Implications for crustal accretion at fast spreading ridges from observations in Jurassic oceanic crust in the western Pacific

2003 ◽  
Vol 4 (1) ◽  
Author(s):  
Robert A. Pockalny ◽  
Roger L. Larson
Keyword(s):  
Oceanic Crust ◽  
Western Pacific ◽  
Crustal Accretion ◽  
Spreading Ridges ◽  
Fast Spreading ◽  
The Western Pacific

Coupled mechanical and hydrothermal modeling of crustal accretion at intermediate to fast spreading ridges

2011 ◽  
Vol 311 (3-4) ◽  
pp. 275-286 ◽  
Author(s):  
Sonja Theissen-Krah ◽  
Karthik Iyer ◽  
Lars H. Rüpke ◽  
Jason Phipps Morgan
Keyword(s):  
Crustal Accretion ◽  
Spreading Ridges ◽  
Fast Spreading

Highly permeable and layered Jurassic oceanic crust in the western Pacific

1993 ◽  
Vol 119 (1-2) ◽  
pp. 71-83 ◽  
Author(s):  
Roger L. Larson ◽  
Andrew T. Fisher ◽  
Richard D. Jarrard ◽  
Keir Becker
Keyword(s):  
Oceanic Crust ◽  
Western Pacific ◽  
The Western Pacific

Seismic Imaging, Arc Magamtism and Megathrust Earthquake under the Western Pacific Subduction Zone

2020 ◽  
Author(s):  
Zhi Wang ◽  
Jian Wang
Keyword(s):  
Partial Melting ◽  
Subduction Zone ◽  
Oceanic Crust ◽  
Mantle Wedge ◽  
Western Pacific ◽  
Arc Magmatism ◽  
S Wave ◽  
Slab Melting ◽  
Megathrust Earthquake ◽  
The Western Pacific

<p>Arc magmatism and megathrust earthquake occurrence in a subduction zone are deemed to attribute to many factors, including structural heterogeneities, fluid contents, temperature, depth of subducting oceanic crust, and etc. However, how these factors affect them is unclear. The extensive arc magmatism observed on the island arcs is considered to be an indicator on chemical exchange between the wedge mantle and the surface in a subduction zone. Megathrust earthquake frequently occurrence is also considered to be attributed to the slab melting and associated interplate coupling of the subducting plate. The Western Pacific subduction zone is regarded as one of the best Laboratory for seismologists to examine these processes due to the densest seismic networks recording numerous earthquakes. Some of the previous studies suggest that the island-arc magmatism is mainly contributed to the melting of peridotite in the mantle wedge due to fluids intrusion from the dehydration process associated with the subducting oceanic crust. They further argued that the oceanic plate could only provide water to the overlying mantle wedge for arc magmatism, but not melt itself due to that it is too cold to melt at a depth between 100 and 200km. However, some of other studies revealed that the hydrated basalt derived from the mid-ocean ridge will be melted with high T and water saturated on the upper interface of the sbuducting plate in the mantle wedge. We consider that the three-dimensional (3-D) P- and S- wave velocity (Vp, Vs) and Poisson’s ratio (σ) structures of the subduction zone, synthesized from a large-quantity of high-quality direct P-, and S-wave arrival times of source-recive pairs from the well located suboceanic events with sP depth phase data could provide a compelling evidence for structural heterogeneity, highly hydrated and serpentinized forearc mantle and dehydrated fluids in the subduction zones. In this study, we combined seismic velocities and Poisson’s ratio images under the entire-arc region of the Western Pacific subduction zone to reveal their effects on megathrust earthquake generation and arc magmatism. We find that a ~10 km-thick low-velocity layer with high-V and high-Poisson’s ratio anomalies is clearly imaged along the upper interface of the subducting Pacific slab. This distinct layer implies partial melting of the oceanic crust due to the deep-seated metamorophic reactions depending on the source of fluids and temperature regime. Such a process could refertilize the overlying mantle wedge and enrich the peridotite sources of basalts under the island arc. Significant low-V and high-Poisson’s ratio anomalies were observed in the mantle wedge along the volcanic front, indicating melting or partial melting of peridotite-rich mantle and then yield tholeiitic magma there. The present study demonstrates that the combined factors of fluid content, mineral composition and thermal regime play a crucial role in both slab melting and arc-magmatism under the Western Pacific subduction zone.</p>

Rifting of Pangea and Formation of Present Ocean Basins

2004 ◽  
Author(s):  
John J. W. Rogers ◽  
M. Santosh
Keyword(s):  
Gulf Of Mexico ◽  
Small Region ◽  
Western Pacific ◽  
Island Arcs ◽  
Spreading Ridges ◽  
The Pacific ◽  
Spreading Centers ◽  
The Mediterranean ◽  
Ocean Lithosphere ◽  
The Western Pacific

At the end of the Paleozoic the supercontinent Pangea was surrounded by the “superocean” Panthalassa (all ocean). We have no way of knowing what islands, island arcs, spreading ridges, and other features most of the ocean contained, because all of it has now been subducted. We can, however, be somewhat more specific about continental fragments and spreading ridges in the small region of Panthalassa directly adjacent to the eastern margin of Pangea. This part of the ocean, known as “Tethys,” left a record of its history as continental fragments continued to rift from the Gondwana (southern) part of Pangea and move across Tethys to collide with the Laurasian (northeastern) margin of Pangea (chapter 8). During the Mesozoic and Cenozoic the positions and configurations of continents and ocean basins gradually attained their present form. Major continental reorganization resulted from movements of fragments across Tethys and the opening of the Atlantic, Indian, Arctic, and Antarctic Oceans and associated smaller seas. The size of Panthalassa, now known as the Pacific Ocean, gradually decreased as other oceans opened and small seas formed by a variety of processes in the western Pacific. Separation and collision of continental plates in what had been the center of Pangea formed the Gulf of Mexico–Caribbean and the Mediterranean. By creating new spreading centers, the breakup of Pangea generated a larger volume of young ocean lithosphere both in the new ocean basins and in the Pacific than the volume occupied by spreading centers in Panthalassa. By filling more of the ocean basins, these ridges forced seawater to rise eustatically onto continental platforms, creating shallow seas and filling cratonic basins where the crust was tectonically depressed. We begin this chapter by discussing the successive changes in Tethys and then the origin of the world’s major ocean basins. This is followed by an investigation of the smaller seas of the western Pacific region and the specific histories of the Gulf of Mexico–Caribbean and the Mediterranean. We continue with a discussion of the causes and locations of rifts that break up supercontinents and finish with a description of eustatic sealevel changes.

Typhoon Havens Handbook for the Western Pacific and Indian Oceans. Change 3

1993 ◽  
Author(s):  
Dennis C. Perryman ◽  
Richard E. Gilmore ◽  
Ronald E. Englebretson
Keyword(s):  
Western Pacific ◽  
The Western Pacific
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