Mid-Cretaceous seafl oor spreading pulse: Fact or fi

摘要: Two main hypotheses compete to explain the mid-Cretaceous global sea-level highstand: a massive pulse of oceanic crustal production that occurred during Cretaceous Normal Superchron (CNS) and “supercontinent breakup effect,” which resulted in creation mid-Atlantic Indian ocean ridges at expense subducting old fl oor Tethys Pacifi c. We have used paleo-age grids, including now subducted two alternative time scales, test these hypotheses. Our models show high average seafl spreading rate 92 mm/a Early decreased 60 Tertiary, with peaks 86 70 105 Ma 75 ago, respectively, correspond observed highstands Cretaceous. Calculations using GTS2004 produce lower rates same period diminish pulse. Global ridge lengths increased earliest but stayed relatively constant through time. However, we fi nd age basins is only weakly dependent on choice scale. The expansive mid- Late epicontinental seas, coupled warm climates oxygen-poor water masses, were ultimately driven by younger faster rather than vast increase mid-ocean length due Pangea or solely higher rates, as suggested previously.