Blueschist from the Mariana forearc records long-lived residence of material in the subduction channel

Tamblyn, Renée; Zack, Thomas; Schmitt, Axel K.; Hand, Martin; Kelsey, David E.; Morrissey, Laura J.; Pabst, Sonja; Savov, Ivan P.

doi:10.1016/j.epsl.2019.05.013

Cited by 41 publications

(37 citation statements)

References 54 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…But no oceanic lithosphere was obducted nor metamorphic soles exhumed, so that the start of subduction cannot be firmly established. Recent datings of rutile in mm-to cm-scale blueschist facies fragments from serpentinite seamounts, at 48-47 Ma (Tamblyn et al, 2019) suggest a ~4 Ma time lag between subduction infancy and cooling of the subduction interface to ~600°C at ~50 km depth.…”

Section: Timescales Of Slabitization: Early Slab Dynamics Viscous Comentioning

confidence: 99%

Slabitization: Mechanisms controlling subduction development and viscous coupling

Agard

Prigent

Soret

et al. 2020

Earth-Science Reviews

View full text Add to dashboard Cite

This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

show abstract

Section: Timescales Of Slabitization: Early Slab Dynamics Viscous Comentioning

confidence: 99%

Slabitization: Mechanisms controlling subduction development and viscous coupling

Agard

Prigent

Soret

et al. 2020

Earth-Science Reviews

View full text Add to dashboard Cite

show abstract

“…These data suggest that most subduction zones record synchronous, punctuated exhumation, indicating that exhumation is likely driven by changes in boundary conditions (Agard et al, 2009) and may not represent a thermal steady state. On the other hand, some studies have determined lengthy residence times for individual blocks prior to exhumation (Tamblyn et al, 2019), such that comprehensive P‐T‐t data from multiple blocks may expose the time‐resolved thermal structure, or metamorphic field gradient, of an individual subduction zone.…”

Section: Introductionmentioning

confidence: 99%

An Exhumation Pulse From the Nascent Franciscan Subduction Zone (California, USA)

et al. 2020

View full text Add to dashboard Cite

We investigated a suite of metabasite blocks from serpentinite matrix and shale matrix mélanges of the California Coast Ranges. Our new data set consists of 40 Ar/ 39 Ar dates of amphibole and phengite and U-Pb dates of metamorphic zircon. Combined with published geochronology, including prograde Lu-Hf garnet ages from the same blocks, we can reconstruct the timing and time scales of prograde and retrograde metamorphism of individual blocks. In particular we find that exhumation from amphibole-eclogite facies conditions occurred as a single episode at 165-157 Ma, with an apparent southward younging trend. The rate and timing of exhumation were initially uniform (when comparing individual blocks) and fast (with cooling rates up to~140°C/Ma). In the cooler and shallower blueschist facies, exhumation slowed and became less uniform among blocks. Considering the subduction zone system, the high-grade exhumation temporally correlates with a magmatic arc pulse (Sierra Nevada) and the termination of forearc spreading (Coast Range Ophiolite). Our findings suggest that a geodynamic one-time event led to exhumation of amphibole-eclogite facies rocks. We propose that interaction of the Franciscan subduction zone with a spreading ridge led to extraction of the forearc mantle wedge from its position between forearc crust and subducting crust. The extraction led to fast and uniform exhumation of subducted rocks into the blueschist facies. We also show that the Franciscan subduction zone did not undergo significant cooling over time and that its initiation was not coeval with blueschist-facies metamorphism of the Red Ant schist of the Sierra Nevada foothills. Plain Language Summary A subduction zone is where oceanic crust of one tectonic plate dives under the crust of another plate. These zones are important drivers of the movement of the continental plates. Special rocks-blueschists and eclogites-form in subduction zones at high pressure and relatively low temperature. The Franciscan Complex forms most of the geology of western California. It consists of rocks that dived into a subduction zone and returned back to the surface. We investigated the history of some of these rocks by determining the age and conditions of their movement. We find that the rocks that subducted to depths of up to 80 km all came up at the same time around 160 million years before present. This suggests that a specific tectonic event occurred at that time; other regional data show that the effects of this event were felt elsewhere along the paleo-Pacific margin. We also investigate rocks in the Sierra Nevada foothills that other researchers suggested to have formed at about the same time and found that they are not correlated.

show abstract

“…The source of zirconium for low‐ T zircon growth can be the breakdown of high‐ T Zr‐bearing magmatic minerals such as clinopyroxene (Rubatto et al, ), and in this scenario the oldest zircons would pre‐date subduction. The zircons close to the age of prograde eclogite metamorphism at c. 490 Ma could also be attributed to prograde low‐ T dissolution–precipitation during subduction (Tamblyn et al, ; Tomaschek et al, ). Zirconium solubility is increased in silicon‐rich alkaline fluids, which form with increasing pressure, allowing zirconium to be dissolved and precipitaed from the fluid (Ayers, Zhang, Luo, & Peters, ; Hermann & Rubatto, ).…”

Section: Discussionmentioning

confidence: 99%

“…Finally, in the currently active Mariana subduction system, blueschist from recently erupted serpentinite‐mud volcanism on forearc trench slope formed in the Eoecene, pointing to c. 48 m.y. of residence time in the subduction channel (Tamblyn et al, ).…”

Section: Discussionmentioning

confidence: 99%

“…A recurring finding is that subducted oceanic rocks now found mixed in mélange can record different P–T–t histories, implying they experienced different evolutions within the subduction channel before becoming exhumed together (Federico et al, ; Krebs et al, ; Porteau et al, ). These samples can also record long‐lived metamorphism within oceanic subduction channels, often coupled with generally slow exhumation rates (Agard, Yamato, Jolivet, & Burov, ; Angiboust, Agard, Glodny, Omrani, & Oncken, ; Guillot, Hattori, Agard, Schwartz, & Vidal, ; Lázaro et al, ; Tamblyn et al, ). In order to preserve deeply buried, long‐lived, refrigerated mineral assemblages, these oceanic‐derived high‐ P rocks must reside for extended time‐scales within the subduction channel (Gerya et al, ).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Subduction and accumulation of lawsonite eclogite and garnet blueschist in eastern Australia

Tamblyn

Hand

Kelsey

et al. 2019

Journal Metamorphic Geology

Self Cite

View full text Add to dashboard Cite

Lawsonite eclogite and garnet blueschist occur as metre‐scale blocks within serpentinite mélange in the southern New England Orogen (SNEO) in eastern Australia. These high‐P fragments are the products of early Palaeozoic subduction of the palaeo‐Pacific plate beneath East Gondwana. Lu–Hf, Sm–Nd, and U–Pb geochronological data from Port Macquarie show that eclogite mineral assemblages formed between c. 500 and 470 Ma ago and became mixed together within a serpentinite‐filled subduction channel. Age data and P–T modelling indicate lawsonite eclogite formed at ~2.7 GPa and 590°C at c. 490 Ma, whereas peak garnet in blueschist formed at ~2.0 GPa and 550°C at c. 470 Ma. The post‐peak evolution of lawsonite eclogite was associated with the preservation of pristine lawsonite‐bearing assemblages and the formation of glaucophane. By contrast, the garnet blueschist was derived from a precursor garnet–omphacite assemblage. The geochronological data from these different aged high‐P assemblages indicate the high‐P rocks were formed during subduction on the margin of cratonic Australia during the Cambro‐Ordovician. The rocks however now reside in the Devonian–Carboniferous southern SNEO, which forms the youngest and most outboard of the eastern Gondwanan Australian orogenic belts. Geodynamic modelling suggests that over the time‐scales that subduction products accumulated, the high‐P rocks migrated large distances (~>1,000 km) during slab retreat. Consequently, high‐P rocks that are trapped in subduction channels may also migrate large distances prior to exhumation, potentially becoming incorporated into younger orogenic belts whose evolution is not directly related to the formation of the exhumed high‐P rocks.

show abstract

Blueschist from the Mariana forearc records long-lived residence of material in the subduction channel

Cited by 41 publications

References 54 publications

Slabitization: Mechanisms controlling subduction development and viscous coupling

Slabitization: Mechanisms controlling subduction development and viscous coupling

An Exhumation Pulse From the Nascent Franciscan Subduction Zone (California, USA)

Subduction and accumulation of lawsonite eclogite and garnet blueschist in eastern Australia

Contact Info

Product

Resources

About