Timing and causes of the mid-Cretaceous global plate reorganization event

• Published in: Earth and planetary science letters Vol. 534; p. 116071
• Main Authors: Olierook, Hugo K.H., Jourdan, Fred, Whittaker, Joanne M., Merle, Renaud E., Jiang, Qiang, Pourteau, Amaury, Doucet, Luc S.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.03.2020
• Subjects: 40Ar/39Ar geochronology; Den föränderliga jorden; eastern Gondwana; Neotethys; slab pull; subduction; The changing Earth; Wharton Basin; slab pull; eastern Gondwana; Wharton Basin; subduction; 40Ar/39Ar geochronology; Neotethys; Ar-40/Ar-39 geochronology
• ISSN: 0012-821X; 1385-013X; 1385-013X
• DOI: 10.1016/j.epsl.2020.116071

Global plate reorganization events (GPREs) can have profound impact on plate velocities, climate and the biotic cycle but the timing and triggers for GPREs remain debated. The timing and causes of the mid-Cretaceous GPRE, one of only two GPREs since the breakup of Pangea, remains poorly constrained because it occurred during the Cretaceous Normal Superchron. Here, we provide a new plagioclase 40Ar/39Ar age of 103.82±0.54 Ma (2σ) at DSDP site 256 along the world's clearest curved fracture zones in the Wharton Basin, off NW Australia. Using Monte Carlo simulations, we compute that the mid-Cretaceous GPRE commenced at 111.2−1.2+1.3 Ma (95% confidence). The mid-Cretaceous GPRE was associated with a significant plate deceleration (minimum ∼26%), similar to the Eocene GPRE, implying that this process is fundamental to plate reconfigurations. We propose that the mid-Cretaceous GPRE was caused by slab-breakoff and cessation of the south-dipping subduction zone in the Mesotethys Ocean at ca. 111 Ma. Ultimately, we posit that subduction zone initiations and cessations are the primary triggers for both post-Pangean GPREs and that top-down processes may be the fundamental drivers for GPREs. •New 40Ar/39Ar age of 103.82±0.54 Ma from DSDP core 256.•Mid-Cretaceous plate reorganization started at 111 Ma.•Plate speeds decelerated during the plate reorganization by at least 26%.•Mid-Cretaceous and Eocene plate reorganization both triggered by top-down processes.