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NASA-CR-200127 



r 

Final Technical Report for NASA Grant NAGS- 1694 y ^ ^ ^ 

Cooperative Research in Terrestrial Planetary 
Geology and Geophysics 



This grant covered the period from July 1991 through August 1994. The research covered a 
number of topics and studied die Earth and Mars. 

1. Earth Studies work stressed interpretation of MAGS AT crustal magnetic anomalies to 
determine the geologic structure, mineralogical composition, magnetic nature and history of 
submarine features. Work was also done in the area of terrestrial remote sensing. 

2. Mars research included work on the early evolution of the Martian atmosphere and 
hydrosphere as well as investigations of large impact basins on Mars. 

Detailed summaries of the research done are attached. 



HI. Current Research Efforts 

Research has been done in several areas including earth studies and planetary science. Details 
are given in the foUowing as weU as a list of publications which resulted from this work. 

1. Earth Studies 

James H. Roark has worked on a study of the Earth's cnistal structure and evolution. 

This project entails geophysical research and computer modeling of MAGSAT crustal 
magnetic anomalies in order to determine the geologic structure, mincralogical composition, 
magnetic nature and history of submarine features. Basic research responsibilities included 
geophysical modeling, background and Hterature work, and training new personnel. Roark is 
now responsible for writing point and cHck modeling programs, data/scientific visualization 
programs and graphics output programs. He has also been requested to write data visualization 
and graphics output programs for other projects at NASA. This has involved use of UNIX, 
C, AVS, and IDL (interactive Data Language) programing on SUN spark workstations and 
CRAY/CONVEX super computers. 

Much of the work involved modeling in the SW-Indian-Antarctic Ocean which showed 
evidence for a TRM (thermal remnant magnetization) contribution from KQZ (Cretaceous Quiet 



Zone) cnist. This modeling also helped constrain the geographical extent of the KQZ crust, the 
amount of TRM, and the nature of poorly understood plateaus off the coast of Antarctica. 

Modeling of the Crozet Plateau showed how magnetization structure could be used to identify 
a different origin for two adjacent oceanic structures. 

Carla Evans has been working with the NASA Biospheric Sciences Branch. Her main task 
has been with the Boreal Ecosystems Atmospheric Study (BOREAS) project as a site liaison for 
Canada. The visits to the sites in Saskatchewan and Manitoba and a detailed search for geo- 
data. An intensive Canadian environmental process has been involved which required providing 
information necessary for their requirements. BOREAS, itself, is a study focussing on the 
interactions between the boreal forest biome and the atmosphere to clarify their roles in global 
change. It is an international cooperative field experiment integrating land surface climatology, 
tropospheric chemistry and terrestrial ecology, with remote sensing playing an integrating role. 

Evans has also been mvolved in geological research primarily consisting of developing a 
catalog of references to Mima Mound terrain in order to document locations to test a seismic 
hypothesis of origin. 

Stephanie Thliveris-Harrison has worked on MAGSAT sata and SEASAT/GEOSAT data. 
The MAGSAT project involved modeling crustal magnetic RTF anomalies over passive margins 
and continental rifl zones concentrating on the Australian Bight region. A consortium of seismic 
data has been acquired and several working models have been produce using IDL graphics on 
the SUNAJNDC system. The current model will be refined focusing on problems associated widi 
scalar/RTP data sets and high heat flow values measured in southeastern Australia. 

Thliveris-Harrison has done a comparative analysis between SEASAT/GEOSAT overland 
radar altimetry data and corresponding topographic data. The SEASAT/GEOSAT data has been 
used for comparative work in several regions around the world (Sudan, Egypt, South America) 
focusing recent efforts specifically on the Colorado plateau. 

Thliveris-Hanison took part in the Mars Observer thermal vacuum tests conducted at GE- 
Astro in New Jersey. She was involved in monitoring the SEPETT test operations related :o 
the Thermal Emission Spectrometer. 

Wolfe also continued work with S. Walter on a book analyzing the applications of satelhtc 
technology to disaster management. Tasks include searching for applicable detailed informauon. 
collecting a large "source" bibliography and reviewing various articles and papers. Impcrtar.: 
work is being done with digital image data (SPOTl, 10 meter resolution; Landsat) to ascena:.-, 
its utility in delineating small features such as buildings which may or may not be altered by 
catastrophic events such as earthquakes, volcanic eruptions and so forth. 

Other aspects of disaster mitigation that are being considered include the prediction of 
catastrophic events, timely warnings of impeding danger, search and rescue in the aftermaih. 
communications (a very important priority), medical care and, most importantly, the logisucal 
support and coordination for all of these efforts including outside humanitarian relief. 



2. Mars Studies 

Martha Schaefer has continued work on modelling the evolution of the Martian atmosphere 
and hydrosphere. The preliminary model was modified from being a steady-state model, to one 
that is time-varying. The method used to attack the problem was the kinetic method, which 
has been applied to terrestrial systems in recent years with much success. This method, which 
treats geochemical cycles as systems of complex geochemical reactions, is capable of elegantly 
handing the interactions between simultaneous chemical reactions needed to understand such a 
complicated system. Work on this model was presented at the Workshop on the Martian Surface 
and Atmosphere Through Tune, in Boulder, CO, September 1991. 

The second research topic concerns volcanic recycling of carbonates. Decomposition of 
carbonates under turbulently-flowing lava holds great promise as mechanism for resupplying the 
atmosphere of Mars with carbon dioxide. Terrestrial komatiites, a reasonable analogy for Martina 
lavas, have been found to significantly erode the rocks over which they flow. Initial modelling 
of this process indicates that a hot, high-volume lava flow is capable of eroding several meters 
of carbonates in a day. If this process occurred over a large area for even a hundred days, 
large amounts of carbon dioxide could be injected back into the Martian atmosphere essentially 
instantaneously. 

Charles H. Wolfe continued work with H.V. Frey (GSFC) on the origins of he Martian 
Crustal Dichotomy. This involves the search for large "Impact Basins" and "Basin Rings" 
associated with these features. 

In the search for multiple ring impact basins in the southern hemisphere of Mars, evidence 
was found for a large (@ 600 km inner diameter) and previously unknown impact basin that is 
centered southwest of the Hellas impact feature near Malea Planitia. Geologic features such as 
"Mountain" units, Noachian etched plains units, massifs and linear features (e.g. faults, ridges 
and channels) among others, appear to be arranged, both concentrically and radially, around a 
central point at approximately 328 degrees W, 66 degrees S. A closer look at the area of this 
possible basin (Malea) has revealed evidence for yet another impact basin in the region south 
of Malea. The evidence for both of these basins is compelling. 

The geomorphology of the southern hemisphere, particularly in this region, is quite chaotic. 
A possible explanation for this amalgamation of terrain is that the area has been influenced by 
impact mechanics from Hellas, South Polar and the two newly proposed impact basins. A search 
continue for new features using Viking and Mariner digital data as well as USGS photomosaics 
in order to gain a better understanding of the geology and geomorphology of the region with 
respect to the Martian crustal dichotomy. 

3. Publications 

Roark, J., and FuUerton, L., Frey, H., Thomas, H., Modeling of MAGSAT RTP Regional 
Crustal Magnetic Anomalies in the SW — Indian-Antarctic Ocean, (abstract, oral presenta- 
tion), EOS Trans. AGU, 72, No. 17, 1991. 



Frey, H., and Roark, J., Diverse Origins of the Crozet Bank and Del Cano Rise (SW 
Indian Ocean) from MAGSAT Crustal Anomaly Data, (being revised for JGR). 

Harrison, S., and Roark, J., Frey, H.. MAGSAT Crustal Magnetic Anomalies at Passive 
Margins: The Australian Bight Anomaly, (abstract in press for Spring AGU conference) 

Blodget, H.W., Taylor, P.T., and Roark, J.H., Shoreline changes along the Rosetta-Nile 
Promontory: Monitoring with satellite observations. Marine Geology, Vol. 99, pg. 67-77, 
1991. 



IV. Future Efforts 

It is anticipated that research will continue in many of the same areas as- were covered in 
the past 12 months. Details of the proposed efforts in the various areas follows. 

1. Earth Studies 

i) Interpretation of MAGSAT crustal magnetic anomalies (Harrison, Roark, Fullerton). 

Additional areas in the Indian-Antarctic Ocean in which remanent magnetization combines 
with induced/viscous magnetization will be studied. Forward modeling will be used to separate 
the different contributions, and the extent of amplitude of the remanent contribution will be used 
to constrain tectonic models of the oceanic crust. The area surrounding AusQ-alia will be studied 
first, in conjunction with the passive margin work already underway. 

Modeling of the MAGSAT signature around the passive margins of Australia will be 
completed in order to determine the magnetization contrast between the continential and ocean 
crust. For the southern margin, a small Cretaceous Quiete Zone adds further complications in 
that remanence may be contributing to the satellite-elevation anomaly. 

A new model of the Ontong-Java Plateau will be completed in order to assess to what 
extent the MAGSAT data can constrain the stiU-controversial nature of this feature. This feature 
was previously modeled but with lower resolution POGO data; the improved resolution of 
MAGSAT should make possible the separation of contributions form the Plateau and the nearby 
convergence zone against which the plateau lies. 

ii) GEOSAT Overland Altimetry (Harrison) 

A blind test of the automated proceedure for extracting river water levels over time wiQ 
be done. Comparison of continental scale topography from combined SEASAT and GEOSAT 
altimeter data with surface data will continue in order ot assess the quality of the satellite 
data in regions with different surface slopes and surface characteristics. Preliminary assessment 
of overland altimetry from TOPEX will begin by comparison with surface data as well as with 
existing satellite altimetry data, where profiles from the different spacecraft crossover one another. 



2. Mars Studies 

i) Martian geologic studies (Wolfe, Roark,, part-time students) 

Work will continue in several areas. The search for evidence of ancient and degraded impact 
basins will shift from the south polar reign to the northern lowlands and Tharsis regions. The 
young plains and volcanic features in these areas makes difficult the identification of ancient 
structures, but inclusion of recently available higher resolution gravity data from a new GSFC 
model will help. 

Forward modeling of the known impact basins, using a three-dimensional Gaussian quadra- 
ture program derived from MAGSAT modeling studies, will be used to constrain the density 
structure below these basins, and to infer the degree of compensation and evolution of the litho- 
sphere during the period of basin formation. The new GSFC gravity model will be the basis 
for comparison. 

Detailed studies of the age of apparently old ridged plains which were likely resurfaced in the 
middle portion of Mars history will shift from the Malea Planum region to outcrops in Cimmeria 
Terra. The origin of these volcanic plains is uncertain; they are not obviously associated with any 
larger impact basin as appears to be the case in Malea. Their age wiU be important in assessing 
the volcanic history of Mars and helping to decide between alternative models (punctuated or 
secxilarly declining volcanism). 

Photogeologic mapping along the dichotomy boundary in the Phaetontis region will complete 
the detaHed study along the weU-exposed parts of this fundamental crustal feature. Detailed 
stratigraphy and relative resurfacing ages will be determined and compared to those in other 
parts of the country. 

ii) Mars Evolution Martha Schaefer will continue research efforts on the modelling the 
evolution of the Martian atmosphere and hydrosphere. Particular attention will be paid to the 
cycling of carbon dioxide between the atmosphere and carbonates. 



A Joint 

NASA/Goddard Space Flight Center — University of Maryland 

Cooperative Research Program in Terrestrial and Planetary 

Geology and Geophysics 



Introduction 

A cooperative reseztrch agreement currently exists between the Astronomy Department of 
the University of Maryland and the Laboratory for Terrestrial Physics of the NASA Goddard 
Space Flight Center. Under this agreement, funding has been provided for both long and 
short term appointments for persons involved in research projects of mutual interest to the 
scientific staffs of the two institutions. These projects cover a fairly broad range of topics 
and are discussed in detail in the body of this proposal. The current proposal asks for a 
continuation of this program. 



Recent Progress 

Investigations of Crustal Structure and Evolution Using MAGS AT Crustal Mag- 
netic Anomaly Data 

James Roark worked on geophysical research and computer modeling of MAGSAT crustal 
magnetic anomalies in order to determine the geologic structure, mineralogical composition, 
magnetic nature and history of submarine features. He recently published seismic refraction 
models from KRISP studies of the East African Rift, which provide important constraints 
on the origin of MAGSAT crustal magnetic anomalies. These constraints were used to 
model the rift to help determine its crustal magnetic stucture. It was determined that some 
combination of (a) higher heat flow producing greater thinning of the magnetic crust in 
the north, (b) higher than usual susceptibility of the upper layer for granitic composition 
{e.g., due to the presence of dikes), and/or (c) variable magnetization contribution from rift 
volcanics may be necessary to explain the observed MAGSAT anomalies. 

In an effort to study both the large-scale magnetization contrast between the continental 
and oceanic crust as well as within the continental crust he has been involved in constructing 
forward models of magnetic anomalies over Australia and its surroundings. Susceptibility 
values required to reproduce the MAGSAT anomaly pattern lie in the range of 0.0008 to 
0.00220 (cgs). Crustal thickness variations appear to play a major role in explaining the 
anomaly pattern, but in some regions it appears that strong crustal susceptibility contrasts 
are more important. 



Stephanie Thliveris-Harrison has continued MAGS AT work on modeling of the Australian 
continent and passive maxgins during much of the past year. This work involves collecting 
and analyzing seismic, geothermal, and lithological data for continental Australia with the 
final computation of a crustal magnetic model(s). She gave an oral presentation of this work 
at the University of Maryland, Astronomy Department and at the American Geophysical 
Union: Spring, 1993. She has continued to work with IDL/graphics on the Sun/UNIX 
system, which has made it possible to produce graphics of various models. 



Mars Studies 

During the past year, Martha Schaefer has been preparing for the data anticipated to be 
arriving this fall from the Mars Observer Laser Altimeter (MOLA). She has been working 
with Maria Zuber at Goddard to modify some of her geophysical modelling programs to run 
on a Unix workstation, amd output results in an easily-interpretable graphical form. 

She is also starting a new topic of research, that of topographic analysis of Martian 
landforms. Currently she is involved in developing the necessary software on the workstation 
for geomorphic analysis of Martian landforms using the topographic data from MOLA. 

Charles Wolfe has worked with Herb Frey on a detailed analysis of the Lunae Planum re- 
gion in the western hemisphere of Mars. This was done to better constrain resurfacing events 
in this area relative to the Martian geologic time scale and also to determine based on sop- 
erposition analysis of craters, if the Luna« Planum indeed represents a standard production 
population of impact craters. 

For some time Lunae Planum has been regarded as a standard production surface for 
impact craters and therefore should represent a reasonably good record of the cratering 
history of the planet over some time period. One would expect, given this, to find a random 
distribution of craters of all sizes. However, the random nature of impacts, over this roughly 
1.1 million square kilometer area, seems to break down at certain crater diameters across the 
Lunae Planum. This may be indicative of resurfacing events that have occurred in Lunae 
Planum at different times throughout Martian history thus affecting estimates of impact 
crater production over time as well as age estimates for different surfaces elsewhere on Mars 
Work is underway to address this issue and will continue throughout next year. 

Wolfe and Frey are also looking at the Xanthe Terra region on Mars to determine if it s 
the site of yet another large, possibly multi-ring, impact basin. This work will further th-- 
search for large impact basins on Mars and help to provide insights into the geomorpholoi^; ■ 
and structural origins of this area. Effects related to the crustal dichotomy will also r.-- 
studied. 



Terrestrial Remote Sensing and Field Studies 

Carla Evans has completed work on a project on the study of Mima Mound formations. 
This involved satellite image analysis as well as a statistical analysis of seismic and feature 
locations. A report on this work was presented at the American Institute of Biological 
Sciences Conference in August 1992. Several publications are completed or in preparation. 

She is also involved in a project on studies of the Aral Sea Basin. This involved an 
analysis of remote sensing data on the area and some work was reported on at the March 
1993 International Symposium on Remote Sensing and Global Environmental Change. 

More recently, Ms. Evans has become involved in the BOREAS Project (BOReal Ecosys- 
tems Atmosphere Study). This is a joint U.S. and Canadian study and will include terrestrial 
ecology, hydrology, lamd surface climatology, trace gas biochemistry, atmospheric chemistry, 
boundary layer meterology, energy and water fluxes, satellite data analysis and integrative 
modelling. Her current work involves organizing and coordinating all activities relating to 
th^ selection of sites in which research towers are to be constructed. These sites are at two 
study areas in Saskatchewan and Manitoba Canada. She also provides information about 
the sites for the Canadian environmental review process in a report. Over 100 international 
scientific research projects have been accepted that will be interactively involved during the 
IPC's. She is also involved with helping these investigators to find study areas for their 
specific scientific needs. 

Penny Masuoka completed the calibration of TM and SPOT data for 56 test sites near 
Kursk, Russia as part of the research being done for the KUREX project. KUREX was 
a joint Russian/U.S. field experiment that took place in the summer of 1991. Concurrent 
satellite and aircraft overflights were made during the field experiment as well as a number of 
ground-based remote sensing, weather, soil and biomass measurements. The TM and SPOT 
calibrated data will be atmospherically corrected and then compared to biomass data. 



Computer Support 

Masuoka has also worked with Martha Schaefer to study ways to analyze laser altimeter 
data and compare it to other data formats such as image, DEM, and map data. Analyzing 
laser altimeter data with other data sets is a challenge due to its different format, a straight 
line of data points. They are currently considering 2 commercial software packages, an 
image processing package with some CIS capability and a GIS package. The GIS and image 
processing capabilities of these 2 packages are being studied to determine their suitability to 
process and analyze the diverse data types for this research. 

Dr. Schaefer also acts as system administrator for a network of seven Sun workstations. 
This involves maintaining the machines, helping determine present and future software and 
hardware needs, and assisting users as necessary. 



Publications in the Last Year 

Christensen, P. R., S. T. Harrison, P. Barbara, and S. Ruff, 1993. Thermal-Infrared Emission 
Spectroscopy of Natural Surfaces; Application to Coated Surfaces Lunar and Planetary 
Science XXIV, 287-288. 

Christensen, P. R. and S. T. Haxrison, 1993. Thermal Infrared Emission Spectroscopy of 
Natural Surfaces: Application to Desert Varnish Coatings on Rocks, Journal of Geophysical 
Research, in press. 

Prey, H., B. Bills, W. Kiefer, S. Nerem, J. Roark, and M. Zuber, 1993. Free-Air and 
Bouguer Gravity Anomalies and the Martian Crustd Dichotomy, Lunar and Planetary Sci- 
ence XXIV, 511-512. 

Prey, H., B. Bills, W. Kiefer, S. Nerem, J. Roark, and M. Zuber, 1993. New Mars Pree- 
Air and Bouguer Gravity: Correlation with Topography, Geology and Large Impact Basins, 
Lunar and Planetary Science XXIV, p. 513-514. 

PuUerton, L., H. Prey, J. Roark, and H. Thomas, Evidence for a Cretaceous Quiet Zone 
NRM Contribution to MAGSAT Data over Conjugate Features in the Southwest Indian 
Ocean, (in preparation). 

Kiefer, W., B. Bills, H. Prey, S. Nerem, J. Roark, and M. Zuber, 1993. An Inversion 
of Geoid and Topography for Mantle and Crustal Structure on Mars, Lunar and Planetary 
Science XXIV, 797-798. 

Roark, J., H. Prey, H. Thomas, Crustal Structure in the East African Rift and MAGSAT 
Crustal Magnetic Anomalies, 1992. EOS Trans. AGU, 73, No. 43, p. 140. 

Thliveris-Harrison, S., J. Roark, H. Frey, and H. Thomas, 1993. MAGSAT Crustal 
Magnetic Anonalies over Australia ajid Surroundings: Continental Scale Modeling, EOS 
Trans. AGU, bf 74, No. 16, p. 111. 

Schaefer, M. W., 1993. Local topography of Mars and its relationship to surface weath- 
ering processes, Lunar and Planetary Science XXIV, pp. 1243-1244. 

Zuber, M., B. Bills, H. Prey, W. Kiefer, S. Nerem, and J. Roark, 1993. Possible Flexu- 
ral Signatures au'ound Olympus and Ascraeus Montes, Mars, Lunar and Planetary Science 
XXIV, 1591-1592. 



Proposed Work in the Coming Year 

It is anticipated that research will continue in many of the same areas as were covered in 
the past 12 months. In addition, some new efforts are being added. Details of the proposed 
efforts in the various areas follows. 



Terrestrial Gravity and Magnetics Studies (Roark, Thiiveris-Harrison, Hoxirly 
Personnel) 

MAGSAT Cnistsd Anomalies: Crustal Magnetics at Plate Margins 

The major objectives of this work are to utilize MAGSAT data to (1) determine the structure, 
nature, and tectonic evolution of submarine plateaus, (2) assess the role of thermal remanent 
magnetization in MAGSAT oceanic anomalies, (3) understand the variable MAGSAT sig- 
nature at passive margins in terms of the crustai structure ot these margins, and (4) assess 
the role of thermal enhancement of viscous magnetization in downgoing slabs at subduction 
zones. Another objective is to model the expected resolution improvement in GAMES- 
elevation data. 

In the next year, we will complete the modeling of the passive margins around Australia. 
The model results for the conjugate plateaus in the southwest Indian-Antarctic Ocean will 
be published. We will study the thermal structure beneath the Conrad Rise, where structure 
seems to play almost no role in the MAGSAT anomaly, but where TRM is important. A study 
will be started of the Falkland Plateau and other "continental" fragments for comparison with 
the Agulhas Plateau model already completed. We will also compute GAMES-elevation (275 
km) versions of all MAGSAT-elevation models to assess expected improvement in resolution 
ajid discriminability between models. 

Geopotential Fields Modeling and Simulations Related to the GAMES (Gravity And 

Magnetics Experiment Satellite) Mission 

One of the main objectives of the MAGSAT mission studies has been the use of these satellite 
data to interpret and define lithospheric structure and information. Because satellite data 
are, of their very nature, global in character, they mwill aid us in making geologic maps that 
cover the Earth. Because magnetic anomaly studies utilizing satellite measurements are a 
very recent activity we have extended our work to include collaboration with other Earth 
scientists pursuing similar research efforts (at such institutions as Purdue, SIU, OSU, and 
Cornell). These joint projects have proven to be very beneficial to our understanding of the 
sources for the MAGSAT data. Such studies will continue and we plan to extend them to 
other researchers as well. 

The present study includes several directions of geopotential fields evaluation. First, we 
- will assess our ability to utilize the expected gravity and magnetic anomaly field to resolve 



distinct and known geologic/tectonic units. Previously, theoretical simulations indicated 
a threefold increase in magnetic anomaly resolution of GAMES over MAGSAT. We will 
evaluate this increase in anomaly resolution and how it may be used to describe structures 
in Earth's crust. Second, we will investigate the benefits of measureing both gravity and 
magnetic fileds with the same spatial positions. 

In the upcoming year, we will obtain complete and up-to-date ground-based digital grav- 
ity and magnetic data sets. These will be upward continued to the GAMES altitude and 
used to simulate our expected geopotential data sets. The simulated data sets will them 
be used to evaluate the nature and type of geologic/tectonic structures we could expect to 
detect with GAMES. Because GAMES will have an orbit significantly different from pre- 
vious geopotential field missions we will investigate new methods and techniquese for data 
reduction, analysis, presentatin, and noise elimination. These results will be presented at sci- 
entific meetings and submitted to appropriate journals; this will introduce the Earth Science 
community to the proposed GAMES mission. 

Early Mars: Impact Basins, Crustal Dichotomy and Volcanic Resurfacing (Roark, 
Wolfe, Reidy, Hourly Personnel) 

Crustal Dichotomy and Dichotomy Boundary 

We will complete in the first year a detailed structural and stratigraphic study of the crustal 
dichotomy boundary in western Acidalia, as a complement to that already done in Isme- 
nius Lacus (Dimitriou, 1990a,b) and for comparison with studies already done further east 
(McGiU and Dimitriou, 1990; Maxwell and McGill, 1988; Frey et al., 1988a). The goal is to 
determine why the topography/physiography/geophysical relations in SE Acidalia/Westem 
Arabia are so different from that further east, whether this portion of the dichotomy and 
dichotomy boundary is more likely due to endogenic or exogenic causes, and to compare the 
deformational and resurfacing history of this area with other portions of the boundary. An 
important objective is to determine, from the cumulative frequency curves, the timmg of 
major resurfacing events, the efficiency of these events in burying older surfaces, the role of 
topography in this efficiency, and the time the original and final topographic dichotomy was 
established here and further east. Direct comparison of the Acidalia region with the Ismenius 
Lacus and Amenthes-Aeolis areas will be done to compare the deformational history and its 
possible variation along the boundary. 

The newly available geophysical data (Smith et al., 1993) will be used to construct simple 
models of the variation in crustal structure across the dichotomy boundary, and how this 
varies along the boundary. The Bouguer gravity signature shows considerable variation along 
the boundary, with changes often but not always in concert with structural changes (Frey 
et al., 1993a). The Bouguer gravity across the boundary seems more consistent, with a 
change of 200 milligals from negative over cratered terrain to positive (or at least relatively 
more positive) over the lowlying plains (Frey et al., 1993a,b). We propose both inversion 
- and forward modeling, in collaboration with Walter Kiefer. Kiefer has already produced 



preliminary models of crustal thickness variations for Mars based on the new gravity model 
(Kiefer et al., 1993). Forward modeling will be based on existing programs available at 
Goddard which have been used by the PI in studies of satellite-derived geophysical data for 
the Earth. Constraints on these models will include the obvious geological and structural 
data, and topographic data. Although we will begin this effort in the first year, it is expected 
that the bulk of this will be accomplished in the second and third year, using improved 
topography and gravity data when it is freely available. 

Large Multi-ring Impact Basins on Mars 

In the coming year we will submit for publication the results of our search for evidence of 
large impact basins in the south polar region, and the implications of the basins we found 
for influencing the distribution of polar deposits and structures (Reidy and Frey, 1993). 

We will continue our mapping and study of the Chryse/Acidalia Basin region (related 
to (a) above), in order to determine how strong is the evidence that the topographic low in 
Chryse has moved over time from that due to the impact to that associated with later filling 
(Stockman and Frey, 1993). The structural and topographic evidence for the Acidalia Basin 
will be documented. The apparent influence of the Acidalia Basin on the evolution of the 
Chryse Basin (Craddock et al., 1993) will be studied, through reconstruction of basin rings 
and anaylsis of superposition relations, as another example (along with Malea B/Hellas) 
of the role of basin overlap, and the relation of these two basins to the development of the 
crustal dichotomy and evolution of the dichotomy boundary in western Mars will investigated 
as part of (a) above. 

In collaboration with Walter Kiefer (USRA/LPI) we will use the newly available geo- 
physical data to model the positive Bouguer gravity anomalies seen in the larger basins 
(Frey et al., 1993b). The anomalies will be modeled both in terms of crustal thinning and 
mantle uplift, and in terms of basin filling (mascons). Constraints on the latter are provided 
in some cases by nearly buried old craters (Hellas, Argyre) or impact basin rims (northern 
Isidis rim). Implications for basin evolution will be studied, both individually and as a func- 
tion of basin size and age. This work will take place largely in the second and third year, 
after the Chryse/Acidalia study is complete, but early models of Hellas, Argyre, Utopia aad 
Isidis will be started in the first year. 

Major Resurfacing Events in Martian History 

In the coming year we will complete the study of the resurfacing history of the Malea Plan::r. 
region, which lies in the overlap of the Malea and Hellas Basins (Frey et al., 1991b; Reidy »-. 
al., 1992). Both age and thicknesses of materials associated with major resurfacing events 
will be determined and compared with our earlier results for Nplr and Hr units in Memnonia 
and Argyre, Lunae Planum, Tempe Terra and elsewhere. Because of the uncertainty about 
crater production curves, which we address below, this study will be done differentially by 
comparison with Luna.e Planum. 



In the first and second yeaxs we propose a re-exanaination of the crater production curve 
controversy by examining first the distribution of craters in given counting areas as a function 
of diameter. We have a large library of crater counts from a variety of surfaces, including 
old cratered terrain in eastern and western Mars, ridged plains in Lunae Planum, Coprates 
and Malea, and smooth plains units north of the dichotomy boundary and elsewhere ((Frey 
et al., 1988; Frey and Grant, 1990; Grant and Frey, 1987; Frey and Grant, 1989; Frey et 
al. 1987, 1989, 1991a). For selected regions the distribution of craters of diflFerent sizes will 
be'plotted to determine which diameters appear to be significantly depopulated (spatially), 
and then compared to resurfacing branches derived from the Neukum and Hiller (1981) and 
Neukum (1983) curves to see which if either of these curves better indicates the diameters 
most affected by depopulation. Areas with uniform distribution of craters over large size 
ranges can be used to approximate production surfaces if these craters are superimposed on 
the terrain. By studying a number of such regions it may be possible to synthesize a better 
"standard production curve" that represents more crater production than crater destruction. 
If we are able to synthesize such a curve, we will compare it to the existing "production" 
curves, an re-assess if necessary the number and timing of resurfacing events those other 
curves imply. 

Terrestrial Remote Sensing and Field Studies (Evans, Schaefer, Graduate Assis- 
teuat) 

Work on the remote sensing of degradation in the Aral Sea Basin will continue. This will 
involve analysis of satellite data and ancillary information. 

The BOREAS project is an international project intended to improve our understanding 
of the interactions of the boreal forest biome and the atmosphere in order to clarify their 
roles in global change. In the upcoming year several field expeditions will be organized to 
collect ground data on the boreal forest in Canada. In addition to the field experiments, 
satellite and other digital data will be analyzed. Results of this project will be published in 
appropriate journals and reports. 

Work will continue on the development of the data system for terrestrial laser altimetry. 
A graphical user interface will be developed, to enable the data to be accessed and displayed 
in an intuitive manner. Existing data from previous field experiments, as well as data from 
a new field experiment, will be incorporated into the system and the results analyzed. 

Image Processing, GIS, and Computer System Support (Masuoka, Schaefer) 

This task comprises computer system support, as well as research into how image processing, 
GIS (Geographic Information System) and visualization software packages are used in remote 
sensing research and how the three types of packages could be more effectively used together. 



Specific topics being studied include: 

• a graphical user interface linking together the major functions from the 3 packages to 
provide scientists with a tool to use the capabilities from the packages without having 
to learn the packages, 

• a study of the current state of image processing software and what types of image 
processing programs are now available, 

• a study of software that could be developed to facilitate the use of the 3 software pack- 
ages for remote sensing (such as, software to convert images between the 3 formats), 
aind 

• a study of the use of image processing software in conjunction with GIS software and 
how it can be used most effectively in remote sensing research. 

A critical element to the research being done above is user assistance and training. This 
"support" work provides numerous opportunities for seeing how image processing, GIS, and 
visualization softwaxe are being used in various remote sensing fields and provides opportu- 
nities to study better ways to use the packages together. 

The network of workstations in the Geodynamics Branch will continue to be administered 
by Dr. Schaefer. 

Mars Observer Laser Altimeter Data Analysis (Schaefer, Roark, Reidy, Hourly 
Personnel) 

Work currently in progress on software development in preparation for the flood of data 
expected from the Mars Observer Laser Altimeter (MOLA) will be continued. This software 
will primarily be used for the display of the data, although some geomorphic analysis software 
is under development also. 

When data begins arriving (late in the fall of 1993), processing and analysis of the data 
will commence. Topics to be studied include: (1) the relationship between the gravity and 
topography fields and what this can tell us about the structure of the subsurface of Mars; 
(2) geomorphology of surface freatures on Mars, including craters, valleys, and small-scale 
enigmatic features, and what this can tell us about the history of the climate and surface 
processes on Mars. 

Volcanology: Physical Modelling and Remote Sensing (Research Associates) 

This new task will be in the area of volcanology, both in physical modelling and in re- 
mote sensing of climatologically-important gases. Specific topics to be studied include the 



10 

dynajnics of explosive eruptive plumes, concentrating on understanding the physical param- 
eters that affect plume rise, and lava flow dynamics. Volcanic plumes also will be studied as 
sources for climatologically-important gases. Remote sensing studies will focus on shortwave- 
length infrared data on extremely high temperature volcanic phenomena. Both the plume 
work and the high temperature studies will use ground-based, aircraft, and orbital remote 
sensing data. Also included will be geologic mapping of terrestrial and extraterrestrial lava 
flows. 



11 



References 

Craddock, R. A., L. S. Grumpier and J. C. Aubele, Geologic history of central Ghryse Plani- 

tia and the Viking 1 landing site, Mars, Lunar Planet. Sci. Conf. XXIV, 335-336, 1993. 

Dimitriou A M Stratigraphy of the Ismenius Lacus SE subquadrangle: clues to an up- 

land/lowllnd boundary forming event? LPSC XXI, 293-294, 1990a (abstract). 

Dimitriou A. M., Minimum estimates for volume removal from the martian fretted terrain 

between 270'W Ld 360°W, LPSC XXI, 291-292, 1990b (abstract). 

Frey, H. and R. A. Schultz, Large impact basins and the mega-impact origin for the cnistal 

dichotomy on Mars. Geophys. Res. Lett. 15, 229-232, 1988. 

Frey, H., A. M. Semeniuk, J. A. Semeniuk and S. Tokarcik. A widespread common age 

resurfacing event in the highland-lowlaad transition zone in eastern Mars. Proceed. Lunar 

Planet. Sci. Conf. 18th, 679-699, 1988a. 

Frey, H. V. And Grant, T. D., Resurfacing History of Tempe Terra and Surroundmgs, J. 

Geophys. Res., 95, 14,249-14,263, 1990. 

Frey, H. V., C. D. Doudnikoff and A. M. Mongeon, Are Noachian-age ndged plains (Nplr) 

actually Early Hesperian iff age? Proc. Lunar Planet. Sci. XXI, 635-644, 1991a. 

Frey H Reidy A M., Wolfe, C. H. and Schultz, R. A., A search for large impact basins in 

the southern hemisphere of Mars, Lunar Planet. Sci. XXII, 419-420, 1991b (abstract). 

Frey, H., Geologic and topographic constraints on the origin and evolution of the martian 

crustal dichotomy, (in preparation), 1993a. Frey, H., Implications of Early Hesperian ages 

for presumed Noachian age volcanic flows on Mars, submitted to J. Geophys. Res./ Planets, 

1993b. ^ _ . , 

Grant, T. D. and Frey, H. V., Resurfacing history of Lunae Planum and Xanthe Terra (ab- 
stract) EOS Trans. Am. Geophys. Un. 68, 1342, 1987. 

Kiefer, W., B. Bills, H. Frey, S. Nerem, J. Roark and M. Zuber, An inversion of geoid and 
topography for mantle and crustal structure on Mars, Lunar Planet. Sci. Conf. XXIV, 

797-780, 1993. 

Majcwell, T. A. and G. E. McGill, Ages of fracturing and resurfacing in the Amenthes region, 
Mars. Proceed. Lunar Planet. Sci. Conf. 18th, 701-711,1988. 

McGill, G. E. and A. M. Dimitriou, Origin of the martian global dichotomy by crustal thin- 
ning in the Late Noachian or Early Hesperian, J. Geophys. Res., 95, 12,595-12,606, 1990. 
Neukum, G. and K. Hiller. Mari;ian ages. J. Geophys. Res., 86, 3097-3121, 1981. 
Neukum, G. and D. U. Wise. Mars: as standard crater curve and possible new time scale, 
Science, 194, 1381-1387, 1976. Reidy, A. M., Sanford, C. A., Frey, H. and Schultz, R. A., A 
search for large impact basins in the southern hemisphere of Mars II: South Polar B? Lunar 
Planet. Sci. XXIII, 419-420, 1992 (abstract). Reidy, A. M. and H. V. Frey, South polar 
impact basins on Mars and their role in the distribution of polar deposits and structures, 
1993 (in preparation) Smith, D. E., F. J. Lerch, R. S. Nerem, M. T. Zuber, G. B. Patel, S. 
K. Fricke and F. G. LeMoine, GMM-1: a 50th degree and order gravitational field model for 
Mars, Lunar Planet. Sci. Conf. XXIV, 1317-1318, 1993. 

Stockman, S. and H. Frey, Chryse impact basin, Mars: a new center and nng assignment 
and evidence for changes over time, (in preparation), 1993. 



12 



Scientific and Technical Personnel 

The principal investigator, Martha W. Schaefer, holds the position of Assistant Research 
Scientist in the Astronomy Department of the University of Maryland at College Park. She 
received S.B. degrees in Physics and in Earth and Planetary Sciences from M.I.T. in 1979, 
and a PhD in Planetary Sciences from M.I.T. in 1983. Before coming to the University of 
Maryland she held positions at the Geophysical Laboratory of the Carnegie Institution of 
Washington and at the Naval Research Laboratory. Her published research includes a wide 
variety of topics, from crystal chemistry and mineralogy, to high-pressure studies and solid 
state physics, to planetary astronomy and Mari:ian geochemistry and geomorphology. She 
is also co-author of an undergraduate planetary science textbook to be published later this 
year. 

The co-investigator, John Trasco, is currently the Associate Director in the Depari;ment 
of Astronomy at the University of Maryland at College Park. He received his B.S. in Physics 
from Fordham University in 1963 and his Ph.D. in Astronomy from Columbia University 
in 1969. Before coming to the University of Maryla»d, he held a faculty position at the 
University of Virginia. He has done research in the area of stellar structure and atmospheres. 
His current responsibilities include oversight of the instructional program in the Department 
of Astronomy. 

Administrative and Detailed Budgetary Information 

This project will be administered through the University of Maryland at College Park, 
Astronomy Department. 



III. Current Research Efforts 

Research has been done in several areas including earth studies and planetary science. Details 
are given in the following as well as a list of publications which resulted from this work. 

1. Earth Studies 

James H. Roark has worked on a study of the Earth's crustal structure and evolution. 

This project entails geophysical research and computer modeling of MAGSAT crustal 
magnetic anomalies in order to determine the geologic structure, mineralogical composition, 
magnetic nature and history of submarine features. Basic research responsibilities included 
geophysical modeling, background and literature work, and training new personnel. Roark is 
now responsible for wilting point and click modeling programs, data/scientific visualization 
programs and graphics output programs. He has also been requested to write data visualization 
and graphics output programs for other projects at NASA. This has involved use of UNIX, 
C, AVS, and DDL (interactive Data Language) programing on SUN spark workstations and 
CRAY/CONVEX super computers. 

Much of the work involved modeling in the SW-Indian-Antarctic Ocean which showed 
evidence for a TRM (thermal remnant magnetization) contribution from KQZ (Cretaceous Quiet 



Zone) crust. This modeling also helped constrain the geographical extent of the KQZ crust, the 
amount of TRM, and the nature of poorly understood plateaus off the coast of Antarctica. 

Modeling of the Crozet Plateau showed how magnetization structure could be used to identify 
a different origin for two adjacent oceanic structures. 

Carla Evans has been working with the NASA Biospheric Sciences Branch. Her main task 
has been with the Boreal Ecosystems Atmospheric Study (BOREAS) project as a site liaison for 
Canada. The visits to the sites in Saskatchewan and Manitoba and a detailed search for geo- 
data An intensive Canadian environmental process has been involved which required providing 
information necessary for their requirements. BOREAS, itself, is a smdy focussing on the 
interactions between the boreal forest biome and the attiosphere to clarify their roles in global 
change. It is an international cooperative field experiment integrating land surface climatology, 
tropospheric chemistry and terrestrial ecology, with remote sensing playing an integrating role. 
Evans has also been involved in geological research primarily consisting of developing a 
catalog of references to Mima Mound terrain in order to document locations to test a seismic 
hypothesis of origin. 

Stephanie ThHveris-Hanison has worked on MAGSAT sata and SEASAT/GEOSAT data. 
The MAGSAT project involved modeling crustal magnetic RTF anomalies over passive margins 
and continental rift zones concentrating on the Australian Bight region. A consortium of seismic 
data has been acquired and several working models have been produce using IDL graphics on 
the SUN/UNIX system. The current model will be refined focusing on problems associated with 
scalar/RTP data sets and high heat flow values measured in southeastern AustraUa, 

ThUveris-Harrison has done a comparative analysis between SEASAT/GEOSAT overland 
radar altimetry data and corresponding topographic data. The SEASAT/GEOSAT data has been 
used for comparative work in several regions around tiie world (Sudan, Egypt, South Amenca) 
focusing recent efforts specifically on the Colorado plateau. 

ThUveris-Hamson took part in the Mars Observer thermal vacuum tests conducted at GE- 
Astro in New Jersey. She was involved in monitoring the SEPETT test operations related to 
the Thermal Emission Spectrometer. 

Wolfe also continued work with S. Walter on a book analyzing the appHcations of sateUite 
technology to disaster management. Tasks include searching for appUcable detaUed information, 
coUecting a large "source" bibUography and reviewing various articles and papers. Important 
work is being done witii digital image data (SPOTl, 10 meter resolution; Landsat) to ascertam 
its utility in delineating small features such as bmldings which may or may not be altered by 
catastrophic events such as earthquakes, volcanic eruptions and so forth. 

Other aspects of disaster mitigation that are being considered include the prediction of 
catastrophic events, timely warnings of impeding danger, search and rescue in the aftermath, 
communications (a very important priority), medical care and, most importantly, the logisucal 
support and coordination for aU of these efforts including outside humanitarian reUef. 



2. Mars Studies 

Martha Schaefer has continued work on modelling the evolution of the Martian atmosphere 
and hydrosphere. The preliminary model was modified from being a steady-state model, to one 
that is time-varying. The method used to attack the problem was the kinetic method, which 
has been appUed to terrestrial systems in recent years with much success. This method, which 
treats geochemical cycles as systems of complex geochemical reactions, is capable of elegantly 
handing the interactions between simultaneous chemical reactions needed to understand such a 
compUcated system. Work on this model was presented at the Workshop on the Martian Surface 
and Atmosphere Through Time, in Boulder, CO, September 1991. 

The second research topic concerns volcanic recycling of carbonates. Decomposition of 
carbonates under turbulenUy-flowing lava holds great promise as mechanism for resupplying the 
atmosphere of Mars with carbon dioxide. Terrestrial komatutes, a reasonable analogy for Martina 
lavas, have been found to significantly erode the rocks over which they flow. Initial modelling 
of this process indicates that a hot, high-volume lava flow is capable of eroding several meters 
of carbonates in a day. If this process occurred over a large area for even a hundred days, 
large amounts of carbon dioxide could be injected back into the Martian atmosphere essentially 
instantaneously. 

Charles H. Wolfe continued work with H.V. Frey (GSFC) on the origins of he Martian 
Crustal Dichotomy. This involves the search for large "Impact Basins" and "Basin Rings" 
associated with these features. 

In the search for multiple ring impact basins in the southern hemisphere of Mars, evidence 
was found for a large (@ 600 km inner diameter) and previously unknown impact basin that is 
centered southwest of the Hellas impact feature near Malea Planitia. Geologic features such as 
"Mountain" units, Noachian etched plains units, massifs and linear features (e.g. faults, ridges 
and channels) among others, appear to be arranged, both concentrically and radiaUy, around a 
central point at approximately 328 degrees W, 66 degrees S. A closer look at the area of this 
possible basin (Malea) has revealed evidence for yet another impact basin in the region south 
of Malea. The evidence for both of these basins is compelling. 

The geomorphology of the southern hemisphere, particularly in this region, is quite chaotic. 
A possible explanation for this amalgamation of terrain is that the area has been influenced by 
impact mechanicsfrom Hellas, South Polar and the two newly proposed impact basins. A search 
continue for new features using Viking and Mariner digital data as wcU as USGS photomosaics 
in order to gain a better understanding of the geology and geomorphology of the region with 
respect to the Martian crustal dichotomy. 

3. Publications 

Roark. J., and FuUerton, L., Frey, H., Thomas. H., Modeling of MAGSAT RTP Regional 
Crustal Magnetic Anomalies in the SW - Indian-Antarctic Ocean, (abstract, oral presenta- 
tion), EOS Trans. AGU. 72, No. 17, 1991. 



Frey, H., and Roark, J., Diverse Origins of the Crozet Bank and Del Cano Rise (SW 
Indian Ocean) from MAGSAT Crustal Anomaly Data, (being revised for JGR). 

Harrison, S., and Roark, J., Frey, H., MAGSAT Crustal Magnetic Anomalies at Passive 
Margins: The Australian Bight Anomaly, (abstract in press for Spring AGU conference) 

Blodget, H.W., Taylor, P.T., and Roark, J.H., Shoreline changes along the Rosetta-Nile 
Promontory: Monitoring with satellite observations. Marine Geology, Vol. 99, pg. 67-77, 
1991. 

iV. Future Efforts 

It is anticipated that research will continue in many of the same areas as were covered in 
the past 12 months. Details of the proposed efforts in the various areas follows. 

1. Earth Studies 

i) Interpretation of MAGSAT crustal magnetic anomalies (Harrison, Roark, Fullerton). 

Additional areas in the Indian-Antarctic Ocean in which remanent magnetization combines 
with induced/viscous magnetization will be studied. Forward modeling will be used to separate 
the different contributions, and the extent of amplitude of the remanent contribution will be used 
to constrain tectonic models of the oceanic crust. The area surrounding Australia will be studied 
first, in conjunction with the passive margin work already underway. 

Modeling of the MAGSAT signature around the passive margins of Australia will be 
completed in order to determine the magnetization contrast between the continential and ocean 
crust. For the southern margin, a small Cretaceous Quiete Zone adds further complications in 
that remanencc may be contributing to the satellite-elevation anomaly. 

A new model of the Ontong-Java Plateau will be completed in order to assess to what 
extent the MAGSAT data can constrain the still-controversial nature of this feature. This feature 
was previously modeled but with lower resolution POGO data; the improved resolution of 
MAGSAT should make possible the separation of contributions form the Plateau and the nearby 
convergence zone against which the plateau lies. 

ii) GEOSAT Overland Altimetry (Harrison) 

A blind test of the automated proceedure for extracting river water levels over time wiU 
be done. Comparison of continental scale topography from combined SEASAT and GEOSAT 
altimeter data with surface data will continue in order ot assess the quality of the satellite 
data in regions with different surface slopes and surface characteristics. Preliminary assessment 
of overland altimetry from TOPEX will begin by comparison with surface data as well as with 
existing satellite altimetry data, where profiles from the different spacecraft crossover one another. 



2. Mars Studies 

i) Martian geologic studies (Wolfe, Roark,, part-time students) 

Work wiU continue in several areas. The search for evidence of ancient and degraded impact 
basins wiU shift from the south polar reign to the northern lowlands and Tharsis regions. The 
young plains and volcanic features in these areas makes difficult the identification of ancient 
structures, but inclusion of recently available higher resolution gravity data from a new GSFC 

model will help. 

Forward modeling of the known impact basins, using a three-dimensional Gaussian quadra- 
ture program derived from MAGSAT modeling studies, will be used to constrain the density 
structure below these basins, and to infer the degree of compensation and evolution of the Utho- 
sphere during the period of basin formation. TTie new GSFC gravity model will be the basis 
{(X comparison. 

Detailed studies of the age of apparently old ridged plains which were likely resurfaced in the 
middle portion of Mars history will shift from the Malea Planum region to outcrops in Cimmena 
Terra The origin of these volcanic plains is uncertain; they are not obviously associated with any 
larger impact basin as appears to be the case in Malea. Tlieir age will be important in assessmg 
the volcanic history of Mars and helping to decide between alternative models (punctuated or 
secularly declining volcanism). 

Photogeologic mapping along the dichotomy boundary in the Phaetontis region will complete 
the detaHed study along the wcU-cxposed parts of this fundamental crustal feature. Detailed 
stratigraphy and relative resurfacing ages wiU be determined and compared to those m other 
parts of the coimtry. 

ii) Mars Evolution Martha Schaefer will continue research efforts on the modelling the 
evolution of the Martian atmosphere and hydrosphere. Particular attention will be paid to the 
cycling of carbon dioxide between the atmosphere and carbonates. 



Summary Report on NASA/Goddard Space Flight Center - University 
of IWaryland Cooperative Research Program in Terrestrial and 
Planetary Geology and Geophysics 



Publications 

Effects due to overlapping large impact basins on Mars; Frey, Herbert, Reidy, 
Anne Marie, Roark, James H. and Stockman, Stephanie; LPSC XXV, 389-390, 
1994. 

Noachian and Hesperian modification of the original Chryse impact basin 
topography; Stockman, Stepanie, and Frey, Herbert; LPSC XXV, 1345-1346, 
1994. 

Conbtributions of Cretaceous Quiet Zone natural remanent magnetization to 
Magsat anomalies in the Southwest Indian Ocean; Lawrence G. Fullerton, Herbert 
V. Frey, James H Roark, and Hemnan H. Thomas; Journal of Geophysical 
Research, Vol. 99, No. B6, Pages 1 1 ,923-1 1 ,936, June 10, 1994. 

Noachian and Hesperian modification of the original Chryse impact basin 
topography; Stockman, Stephanie, and Frey, Herbert V.; Geophys. Res. Lett., 
accepted, 1995. 

Early Mars: Impact Basins, Crustal Dichotomy, and Volcanic Resurfacing 

Work continued on the study of large impact basins on Mars. Effects of overlap on 
impact basin structure and morphology were detemnined. The distribution of related 
volcanic features seems to be related to basin overlap, as does presen/ation of ancient 
terranes ,and channel flow. 

A new center and ring alignment for the Chryse impact basin was proposed based on 
photogeolog mapping and re-examination of the published geology. This work was 
presented at the Lunar and Planetary Science conference in 1994, and is the supject of 
a paper recently accepted by Geophysical Research Letters. 

Terrestrial Gravity and Magnetics Studies 

The MAGSAT group had a major publication in 1994 (see above). In this paper the 
Magsat magnetic anomalies over the Southwest Indian Ocean were modeled using a 
combination of Induced plus viscous remanent magnetization. Models of conjugate 



structures showed that induced plus viscous remanent magnetization models 
reproduces the Magsat anomalies associated with non-Cretaceous Quiet Zone cmst 
and a dominant natural remanent magnetization component are required to explain the 
anomalies associated with Cretaceous Quiet Zone crust. 

J. Roark also perfomned the following duties/accomplishments: 

1 . Computer software development and programming and systems support. 

(a). Wrote several IDL programs to display Mars gravity/topography 
and Earth topography data. 

(b). Used PCI software to enhance TM images of the Bolivian 
Andes. 

(c). Began learning UNIX system administration duties. 

(d). Installed cdmosaic and cdbrowse software used to view and 
mosaic Mars viking data. 

S. Harrison's research continued to focus on fonward modeling Magsat reduced-to-pole 
(RTP) cmstal magnetic anomalies over the Australian continent and its southem 
passive margin (Australian Bight). The focus of this project changed during the course 
of the past year in that modeling procedures are approached differently (i.e. absolute 
modeling as opposed to modeling with a background) and larger surface areas are 
included. These changes are being incorporated into the cun'ent model. 

Results from this work are being written up for publication. 



Terrestrial Remote Sensing and Field Studies 

BOREAS Project 

The BOREAS (BOReal Ecosystem Atmosphere Study) Project conducted 5 sets 
of experiments in Canada from March - October each lasting from 3 - 5 
weeks. C.S. Evans acted as the Study Area Manager for 3 of the 
experiments at the Southern Study Area in Candle Lake, Saskatchewan. This 
entailed managing the office staff of 5-6 persons and keeping track of over 
200 scientists and field crews over a 100km X 100km area. In addition, 
support was given to the Mission Manager which included keeping track of 
the location of up to 10 aircraft surveying the study area. The rennaining 
time back at the office was used to coordinate these remote activities 



(logisitcs) and to provide science support to the Principal Investigators. 

GSFC Distributed Active Archive Center (GDAAC) Educational Outreach Program 

C. S. Evans was involved with the initial stage of coordinating a new Educational 
Outreach Program with Robin Bell in code 902.2 (Goddard DAAC). This new program 
has been established in order to provide a product containing the data available from 
the GDAAC that highschool, community college and undergraduate levels can use in 
the classroom. The first topic will be on the use of TOMS data for global ozone 
measurements and the product will be distributed on CDs. A working partnership has 
been established with the Univ.of Maryland Joint Educational Initiative (JEI) group. The 
first product is targeted to be completed by August 1995 for use in a JEI workshop. 

Data System for Terrestrial Laser Altimetry 

M. Schaefer developed a user-friendly data system for the analysis of ten-estrial laser 
altimetry data. This system, written in IDL, enables the data to be accessed and 
displayed in an intuitive manner. It is extendable, and enables new subroutines for data 
display and analysis to be added easily. 



Computer System Support 

M. Schaefer administered the network of Sun workstations and X tenninals in the 
Geodynamics Branch. She installed the upgraded CPU to the main sen/er , and added 
more memory and disk space, enabling greater efficiency for the system.