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Abstract
The tectonic evolution of the Caroline Plate during the Oligocene to Early Miocene was mainly controlled by two fulcrums. The west fulcrum at Palau Island remained fixed during 29–25 Ma as the Ayu Trough rifted and produced the abyssal hills parallel to its boundaries, and the Pacific Plate and part of the Caroline Plate subducted to the north. At the northeast corner of the Caroline Plate, the east fulcrum is surrounded by a series of arc seamount chains. These chains resulted from the convergence between the Caroline Plate and the Pacific Plate and crustal softening of the northeastern Caroline Plate induced by the Caroline Hotspot at ∼25 Ma. This softening of the crust also led to the dysfunction of the east fulcrum, and the west fulcrum migrated south, which caused dextral motion along the Ayu Rift and the development of an en echelon structure. The Yap Trench was a part of the spreading center in the Parece-Vela Rift at ∼29 Ma. However, sinistral motion along the Parece-Vela Rift at around 20–15 Ma led to the exposure of the subducted Yap Trench and left a triangular region with distinctive geophysical characteristics in the surrounding area.
Details
1 Ministry of Natural Resources, Key Laboratory of Tropical Marine Ecosystem and Bioresource, Fourth Institute of Oceanography, Beihai, China (GRID:grid.453137.7) (ISNI:0000 0004 0406 0561)
2 Ocean University of China, Key Lab of Submarine Geosciences and Prospecting Techniques, MOE, College of Marine Geosciences, Qingdao, China (GRID:grid.4422.0) (ISNI:0000 0001 2152 3263); Ocean University of China, Frontiers Science Center for Deep Ocean Multispheres and Earth System, Key Lab of Submarine Geosciences and Prospecting Techniques, MOE and College of Marine Geosciences, Qingdao, China (GRID:grid.4422.0) (ISNI:0000 0001 2152 3263); Pilot National Laboratory for Marine Science and Technology (Qingdao), Laboratory for Marine Mineral Resources, Qingdao, China (GRID:grid.484590.4) (ISNI:0000 0004 5998 3072)