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Critiquing Articles - Thoughts/Questions Regarding Wikipedia's "Plate tectonics" Article

• Overall, this article reports comprehensive, unbiased facts/information regarding plate tectonics
• I noticed that the first sentence lacks clarity and cohesion
• Great organization of headings and sections
• Sections are comprehensive and proportional to one another
• Reference links I tried worked
• Some facts/information (especially within the first, introductory section) could be accompanied by more citations
• Article rated "C-Class" on quality scale
• Unreferenced figures/images
• Great mention of current competing mantle flow theories
• Subtopics are overrepresented; article may provided too much information; could possibly provide links to other articles instead?
• Information regarding plate tectonics is presented in far more depth in article than that presented in previous ESS classes
• I have learned most of information outlined in article over the course of multiple ESS classes; article provides detailed and comprehensive snapshot of plate tectonics
• Great organization of "References" section; plenty of further suggested reading provided

Critiquing Articles - Thoughts/Questions Regarding Wikipedia's "Divergent boundary" Article

• Article lacks sufficient citations and references
• Only one referenced reputable publication
• Article rated "Start-Class" on quality scale
• With only one referenced publication, article fails to provide comprehensive facts/information regarding subject
• Could provide map showing locations of Earth's major divergent boundaries
• Could provide sections detailing the geomechanics driving divergent boundaries
• Article provides supplemental links to information regarding Physical Oceanography, which might be unnecessary
• Subtopics are underrepresented
• Unreferenced figures/images
• Overall, information presented regarding divergent boundaries in article aligns with that detailed in ESS classes
• Article could be improved in organization, and with citations and more references

Choose Your Topic - "Molucca Sea Plate" Article Contributions

• In introductory section, I plan on adding a hyperlink to article regarding information on "microplates"

• Under "Contents," I plan to add headings for and corresponding information pertaining to "History," "Geology," and perhaps "Tectonic Activity (Earthquakes)"
• I plan on adding citations to existing information, as well as adding a few more references
• I plan on adding a "snapshot" of information regarding the Molucca Sea Plate, including, dimensions (length, width, density), geology, location, and coordinates of the plate

Choose Your Sources - "Molucca Sea Plate" Annotated Bibliography

A. Silver, Eli & Moore, J. (1978). The Molucca Sea Collision Zone, Indonesia. Journal of Geophysical Research. 83. 1681-1691. 10.1029/JB083iB04p01681.

• The crustal collision of the Molucca Sea Plate is formed by surface intersection of “oppositely dipping Benioff zones” which is overlain by the Sangihe and Halmahera volcanic arcs.

Bader, Anne Gaelle & Pubellier, Manuel. (2008). Forearc deformation and tectonic significance of the ultramafic Molucca Central Ridge, Talaud islands (Indonesia). Island Arc. 9. 653 - 663. 10.1111/j.1440-1738.2000.00309.x.

• Detached ophiolitic series and thick melanges are overlain by forearc deposits; subduction-driven east-west shortening of the Snellius Plateau caused the thrust melanges to reactivate and deform the forarc series.

Fischer, TP,Hilton, DR,Sharp, ZD,Hartono, U, Clor, Laura E, Fischer, Tobias P, Hilton, David R, Sharp, Zachary D, & Hartono, Udi. (2005). Volatile and N isotope chemistry of the Molucca Sea collision zone: Tracing source components along the Sangihe Arc, Indonesia. Geochemistry, Geophysics, Geosystems G³., 6(3), N/a.

• Research considering volcanic gas and nitrogen isotope variation correlate the “oblique collision between the two arcs has caused sediment obduction, decoupling the accretionary wedges from the underlying oceanic plate.”

McCaffrey, R. (1991), Earthquakes and ophiolite emplacement in the Molucca Sea Collision Zone, Indonesia, Tectonics, 10(2), 433–453, doi:10.1029/90TC02553.

• Exposed ophiolitic rocks can be found on the islands of the submarine Talaud-Mayu Ridge, which bisects the arc-arc collision zone of the Molucca Sea Plate; these ophiolites provide insight regarding the relationship between earthquakes and uplift surrounding the plate.

McCaffrey, R. , Silver, E. A. and Raitt, R. W. (2013). Crustal Structure of the Molucca Sea Collision Zone, Indonesia. In The Tectonic and Geologic Evolution of Southeast Asian Seas and Islands, D. E. Hayes (Ed.). doi:10.1029/GM023p0161

• The arc-arc collision zone of the Molucca Sea Plate is characterized as a thick, low velocity layer.

Mikhailov, V,Diament, M,Deplus, C,Louat, R, Widiwijayanti, Christina, Mikhailov, Valentin, Diament, Michel, Deplus, Christine, Louat, Rémy, . . . Gvishiani, Alexei. (2003). Structure and evolution of the Molucca Sea area: Constraints based on interpretation of a combined sea-surface and satellite gravity dataset. Earth and Planetary Science Letters, 215(1-2), 135-150.

• Research suggests that anchoring of the Snellius Plateau caused the Philippine subduction zone to shift eastwards which drove slices of forearc lithosphere below the Talaud Archipelago.

Philippines, Iran, Alaska (and the Far North): Earthquakes 5-11 January 2017

Jennifer Young - https://www.decodedscience.org/philippines-iran-alaska-far-north-earthquakes-5-11-january-2017/60479

• During January 2017, a 7.3 magnitude earthquake deep beneath the Celebes Sea, which the USGS attributed to the “deep reverse faulting within the inclined seismic zone defining the deep limit of the Molucca Sea microplate beneath the Celebes Sea Basin.”

Pubellier, M, Bader, Anne Gaelle, & Pubellier, Manuel. (2000). Forearc deformation and tectonic significance of the ultramafic Molucca central ridge, Talaud islands (Indonesia). The Island Arc., 9(4), 653-663.

• Situated south of Mindanao, the Molucca Sea is a narrow basin underlined by a north‐south ophiolitic ridge, which uplifts the central region of the basin.

Tiberi, C,Deplus, C,Diament, M,Mikhailov, V, Widiwijayanti, Christina, Tiberi, Christel, Deplus, Christine, Diament, Michel, Mikhailov, Valentin, & Louat, Rémy. (2004). Geodynamic evolution of the northern Molucca Sea area (Eastern Indonesia) constrained by 3-D gravity field inversion. Tectonophysics, 386(3-4), 203-222.

• The density of the Molucca sea plate is highly variable in the horizontal direction.

Zhang, Q., F. Guo, L. Zhao, and Y. Wu (2017), Geodynamics of divergent double subduction: 3‐D numerical modeling of a Cenozoic example in the Molucca Sea region, Indonesia, J. Geophys. Res. Solid Earth, 122, 3977–3998, doi:10.1002/2017JB013991.

• The Molucca Sea Plate is represents a Cenozoic example of divergent double subduction (DDS), which describes the subduction on both sides of a single oceanic plate.

Draft Your Article - Part 1

Tectonic Activity

• During January 2017, a 7.3 magnitude earthquake deep beneath the Celebes Sea, which the USGS attributed to the “deep reverse faulting within the inclined seismic zone defining the deep limit of the Molucca Sea microplate beneath the Celebes Sea Basin.”

Future Projections

• Future projections regarding the Molucca Sea Plate movement/subduction; more research needed.

The Molucca Sea Plate

Located in the western Pacific Ocean near Indonesia, the Molucca Sea Plate has been classified by scientists as a fully subducted microplate that is part of the Molucca Sea Collision Complex. The Molucca Sea Plate represents the only known example of divergent double subduction (DDS), which describes the subduction on both sides of a single oceanic plate.

Tectonic Setting

Molucca Sea Collision Zone modified from Zhang et al. using GeoMapApp

The Molucca Sea Plate is one of many tectonic features that compose the Molucca Sea Collision Complex, which refers to the tectonic relationship of the Sangihe Plate, Halmahera Plate, and the Molucca Sea Plate, in addition to the volcanic Halmahera and Sangihe Arcs. The southeast moving Sangihe Plate is situated along the western boundary of the Molucca Sea Plate. The northwest moving Halmahera Plate is situated along the eastern boundary of the Molucca Sea Plate. In the western Pacific Ocean, the Molucca Sea is bordered by the Indonesian Islands of Celebes (Sulawesi) to the west, Halmahera to the east, and the Sula Islands to the south. The Molucca Sea borders the Banda Sea to the south and the Celebes Sea to the west. To the north is the Philippine Sea and to the east is the Halmahera Sea. Situated south of Mindanao, the Molucca Sea is a narrow basin underlined by a north‐south ophiolitic ridge, which uplifts the central region of the basin.

Cross Section of Molucca Sea Collision Zone modified by Zhang et al.

Plate Mechanics

(Asymmetric) Double Divergent Subduction Zone

While the scientific community has not come to a consensus as to when the Molucca Sea Plate became fully subducted, the dominant theory is that the Molucca Sea Plate has been completely subducted beneath the overriding Halmahera and Sangihe Plates.

When actively subducting, the crustal collision of the Molucca Sea Plate was formed by surface intersection of “oppositely dipping Benioff zones” (also known as divergent double subduction) which results in the the Sangihe and Halmahera volcanic arcs. The force exerted by the thick overlying collision complex of the Halmahera and Sangihe Plates effectively depressed the crust of the Molucca Sea Plate. The plate itself features an asymmetrical morphology, configured in an inverted U-shape. The arc-arc collision zone of the Molucca Sea Plate is characterized as a thick, low velocity layer, which is highly variable in density. The variable in density of the Molucca Sea Plate led to different subduction velocities on the two sides. Divergent Double Subduction may facilitate various tectonic processes, including closure of ocean basins, accretion and amalgamation of volcanic arcs, and growth of continents.

Earthquakes

Historically, the Molucca Sea Plate has experienced hundreds of earthquakes ranging in magnitude. The most recent large earthquake occurred on January 2017 when a 7.3 magnitude earthquake deep beneath the Celebes Sea, which the USGS attributed to the “deep reverse faulting within the inclined seismic zone defining the deep limit of the Molucca Sea microplate beneath the Celebes Sea Basin.”

Geology

The geologic characteristics displayed on the surrounding islands provide insight regarding the complex plate movement of the divergent double subducting plate. Detached ophiolitic series and thick melanges are overlain by forearc deposits; subduction-driven east-west shortening of the Snellius Plateau caused the thrust melanges to reactivate and deform the forearc series. Exposed ophiolitic rocks can be found on the islands of the submarine Talaud-Mayu Ridge, which bisects the arc-arc collision zone of the Molucca Sea Plate; these ophiolites provide insight regarding the relationship between earthquakes and uplift surrounding the plate.

See Also

Molucca Sea Collision Zone

Sangihe Plate

Halmahera Plate

List of earthquakes in Indonesia