Model data repository of "Styles of Trench-parallel Mid-ocean Ridge Subduction Affect Cenozoic Geological Evolution in circum-Pacific Continental Margins"
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This dataset contains the data used in Wu et al. (2022): "Styles of Trench-parallel Mid-ocean Ridge Subduction Affect Cenozoic Geological Evolution in circum-Pacific Continental Margins".Keywords:
Continental Margin
Summary A transect of four coreholes, drilled by the Glomar Challenger across the Irish continental margin at the Goban Spur, evidences a dynamic palaeoceanographic regime during the late Mesozoic and Cenozoic. Shallow marine waters invaded the rift-stage grabens of the Goban Spur in the early Barremian. Thereafter, the margin subsided rapidly, producing a pelagic depositional regime by late Barremian time. Deep marine conditions were maintained as sea-floor spreading began in the early Albian, and chiefly pelagic deposition continued to the present. Among a series of significant post-rift oceanographic changes, one of the most notable is the familiar fluctuation of oxic and anoxic sea-floor environments during the Cenomanian and Turonian. Another marked change took place during the late Palaeocene, when cooler, oxygen-rich, northern bottom waters reached the Goban Spur as a consequence of rifting and sea-floor spreading between Greenland, Rockall Plateau, and Norway. Later during the Cenozoic, the initial production of Antarctic bottom water, several accelerations of polar icecap growth, and fluctuating eustatic sea-level produced a variety of circulatory shifts on the Goban Spur. A particularly significant sedimentological consequence of these interacting processes was the widespread creation of numerous erosional and non-depositional unconformities.
Continental Margin
Margin (machine learning)
Circulation (fluid dynamics)
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A general theory for forced barotropic long trench waves in the presence of linear bottom friction is presented. Two specific forcing mechanisms are considered: (i) transverse fluctuations in a western boundary current as it flows across a trench, and (ii) a traveling wind system that moves parallel to the trench. The mechanisms (i) and (ii) are applied to the Japan-Kuril trench and Aleutian trench, respectively. In the case of the Japan-Kuril trench it is found that 3-month period fluctuations in the Kuroshio are able to generate currents along the trench of 0 (10 cm s−1) and coastal sea level variations of O (7 cm). In the case of the Aleutian trench, traveling wind systems in the northeast Pacific may produce a near resonant response. Such a response consists of velocity fluctuations of 0 (10 cm s−1) along the trench and of 0 (4 cm s−1) across the trench, the coastal sea level fluctuations can be up to 12 cm. While these estimates should be regarded as tentative because of the uncertainty in the value of the bottom friction coefficient, they nevertheless suggest that trench wave motions could produce significant long-time scale velocity and sea level fluctuations in the North Pacific trenches.
Barotropic fluid
Forcing (mathematics)
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Tsunami earthquake
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Slab
Slab window
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Slab width plays a major role in controlling subduction dynamics and trench motion. However, observations on natural narrow subduction zones do not show any correlation between slab width and trench velocities, indicating that other factors may have a greater impact. Here, we use 3D numerical subduction models to evaluate the effect of slab width, strength of slab coupling to the lateral plate and overriding plate thickness on trench kinematics. Model results show that slab width has little influence on trench migration rates for narrow subduction zones, but that the thickness of the overriding plate plays a major role, with trench velocities decreasing as the thickness increases. These results explain trench velocities observed in natural narrow subduction zones showing no relation with slab width but an inverse dependence on overriding plate thickness. Finally, we find that the overriding plate thickness also significantly affects the trench shape.
Slab
Slab window
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Continental Margin
Passive margin
Convergent boundary
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Abstract The near‐trench behavior of subduction megathrust faults is critical for understanding earthquake hazard and tsunami generation. The shallow subduction interface is typically located in unconsolidated sediments that are considered too weak to accumulate elastic strain. However, the spectrum of shallow fault slip behavior is still elusive, due in large part to the lack of near‐field observations. Here we combine measurements from seafloor pressure sensors near the trench and an onshore GPS network in a time‐dependent inversion to image the initiation and migration of a well‐documented slow slip event (SSE) in 2007 at the Nicoya Peninsula, Costa Rica. Our results show that the shallow SSE initiated on the shallow subduction interface at a depth of ~15 km, where pore fluid pressure is inferred to be high, and propagated all the way to the trench. The migrating event may have triggered a second subevent that occurred 1 month later. Our results document the release of elastic strain at the shallow part of the subduction megathrust and suggest prior accumulation of elastic strain. In conjunction with near‐trench shallow slow slip recently reported for the Hikurangi subduction zone and trench breaching ruptures revealed in some large earthquakes, our results suggest that near‐trench strain accumulation and release at the shallower portions of the subduction interface is more common than previously thought.
Seafloor Spreading
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Slab
Slab window
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In the southernmost Kuril Trench, the tsunami source regions vary their along-trench extent even among earthquakes occurring within the same segment. Recent studies suggest that the tsunami source of the 1952 Tokachi-oki earthquake (M 8.1) differs from but partially overlaps with that of the 2003 Tokach-oki earthquake (M 8.0). Furthermore, the along-trench extent among the earthquakes seems to differ between deep and shallow portions of the subduction interface. A seismic gap has been recognized along the deep subduction interface between the sources of the 1952 and 1973 earthquakes. We propose that the gap is now larger, including both shallow to deep portions of the interface between the 1973 and 2003 earthquakes. Variability in spatial extent of large subduction earthquakes in both along-trench direction and trench-normal direction makes it difficult to forecast future earthquakes in the southernmost Kuril Trench.
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