Paleo-vertical motions of the Pacific plate: Mantle processes and oceanic lithosphere subsidence

Evidence for vertical motion and widespread volcanism in the Pacific Ocean basin has been recognized since the time of Charles Darwin. Oceanic islands generally form on bathymetric swellswide area of seafloor shallower than that expected for its ageand ultimately subside to form atolls and guyots. Geologic reconstruction of the subsidence history of western Pacific guyots and atolls, points towards uplift during the Cretaceous time followed by subsidence to present-day depths at uncharacteristic rates likely linked to the widespread intraplate volcanism in the region. The observed present-day bathymetry in the region, generally called the Pacific Superswell, is also anomalous and sits shallower than that expected for the lithosphere of corresponding age. Mechanisms, such as lithospheric reheating of the oceanic plate and dynamic topography, associated with unusually hot underlying mantle and high igneous activity, can plausibly explain the reconstructed subsidence history. Though, the existence of a large mantle thermal anomaly (Darwin Rise) in west-central Pacific mantle is generally agreed upon, its spatiotemporal evolution and reflection on Pacific geology is relatively little understood which motivates this study. In an integrative Bayesian framework, we use different datasets such as temporally rich subsidence information from guyots, atolls, and carbon compensation paleo-depths and spatially rich high-resolution present-day bathymetry data. Incorporating recent plate reconstruction models and using Markov chain Monte Carlo methods, we recover posterior distributions for the model parameters characterizing the intrinsic subsidence of the oceanic lithosphere, in conjunction with the subsidence behavior associated with space-time evolution of thermal anomalies in the Pacific mantle. Using this data-driven approach to guide our understanding of the past and present mantle structure and dynamics, we focus on the interaction between plate tectonic regime and underlying anomalously hot mantle.