T88 Crustal Architecture of Rifted Continental Margins II

Tuesday, 6 November 2001
1:30 PM - 5:30 PM

BOUNDARY ELEMENT MODELING OF THE ARCUATE GEOMETRY OF THE TRANSANTARCTIC MOUNTAINS FRONT

Paper number: T88-7
Program: Technical Sessions
Time: 1:30 PM – 5:30 PM

Authors

Abstract

The Transantarctic Mountains (TM) are intracontinental and commonly described as a rift shoulder uplifted along a major boundary fault marking the Transantarctic Mountains front (TMF). The TMF is the boundary between East and West Antarctica, as well as a major discontinuity in crustal thickness (~40 km vs. ~25 km, respectively). As demonstrated by fission-track analysis, initiation of the primary uplift throughout all of the Transantarctic Mountains occurred in the Eocene. By implication this also was the time of faulting along the TMF. Recently recognized sea-floor spreading in the vicinity of the Adare Trough off Northern Victoria Land suggests a genetic link with uplift of the TM. The geometry of the TMF is one of two long arcs each ~750 km in length that intersect at Mt. Discovery, a large shield volcano to the south of McMurdo Sound. We have investigated the formation of the TMF through a series of boundary element models of fracture propagation, analyzing the effects of different loading conditions and initial crack configuration. We have successfully modeled the double-arc geometry of the TMF with two interacting fractures propagating under applied tension and shear loading.

An interesting second–order feature of the TMF is Minna Bluff, a 50 km long ridge of fissure basalt that radiates from Mt. Discovery, equiangularly from the intersection of the arcs of the TMF, and ends in a pronounced hook. This fracture pattern also can be mimicked by our model suggesting that it was formed at the same time as the main faulting along the TMF. That the basalts on Minna Bluff are dated at <10 Ma implies that they rose along a fracture that had been previously established.

Our model has implications for arcuate fault chains found elsewhere on Earth (e.g. the coastline of southeastern Greenland), or extraterrestrially (e.g. the surface of Europa).