Deep-Time Landscape Evolution Modelling in the Context of Tectonics, Geodynamics, and Eustasy

Abstract

An understanding of landscape evolution, primarily in the context of erosion, sediment dispersal and deposition through time can aid in better constraining the resource potential of sedimentary basins. Many resource-rich sedimentary basins have developed over millions of years in regions which have had complex tectonic and geodynamic histories, such as the Gulf of Papua and the North Slope of Alaska. New developments in numerical modelling enable the linking of deep Earth and surface processes across spatial and temporal scales. The open-source code Badlands (https://badlands.readthedocs.io) allows for the modeling of landscape dynamics over local to continental scales and timescales of up to hundreds of millions of years. These models have the capability to simulate hillslope processes, fluvial erosion, reef growth, and carbonate platform development, as well as terrestrial and marine sediment transport and deposition in response to both spatially and temporally varying tectonic and climatic forcing. Therefore, the main provenance areas, the sedimentary basin filling and associated stratigraphic evolution can be examined. This study presents new methods to capture carbonate platform development, as well as 3D tectonic displacements (including dynamic topography) in landscape evolution models. By linking plate tectonic reconstructions, deep mantle flow, and eustasy to surface process models, the complex tectonic histories of a region can be captured. Newly-developed deforming plate tectonic reconstructions from GPlates are linked to numerical models of mantle flow using CitcomS, allowing us to compute time-evolving dynamic topography that can be incorporated with the boundary conditions applied to our surface process models. These new modeling capabilities are demonstrated for two distinct regions, Papua New Guinea and the North Slope of Alaska. The Papua New Guinea models focus on the tectonic and carbonate platform development of the region over the past two million years. Papua New Guinea's tectonic history involves rifting and subsequent basin inversion, resulting in the uplift of the Muller Ranges and the ongoing development of a foreland basin. Sediment deposition in the Gulf of Papua has peaked over the last five million years and reef systems have gone through phases of proliferation and burial. The carbonate growth module in Badlands tracks the carbonate platform development through time in response to changes in eustatic sea level, uplift, subsidence, and sediment input from the continent. The North Slope of Alaska models incorporate 3D tectonic displacements (geodynamics included), in order to model its landscape evolution since the Jurassic. The models capture the North Slope’s counter-clockwise rotation away from the Canadian Arctic Islands and subsequent collision with the Koyukuk oceanic-island arc, which resulted in the uplift of the Brooks Range Orogen and the formation of the adjacent flexural foreland Colville Basin from the Early Cretaceous to present. The modelled sediment thicknesses and resulting mountain range elevations in both cases matched that of present day. Additionally, the modelled sediment dispersal patterns on the North Slope were similar to predicted sediment dispersal patterns through time. These approaches represent a major leap in capturing the evolving paleogeography of complex tectonic regions, allowing us to interrogate the erosional and depositional histories in unprecedented detail. In addition, the approaches presented here are open-source community tools that are revolutionizing the fusion of data and models in de-risking frontier exploration and helping us better understand fundamental Earth processes across a wide range of spatial and temporal scales.

AAPG Datapages/Search and Discovery Article #90371 © 2020 AAPG Asia Pacific Region, The 1st AAPG/EAGE PNG Geosciences Conference, PNG’s Oil and Gas Industry: Maturing Through Exploration and Production, Port Moresby, Papua New Guinea, February 25-27, 2020