The role of subduction erosion in the generation of Andean and other convergent plate boundary arc magmas, the continental crust and mantle

Stern, Charles R.

doi:10.1016/j.gr.2020.08.006

Cited by 36 publications

(12 citation statements)

References 206 publications

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“…First, the secular geochemical variations observed for long periods of time are not compatible with the expected decrease of crustal contaminants in a protracted process of assimilation. Second, there is no clear correlation between major-element compositions and evolved isotopic ratios (Nielsen and Marschall, 2017;Stern, 2020). Although a positive correlation between silica and the Sr isotopic ratio has been found in some lavas of the Andean Central volcanic zone (Davidson et al, 1991), other Andean volcanic centers show a scattered distribution or a constant Sr initial ratio for a wide range of silica content in lavas (Davidson et al, 1991).…”

Section: Crustal Origin: Melting Assimilation and Mashmentioning

confidence: 99%

Secular variations of magma source compositions in the North Patagonian batholith from the Jurassic to Tertiary: Was mélange melting involved?

et al. 2021

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This study of Sr-Nd initial isotopic ratios of plutons from the North Patagonian batholith (Argentina and Chile) revealed that a secular evolution spanning 180 m.y., from the Jurassic to Neogene, can be established in terms of magma sources, which in turn are correlated with changes in the tectonic regime. The provenance and composition of end-member components in the source of magmas are represented by the Sr-Nd initial isotopic ratios (87Sr/86Sr and 143Nd/144Nd) of the plutonic rocks. Our results support the interpretation that source composition was determined by incorporation of varied crustal materials and trench sediments via subduction erosion and sediment subduction into a subduction channel mélange. Subsequent melting of subducted mélanges at mantle depths and eventual reaction with the ultramafic mantle are proposed as the main causes of batholith magma generation, which was favored during periods of fast convergence and high obliquity between the involved plates. We propose that a parental diorite (= andesite) precursor arrived at the lower arc crust, where it underwent fractionation to yield the silicic melts (granodiorites and granites) that formed the batholiths. The diorite precursor could have been in turn fractionated from a more mafic melt of basaltic andesite composition, which was formed within the mantle by complete reaction of the bulk mélanges and the peridotite. Our proposal follows model predictions on the formation of mélange diapirs that carry fertile subducted materials into hot regions of the suprasubduction mantle wedge, where mafic parental magmas of batholiths originate. This model not only accounts for the secular geochemical variations of Andean batholiths, but it also avoids a fundamental paradox of the classical basalt model: the absence of ultramafic cumulates in the lower arc crust and in the continental crust in general.

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Section: Crustal Origin: Melting Assimilation and Mashmentioning

confidence: 99%

Secular variations of magma source compositions in the North Patagonian batholith from the Jurassic to Tertiary: Was mélange melting involved?

et al. 2021

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“…Our model can be described as (a) extraction of basalt from the mantle, largely at arcs generating LMS, but also in oceans forming oceanic crust, (b) subduction of LMS arc crust, as well as pre‐existing CC and buoyant oceanic crust (including ridges, seamounts, and plateaus), and reworking this mixture into mélange diapirs that rise and melt in the mantle wedge to generate HMS. Both LMS and HMS may be generated by arc magmatism and destroyed by subduction and subduction erosion (Stern, 2020; Straub et al., 2020). But remelting of recycled LMS and HMS can only generate HMS, resulting in high preservation potential for HMS during long‐term subduction.…”

Section: Implications For Continental Crust Formationmentioning

confidence: 99%

Formation of Continental Crust by Diapiric Melting of Recycled Crustal Materials in the Mantle Wedge

Wang

Zhu

et al. 2022

Geophysical Research Letters

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Continental crust (CC) provides the long-term record of origin and evolution of Earth's lithosphere, atmosphere, hydrosphere, and biosphere (Cawood et al., 2013). On the modern Earth, and since the commencement of plate tectonics, the CC is interpreted to be extracted primarily by subduction-related magmatism from the mantle (Rudnick, 1995) in accretionary orogens (Cawood et al., 2009). However, this raises a well-known paradox of CC formation that mantle-derived melts are generally basaltic and differ from CC, which has an overall andesitic-dacitic composition (Figure 1a; Rudnick & Gao, 2014). Resolving this discrepancy has proven to be a challenge, and three models are generally invoked: (a) delamination of mafic/ultramafic rock of lower crust into the mantle (

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“…Very shallow slab dips (ca. 5°–10°) in the Pampean segment, likely related to subduction of the Juan Fernández seamount chain (Stern, 2020; Yáñez et al., 2001), are associated with greatest amount of Andean shortening and most pronounced basement uplifts within both the Andes (Aconcagua fold‐thrust belt, Cordillera Frontal and Precordillera) and the adjacent basin (Sierras Pampeanas), reaching topographic elevations of nearly 7,000 m in the orogen and above 6,000 m in the broken retroarc region. As subduction angle increases southwards, from ca.…”

Section: The Knight’s Move: Transcontinental Transport Followed By Li...mentioning

confidence: 99%

Transcontinental retroarc sediment routing controlled by subduction geometry and climate change (Central and Southern Andes, Argentina)

et al. 2021

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Central Argentina from the Pampean flat-slab segment to northern Patagonia (27°-41°S) represents a classic example of a broken retroarc basin with strong tectonic and climatic control on fluvial sediment transport. Combined with previous research focused on coastal sediments, this actualistic provenance study uses framework petrography and heavy-mineral data to trace multistep dispersal of volcaniclastic detritus first eastwards across central Argentina for up to ca. 1,500 km and next northwards for another 760 km along the Atlantic coast. Although detritus generated in the Andes is largely derived from mesosilicic volcanic rocks of the cordillera, its compositional signatures reflect different tectono-stratigraphic levels of the orogen uplifted along strike in response to varying subduction geometry as well as different character and crystallization condition of arc magmas through time and space. River sand, thus, changes from feldspatho-litho-quartzose or litho-feldspatho-quartzose in the north, where sedimentary detritus is more common, to mostly quartzo-feldspatho-lithic in the centre and to feldspatho-lithic in the south, where volcanic detritus is dominant. The transparent-heavy-mineral suite changes markedly from amphibole ≫ clinopyroxene > orthopyroxene in the north, to amphibole ≈ clinopyroxene ≈ orthopyroxene in the centre and to orthopyroxene ≥ clinopyroxene ≫ amphibole in the south. In the presently dry climate, fluvial discharge is drastically reduced to the point that even the Desaguadero trunk river has become endorheic and orogenic detritus is dumped in the retroarc basin, reworked by winds and temporarily accumulated in dune fields. During the Quaternary, instead, much larger amounts of water were released by melting of the Cordilleran ice sheet or during pluvial events. The sediment-laden waters of the Desaguadero and Colorado rivers then rushed from the tract of the Andes with greatest topographic and structural elevation, fostering alluvial fans inland and flowing in much larger valleys than today towards the Atlantic Ocean. Sand and gravel supply to the coast was high

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The role of subduction erosion in the generation of Andean and other convergent plate boundary arc magmas, the continental crust and mantle

Cited by 36 publications

References 206 publications

Secular variations of magma source compositions in the North Patagonian batholith from the Jurassic to Tertiary: Was mélange melting involved?

Secular variations of magma source compositions in the North Patagonian batholith from the Jurassic to Tertiary: Was mélange melting involved?

Formation of Continental Crust by Diapiric Melting of Recycled Crustal Materials in the Mantle Wedge

Transcontinental retroarc sediment routing controlled by subduction geometry and climate change (Central and Southern Andes, Argentina)

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