Other
Scientific paper
May 2004
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2004agusm.p32a..01j&link_type=abstract
American Geophysical Union, Spring Meeting 2004, abstract #P32A-01
Other
5418 Heat Flow, 5430 Interiors (8147), 5440 Magnetic Fields And Magnetism, 5475 Tectonics (8149), 5480 Volcanism (8450)
Scientific paper
One of the most dramatic discoveries of the Mars Global Surveyor (MGS) mission is that of crustal magnetic field sources of multiple scales, strength and geometry. Current global field models exhibit similar large-scale features: intense magnetic fields (requiring crustal magnetizations approximately an order of magnitude greater than on Earth) over the Noachian-age Terra Cimmeria southern hemisphere region, weaker isolated anomalies over the northern hemisphere and over other southern hemisphere areas, and a general paucity of strong magnetic fields over the major impact basins. Challenges in constructing such models include the variable maximum spatial resolution in the magnetic field data, and the removal of magnetic fields of non-crustal origin. Three hypotheses for the timing of a dynamo have been proposed. In the first hypothesis, dynamo onset post-dates the youngest observed impact basins on Mars. In the second hypothesis, the dynamo is short-lived, with onset in the early Noachian and cessation prior to the formation of Argyre and Hellas. In the third hypothesis, early Noachian dynamo onset is invoked, but duration into the late Noachian or early Hesperian is permitted. Fundamental to distinguishing among these various hypotheses and to explaining the observed global distribution of magnetic anomaly amplitudes is establishing the relative timing of crustal formation, the duration of any dynamo regime (and indeed the driving mechanism for such a dynamo), and the effect of post-emplacement crustal modification on any acquired magnetic remanence. Accordingly, in this talk we review progress in addressing the following issues essential to understanding the history of Mars' magnetic field: (1) The timing of crustal formation in northern and southern hemispheres, (2) A quantitative assessment of magnetic anomalies in the major impact basins (specifically Hellas and Argyre), (3) Potential candidates for the magnetic carrier, along with rock magnetic properties that are important to remanent acquisition and any subsequent demagnetization, (4) An assessment of the effectiveness of thermal, hydrothermal, and shock demagnetization mechanisms, and geographically where these may have been active, (5) Energetics available to drive a martian dynamo. Based on current understanding, our preferred hypothesis is an early short-lived global magnetic field. Open questions critical to further progress include the relative timing of dynamo cessation and the onset of Tharsis magmatism, and the process(es) responsible for formation of the dichotomy.
Johnson Clifton L.
Phillips James R.
No associations
LandOfFree
Mars Magnetic Field: Implications for Crustal Formation and Evolution does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Mars Magnetic Field: Implications for Crustal Formation and Evolution, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Mars Magnetic Field: Implications for Crustal Formation and Evolution will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1177670