Japan Geoscience Union Meeting 2015

Presentation information


Symbol S (Solid Earth Sciences) » S-CG Complex & General

[S-CG64] Ocean Floor Geoscience

Thu. May 28, 2015 9:00 AM - 10:45 AM A05 (APA HOTEL&RESORT TOKYO BAY MAKUHARI)

Convener:*Kyoko Okino(Ocean Research Institute, University of Tokyo), Keiichi Tadokoro(Research Center for Seismology, Volcanology and Earthquake and Volcano Research Center, Nagoya University), Osamu Ishizuka(Geological Survey of Japan, AIST), Tomohiro Toki(Faculty of Science, University of the Ryukyus), Narumi Takahashi(Research and Development Center for Earthquake and Tsunami, Japan Agency for Marine-Earth Science and Technology), Chair:Hiroshi Sato(School of Business Administration, Senshu University), Takehi Isse(Earthquake Research Institute)

9:45 AM - 10:00 AM

[SCG64-19] On the origin of seafloor flattening

*Jun KORENAGA1 (1.Department of Geology and Geophysics, Yale University)

Keywords:seafloor flattening, mantle convection, internal heating, early Earth, surface environment

The subsidence of an aging seafloor starts to slow down at 〜70 Ma old with respect to the prediction of simple half-space cooling, and this phenomenon has long been known as seafloor flattening. The flattening signal remains even after removing the influence of the emplacement of hotspot islands and oceanic plateaus. The combination of small-scale convection and radiogenic heating has been suggested as a mechanism to explain seafloor flattening, and this study explores a possibility of using the magnitude of seafloor flattening to constrain the amount of radiogenic heating in the convecting mantle. By comparing properly scaled geodynamic predictions with the observed age-depth relation of the normal seafloor, the mantle heat production is estimated to be 〜12±3 TW, which supports geochemistry-based estimates. A widely-held notion that small-scale convection enhances cooling thus being unable to explain seafloor flattening is suggested to be incorrect. The ability to predict the age-depth relation of seafloor based on the thermal budget of Earth has an important bearing on the future theoretical study of early Earth evolution.