Analysis of flexural evolution of the lithosphere over the past 4.6 Ma around Ross Island, West Antarctica

• Main Authors: Jha, Sumant, author, Harry, Dennis L., advisor, Aster, Rick C., committee member, Schutt, Derek L., committee member, Amberg, Gregory C., committee member
• Format: Text
• Language: English
• Published: Colorado State University. Libraries 2020
• Subjects: Antarctic; West Antarctica; Victoria Land; Ross Island; Antarc*; Antarctica
• Online Access: https://hdl.handle.net/10217/199794

2019 Fall. Includes bibliographical references. Ross Island is in the southern Victoria Land Basin along the western margin of the West Antarctic Rift System. Episodic volcanism since ca. 4.6 Ma produced a discontinuous sedimentary moat around the island coeval with ongoing extension. The moat is a composite of four smaller flexural sub-basins created during four distinct phases of volcanism on Ross Island. In this research we determine the flexural rigidity of lithosphere under Ross Island, to understand the load partitioning between surface (relief) and subsurface (e.g. the density anomaly in crust/mantle) and to test the hypothesis that the strength of the lithosphere around the island varied with time over last 4.6 Ma. An interactive toolbox called Toolbox for Analysis of Flexural Isostasy (TAFI) was developed in MATLAB to model the flexure around Ross Island. TAFI supports two-dimensional (2-D) and three-dimensional (3-D) modeling of flexural subsidence and uplift of the lithosphere in response to vertical tectonic loading. Flexural deformation is approximated as bending of a thin elastic plate overlying an inviscid fluid asthenosphere. The associated gravity anomaly is calculated by summing the anomalies produced by flexure of each density interface within the lithosphere, using Parker's algorithm. TAFI includes MATLAB functions provided as m-files (also called script files) to calculate the Green's functions for flexure of an elastic plate subjected to point or line loads, and functions to calculate the analytical solution for harmonic loads. Numerical solutions for flexure due to non-impulsive two-dimensional (2-D) or three-dimensional (3-D) loads are computed by convolving the appropriate Green's function with a spatially discretized load function read from a user-supplied file. TAFI uses MATLAB's intrinsic functions for all computations and does not require any other specialized toolbox, functions, or libraries except those distributed with TAFI. The modeling functions within TAFI can be called ...