Formation of mantle “lone plumes” in the global downwelling zone — A multiscale modelling of subduction-controlled plume generation beneath the South China Sea
MetadataShow full item record
It has been established that almost all known mantle plumes since the Mesozoic formed above the two lower mantle large low shear velocity provinces (LLSVPs). The Hainan plume is one of the rare exceptions in that instead of rising above the LLSVPs, it is located within the broad global mantle downwelling zone, therefore classified as a “lone plume”. Here, we use the Hainan plume example to investigate the feasibility of such lone plumes being generated by subducting slabs in the mantle downwelling zone using 3D geodynamic modelling. Our geodynamic model has a high-resolution regional domain embedded in a relatively low resolution global domain, which is set up in an adaptive-mesh-refined, 3D mantle convection code ASPECT (Advanced Solver for Problems in Earth's ConvecTion). We use a recently published plate motion model to define the top mechanical boundary condition. Our modelling results suggest that cold slabs under the present-day Eurasia, formed from the Mesozoic subduction and closure of the Tethys oceans, have prevented deep mantle hot materials from moving to the South China Sea from regions north or west of the South China Sea. From the east side, the Western Pacific subduction systems started to promote the formation of a lower-mantle thermal-chemical pile in the vicinity of the future South China Sea region since 70 Ma ago. As the top of this lower-mantle thermal-chemical pile rises, it first moved to the west, and finally rested beneath the South China Sea. The presence of a thermochemical layer (possible the D? layer) in the model helps stabilizing the plume root. Our modelling is the first implementation of multi-scale mesh in the regional model. It has been proved to be an effective way of modelling regional dynamics within a global plate motion and mantle dynamics background.
Showing items related by title, author, creator and subject.
Variable involvements of mantle plumes in the genesis of mid-Neoproterozoic basaltic rocks in South China: A reviewWang, Xuan-ce; Li, X.; Li, W.; Li, Zheng-Xiang (2009)Ca. 825-720 Ma global continental intraplate magmatism is generally linked to mantle plumes or a mantle superplume that caused rifting and fragmentation of the supercontinent Rodinia. Widespread Neoproterozoic igneous ...
Identification of an ancient mantle reservoir and young recycled materials in the source region of a young mantle plume: Implications for potential linkages between plume and plate tectonicsWang, Xuan-Ce; Li, Zheng-Xiang; Li, X.; Xu, Y.; Li, X.; Li, J. (2013)Whether or not mantle plumes and plate subduction are genetically linked is a fundamental geoscience question that impinges on our understanding of how the Earth works. Late Cenozoic basalts in Southeast Asia are globally ...
Temperature, Pressure, and Composition of the Mantle Source Region of Late Cenozoic Basalts in Hainan Island, SE Asia: a Consequence of a Young Thermal Mantle Plume close to Subduction Zones?Wang, Xuan-Ce; Li, Zheng-Xiang; Li, X.; Li, J.; Liu, Y.; Long, W.; Zhou, J.; Wang, F. (2012)Basaltic lavas from Hainan Island near the northern edge of the South China Sea have an age range of between late Miocene (about 13 Ma) and Holocene, with a peak age of late Pliocene to middle Pleistocene. The basaltic ...