Atypical crustal structure of the Makran subduction zone and seismotectonic implications

Yu, Chuanhai1,2; Xu, Min1,2,6; Lin, Jian1,2,3; Yang, Hongfeng4; Zhao, Xu5; Zeng, Xin5; He, Enyuan1; Zhang, Fan1,2; Sun, Zhen1,2

2024-10-01

10.1016/j.epsl.2024.118896

EARTH AND PLANETARY SCIENCE LETTERS   影响因子和分区

0012-821X

1385-013X

The Makran subduction zone is atypical due to the thick sediment input and shallow subduction angles, and thus is highly susceptible to megathrust earthquakes. However, the thick sedimentary layers and their underlying crustal structure of the Makran slab are still poorly understood. Here we present a high-resolution crustal velocity model of the Makran subducting slab offshore Pakistan obtained from an active-source wide-angle ocean bottom seismic experiment, revealing fine structure in density and porosity. The results reveal that the incoming sedimentary layer is up to 8.5 km thick with an abrupt gradient change in porosity at 4-5 km depth, indicating a critical depth of compaction and consolidation. The igneous crust is 6-12 km thick with an average subduction dip angle of similar to 2 degrees. On either flank of the Little Murray Ridge, divergent crustal structures suggest the plausible existence of distinct tectonic provenances or divergent tectonic evolutionary trajectories for the oceanic crust on each side. The Little Murray Ridge may represent a remnant of the paleo-oceanic boundary, possibly associated with the phenomenon of low-density underplating. The subducting consolidated sediments and uppermost crust with high-water content could significantly influence earthquake rupture mechanisms at both the decollement and igneous basement interfaces. These findings suggest that the decollement and igneous basement interface both have the potential to trigger large earthquakes in the Makran subduction zone.

Makran subduction zone Crustal structure Ocean bottom seismometer Consolidated sediments Water content Seismotectonics

SCI ; EI

英语

通讯

National Natural Science Foundation of China[42306087] ; Guangdong Basic and Applied Basic Research Foundation["2021B1515020023","2022A1515110879"] ; Chinese Academy of Sciences["Y4SL021001","133244KYSB20180029","131551KYSB20200021","ISEE2021PY03"]

Geochemistry & Geophysics

Geochemistry & Geophysics

WOS:001279715400001

ELSEVIER

20243016754935

Buildings ; Earthquakes ; Offshore oil well production ; Porosity ; Sedimentology ; Tectonics

Buildings and Towers:402 ; Geology:481.1 ; Soil Mechanics and Foundations:483 ; Seismology:484 ; Oil Field Production Operations:511.1 ; Physical Properties of Gases, Liquids and Solids:931.2

GEOSCIENCES

Web of Science

1.Chinese Acad Sci, Key Lab Ocean & Marginal Sea Geol, South China Sea Inst Oceanol, Guangzhou, Peoples R China
2.CAS, China Pakistan Joint Res Ctr Earth Sci, HEC, Islamabad, Pakistan
3.Southern Univ Sci & Technol, Dept Ocean Sci & Engn, Shenzhen, Peoples R China
4.Chinese Univ Hong Kong, Fac Sci, Earth Syst Sci Programme, Hong Kong, Peoples R China
5.Sun Yat Sen Univ, Ctr Ocean Expedit, Sch Atmospher Sci, Zhuhai, Peoples R China
6.Univ Chinese Acad Sci, Beijing, Peoples R China

Yu, Chuanhai,Xu, Min,Lin, Jian,et al. Atypical crustal structure of the Makran subduction zone and seismotectonic implications[J]. EARTH AND PLANETARY SCIENCE LETTERS,2024,643.

Yu, Chuanhai.,Xu, Min.,Lin, Jian.,Yang, Hongfeng.,Zhao, Xu.,...&Sun, Zhen.(2024).Atypical crustal structure of the Makran subduction zone and seismotectonic implications.EARTH AND PLANETARY SCIENCE LETTERS,643.

Yu, Chuanhai,et al."Atypical crustal structure of the Makran subduction zone and seismotectonic implications".EARTH AND PLANETARY SCIENCE LETTERS 643(2024).