Middle Miocene tectonic boundary conditions for use in climate models

Abstract

[1] Utilizing general circulation models (GCMs) for paleoclimate study requires the construction of appropriate model boundary conditions. We present a middle Miocene paleotopographic and paleobathymetric reconstruction geographically constrained at 15 Ma for use in GCMs. Paleotopography and paleogeography are reconstructed using a published global plate rotation model and published geological data. Paleobathymetry is reconstructed through application of an age-depth relationship to a middle Miocene global digital isochron map, followed by the overlay of reconstructed sediment thickness and large igneous provinces. Adjustments are subsequently made to ensure our reconstruction may be utilized in GCMs.

Boundary conditions for the Middle Miocene Climate Transition (MMCT v1.0)

“…Also based on Rögl (1999), the Paratethys was intermittently connected and disconnected from the global ocean during the Burdigalian to Serravallian interval. In Herold et al (2008), as in our reconstruction, the Paratethys is connected to the global ocean. In view of the variable configuration of the Tethys/Paratethys across the Middle Miocene, it would be recommendable to test different Tethys/Paratethys configurations when performing Middle Miocene experiments with GCMs, although such testing can be limited by model constraints: seas disconnected from the global ocean can produce freshwater imbalance in GCMs and narrow ocean passages require high resolution ocean grids to allow ocean flux calculation (Rosenbloom et al, 2011).…”

“…The Bering Strait was closed and the Hudson Bay removed. Unlike Herold et al (2008), who assumed the Tethys seaway closed, we decided to leave the seaway open.…”

“…2, Table 1). Both global topography/bathymetries are mainly based on the 2°x2° reconstruction of Herold et al (2008), although some important modifications, which will be described below, were applied to their original dataset. To reconstruct paleogeography and paleotopography Herold et al (2008) used a global plate rotation model and geological data.…”

“…Sediment thickness and large igneous provinces were also considered in the reconstruction of ocean depth. In Herold et al (2008), the Andes and the Tibetan plateau were set with estimated Early to Middle Miocene elevations. The Rocky mountains and the east African topography were reduced to 75 and 25% of their current elevation, respectively.…”

“…Some important modifications were applied to the original dataset of Herold et al (2008) regarding Antarctic ice-sheet geometry, sea-level and configuration of the South East Asian and Panama passages.…”