Dynamics of Oceanic Slab Tearing During Transform-Fault Horizontally-Oblique Subduction: Insights From 3D Numerical Modeling

Xin, Jie1; Zhang, Huai1,2,3; Orellana-Rovirosa, Felipe4; Li, Zhong-Hai1; Liu, Liang5; Xu, Yi-Gang5; Zhang, Zhen1; Shi, Yaolin1

2023-07-01

10.1029/2023JB027041

JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH   影响因子和分区

2169-9313

2169-9356

["Oceanic-plates vertical tearing is seismically identified in the present-day Earth. This type of plate tearing is frequently reported in horizontally-oblique subduction zones where transform-faulted oceanic plates are subducting (or subducted). However, the mechanisms behind vertical slab tearing are still poorly understood, thus we utilize 3D time-dependent Stokes' flow thermo-mechanical numerical models to further study this problem. We find that (a) the age offset of transform fault and (b) the horizontal obliqueness of subduction fundamentally control the tearing behavior of two generic, materially homogeneous oceanic slabs separated by a low-viscosity zone. The two slabs sequentially bend, which combined with the age-thickness difference between slabs, causes the differential sinking of them. Based on the modeling results, well-developed slabs vertical tearing would happen when the oblique angle of subduction is =30 degrees or the age ratio of the secondly bent to firstly bent slab being similar to<0.6. Quantifying the horizontal distance-vector between sinking slabs, we find that subduction at medium-low horizontal-obliqueness angles (<= 40 degrees) of young lithosphere (slabs-average similar to 15 Myr) tends to produce fault-perpendicular tearing. Contrastingly, old-age slabs (average >= 30 Myr) with medium-large obliqueness angles (similar to>20 degrees) tend to produce fault-parallel tearing, related to differential slab-hinge retreat or rollback. Correlations between slabs' (a) computed tearing horizontal-width and (b) scaling-theory forms of their subduction-velocity differences, are reasonable (0.76-0.97). Our numerically predicted scenarios are reasonably consistent with plate-tear imaging results from at least four natural subduction zones. Our modeling also suggests that continual along-trench variation in subduction dip angle may be related to a special case of oblique subduction.","Plain Language Summary Oceanic tectonic plates can tear-off through time as they plunge and sink into the Earth's mantle and are especially favored when plates have preexisting fault-weak zones. Two primary conditions promote oceanic tectonic slabs' tearing: (a) Obliqueness of a plate's horizontal velocity with respect to the overriding-plate coastline and trench, leading to the two slabs sequentially bending yet having differences in deformation; (b) Differences in slab-age between two sides of a displaced fault-zone that created an offset in plate age and thickness. To understand these processes, we present 3D numerical models that simulate tectonic evolution and deformations, and we compare model results with analytical studies as well as with natural observations from seismic imaging. Age differences across fault-zones combined with subduction horizontal obliqueness control the generation and development of vertical tearing. Furthermore, two geometrical patterns of vertical tearing are largely consistent with observations. Our findings suggest that along-trench changes in the steep angle between the slab and surface (dip angle) may be related to a special case of oblique subduction. Observing the age contrast across faults and the horizontal obliqueness of plates' motion allows predictions of the tearing pattern, evolution, and local mantle flow."]

oceanic slabs vertical tearing horizontally oblique subduction transform-fault offset 3D numerical models Stokes' flow

SCI

英语

NI论文

其他

National Science Foundation of China["41725017","U2239205"] ; National Key Ramp;D Program of the Ministry of Science and Technology of China[2020YFA0713401]

Geochemistry & Geophysics

Geochemistry & Geophysics

WOS:001027285200001

AMER GEOPHYSICAL UNION

GEOSCIENCES

Web of Science

1.Univ Chinese Acad Sci, Coll Earth & Planetary Sci, Key Lab Computat Geodynam, Beijing, Peoples R China
2.Univ Chinese Acad Sci, Beijing Yanshan Earth Crit Zone Natl Res Stn, Beijing, Peoples R China
3.Southern Marine Sci & Engn Guangdong Lab Zhuhai, Zhuhai, Peoples R China
4.Southern Univ Sci & Technol, Dept Ocean Sci & Engn, Shenzhen, Peoples R China
5.Chinese Acad Sci, Guangzhou Inst Geochem, State Key Lab Isotope Geochem, Guangzhou, Peoples R China

Xin, Jie,Zhang, Huai,Orellana-Rovirosa, Felipe,et al. Dynamics of Oceanic Slab Tearing During Transform-Fault Horizontally-Oblique Subduction: Insights From 3D Numerical Modeling[J]. JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH,2023,128(7).

Xin, Jie.,Zhang, Huai.,Orellana-Rovirosa, Felipe.,Li, Zhong-Hai.,Liu, Liang.,...&Shi, Yaolin.(2023).Dynamics of Oceanic Slab Tearing During Transform-Fault Horizontally-Oblique Subduction: Insights From 3D Numerical Modeling.JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH,128(7).

Xin, Jie,et al."Dynamics of Oceanic Slab Tearing During Transform-Fault Horizontally-Oblique Subduction: Insights From 3D Numerical Modeling".JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH 128.7(2023).