2 Evolution of the South Atlantic, Adjacent Continents, and Passive Continental Margins in General

Monday, 5 September 2011
11:00 AM - 5:35 PM
A 125

SEA LEVEL AND VERTICAL MOTION OF CONTINENTS SINCE THE LATE CRETACEOUS FROM DYNAMIC EARTH MODELS

Paper number: 2-15
Program: Theme Sessions
Time: 4:20 PM – 4:35 PM

Authors

Abstract

We present results of global dynamic earth models (DEMs), which combine inverse and forward models of mantle convection. Seismic tomography is used to define initial conditions for the inverse models. DEMs assimilate plate tectonic reconstructions since the Late Cretaceous, and account for the influence of the geoid and the evolving sea floor paleogeography self-consistently. We use an integrated plate reconstruction-mantle convection framework that enables linkage between dynamic topography calculated in mantle reference frame and geologic observations obtained in a plate frame of reference, which is essential for sea-level studies. As DEMs account for the most important factors controlling long-term sea-level change self-consistently, we present implications for the influence of the mantle and regional and global sea-level change and vertical motion of continents.

We find that neither dynamic topography nor paleobathymetry (related to evolving age of the sea floor, emplacement of large igneous provinces and sedimentation) are dominant factors controlling the global patterns of marine sedimentation on continents since the Late Cretaceous. Dynamic topography appears to be important in controlling the flooding patterns in North America and Australia since the Late Cretaceous, Sundaland since the Oligocene, and Arabia during Cenozoic. Sea-level variations due to changing paleobathymetry play more important roles in controlling flooding in Eurasia and northern India. Mantle dynamics also contributes to Cenozoic long-wavelength tilting of Australia and Siberia. DEMs suggest that dominant factor controlling global sea level since the Late Cretaceous is changing age of sea floor, resulting in a large amplitude sea‐level fall since the Late Cretaceous, with dynamic topography offsetting this fall.