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Detachment and Accretion-Related Syn-Rift Seaward Dipping Sequences in the NW South China Sea
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DOI:10.1111/bre.70103.png)
Abstract
En 中文
Seaward-dipping sequences (SDS) are typically observed in sediment-driven progradation of slope deposits in post-rift sequences, or along magma-rich rifted margins, where they are primarily formed by subaerial lava flows and referred to as seaward dipping reflections (SDRs). However, new seismic reflection data from the sediment-rich northwestern South China Sea (NW-SCS) reveal the existence of SDS in sediment-rich syn-rift sequences, here referred to as syn-rift sedimentary SDS. Based on a detailed tectono-stratigraphic analysis, we describe how these syn-rift sedimentary SDS differ from magmatic SDRs and propose a conceptual model for their formation. We show that the formation of these sequences is most likely controlled by a combination of high sediment supply rates, rapid subsidence and creation of horizontal accommodation space, first along large-offset detachment faults and later, during breakup, by magmatic accretion. While inner magmatic SDRs typically form in subaerial conditions above continent-dipping faults, we suggest that syn-rift sedimentary SDS can derive from turbiditic flows in a relatively deep-water environment above oceanward-dipping detachment faults and/or interfinger with magmatic additions. Finally, we discuss the implications of syn-rift sedimentary SDS for the interpretation of rifted margins in general.
Keywords:
detachment faults
SDRs
seaward-dipping sequences
South China Sea
syn-rift sediment rich margin
Journal
IF:
2.6
Papers:
106
Citations:
4.2K
