Metamorphic gradient modification in the Early Cretaceous Northern Andes subduction zone: A record from thermally overprinted high-pressure rocks

Abstract. The exhumation of high and ultra-high pressure rocks is ubiquitous in Phanerozoic orogens created during continental collisions, and is common in many ocean-ocean and ocean-continent subduction zone environments. Three different tectonic environments have previously been reported, which exhume deeply buried material by different mechanisms and at different rates. However it is becoming increasingly clear that no single mechanism dominates in any particular tectonic environment, and the mechanism may change in time and space within the same subduction zone. In order for buoyant continental crust to subduct, it must remain attached to a stronger and denser substrate, but in order to exhume, it must detach (and therefore at least locally weaken) and be initially buoyant. Denser oceanic crust subducts more readily than more buoyant continental crust but exhumation must be assisted by entrainment within more buoyant and weak material such as serpentinite or driven by the exhumation of structurally lower continental crustal material. Weakening mechanisms responsible for the detachment of crust at depth include strain, hydration, melting, grain size reduction and the development of foliation. These may act locally or may act on the bulk of the subducted material. Metamorphic reactions, metastability and the composition of the subducted crust all affect buoyancy and overall strength. Subduction zones change in style both in time and space, and exhumation mechanisms change to reflect the tectonic style and overall force regime within the subduction zone. Exhumation events may be transient and occur only once in a particular subduction zone or orogen, or may be more continuous or occur multiple times.

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Subduction zone intermediate-depth seismicity: Insights from the structural analysis of Alpine high-pressure ophiolite-hosted pseudotachylyte (Corsica, France)

Journal of Structural Geology ◽

10.1016/j.jsg.2016.04.002 ◽

2016 ◽

Vol 87 ◽

pp. 95-114 ◽

Cited By ~ 16

Author(s):

Rémi Magott ◽

Olivier Fabbri ◽

Marc Fournier

Keyword(s):

High Pressure ◽

Structural Analysis ◽

Subduction Zone ◽

Intermediate Depth

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High-pressure experimental verification of rutile-ilmenite oxybarometer: Implications for the redox state of the subduction zone

Science China Earth Sciences ◽

10.1007/s11430-016-9082-5 ◽

2017 ◽

Vol 60 (10) ◽

pp. 1817-1825 ◽

Cited By ~ 4

Author(s):

RenBiao Tao ◽

LiFei Zhang ◽

Vincenzo Stagno ◽

Xu Chu ◽

Xi Liu

Keyword(s):

High Pressure ◽

Subduction Zone ◽

Experimental Verification ◽

Redox State

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Monazite solubility in hydrous silicic melts at high pressure conditions relevant to subduction zone metamorphism

Earth and Planetary Science Letters ◽

10.1016/j.epsl.2012.01.002 ◽

2012 ◽

Vol 321-322 ◽

pp. 104-114 ◽

Cited By ~ 28

Author(s):

Susanne Skora ◽

Jon Blundy

Keyword(s):

High Pressure ◽

Subduction Zone

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Erosion and regional exhumation of an Early Cretaceous subduction/accretion complex in the Northern Andes

International Geology Review ◽

10.1080/00206814.2019.1596042 ◽

2019 ◽

Vol 62 (2) ◽

pp. 186-209 ◽

Cited By ~ 4

Author(s):

D. S. Avellaneda-Jiménez ◽

A. Cardona ◽

V. Valencia ◽

J. S. Barbosa ◽

J. S. Jaramillo ◽

...

Keyword(s):

Early Cretaceous ◽

Northern Andes ◽

Cretaceous Subduction

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Carbonation of subduction-zone serpentinite (high-pressure ophicarbonate; Ligurian Western Alps) and implications for the deep carbon cycling

Earth and Planetary Science Letters ◽

10.1016/j.epsl.2016.02.034 ◽

2016 ◽

Vol 441 ◽

pp. 155-166 ◽

Cited By ~ 46

Author(s):

Marco Scambelluri ◽

Gray E. Bebout ◽

Donato Belmonte ◽

Mattia Gilio ◽

Nicola Campomenosi ◽

...

Keyword(s):

High Pressure ◽

Carbon Cycling ◽

Subduction Zone ◽

Western Alps

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Geochemical and Nd isotopic constraints for the origin of eclogite protoliths, northern Cordillera: implications for the Paleozoic tectonic evolution of the Yukon-Tanana terrane

Canadian Journal of Earth Sciences ◽

10.1139/e99-070 ◽

1999 ◽

Vol 36 (10) ◽

pp. 1697-1709 ◽

Cited By ~ 12

Author(s):

Robert A Creaser ◽

Jo-Anne S Goodwin-Bell ◽

Philippe Erdmer

Keyword(s):

High Pressure ◽

Subduction Zone ◽

Convergent Margins ◽

Metasedimentary Rocks ◽

High Pressure Metamorphism ◽

Distal Edge ◽

History Of ◽

Convergent Plate Margin ◽

Ocean Ridge ◽

Subduction Zone Magmatism

On the basis of trace-element data, basaltic protoliths for Paleozoic eclogites from the Yukon-Tanana terrane (YTT) have diverse origins. Eclogites from Stewart Lake and the Simpson Range have characteristics of basaltic protoliths generated by subduction-zone magmatism, are hosted by serpentinitic-gabbroic rocks, and record Mississippian high-pressure metamorphism and cooling. In contrast, eclogites from Faro, Ross River, and Last Peak show either within-plate geochemistry or mid-ocean ridge protolith geochemistry with a small subduction component, are hosted by continental metasedimentary rocks of the Nisutlin assemblage, and record Permian high-pressure metamorphism and cooling. We interpret these results to derive from the following tectonic events in the Paleozoic history of the YTT: (1) activity at a Devonian-Mississippian convergent plate margin at the distal edge of North America, with near-contemporaneous subduction-zone magmatism and high-pressure metamorphism; (2) Mississippian rifting of that margin to form the outboard YTT, the Slide Mountain marginal basin, and the Faro, Ross River, and Last Peak eclogite protoliths; and (3) west-dipping subduction of the Slide Mountain Ocean under the outboard YTT in Permian time, to produce the Faro, Ross River, and Last Peak eclogites and Permian arc magmatism throughout the YTT. The basaltic protoliths of the Paleozoic YTT eclogites bear close similarity to those produced in rifted convergent margins, such as the Miocene Japanese arc - back-arc system.

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Accretion-controlled forearc deformation pulses recorded by high-pressure paleo-accretionary wedges: the example of the Hellenic subduction zone

10.5194/egusphere-egu21-5897 ◽

2021 ◽

Author(s):

Armel Menant ◽

Onno Oncken ◽

Johannes Glodny ◽

Samuel Angiboust ◽

Laurent Jolivet ◽

...

Keyword(s):

High Pressure ◽

Subduction Zone ◽

Numerical Models ◽

Carbonaceous Material ◽

Plate Interface ◽

Stress Regime ◽

Hellenic Subduction Zone ◽

Driving Mechanisms ◽

Wide Range

Subduction margins are the loci of a wide range of deformation processes occurring at different timescales along the plate interface and in the overriding forearc crust. Whereas long-term deformation is usually considered as stable over Myr-long periods, this vision is challenged by an increasing number of observations suggesting a long-term pulsing evolution of active margins. To appraise this emerging view of a highly dynamic subduction system and identify the driving mechanisms, detailed studies on high pressure-low temperature (HP-LT) exhumed accretionary complexes are crucial as they open a window on the deformation history affecting the whole forearc region.In this study, we combine structural and petrological observations, Raman spectroscopy on carbonaceous material, Rb/Sr multi-mineral geochronology and thermo-mechanical numerical models to unravel with an unprecedented resolution the tectono-metamorphic evolution of the Late-Cenozoic HP-LT nappe stack cropping out in western Crete (Hellenic subduction zone). A consistent decrease of peak temperatures and deformation ages toward the base of the nappe pile allows us to identify a minimum of three basal accretion episodes between ca. 24 Ma and ca. 15 Ma. On the basis of structural evidences and pressure-temperature-time-strain predictions from numerical modeling, we argue that each of these mass-flux events triggered a pulse in the strain rate, sometimes associated with a switch of the stress regime (i.e., compressional/extensional). Such accretion-controlled transient deformation episodes last at most ca. 1-2 Myr and may explain the poly-phased structural records of exhumed rocks without involving changes in far-field stress conditions. This long-term background tectonic signal controlled by deep accretionary processes plays a part in active deformations monitored at subduction margins, though it may remain blind to most of geodetic methods because of superimposed shorter-timescale transients, such as seismic-cycle-related events.

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Latest Triassic to Early Cretaceous tectonics of the Northern Andes: Geochronology, geochemistry, isotopic tracing, and thermochronology

Andean Tectonics ◽

10.1016/b978-0-12-816009-1.00009-5 ◽

2019 ◽

pp. 173-208

Author(s):

Richard A. Spikings ◽

Ryan Cochrane ◽

Cristian Vallejo ◽

D. Villagomez ◽

Roelant Van der Lelij ◽

...

Keyword(s):

Early Cretaceous ◽

Northern Andes ◽

Isotopic Tracing

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Reconstruction of the Jurassic to Early Cretaceous tectono-magmatic evolution of the Northern Andean Arc from their Crustal Thickness and Thermobarometry

10.5194/egusphere-egu21-10222 ◽

2021 ◽

Author(s):

Luisa Chavarria ◽

Camilo Bustamante ◽

Agustín Cardona ◽

Germán Bayona

Keyword(s):

Early Cretaceous ◽

Deep Level ◽

Thermal Flux ◽

Volcanic Rocks ◽

Mineral Chemistry ◽

Crustal Thickness ◽

First Episode ◽

Magma Source ◽

Northern Andes ◽

Last Stage

Igneous rocks in magmatic arcs record variations in composition, thermal flux, and subduction dynamics through time. In the Northern Andes, arc magmatism of the Jurassic age registers a complicated history, including the fragmentation of Pangea at the end of the Triassic and the beginning of a new subduction zone in the Jurassic located at the western margin of South America.We characterized the crustal thickness variations of the Early Jurassic to Early Cretaceous (194-130 Ma) in plutonic and volcanic rocks of the Northern Andes of Colombia and Ecuador, using trace elements signatures and analyzed the implications of the emplacement conditions during the last stage of the magmatism using Al-in-hornblende thermobarometry and mineral chemistry. Moderate rare earth elements (REE) slopes and depleted heavy REE patterns show that the primary residual magma source was amphibole, but plagioclase and pyroxene were also significant residual phases indicating that the magma source was formed in a crust that varied in thickness from 35-50 km. The La/Yb and Sr/Y crustal quantifications variations indicate that the arc underwent two thickening episodes. The first episode (190 to 180 Ma) is associated with a magmatic event. The second episode (165 to 154 Ma) is related to the shift to an oblique subduction setting and a subsequent collisional event that produced medium P-T metamorphic rocks. In the Late Jurassic to Early Cretaceous (154-130 Ma), the crust became thinner and, in this scenario, was emplaced the last stage of plutonism with depths that varied from shallow to deep level (until 25.5 km) in the crust.

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