Sixth International Conference on Mars (2003) 3065.pdf THE THARSIS REGION OF MARS: NEW INSIGHTS FROM MAGNETIC FIELD OBSERVATIONS. C. L. Johnson1 and R. J. Phillips2, 1Institute for Geophysics and Planetary Physics, Scripps Institution of Oceanogra- phy, 9500 Gilman Drive, La Jolla, CA 92093-0225 (
[email protected]), 2Dept. of Earth and Planetary Sci- ences, Washington University, Campus Box 1169, One Brookings Drive, St. Louis, MO 63130 (phil-
[email protected]) Introduction: The Tharsis volcanic province a revised scenario for the evolution of Tharsis pre- dominates the western hemisphere of Mars. The re- sented. gional topography comprises a long-wavelength rise of Previous Models for Tharsis Formation: A vari- several kilometers elevation. Superposed on this are ety of models for the formation of Tharsis have been the Tharsis Montes, Olympus Mons and Alba Patera. proposed, and predicted gravity, topography and tec- To the southeast, the Tharsis rise includes Solis, Syria tonic stresses compared with available observations. and Sinai Planae, bounded by Valles Marineris, Clari- These models include dynamic support of topography tas Fossae, and the Coprates rise. The region also by a large mantle plume [11,12]; regional uplift due to dominates the gravity field of the western hemisphere, underplating of crustal material derived from the with typical free air anomalies of several hundred mil- northern hemisphere [13]; uplift due to solely mantle ligals, and a peak free air anomaly greater than 1000 anomalies - thermal and/or compositional [14], and milligals over Olympus Mons. including crustal thickening by intrusion [6]; flexural Tectonic deformation is pervasive throughout the loading due to volcanic construction [2, 15, 16].