Formation mechanism of the moniliform seamounts outside the West Melanesian Trench

Abstract

Our study on the seamounts in the southeast Caroline Plate reveals a formation of a special kind of seamounts in the oceanic basin. These moniliform seamounts link up like the reason of hotspots, but the tectonic factors lead to their formation. The differential motions of the Caroline, North Bismarck, and Pacific plates resulted in the shear stress field by the West Melanesian Trench. The R and R′ faults can be distinguished obviously by seafloor topography. The evolution history of these seamounts can be subdivided into two stages as follows. (a) The R′ faults developed firstly as normal faults to generate ridges on these faults as the release of the underlying sediments. (b) The R faults appeared as shear faults and cut off the ridge from the older R′ faults. These faults can be very deep fractures, which cut through the lithosphere and produced a NW‐trending negative anomaly in isostatic gravity anomaly. As the pressure is released by the R faults, the sediments releasing under the R faults accumulated into these seamounts. The other sections of the R faults performed like a valley because of the leakage of sediments along the faults. Sediments would also release along the R faults to generate ridges when no seamount occurs on the faults.