Ocean-plate stratigraphy (OPS) refers to the lithostratigraphic column atop an ocean plate, which becomes scraped off during subduction and preserved in accretionary complex (AC). Herein, based on structural, stratigraphic, and geochronological studies of ACs from the Bangong-Nujiang suture, we demonstrate that OPS can facilitate interpreting structural and compositional heterogeneities in ACs. Carefully correlated OPSs reveal that, on the overall sediment-rich lower plate, different types of basement topography correspond to the accretion of distinct litho-structural assemblages. In particular, subduction of the major, high-relief Zhonggang seamount eroded the earlier margin and was subsequently accreted as coherent seamount slices. In contrast, subduction of the lower-relief, Gaize seamount halted frontal accretion of trailing sediments, which were dragged downward to the seismogenic depth and underplated as pervasive, shear-related broken formations. Such broken formations may fingerprint past lower-relief-seamount subduction in other fossil ACs.
|Journal||Geophysical Research Letters|
|State||Published - Sep 28 2021|
Bibliographical noteFunding Information:
This study was supported by the Chinese National Natural Science Foundation (No. 41102065 and 41872110) and Chengdu University of Technology (2020ZF11407). We thank the editor Lucy Flesch and three reviewers (Dr. David Buchs and two anonymous) for critical reviews and constructive comments.
© 2021. American Geophysical Union. All Rights Reserved.
- Bangong-Nujiang Meso-Tethys suture
- Melange fabric
- accretionary complex
- ocean-plate stratigraphy
- oceanic basement topography
- trench fill
ASJC Scopus subject areas
- Earth and Planetary Sciences (all)