Investigation of an oceanic plateau formation and rifting initiation model implied by the Caroline Ridge on the Caroline Plate, western Pacific

ABSTRACT

The rifting of oceanic plateaus is an important mechanism for initiating lithospheric break-up and subsequent seafloor spreading. In this study, we present the latest multichannel seismic data investigating the Caroline Ridge and provide one of the typical cases for initial oceanic plateau evolution. We reveal that a smooth basement reflector (R2), as the top of the lava flows, is subparallel to the sediments with horizontal seismic reflections over the surface of the Caroline Ridge. Thick layer-parallel lava flows beneath the R2 appear within the crust. Large seamounts in the Sorol Trough possess abundant saucer-shaped intracrustal reflectors, and the overlying sediments were destroyed by intrusive bodies. The overlying sedimentary sequences, basement, and thick lava flows on the Caroline Ridge flanks were faulted by opposing normal fault sets, and the eruptions of the seamounts deformed the strata. A widespread bright horizontal reflector (R1), as an unconformity inside the Caroline Ridge sediments, truncates the lower tilted sediment layers and is itself cut by normal faults in the flank strata. Furthermore, we propose that subaerial lava flows extended laterally from the hotspot magmatism localizing in the Sorol Trough and led to Caroline Ridge formation. The initial rifting of the Caroline Ridge occurred during the Early-Middle Miocene. Limited volcanoes concentrate only in the Sorol Trough due to the attenuated thermal effect. It is suggested that dome uplifting and far-field force could have jointly caused initial rifting process of the Caroline Ridge.

KEYWORDS:

• Caroline Ridge
• Sorol Trough
• Oceanic plateau rifting
• Hotspot
• Seismic profile
• Sedimentary sequence
• Crustal structure

Article Highlights

• Subaerial layer-parallel lava flows extended laterally from the hotspot magmatism localizing in the Sorol Trough and led to the formation of the Caroline Ridge.

• Reflector R1 truncates the underlying Oligocene strata in the Caroline Ridge flanks, representing the rifting event of the Caroline Ridge

• Initial rifting of the Caroline Ridge was controlled by extensional forces after the major hotspot magmatism.

Acknowledgments

We would like to acknowledge the whole scientists and crews of the research vessel “KEXUE”, who provide technical assistance. The seismic data and used for this study are archived on the webpage: https://my.pcloud.com/publink/show?code=kZ5vyA7Z2s7MMk7yGJmxtGhtPPkMPBkdsPRy.

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplementary Material

Supplemental data for this article can be accessed here.

Additional information

Funding

This study was supported by the National Natural Science Foundation of China (No. 41976051, 91958211), National Program on Global Change and Air-Sea Interaction (No. GASI-GEOGE-01), Key Research Program of Center for Ocean Mega-Science of CAS (No. COMS2019Q10), and RV KEXUE Advanced User Program (No. KEXUE2018G10).