Presentation on theme: "Surface Magnetization of Terra Meridiani, Mars Renee French Earth 438 Winter 2014 Opportunity looking out on Santa Maria Crater, sol 2466 (~7 years)"— Presentation transcript:
Surface Magnetization of Terra Meridiani, Mars Renee French Earth 438 Winter 2014 Opportunity looking out on Santa Maria Crater, sol 2466 (~7 years)
Motivation Terra Meridiani has been proposed as a site of past seafloor spreading due to magnetic offsets in the MGS Magnetometer data at 400 km altitude (Connerney et al., 2005) – If this data is continued to the surface, are the magnetic offsets still observed? – Can magnetic offsets, and thus transform faults, be tied to other geologic features (i.e., offset craters, regional differences in geology)? – What other mechanisms can produce the observed magnetization? – Any other data to suggest that Terra Meridiani was once an active plate boundary? – Can data from MER Opportunity provide any ground truth for this hypothesis?
Burns Formation Facies McLennan et al. (2005) Data best supports eolian environment with a fluctuating groundwater table
From Acuña et al. (1999): Measured vertical component of the magnetic field (no altitude correction). Includes aerobraking data. Solid line is the boundary between the northern lowlands and southern highlands. Martian Magnetization
From Connerney et al. (2005): Measured radial (vertical) component of the magnetic field at 400km altitude
Past Seafloor Spreading? Map of the magnetic field at 400 km altitude (Connerney et al., 2005). Dashed lines represent transform faults, letters refer to impact basin names. Map of the magnetic field as a function of latitude (Connerney et al., 2005). Green and orange represent profiles taken to the west and east of the central meridian, respectively.
Methods 2D Fourier Transform Downward continuation; k>25 filtered out Inverse Fourier Transform Geologic units from Scott and Tanaka (1986), Greeley and Guest (1987).
Geology Subdued crater unit Etched unitCratered unit Dissected unit Ridged Plains material Chaotic material Older Channel material Hilly unit Mottled Smooth Plains unit Ridged unit Crater materials Smooth unit Undivided material Cratered unit Hilly unit Crater materials Ridged Plains material Smooth unit Scott and Tanaka (1986), Greeley and Guest (1987) All units are interpreted as some type of igneous rock 20S, 340E 20N, 20E
Discussion Downward continued field agrees well with low altitude data. Offsets observed by Connerney et al. (2005) at altitude are also observed at the surface – No other geophysical signature of faults Possible influence from multi-ring basins – May not be a source of magnetization, but rather weaken the intensity Magnetic mineralogy constrained by Opportunity – Will use when considering source models Geologic history from Burns formation does not match a seafloor spreading environment – However, this outcrop is only 7 m thick