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UNMIXING THE SNCS:
Chemical, Isotopic, and Petrologic
Componensts of the Martian Meteorites
October 11-13, 2002
Houston Texas
FIRST ANNOUNCEMENT
May 2002
SPONSORED BY
Lunar and Planetary Institute
SCIENTIFIC ORGANIZERS
Allan H. Treiman Christopher D. K. Herd
Lunar and Planetary Institute Lunar and Planetary Institute
Phone: 281-486-2117 Phone: 281-244-2021
E-mail: treiman@lpi.usra.edu E-mail: herd@lpi.usra.edu
CO-CONVENERS
John Jones, NASA Johnson Space Center
David Mittlefehldt, NASA Johnson Space Center
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When and Where
A workshop on Unmixing the SNCs will be held on October 11-13,
2002, at the Lunar and Planetary Institute (LPI). The LPI is
housed in the Center for Advanced Space Studies, 3600 Bay Area
Boulevard, Houston, Texas.
Purpose and Scope
Martian meteorites,
pite being all basalts or their
derivatives, show an enormous range of chemical and isotopic
compositions. In some respects this breadth is greater than that
of all basaltic rocks on Earth. Much of the compositional
variability can be modeled as mixtures of chemical and isotopic
components, and some components have been assigned to specific
geological/chemical reservoirs: mantle, crust, atmosphere,
regolith, and hydrosphere. If mixing components in the SNCs can be
characterized, we will gain insight into hidden aspects of martian
geology and geochemistry – hitherto unsampled rock types and/or
poorly characterized processes and geological environments.
But just what are the components that make up the martian
meteorites? What are their chemical and isotopic properties? Do
they represent recognizable source rocks, reservoirs, or
geochemical processes? Are physical traces of them, mineral
grains, or xenoliths recognizable in the meteorites? And how have
they come to be mixed?
* Among the shergottites, many seemingly unrelated chemical and
isotopic parameters are strongly correlated: e.g., oxygen
fugacity, initial Sr and Nd isotope ratios, and La/Yb ratio.
These correlations suggest that the martian basalts are
mixtures of distinct chemical/isotopic components (rock types
or chemical reservoirs), the end members of which may not be
represented among the meteorites themselves. Do these
components represent mantle sources, crustal contaminants,
metasomatic influxes, or what?
* More than 10 years ago, it was shown that some radioisotope
parameters in the shergottites could be represented as
mixtures from several reservoirs, one of which is consistent
with the source material of the nakhlites. Can other
radioisotope systems be explained by these same components,
are different components required, or are additional
components required?
* The heavy noble gases in the martian meteorites are
interpretable as mixtures of discrete components, including
atmosphere, primitive mantle, and fractionated atmosphere.
Are these noble gas components associated with components
defined by other chemical and isotopic systems (e.g., an
atmospheric signature of high D/H and high D17O)?
* The bulk chemical compositions of some shergottite basalts
are represented well as mixtures of lherzolites and other
shergottites. Could this relationship imply that these
shergottites are impact melts?
* Shock melts in the shergottites can contain the high
concentrations of a surface component – the martian
atmosphere. Are other surface components detectable in the
shock melts or elsewhere in the meteorites? For instance, it
has been proposed that that shock melts contain traces of
regolith or dust. Can this be confirmed or extended? How else
might the martian meteorites retain clues to the nature of
martian regolith?
If these many proposed mixing components can be characterized, we
will gain insight into hidden aspects of martian geology and
geochemistry – hitherto unsampled rock types and/or poorly
characterized processes and geological environments. While
important to the petrologist and geochemist, this knowledge could
be useful in interpreting spacecraft data about Mars. For
instance, if mantle components can be defined, they will help in
interpreting geophysical data on the martian interior (as from the
MOLA and magnetometer instruments on MGS) by constraining the
chemical and thermal states of the mantle. If crustal and regolith
components can be recognized, they may be critical in interpreting
chemical and mineralogical data for the martian surface, as from
the TES instrument on MGS and the Gamma-Ray Spectrometer on Mars
Odyssey, or data obtained in situ at the surface by rovers such as
MER. In this way, unmixing the martian meteorites can strengthen
the ties between sample science and remote sensing science, and
further demonstrate the importance of laboratory sample analyses
to our deeper understanding of the solar system.
Through this LPI workshop, we seek to assemble experts and
researchers in martian geochemistry and petrology to share and
diversify their knowledge of martian meteorites and of Mars. Among
the questions we will consider are:
* How many chemical/isotopic components can be recognized, and
are some meteorites purely a single component?
* What are the chemical and isotopic characteristics that
define the different components?
* Do these components correspond to recognizable rock types or
processes?
* Do their chemical/isotopic characteristics suggest specific
geologic or tectonic settings?
* Are these components predicted by (or consistent with)
postulated events in Mars’ history, like a magma ocean, a
warm wet epoch, or mantle plumes?
Workshop Format
The intent of the workshop is to bring new and existing results on
chemical and isotopic components of the martian basalts to a
single forum through oral and poster presentations. We envision a
few invited talks, and many contributed talks with time scheduled
for minimally moderated discussion. Poster presentations will have
high visibility through short summary presentations and scheduled
time for viewing and discussion.
Abstracts are welcome from all disciplines related to the
chemical, isotopic, or petrologic characteristics of martian
basalts and their precursor components. Studies related to martian
meteorites are expected to dominate, but we welcome contributions
based on remote sensing data or in situ investigations.
Contingent on review, accepted abstracts will be published in a
referenceable abstract volume that will be distributed to workshop
participants. Given sufficient interest, the organizers will
arrange for a collection of papers derived from the workshop to be
published together in a peer-reviewed journal. The workshop
abstracts and preliminary program will also be available in
electronic format and will be posted on the meeting Web site on or
before August 30, 2002. These files will be in PDF format,
viewable with version 4.0 or higher of Adobe Acrobat Reader.
Call For Abstracts
The deadline for electronic submission of abstracts will be August
8, 2002.
Abstracts should not exceed two pages (including text, figures,
and tables). Abstracts should be submitted using the electronic
submission form by 5:00 p.m. August 8, 2002, U.S. Central Daylight
Savings Time (the abstract submission form will be available by
July 1, 2002). Abstracts can be submitted in a variety of formats.
Templates and detailed instructions for formatting and submitting
your abstract are provided.
Note that electronic submission of files is not always
instantaneous; gateways can be shut down temporarily, local
routers can fail, network traffic can be heavy, etc. Because your
file must be received at the LPI by 5:00 p.m. CDT, it is in your
best interest to submit early to allow for possible technical
problems or delays in transmission. Please DO NOT wait until the
last minute to access the system; access to the Web form will
terminate at 5:00 p.m. CDT.
Registration
A registration fee of $50.00 ($25.00 for students) is required of
each participant to cover catering and related costs. The
registration fee does not include meals, travel, lodging, etc. You
must register and pay by September 3, 2002, to avoid a late fee of
$15.
To preregister, please return the downloadable preregistration
form with your payment by September 3, 2002, or you may use the
electronic preregistration form if paying by credit card. Non-U.S.
participants who state on the preregistration form that they have
a currency exchange problem may pay in cash at the meeting and
avoid the late fee.
Hotel Reservations
Participants are responsible for making their own travel and hotel
reservations. For your convenience, we have provided a list of
local hotels and a local area map showing their locations.
Additional Information
For more information regarding the scientific objectives of this
workshop, contact one of the organizers listed at the top of this
announcement. For information regarding logistics, contact the LPI
meeting coordinator, Paula Walley (phone: 281-486-2144;
e-mail:walley@lpi.usra.edu). For more information regarding
abstracts, contact the LPI abstract coordinator, Reneé Dotson
(phone: 281-48-2188; e-mail:dotson@lpi.usra.edu).
