Coupled supercontinent-mantle plume events evidenced by oceanic plume record

• Published in: Geology (Boulder) 2020-02, Vol.48 (2), p.159-163
• Main Authors: Doucet, Luc S, Li, Zheng-Xiang, Ernst, Richard E, Kirscher, Uwe, Gamal El Dien, Hamed, Mitchell, Ross N
• Format: Article
• Language: English
• Subjects: Basalt; Columbia Supercontinent; Cycles; cyclic processes; Earth; Earth history; Earth mantle; geodynamics; Geology; Geophysics; global; Hot spots (geology); large igneous provinces; low-velocity zones; Lower mantle; Magma; Mantle; Mantle plumes; Neoproterozoic; Oceanic islands; Ophiolites; paleogeography; Pangaea; Pangea; Periodic variations; Periodicity; Phanerozoic; plate tectonics; Plumes; Precambrian; Proterozoic; Rodinia; solid Earth (tectonophysics); Subduction; supercontinents; Temporal variations; Time series; upper Precambrian
• ISSN: 0091-7613; 1943-2682
• DOI: 10.1130/G46754.1

The most dominant features in the present-day lower mantle are the two antipodal African and Pacific large low-shear-velocity provinces (LLSVPs). How and when these two structures formed, and whether they are fixed and long lived through Earth history or dynamic and linked to the supercontinent cycles, remain first-order geodynamic questions. Hotspots and large igneous provinces (LIPs) are mostly generated above LLSVPs, and it is widely accepted that the African LLSVP existed by at least ca. 200 Ma beneath the supercontinent Pangea. Whereas the continental LIP record has been used to decipher the spatial and temporal variations of plume activity under the continents, plume records of the oceanic realm before ca. 170 Ma are mostly missing due to oceanic subduction. Here, we present the first compilation of an Oceanic Large Igneous Provinces database (O-LIPdb), which represents the preserved oceanic LIP and oceanic island basalt occurrences preserved in ophiolites. Using this database, we are able to reconstruct and compare the record of mantle plume activity in both the continental and oceanic realms for the past 2 b.y., spanning three supercontinent cycles. Time-series analysis reveals hints of similar cyclicity of the plume activity in the continent and oceanic realms, both exhibiting a periodicity of ∼500 m.y. that is comparable to the supercontinent cycle, albeit with a slight phase delay. Our results argue for dynamic LLSVPs where the supercontinent cycle and global subduction geometry control the formation and locations of the plumes.