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Two -stage Subduction Initiation around the Caribbean Plumehead Plate

This presentation discusses the different types of Subduction Zone Nucleation (SNSZ) and the induced nucleation of a subduction zone (INSZ) around the Caribbean Plumehead Plate. It explores various models and examples of subduction initiation, including passive margin collapse, transform/fracture zone collapse, and plume-induced subduction initiation. The session also highlights the geological evolution of the Greater Antilles and the Cuban subduction zone.

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Two -stage Subduction Initiation around the Caribbean Plumehead Plate

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  1. Two-stage Subduction Initiation around the Caribbean PlumeheadPlate Bob Stern (U TX Dallas USA) Scott Whattam (Korea U., Korea) Taras Gerya (ETH, Switzerland) James Pindell (Rice U., USA) T224 Tuesday 8:05am Mile High Ballroom 2C

  2. Induced Nucleation of a Subduction Zone (INSZ) 2 types Spontaneous Nucleation of a Subduction Zone (SNSZ) 3 types

  3. Induced Nucleation of a Subduction Zone (INSZ) 2 types Spontaneous Nucleation of a Subduction Zone (SNSZ) 3 types

  4. Induced Nucleation of a Subduction Zone (INSZ) 2 types Spontaneous Nucleation of a Subduction Zone (SNSZ) 3 types

  5. SNSZ requires lithospheric failure. It requires a lithospheric weakness to exploit and density inversion between lithosphere and asthenosphere. 3 types of SNSZ • Passive Margin Collapse • Unlikely; no Cenozoic examples • Transform/Fracture Zone Collapse • Ex. modern IBM, Late Cretaceous SW Asia) • Plume Induced Subduction Initiation (PISI) • Late Cretaceous of SW Caribbean

  6. 1. Passive Margin Collapse No Cenozoic examples. Seems difficult to accomplish. Wilson cycle ocean closing vectors probably ~90° to opening vectors because new subduction zones form on transforms, not along rifted continental margins Look at Gulf of Mexico example

  7. The Gulf of Mexico USA Cuba Mexico

  8. Dallas Houston Modified after Pindell and Kennan 2009

  9. Gulf of Mexico vertical gravity gradient map from satellites (CryoSat-2 and Jason-1) reveals the Jurassic spreading ridge. Uninterpreted Interpreted The VGG reveals the extinct spreading ridges and fracture zones as well as a significant change in amplitude across the boundary between continental and oceanic crust (COBs). This is a Mercator projection; grayscale saturates at T20 eotvos units. (Sandwell et al., 2014)

  10. North-south (dip) cross-section of the NW Gulf of Mexico continental margin. 165 Ma oceanic crust + 20 km sediments = no lithospheric failure or even earthquakes).

  11. Late Jurassic (M16; 141 Ma) reconstruction of the Proto-Caribbean Good place for transform margin collapse and formation of new subduction zone (Greater Antilles Arc). Pindell et al. 2011

  12. Interested to learn more about Subduction Initiation and the Greater Antilles? Pardee Symposium P4. Geologic Evolution of Cuba Wed., 28 Sept., 8 a.m.-noon Mile High Ballroom 2A/3A

  13. Induced Nucleation of a Subduction Zone (INSZ) 2 types Spontaneous Nucleation of a Subduction Zone (SNSZ) 3 types

  14. 2. Transform margin collapse (Uyeda & Ben Avraham model*) Eocene ~50 Ma Problem: Old lithosphere is very strong, but a properly oriented fracture zone could allow it to begin to sink. *of course it’s more complicated, see Leng and Gurnis GRL 2015

  15. A. Exploitation of Lithospheric Weakness

  16. B. Lithospheric Collapse & Formation of Infant Arc (proto-forearc*) by seafloor spreading *Nursery of most ophiolites

  17. C. Proto-forearc widens by seafloor spreading as lithospheric subsidence continues spreading Trench rollback Trench rollback draws in more asthensophere

  18. Interested to learn more about IBM SNSZ? Studying an Ophiolite in its Natural Environment:IODP Leg 352 Drilling in the Izu-Bonin-Mariana (IBM) Forearc T209 Wed. 3:20 pm Room 203

  19. D. Forearc cools soon after true subduction (down-dip motion of plate) begins When and why lithospheric subsidence develops down-dip motion is not understood. Mature arc system begins as forearc cools Stern & Bloomer 1992

  20. E. Mature Subduction Zone

  21. Induced Nucleation of a Subduction Zone (INSZ) 2 types Spontaneous Nucleation of a Subduction Zone (SNSZ) 3 types

  22. Late Cretaceous evolution of the Caribbean plate Galapagos Hotspot

  23. Plume- induced SI: the Late Cretaceous Caribbean example Cartoon depicting construction of (a) the early 140–110 Ma oceanic plateau followed by the subsequent evolution of subduction zones around the plume head through Late Cretaceous time. Whattam and Stern 2014

  24. Plume- induced SI: the Late Cretaceous Caribbean example

  25. Numerical experiments of mantle plume impinging on oceanic lithosphere The initial model setup impinges a thermal mantle plume (100-300 km in diameter) into an oceanic lithosphere with 8-30 km thick mafic crust composed of 3 km basalts and 5-27 km gabbro (Gerya et al., Nature 2015).

  26. PISI early stage: Plume head impinges on base of lithosphere 20 Ma lithosphere; modern Earth Plume head impingment: oceanic plateau development formation of an incipient trench and a nearly-circular slab at the plateau margins

  27. PISI late stage: Lithosphere ruptures and collapses into Subduction Zone as plume head expands tearing of the circular slab formation of four retreating subduction zones

  28. Induced Nucleation of a Subduction Zone (INSZ) 2 types Spontaneous Nucleation of a Subduction Zone (SNSZ) 3 types

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