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Major Element Analyses of the Target Rocks at Meteor Crater, Arizona

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Major Element Analyses of the Target Rocks at Meteor Crater, Arizona NASA/TM-2002-210787 Major Element Analyses of the Target Rocks at Meteor Crater, Arizona Thomas H. See Lockheed-Martin Space Operations Houston, Texas Friedrich HSrz and David W. Mittlefehldt NASA Johnson Space Center Houston, Texas Laura Varley Lunar and Planetary Institute Houston, Texas Stan Mertzman Franklin & Marshall College Lancaster, Pennsylvania David Roddy United States Geological Survey Flagstaff, Arizona August2002 THE NASA STI PROGRAM OFFICE . IN PROFILE Since its founding, NASA has been • CONFERENCE PUBLICATION. dedicated to the advancement of Collected papers from scientific and aeronautics and space science. The NASA technical conferences, symposia, Scientific and Technical Information (STI) seminars, or other meetings sponsored Program Office plays a key part in helping or cosponsored by NASA. NASA maintain this important role. • SPECIAL PUBLICATION. Scientific, technical, or historical information from The NASA STI Program Office is operated NASA programs, projects, and mission, by Langley Research Center, the lead often concerned with subjects having center for NASA's scientific and technical substantial public interest. information. The NASA STI Program • TECHNICAL TRANSLATION. English- Office provides access to the NASA STI language translations of foreign Database, the largest collection of scientific and technical material aeronautical and space science STI in the pertinent to NASA's mission. world. The Program Office is also NASA's institutional mechanism for disseminating Specialized services that complement the the results of its research and development STI Program Office's diverse offerings activities. These results are published by include creating custom thesauri, NASA in the NASA STI Report Series, building customized databases, which includes the following report types: organizing and publishing research results.., even providing videos. • TECHNICAL PUBLICATION. Reports of completed research or a major For more information about the NASA STI significant phase of research that Program Office, see the following: present the results of NASA programs and include extensive data or • Access the NASA STI Program Home theoretical analysis. Includes Page at http://www.sti.nasa.gov compilations of significant scientific and technical data and information deemed • E-mail your question via the Internet to to be of continuing reference value. [email protected] NASA's counterpart of peer-reviewed formal professional papers but has less • Fax your question to the NASA Access stringent limitations on manuscript Help Desk at (301) 621-0134 length and extent of graphic presentations. • Telephone the NASA Access Help Desk • TECHNICAL MEMORANDUM. at (301) 621-0390 Scientific and technical findings that are preliminary or of specialized interest, • Write to: e.g., quick release reports, working NASA Access Help Desk papers, and bibliographies that contain NASA Center for AeroSpace Information minimal annotation. Does not contain 7121 Standard extensive analysis. Hanover, MD 21076-1320 • CONTRACTOR REPORT. Scientific and technical findings by NASA- sponsored contractors and grantees. NASA/TM-2002-210787 Major Element Analyses of the Target Rocks at Meteor Crater, Arizona Thomas H. See Lockheed-Martin Space Operations Houston, Texas Friedrich H6rz and David W. Mittlefehldt NASA Johnson Space Center Houston, Texas Laura Varley Lunar and Planetary Institute Houston, Texas Stan Mertzman Franklin & Marshall College Lancaster, Pennsylvania David Roddy United States Geological Survey Flagstaff, Arizona Lyndon B. Johnson Space Center National Aeronautics and Space Administration August 2002 Acknowledgements We greatly appreciate the support by D. Barringer and J. Shoemaker and their staff of the Meteor Crater Enterprises, Inc., Flagstaff, Arizona. Their participation made for pleasurable fieldwork. L. Varley gratefully acknowledges support for the XRD investigations by the Summer Intern Program of the Lunar and Planetary Institute, Houston, Texas. Dedication This report is dedicated to our co-author Dr. David J. Roddy (1932-2002), United States Geological Survey, Flagstaff, Arizona. David was an unselfish supporter of all Meteor Crater studies and he last climbed the walls of his beloved crater during the collection of this sample suite. We will remember him fondly as a respected colleague and dear friend who made profound contributions to the basic understanding of impact processes. Available from: NASA Center for AeroSpace Information National Technical Information Service 7121 Standard 5285 Port Royal Road Hanover, MD 21076-1320 Springfield, VA 22161 This report is also available in electronic form at http:lltechreports.larc.nasa.govlcgi-binlNTR Contents Page 1 ABSTRACT ................................................................................................................... .............................................. INTRODUCTION ............................................................. Procedures and Methods ........................................................................................... 3 3 Field Procedures .................................................................................................... ..... XRF Analysis ..................................................................................................... XRD Analyses ........................................................................................................ 6 Results ....................................................................................................................... 6 6 Bulk Composition ................................................................................................... Modal Composition ................................................................................................. 7 Examples of Data Utilization ...................................................................................... 9 Target Rocks and Impact Melts .............................................................................. 9 CO2 Loss From Carbonates During Hypervelocity Impact ................................... 11 Conclusions ..................................................... 12 14 References .............................................................................................................. Table Table 1. Composition of individual stratigraphic subsections at Meteor Crater and average compositions of the major geologic formations ................................ 18 Figures Figure 1. Summary plot of the major element concentrations, normalized to a volatile-free basis, of the target rocks at Meteor Crater, AZ .............................. 19 Figure 2. Correlation plot of CaO + MgO versus total loss-on-ignition (LOI) for the 12 Kaibab samples summarized in Table 1 ............................................... 20 Figure 3. Modal content (wt %) of quartz in the Kaibab Formation at Meteor Crater, AZ, based on XRD studies ........................................................... 21 Figure 4. Comparison of the measured SiO2, MgO, and CaO contents (wt %) of 12 Kaibab subsections based on XRF and comparison with stoichiometric calculations using the modal abundance of quartz and dolomite from XRD ........ 22 Figure 5. Comparison of the major-element composition of the target rocks and impact melts at Meteor Crater, AZ ........................................................................ 23 ..° III iv ABSTRACT We collected ~ 400 rock chips in continuous vertical profile at Meteor Crater, Arizona, representing---from bottom to top--the Coconino, Toroweap, Kaibab, and Moenkopi Formations. These rock chips were subsequently pooled into 23 samples for compositional analysis by X-ray fluorescence methods, each sample reflecting a specific stratigraphic "subsection" - 5-10 m thick. In addition, the modal abundance of quartz, dolomite, and calcite was determined for the entire Kaibab Formation at vertical resolutions of 1-2 meters using 57 samples. The purpose of these investigations was to support ongoing compositional analyses of the impact melts and their stratigraphic source depth(s) and other studies at Meteor Crater that depend on the composition of the target rocks. The Coconino Formation comprises the lower half of the crater cavity, from - 90 m below the original target surface to the bottom of the crater. It is an exceptionally pure sandstone composed of > 97 wt % SiO2. The Toroweap is only 2 m thick and compositionally similar to Coconino; therefore, it is not a good compositional marker horizon. The Kaibab Formation, ~ 80 m thick, is highly variable in SiO2, MgO, and CaO. On a CO2-free basis, the average Kaibab contains 53 wt % SiO2, 16 wt % MgO, and 26 wt % CaO. X-ray diffraction studies show that the Kaibab Formation at Meteor Crater is dominated by dolomite and quartz, albeit in highly variable proportions; calcite is a minor phase at best. The Kaibab at Meteor Crater is therefore a sandy dolomite rather than a limestone, consistent with pronounced facies changes in the Permian of southeast Arizona over short vertical and horizontal distances. The Moenkopi forms the 12-m-thick cap rock and is a calcareous silt that has the highest AI203 (~ 7.5 wt %) and FeO (~ 4 wt %) concentrations of all target rocks. With several examples, we illustrate how this systematic compositional and modal characterization of the target lithologies may contribute to an understanding of Meteor Crater, such as the depth of its melt zone, and to impact cratering in general, such as the liberation
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