P3: Magnetostratigraphy and geology of Cenozoic sections related to the Columbia River-Yellowstone plume system

Supervisors

Prof. Stuart Gilder, Prof. Anke Friedrich

Advisors (int.)

Dr. Michael Wack (LMU), Dr. Simon Kübler (LMU), Dr. Donja Aßbichler (LMU)

Advisors (ext.)

Prof. Robert Anderson (Univ. Colorado), Prof. Brian Wernicke (CalTech)

Description

Models of dynamic topography need to be tested against and calibrated by the geological record. Specifically, this RTG is built on a geological model that ties the event-based records of uplift, deformation, and erosion to the sedimentary record and landscape evolution. The volume and rates of erosion, the sedimentary record will be constrained by quantifying sedimentation rates, volume and provenance by synthesizing existing data and by targeting strategic sections for new magnetostratigraphic and geo-/thermochronological work. Magnetostratigraphy gives a detailed time model of the sedimentary record preserved in the distal region of a dynamically active region, thereby yielding a very precise 2D-deposition rate. The sedimentation time-model enables observation of changes in source characteristics based on the types and abundances of magnetic minerals. Magnetic anisotropy provides the possibility to place constraints on paleo-flow directions and hydrodynamic transport conditions. Finally, the volume of material eroded from the source region will be reconstructed by a combination of provenance analysis, budget calculations, and landscape modeling using the Landlab tool kit, which is the main focus of P7. 

Main objectives

• Compilation and synthesis of existing sedimentary-budget and -rate data for the target region (phase I: western North America) to construct an empirical model of evolution of large river systems. 
• Identification of regions of critical data importance and implementation of a sampling strategy to acquire magnetostratigraphic, thermochronological, and provenance-suitable rock sections. 
• Determination of detailed 2D-sedimentation rate using magnetostratigraphy. 
• Map the target region stratigraphically to visualize the distribution of unconformities and hence hiatus, which will be tied to the dynamic uplift events in the source region. 
• Determination of the timing of erosion and location of the source region based on provenance and chronological analyses.
• Determination of magnetic anisotropies in the sedimentary records in order to determine the direction and velocity of paleo-stream flow.  
• Preparation for future analog experimental flume studies to better quantify the relationship between hydrodynamic regime and magnetic anisotropies. Magnetic anisotropy can also indicate strain conditions acting since sedimentation.

RTG coupling

Input:

• Geological model (P4) provides expertise on sampling site selection.

Output:

• Paleoflow directions and changes of sedimentation rates over time of study sites as input for plume-stratigraphic model (P4), the landscape evolution model (P7) and the lithospheric transfer function (P8). In particular, uncertainties will be incorporated into the integrated process model (P9).
• The combined output of P3+P7 is a sequential mapping of river network evolution on the interregional scale of interest. This model will then be incorporated in the event-and process-based geological model (P4).
• The sequential paleodrainage maps serve as a rough proxy for paleotopography needed in P1, P2, and P7 via further integration and analysis by P4.