper Cretaceous sediments and intrusive rocks in the Western Sumatra Arc (Advokaat et al, 2018;Barber et al, 2005;Zhang et al, 2019). 2.…”

Section: Implication Of the Sole Age: Estimating The Duration Of Flipmentioning

confidence: 91%

“…The Woyla Arc is then accreted to Sundaland once the Ngalau Plate was entirely consumed ( Figure 7d; Advokaat et al, 2018). Magmatism on the Western Sumatra Arc occurs until at least 85 Ma in the southernmost part (Zhang et al, 2019) and could have stopped earlier to the north (Wang et al, 2014).…”

Section: Implication Of the Sole Age: Estimating The Duration Of Flipmentioning

confidence: 99%

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History of Subduction Polarity Reversal During Arc‐Continent Collision: Constraints From the Andaman Ophiolite and its Metamorphic Sole

et al. 2020

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Subduction polarity reversal during arc-continent collision has been proposed as a key mechanism to initiate new subduction zones. Despite often interpreted, well-exposed geological record that document the reversal is sparse. The ophiolitic lithounits of the Andaman and Nicobar Islands have been proposed to have formed during the initiation of a new subduction zone following the collision of the Woyla Arc of Sumatra with Sundaland (Eurasia). We here present new field, petrological and geochronological data to evaluate the timing of the initiation of Andaman subduction. We targeted the previously inferred but unstudied metamorphic sole of the Andaman ophiolites that witnessed juvenile subduction. Thermodynamic modeling reveals that the exposed amphibolites of the sole formed at around 0.9 GPa and 675°C. We dated two samples of the metamorphic sole using the Ar/Ar method on amphibole, giving cooling ages of 106.4 ± 2.1 and 105.3 ± 1.6 Ma. This is similar to published ages from plagioclase xenocrysts in recent Barren Island volcanics and in zircons from a gabbro sample from the Andaman ophiolite, which we interpret as the age of the original ophiolite formation. The Ar/Ar ages are considerably older than arc magmatic gabbros and plagiogranites of the overlying ophiolite previously dated at 99-93 Ma and thought to reflect the ophiolite age but recently reinterpreted as a volcanic arc built on the ophiolite. Combined with the ages of Woyla-Sundaland collision, we argue that subduction polarity reversal occurred in a transient period of perhaps some 10 Myr, similar to recent settings.

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Section: Implication Of the Sole Age: Estimating The Duration Of Flipmentioning

confidence: 74%

Section: Implication Of the Sole Age: Estimating The Duration Of Flipmentioning

confidence: 91%

Section: Implication Of the Sole Age: Estimating The Duration Of Flipmentioning

confidence: 99%

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History of Subduction Polarity Reversal During Arc‐Continent Collision: Constraints From the Andaman Ophiolite and its Metamorphic Sole

et al. 2020

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“…In this scenario, increased hydrous flux will lead to increased partial melting and will produce high‐volume of magmas. Positive correlations between increased convergence rate and flare‐ups have been observed in some arcs (e.g., Huang & Lundstrom, 2007), although other studies show magmatic flare‐ups coincide with low and/or decreasing convergence rates (e.g., Shellnutt et al, 2014) or show no obvious correlation (Ducea et al, 2015b; Zhang et al, 2019). Estimated convergence velocities between Arabia and Eurasia during the period 110–70 Ma (Agard et al, 2007) and 50–0 Ma (McQuarrie & van Hinsbergen, 2013) indicate that the 110–80 Ma magmatic flare‐up occurred at relatively high convergence rate and with high obliquity (Figures 9g and 9h), whereas the magmatic lull at 75–50 Ma was simultaneous with a low convergence rate.…”

Section: Discussionmentioning

confidence: 99%

Neotethyan Subduction Ignited the Iran Arc and Backarc Differently

Moghadam

et al. 2020

JGR Solid Earth

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Most arcs show systematic temporal and spatial variations in magmatism with clear shifts in igneous rock compositions between those of the magmatic front (MF) and those in the backarc (BA). It is unclear if similar magmatic polarity is seen for extensional continental arcs. Herein, we use geochemical and isotopic characteristics coupled with zircon U‐Pb geochronology to identify the different magmatic style of the Iran convergent margin, an extensional system that evolved over 100 Myr. Our new and compiled U‐Pb ages indicate that major magmatic episodes for the NE Iran BA occurred at 110–80, 75–50, 50–35, 35–20, and 15–10 Ma. In contrast to NE Iran BA magmatic episodes, compiled data from MF display two main magmatic episodes at 95–75 and 55–5 Ma, indicating more continuous magmatism for the MF than for the BA. We show that Paleogene Iran serves as a useful example of a continental arc under extension. Our data also suggest that there is not a clear relationship between the subduction velocity of Neotethyan Ocean beneath Iran and magmatic activity in Iran. Our results imply that the isotopic compositions of Iran BA igneous rocks do not directly correspond to the changes in tectonic processes or geodynamics, but other parameters such as the composition of lithosphere and melt source(s) should be considered. In addition, changes in subduction zone dynamics and contractional versus extensional tectonic regimes influenced the composition of MF and BA magmatic rocks. These controls diminished the geochemical and isotopic variations between the magmatic front and backarc.

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“…In this study, we use numerical modeling and scaling analysis to address the following questions: (1) What controls the total volume (Paulsen et al, 2016), BM = Bohemian Massif (Hajná et al, 2017), CM = Coast Mountains batholith (Cecil et al, 2018), GA = Gangdese-Burma-Sumatra arc (X. Zhang et al, 2019), NC = North China (Cope, 2017), NZ = New Zealand (Schwartz et al, 2017), SA = South American Cordilleran arcs (Kirsch et al, 2016;Pepper et al, 2016), SC = South China (Li et al, 2007), NA = North American Cordilleran arcs (Kirsch et al, 2016;Paterson & Ducea, 2015), TA = Taknar complex (Moghadam et al, 2017). Base map modified from Tsujimori et al (2006) and Erdman and Lee (2014).…”

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confidence: 99%

Does Underthrusting Crust Feed Magmatic Flare‐Ups in Continental Arcs?

Yang

Cao

Gordon

et al. 2020

Geochem Geophys Geosyst

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Compilations of U/Pb zircon geochronology from igneous rocks and arc-derived sediments show age peaks and troughs defining magmatic "flare-ups" and "lulls," respectively, on the timescales of tens of millions of years (e.g., Paterson & Ducea, 2015). Typically, these flare-ups or high magma flux events last ∼30 Myr and are separated by magmatic lulls spanning 20-50 Myr (e.g., Kirsch et al., 2016). Magma generation rates during the lulls in a continental arc are comparable to the rate of mantle-derived primitive magma generation in island arcs (DeCelles et al., 2009), representing a baseline for the magma contribution from the mantle wedge. The Armstrong unit (AU) is used to quantify the baseline magma generation rate, with 1 AU = 30 km 3 /Myr per kilometer length of arc (DeCelles et al., 2009; Reymer & Schubert, 1984). During a flare-up, the magma generation rate reaches 3-4 AU in the upper-middle crust (DeCelles et al., 2009). The AU can be converted to a volumetric flux (km 3 /km 2 /Myr or km/Myr) if the arc width is known. Given a characteristic arc width of 100 km, the baseline 1 AU is ∼0.3 km 3 /km 2 /Myr. For flare-ups in continental magmatic arcs, an estimated volumetric flux of ∼1 km 3 /km 2 /Myr (∼3-4 AU equivalent) is proposed for the main arc and > 0.6 km 3 /km 2 /Myr (>2 AU equivalent) for a broader region from the forearc to the retro-arc (Ratschbacher et al., 2019). This volumetric flux is also referred to as the magmatic thickening rate (km/Myr), representing

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A 6000-km-long Neo-Tethyan arc system with coherent magmatic flare-ups and lulls in South Asia

Cited by 86 publications

References 33 publications

History of Subduction Polarity Reversal During Arc‐Continent Collision: Constraints From the Andaman Ophiolite and its Metamorphic Sole

History of Subduction Polarity Reversal During Arc‐Continent Collision: Constraints From the Andaman Ophiolite and its Metamorphic Sole

Neotethyan Subduction Ignited the Iran Arc and Backarc Differently

Does Underthrusting Crust Feed Magmatic Flare‐Ups in Continental Arcs?

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