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Home , Life on Mars, Martian meteorite

Vol. 7, No. 7 July 1997 INSIDE • Call for Editors, p. 15 GSA TODAY • Employment Service, p. 21 • 1997 GSA Annual Meeting, p. 28 A Publication of the Geological Society of America Evidence for in a ?

Harry Y. McSween, Jr. Department of Geological Sciences, University of Tennessee, Knoxville, TN 37996

ABSTRACT The controversial hypothesis that the ALH84001 mete- orite contains relics of ancient martian life has spurred new findings, but the question has not yet been resolved. probably results, at least in part, from terrestrial contamination by Antarctic ice meltwater. The origin of nanophase and sulfides, suggested, on the basis of their sizes and morphologies, to be biogenic remains con- tested, as does the formation temperature of the carbonates that contain all of the cited evidence for life. The reported nanofossils may be whiskers and platelets, proba- bly grown from a vapor. New observations, such as the possi- ble presence of and shock metamorphic effects in the carbonates, have not yet been evaluated. Regardless of the ultimate conclusion, this controversy continues to help define strategies and sharpen tools that will be required for a exploration program focused on the search for life.

INTRODUCTION Since the intriguing proposal last summer that martian mete- orite Allan Hills (ALH) 84001 contains biochemical markers, bio- genic minerals, and microfossils (McKay et al., 1996), scientists and the public alike have been treated to a variety of claims sup- porting or refuting this hypothesis. Occasionally, the high visibil- ity of the controversy has overshadowed the research effort (e.g., Begley and Rogers, 1997), but I believe that will benefit significantly from this experience. If the hypothesis is confirmed, Figure 1. Mars is thought to be the of a dozen igneous it will rank among the major discoveries of all time. If not, McKay (). The ALH84001 was recovered in and his colleagues have still demonstrated that microparticles, - in 1984, but it was not recognized as a martian sample until uble minerals, and possibly organic matter can survive on the red a decade later. This orthopyroxene cumulate (cube is 1 cm) is planet for billions of , which provides a hopeful outlook for a crosscut by fracture zones (see thin section view; long axis is ~0.5 cm), focused on the search for life. within which tiny carbonate globules were deposited. The carbonate grains are associated with organic matter and contain microparticles This article reviews recently published research bearing on suggested to be martian nanofossils and biogenic minerals. this important topic. Most of this literature exists only as confer- Photographs courtesy of NASA. ence abstracts and technical comments in scientific journals. There seems to be virtually no argument, at least within the plane- tary science community, that ALH84001 is a sample of the ancient (~4.5 Ga) martian (e.g., Mittlefehldt, 1994; McSween, 1994; a sample containing ~1 ppm PAHs ranks as a triumph of analyti- Clayton and Mayeda, 1996; Goswami et al., 1997). This ultramafic cal ingenuity. Although PAHs do not play a significant role in the (Fig. 1) is crosscut by zones containing small of terrestrial , they can form by geochem- carbonate grains, which are the hosts for organic matter as well as ical transformation of certain hydrocarbons present in decayed reported biogenic materials and microfossils. This article addresses organisms. PAHs also form by abiotic processes such as the and expands upon the four lines of evidence for possible biologic combustion of fuels, and they are common constituents activity cited by McKay et al. (1996). of chondritic meteorite kerogens (Zenobi et al., 1989). Anders (1996) noted that PAHs are produced by pyrolosis (thermal ORGANIC MATTER decomposition) whenever graphite formation is kinetically inhib- McKay et al. (1996) described fused hydrocarbon rings (poly- ited. He further pointed out that the “few specific PAHs” from C14 cyclic aromatic hydrocarbons, or PAHs) associated with the car- bonates in ALH84001. The identification of specific molecules in Meteorite continued on p. 2 IN THIS ISSUE GSA TODAY July Vol. 7, No. 7 1997 Evidence for Life in a Research and Fellowship Opportunities ..... 19 ...... 1 Officers and Past Chairs of GSA TODAY (ISSN 1052-5173) is published In Memoriam ...... 2 Sections and Divisions ...... 20 monthly by The Geological Society of America, Inc., Correction ...... 2 GSA Employment Service ...... 21 with offices at 3300 Penrose Place, Boulder, Colorado. GSAF Update ...... 6 AIPG Becomes Associated Society ...... 21 Mailing address: P.O. Box 9140, Boulder, CO 80301- 9140, U.S.A. Periodicals postage paid at Boulder, Col- Rock —Florence Bascom ...... 8 July Bulletin and Geology Contents ...... 24 orado, and at additional mailing offices. Postmaster: Penrose Conference Scheduled ...... 10 Environmental & Engineering Send address changes to GSA Today, Membership Ser- Washington Report ...... 11 Geoscience Contents ...... 25 vices, P.O. 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STAFF: Prepared from contributions from the GSA staff and membership. Executive Director: Donald M. Davidson, Jr. Meteorite continued from p. 1 technique similar to that used by McKay Science Editors: Suzanne M. Kay, Department of Geo- et al. (1996) for ALH84001. EETA79001 logical Sciences, Cornell University, Ithaca, NY 14853; Molly F. Miller, Department of Geology, Box 117-B, to C22 in ALH84001 suggested to be bio- also contains a low- assortment of Vanderbilt University, Nashville, TN 37235 genic by McKay et al. (1996) comprise all unalkylated PAHs with from C14 to Forum Editor: Bruce F. Molnia homologs in this number range, C , as well as a weaker high-mass enve- U.S. Geological Survey, MS 917, National Center, 22 Reston, VA 20192 and thus do not require a selective (biolog- lope. The abundance of PAHs (~1 ppm) is Managing Editor: Faith Rogers ical) source. Clement and Zare (1996) similar to that in ALH84001, although the Production & Marketing Manager: James R. countered that differences in alkylation relative proportions of specific PAHs Production Editor and Coordinator: Joan E. Manly Graphics Production: Joan E. Manly, Leatha L. Flowers (the addition of side chains) of the low- inferred from the spectra are slightly dif- mass and high-mass envelopes of the ferent, possibly resulting from differences ADVERTISING: Classifieds and display: contact PAHs suggest both low- and high-tempera- in ionization efficiencies for the distinct Ann Crawford (303) 447-2020; fax 303-447-1133; ture processing, which might arise through laser wavelengths used in the analyses. [email protected] diagenesis of decomposed biologic matter. Becker et al. (1997) also performed experi- Issues of this publication are available as electronic Bell (1996) suggested that abiotic PAHs ments demonstrating that PAHs are selec- Acrobat files for free download from GSA’s Web Site. They can be viewed and printed on various personal could have accreted to Mars as constitu- tively adsorbed onto carbonate. This find- computer operating systems: MSDOS, MSWindows, ents of organic-rich impactors, ing, along with the determination that the Macintosh, and Unix, using the appropriate Acrobat several of which still remain in martian assortment of PAHs in both martian mete- reader. The readers are widely available, free, including from GSA at: http://www.geosociety.org/pubs/index.htm. orbit as the moons and . orites is similar to that measured in This publication is included on GSA’s annual CD-ROM, New research has focused mostly on Antarctic ice, suggests that the PAHs in GSA Journals on Compact Disc. Call GSA Publication characterization of the organic matter in both meteorites may result from organic Sales for details. EETA79001, another martian meteorite contamination by ice meltwater. On the Printed in U.S.A., using pure soy inks and recyclable found in Antarctica. Becker et al. (1997) paper. extracted PAHs using a laser ionization Meteorite continued on p. 3

2 GSA TODAY, July 1997 Meteorite continued from p. 2 magnetite morphologies in this meteorite distribution and random arrangement, would imply a rich community of organ- and were argued to be similar in size and basis of the low abundances of PAHs in isms. Bradley et al. (1996) suggested that morphology to magnetites in ALH84001 ice, et al. (1997a) suggested that the whisker morphologies containing carbonates. the quantity of meltwater that would have internal structural defects (Fig. 2) and McKay et al. (1996) suggested that to be flushed through the meteorite was twins are unlike the characteristics of bio- tiny grains of pyrrhotite inside the carbon- prohibitive; however, Antarctic meteorites genic magnetite. Thomas-Keprta et al. ates in ALH84001 may have formed by are sometimes found in puddles, and (1997) noted that twinning does some- sulfate-respiring . Biogenic sulfides evaporation of this water would concen- times occur in biologically induced mag- typically contain isotopically light , trate PAHs. The presence of optically netite, and that at least one bacterium is as terrestrial bacteria preferentially utilize active amino acids (almost exclusively known to produce magnetite rods, 32S in making excreted sulfide. Small L-enantiomers, the same forms found in although the specific dislocations seen in grains of occurring outside the car- terrestrial proteins) in EETA79001 ALH84001 magnetite whiskers have not bonates in ALH84001 have been inferred, (McDonald and Bada, 1995) supports the yet been observed in biogenic grains. on the basis of textural criteria, to have idea of organic contamination in the polar Magnetotactic bacteria string - coprecipitated with carbonate (although environment, and the measured carbon lographically oriented magnetite grains Gibson et al. [1996] suggested that these isotopic compositions of organic matter in together into chains (magnetosomes; Fig. were unrelated to the sulfides within car- both meteorites (δ13C = –22‰ to –25‰; 2) that increase the net magnetic moment, bonates). Measured sulfur isotopic compo- Wright et al., 1989; Grady et al., 1994) are used for sensing Earth’s geomagnetic field. sitions of the pyrite grains (δ34S = +2‰ to indistinguishable from terrestrial values. Thomas-Keprta et al. (1997) interpreted +8‰; Shearer et al., 1996; Greenwood et The carbon isotopic composition of the five or six aligned cuboid particles in al., 1997) appear to be inconsistent with carbon source (presumably the atmo- ALH84001 as a possible magnetosome, but biologic formation, unless the sulfate pre- sphere, with δ13C = ~ +40‰) implies a without data on crystallographic orienta- cursor was extremely isotopically heavy, fractionation of >60‰ between it and tions of the grains or evidence for the for- the supply of sulfate was limited, or mar- organic matter (Grady et al., 1996). Iso- mer existence of an organic membrane tian organisms utilized sulfur via different topic effects of this magnitude on Earth holding the chain together. However, the biochemical pathways. require a complex community of organ- preservation of intact fossil magnetosomes McKay et al. (1997) recently proposed isms that includes -producing is uncommon (Chang and Kirschvink, yet another kind of biogenic material in bacteria and methylotropic bacteria that 1989). ALH84001—lacy network structures in convert methane into biomass. Such an Magnetotactic bacteria produce mag- acid-etched carbonates and interpretation for ALH84001 depends on netite within their cells, but some other which resemble microbially secreted the assumption that both the atmosphere terrestrial bacteria form extracellular mag- organic polymers (biofilms). Although and organic matter equilibrated with the netite (Stolz et al., 1990). Vali et al. (1997) they contain carbon, an organic composi- same fluid. A previous announcement of described extracellular magnetite pro- tion for these curious structures has not even more extreme carbon isotopic frac- duced in the laboratory by thermophilic yet been established. tionation in ALH84001 carbonate (widely bacteria; the diamond-shaped grains in reported in the British press as evidence these cultures show a wide range in size Meteorite continued on p. 4 for life) can now be explained as possible laboratory contamination (Wright et al., 1997b).

BIOGENIC MATERIALS Another line of evidence for life in ALH84001 cited by McKay et al. (1996) is the presence within carbonates of nanophase magnetite grains morphologi- cally similar to those produced by terres- trial magnetotactic bacteria. Coexisting sulfides (pyrrhotite and greigite were ten- tatively identified) within the carbonates were also suggested to be biogenic. McKay et al. (1996) argued that coprecipitation of magnetite and sulfides, with concomitant dissolution of carbonate (inferred from its porous microtexture), indicates disequilib- rium and thus points to biologic media- tion. The geochemical basis for this argu- ment has been criticized by Anders (1996) and Browning and Bourcier (1997). Bradley et al. (1996) presented trans- mission electron microscopic images of a variety of tiny magnetite whiskers (rods and ribbons) and platelets in ALH84001 carbonates, adding to the assortment of Figure 2. TEM images of single-domain magnetite grains within ALH84001 carbonates and in magne- cuboid, teardrop, and irregular grains totactic bacteria. a: Chains of crystallographically oriented nanophase magnetites in Magnetococcus bac- described by McKay et al. (1996). The terium are linked by lipid membranes (scale bar is 100 nm; from Stolz et al., 1990). b: Well-formed mag- morphologies of bacterially produced netite platelet in ALH84001 appears morphologically similar to some biogenic magnetites. c: Magnetite magnetite grains are generally species- whisker in ALH84001 contains an axial screw dislocation, indicative of spiral growth, probably from a specific (Bazylinski, 1995), so the diverse vapor. Lattice fringe orientations on either side of the dislocation (marked by white lines) are distinct. Platelet and whisker images from John Bradley (MVA, Inc.).

GSA TODAY, July 1997 3 Meteorite continued from p. 3 The nanofossil controversy, although (McKay and Lofgren, 1997). Romanek et important in itself, may possibly be moot al. (1994) used the oxygen isotopic com- NANOFOSSILS in the case of ALH84001. Bradley et al. positions of carbonates, determined from (1997) proposed that the magnetite an acid dissolution model, to argue that Perhaps the most exciting suggestion whiskers and platelets they observed in they formed by reaction with aqueous flu- by McKay et al. (1996) was that tiny carbonates are the nanofossils described ids at temperatures <80 °C. Hutchins and “ovoid and elongated forms” in by McKay et al. (1996). No other Jakosky (1997) revised the carbonate for- ALH84001 carbonates were nanofossils. microparticles with the sizes and mor- mation temperatures to <250 °C on the Examination of uncoated microparticles in phologies of the nanofossils have been basis of a model of atmospheric fractiona- ALH84001 using atomic force microscopy observed in the carbonates, and fields tion of oxygen and carbon prior to incor- (Steele et al., 1997) demonstrates that they of oriented magnetite whiskers resemble poration in carbonates. New micro- are not artifacts of sample preparation. published SEM images of nanofossils (Fig. probe analyses of oxygen in Although some microparticles in terrestrial 3). The spiral growth mechanism deduced carbonate globules indicate highly vari- carbonates have been described as nano- from the presence of axial screw disloca- able compositions. In particular, Valley (e.g., Folk, 1993), the evidence is tions in magnetite whiskers (Bradley et al., et al. (1997) reported δ18O = +9.5‰ to exclusively morphological, and the 1996) argues against replacement of 20.5‰, whereas Leshin et al., 1997 indi- hypothesis remains controversial. by magnetite. cated values of +5.6‰ to +21.6‰. Valley The microparticles described as et al. (1997) argued that precipitation of nanofossils in ALH84001 are generally CONDITIONS OF carbonates with these compositions sug- 30 to 150 nm in longest dimension, sig- CARBONATE FORMATION gests nonequilibrium processes at tem- nificantly smaller than terrestrial microor- peratures <300 °C. Leshin et al. (1997) ganisms. Only viral symbionts and The documentation of terrestrial explained a correlation of carbonate that cannot be recultured are commonly and martian microfossils and mineral chemistries with oxygen isotopes of this size. The internal volumes of these requires, among other criteria, that the (Fig. 4) as possibly resulting from high- microparticles are commonly thought by paleoenvironment be a plausible one for temperature processes. biologists to be too small to hold sufficient biological activity (e.g., Knoll and Walter, Harvey and McSween (1996) noted organic solute molecules to carry out the 1996). Thus, understanding the formation that the apparent absence of hydrous phyl- required metabolic and genetic functions conditions of the ALH84001 carbonate losilicates in ALH84001 was inconsistent (e.g., Morowitz, 1996). However, it is globules, which are the containers for vir- with reaction of an aqueous hydrothermal plausible that starved bacteria could tually all of the evidence cited for life, is fluid with an host rock. have shrunk prior to their encapsulation critical to the argument. Terrestrial organ- They favored a high-temperature reaction within the carbonates. Thomas-Keprta isms survive at temperatures generally involving a CO -rich, supercritical fluid. et al. (1997) sidestepped the size issue by below 120 °C, and it seems unlikely that 2 Thomas-Keprta et al. (1997) described suggesting that elongated filaments in extraterrestrial biota could exist at temper- several nanometer-sized grains with basal ALH84001 may be discarded bacterial atures far in excess of this value. Con- spacings of 10–11 Å, which they inter- appendages. straining the temperature of formation for preted as smectites. Such grains appear the carbonates has proved to be the most to be rare. Valley et al. (1997) described contentious subject to date. terrestrial carbonate veins that formed Globular carbonates in ALH84001 at low temperatures from aqueous fluids are chemically zoned (Fig. 4), with calcite- without producing hydrous minerals. ankerite cores and magnesite-siderite rims Comparisons of ALH84001 carbonate (Harvey and McSween, 1996). Granular elemental compositions and phase equi- carbonates are compositionally similar to globule cores and are concentrated in pockets and veins throughout the rock Meteorite continued on p. 5

Figure 4. Backscattered electron image (above) of a zoned carbonate globule shows a core of calcite- ankerite (gray) and rim of magnesite (black)-siderite (white) (horizontal axis figure is ~150 µm; courtesy of David Mittlefehldt, Lockheed-Martin Engineering Science Services). Some carbonates have been frac- tured and disaggregated by shock. Elemental and oxygen isotopic compositional variations (from Harvey Figure 3. Comparison of an SEM image of and McSween [1996] and L. Leshin [personal commun.], respectively) are illustrated in the figure below. putative nanobacteria in ALH84001 carbonates The 700 °C phase boundaries are from Anovitz and Essene (1987); carbonate analyses bridging the gap (above) and a TEM image of oriented magnetite between ankerite and siderite represent points overlapping several grains. Chemical zoning in carbon- whiskers in carbonates (below). Photomicrographs ates has been cited as evidence for disequilibrium between zones, but the correlation between calcium courtesy of NASA and John Bradley (MVA, Inc.), content and oxygen isotopic composition may also be rationalized by closed-system fractionation within respectively. a fluid-poor system.

4 GSA TODAY, July 1997 Meteorite continued from p. 4 libria, suggesting formation temperatures THE OF of >650 °C (Mittlefehldt, 1994; Harvey and McSween, 1996), have been criticized by MAGMATISM IN THE some workers (McKay and Lofgren, 1997; Shearer et al., 1996; Treiman, 1997; Valley APPALACHIAN OROGEN et al., 1997), who stressed that extensive edited by A. Krishna Sinha, Joseph B. Whalen zoning and isotopic heterogeneity make and John P. Hogan, 1997 any attempt to use mineral-exchange geothermometry suspect. Disequilibrium The thermal evolution of mountain belts is would presumably also invalidate temper- commonly recorded in the distribution, origin, ature constraints imposed by stable iso- and ages of magmatism. In this volume, 20 tope fractionation (Romanek et al., 1994; contributors present the latest petrological, Leshin et al., 1997). Kinetic control of isotopic, and geochemical evidence to highlight growth might offer an explanation as to why different lines of evidence suggest the contribution of igneous rocks to the evolution distinct formation conditions. of the Appalachian orogen in both Canada and Several other assessments of tempera- the United States. These papers emphasize the ture have reached conflicting conclusions. use of modern geochemical and petrologic data The assemblage of tiny magnetite whiskers to discriminate the sources yielding , and platelets described in ALH84001 car- bonates by Bradley et al. (1996) resemble and thus the nature of the crust and mantle. The grains of many substances condensed wealth of data available in this work provides a significant stepping-stone to more from vapors, and the spiral growth mecha- rigorous interpretation of the assembly and origin of the Appalachian orogen. nism documented for some magnetite MWR191, 438 p., indexed, ISBN 0-8137-1191-6, $135.00, GSA Members $108.00 whiskers (Fig. 2) is consistent with vapor- phase growth. Natural magnetite whiskers have been described in terrestrial volcanic 1-800-472-19881-800-472-1988 fax 303-447-1133 • www.geosociety.org sublimates and grown experimentally Publication Sales • P.O. Box 9140 • Boulder, CO 80301 • 303-447-2020 Memoir volumes are from hot (<800 °C) fumarole gases. 8-1/2" x 11" hardbound. Kirschvink et al. (1997) marshaled PRICES INCLUDE SHIPPING AND HANDLING magnetic evidence in support of a low- temperature origin of ALH84001 carbon- ates. From a breccia zone they separated two joined orthopyroxene grains, one of phism synchronous with or postdating ers will disagree. Even if some martian which contained carbonate globules on its carbonate formation implies that, how- organic matter is present, it may be impos- surface. Each grain had stable ever the carbonates in ALH84001 formed, sible to disentangle its properties from the natural remnant magnetization (NRM) they must have undergone significant apparent overprint of terrestrial contami- with directions differing by 50° to 80°. temperature excursions. nation. The mineralogical characterization These researchers concluded that the of the nanofossils as magnetite whiskers grains were not significantly heated after CONCLUSIONS AND OUTLOOK and platelets requires independent confir- rotation in the breccia zone. Since the car- mation. Before we can constrain the tem- The question of whether ALH84001 bonates precipitated from fluids percolat- perature of formation of the carbonates, it contains evidence for early martian life ing through this crushed zone at some will be necessary to ascertain whether they remains unresolved. Part of the difficulty later time, they must have formed at low formed by equilibrium or disequilibrium in addressing this problem relates to the temperature. The NRM temperature con- processes. In any case, the recognition highly interdisciplinary nature of the argu- straint assumes that no rotation of grains that shock has affected this meteorite after ments, involving complex and sometimes occurred after carbonate formation. How- carbonate formation suggests that the arcane aspects of , igneous and ever, the carbonate globules themselves temperature history of the carbonates was carbonate , , are sometimes fractured and fragmented more complex than has been appreciated. and micropaleontology, (Fig. 4), allowing the possibility that asso- More studies of the morphology, structure, organic chemistry, shock metamorphism, ciated pyroxene grains were rotated by and chemistry of proposed biominerals hydrogeology, and paleomagnetism. shock following carbonate formation. and biofilms in ALH84001 are necessary Another difficulty derives from the fact Scott et al. (1997) described shock- before the origin of these materials can be that we do not commonly observe and melted veins of plagioclase and silica specified. analyze rocks or, for that matter, fossilized glasses containing carbonate in Regardless of whether or not or living organisms at these scales. As a ALH84001. They envisioned the carbon- ALH84001 is ultimately judged to contain result, there are not enough studies of ates having formed at high temperatures relics of ancient martian organisms, the terrestrial analogs to allow adequate inter- during an . Their sample report of McKay et al. (1996) has focused pretations of the data. There is now a seri- apparently did not contain the carbonate scientists’ concentration (not to mention ous attempt to supplement the terrestrial globules studied by McKay et al. (1996), the attention of the rest of the world) on database with studies at these scales but chemical zoning patterns suggest that the possibility of . Mars (e.g., Allen et al., 1997; Vali et al., 1997). these carbonates were part of the same is the most Earthlike of planets, and it is My own assessment is that two of the generation. McKay and Lofgren (1997) certainly within the realm of possibility four lines of evidence cited by McKay et al. likewise noted the presence of feldspathic that it once harbored microorganisms. (1996)—the presence of extraterrestrial glass, but their observation that the glass NASA’s planned Mars exploration program organic matter and of nanofossils in intrudes carbonate globules argues that will directly address the question of life, ALH84001—have been seriously chal- shock melting postdated carbonate forma- lenged and possibly refuted, although oth- tion. The observation of shock metamor- Meteorite continued on p. 6

GSA TODAY, July 1997 5 GSAF UPDATE

Valerie G. Brown, Director of Development, GSA Foundation

From the Ground Up Revenue 1992–1995 1996 1997 Total In May, we reported on the 1996 Second Century Fund fund-raising results. The accompanying Members $2,278,375 $ 262,313 $ 50,816 $2,591,505 chart shows the cumulative fund-raising Other Individuals $ 1,300 $ 3,226 $ 200 $ 4,726 results from the inception of the Second Government $ 544,512 $ 594,869 $ 0 $1,139,381 Century Fund campaign in 1992 to the Foundations $ 513,165 $ 16,000 $ 10,000 $ 539,165 end of April 1997, summarizing both the Industry $ 693,500 $ 74,712 $ 500 $ 768,712 total gifts received and the sources of the Annual Campaign $ 480,391 $ 104,522 $ 8,746 $ 593,659 gifts. The revenues include cash, pledges, Pardee Bequest $2,677,309 $2,677,309 program grants, and deferred gifts, reflect- Total Revenues $7,188,552 $1,055,642 $ 70,262 $8,314,457 ing the considerable variety not only of those who support GSA but also of the ways in which support can be given. sity of Queensland in Australia. He came The GSA Foundation is truly fortu- to the United States in 1977 as a senior nate to be the beneficiary of such excel- geologist for Superior Oil’s Minerals Divi- lence and experience. Dummett Joins sion. Since 1989, Dummett has been affili- Foundation Board ated with BHP Minerals, where he now serves as senior vice president and group A Milestone The GSA Founda- general manager of the Exploration Since beginning the program in 1988, tion is honored to Group. the GSA Foundation has awarded over welcome Hugo T. Dummett’s contributions to his pro- $125,500 to the GSA sections for match- Dummett as its fession have been equally wide-ranging. He ing student travel grants. Each year, the newest trustee. is a member of the Association of Explora- grants assist college students to attend A member of GSA tion Geochemists, the Society of Economic the section meetings and GSA’s Annual since 1985, Dummett Geologists, which named him as the 1996 Meeting. In 1997, the Foundation has established an Thayer Lindsley Distinguished Lecturer, increased the amount of its awards important career and the American Institute of Mining Engineers, to $4,000 per section. reputation in miner- the Geological Society of South Africa, and The awards are paid from the un- als exploration. the USGS resource program advisory board restricted gifts GSA members make to the A graduate of South Africa’s Univer- to the National Academy of Sciences. In Foundation. This is another important sity of Witwatersrand, Dummett worked 1997, he was awarded the William L. Saun- benefit made possible by your in South Africa and Canada before pursu- ders Medal by the Society for Mining, generosity! ■ ing postgraduate education at the Univer- Metallurgy and Exploration.

Meteorite continued from p. 5 Begley, S., and Rogers, A., 1997, War of the worlds: Gibson, E. K., Jr., McKay, D. S., Thomas-Keprta, K. L., Newsweek, v. 129, no. 6, p. 56–58. and Romanek, C. S., 1996, Response to technical com- ment: Science, v. 274, p. 2125. among other topics, over the next decade. Bell, J. F., 1996, Technical comment: Science, v. 274, p. 2121–2122. Goswami, J. N., Sinha, N., Murty, S. V. S., Mohapatra, The controversy about possible biological R. K., and Clement, C. J., 1997, Nuclear tracks and light Bradley, J. P., Harvey, R. P., and McSween, H. Y., Jr., noble gases in : Preatmospheric size, activity in a martian meteorite is allowing 1996, Magnetite whiskers and platelets in the fall characteristics, cosmic-ray exposure duration and the scientific community to reexamine its ALH84001 martian meteorite: Evidence of vapor phase formation age: & , v. 32, growth: Geochimica et Cosmochimica Acta, v. 60, thinking and hone its skills for that effort. p. 91–96. p. 5149–5155. Grady, M. M., Wright, I. P., Douglas, C., and Pillinger, Bradley, J. P., Harvey, R. P., and McSween, H. Y., Jr., ACKNOWLEDGMENTS C. T., 1994, Carbon and in ALH84001 (abs.): 1997, Magnetite whiskers and platelets in the Meteoritics, v. 29, p. 469. I appreciate thoughtful and construc- ALH84001 martian meteorite: Evidence of vapor phase growth (ab.): Lunar and Planetary Science, v. 28, Grady, M. M., Wright, I. P., and Pillinger, C. T., 1996, tive reviews by Peter Buseck, Andy Knoll, p. 147–148. Opening a martian can of worms?: Nature, v. 382, p. 575–576. and John Valley. Browning, L. B., and Bourcier, W. L., 1997, Did the porous carbonate regions in ALH84001 form by low Greenwood, J. P., Riciputi, L. R., and McSween, REFERENCES CITED temperature inorganic processes? (ab.): Lunar and Plan- H. Y., Jr., 1997, Sulfur isotopic variations in sulfides etary Science, v. 28, p. 161. from shergottites and ALH84001 determined by ion Allen, C. C., Thomas-Keprta, K. L., McKay, D. S., and microprobe: No evidence for (abs.): Lunar Chang, S.-B. R., and Kirschvink, J. L., 1989, Magnetofos- Chafetz, H. S., 1997, Nanobacteria in carbonates (abs.): and Planetary Science, v. 28, p. 459–460. Lunar and Planetary Science, v. 28, p. 29–30. sils, the magnetization of sediments, and the evolution of magnetite biomineralization: Annual Review of Earth Harvey, R. P., and McSween, H. Y., Jr., 1996, A possible Anders, E., 1996, Technical comment: Science, v. 274, and Planetary Sciences, v. 17, p. 169–195. high-temperature origin for the carbonates in the mar- p. 2119–2120. tian meteorite ALH84001: Nature, v. 382, p. 49–51. Clayton, R. N., and Mayeda, T. K., 1996, Oxygen iso- Anovitz, L. M., and Essene, E. J., 1987, Phase equilibria tope studies of achondrites: Geochimica et Cosmochim- Hutchins, K. S., and Jakosky, B. M., 1997, Carbonates in in the system CaCO3-MgCO3-FeCO3*: Journal of Petrol- ica Acta, v. 60, p. 1999–2017. martian meteorite ALH84001: A planetary perspective ogy, v. 28, p. 389–414. on formation temperature: Geophysical Research Let- Clement, S. J., and Zare, R. N., 1996: Response to tech- ters (in press). Bazylinski, D. A., 1995, Structure and function of the nical comment: Science, v. 274, p. 2122–2123. bacterial magnetosome: ASM News, v. 61, p. 337–343. Kirschvink, J. L., Maine, A., and Vali, H., 1997, Paleo- Folk, R. L., 1993, SEM imaging of bacteria and nanobac- magnetic evidence of a low-temperature origin of car- Becker, L., Glavin, D. P., and Bada, J. L., 1997, Poly- teria in carbonate sediments and rocks: Journal of Sedi- bonate in the martian meteorite ALH84001: Science, cyclic aromatic hydrocarbons (PAHs) in Antarctic mar- mentary Geology, v. 63, p. 990–999. tian meteorites, carbonaceous and polar ice: v. 275, p. 1629–1633. Geochimica et Cosmochimica Acta, v. 61, p. 475–481. Meteorite continued on p. 7

6 GSA TODAY, July 1997 Donors to the Foundation— GSA Foundation March and April 1997 Digging Up P.O. Box 9140 the Past Boulder, CO 80301 (303) 447-2020 • [email protected] Biggs Excellence J. Hoover Mackin Most memorable in Earth Science Award early geologic Education Fund Joseph A. Mason experience: Enclosed is my contribution in the amount of Laurel Pringle Goodell Minority Fund “Never having seen $______. Blechschmidt Fund Frederic H. Wilson my Ph.D. thesis area, Please add my name to the Century Plus Roster Xerox Corporation, USA* the first sight of (gifts of $150 or more). Research Fund snow capped Doris M. Curtis Richard W. Please credit my gift to the Ruby-East Memorial Allmendinger ______Fund. Humboldt Range Grover & Sally E. Murray David J. Borns made me gasp, PLEASE PRINT (in memory of Dorothy Yehuda Eyal ‘It’s mine all Jung Echols & Chilton E. Paul F. Hoffman mine!’” Name ______Prouty) K. Aubrey Hottell Gregory K. Middleton Address ______John T. Dillon Alaska —Robert P. Jeanette M. Sablock Scholarship Award Sharp City/State/ZIP ______Elizabeth L. Miller SAGE Wolfgang H. Berger Phone ______Dwornik Planetary Thomas C. Davenport Geoscience Award Jonathan D. Fernald Joseph M. Boyce Pamela P. Fisco Richard D. Harvey Unrestricted— Asahiko Taira GEOSTAR Peter A. Nielsen Cornelius S. Hurlbut, Jr.* Foundation Manuel Tello-B* Manuel Tello-B* David A. Stephenson* Frederick L. Klinger Andrew G. Alpha Richard I. Walcott Jeffrey M. Krempasky Stanton N. Ballard Dean G. Wilder Hydrogeology Second Century Fund Howard & Jean Lipman W. Berry, Jr.* Garrett E. Zabel Division Award Barbara A. Bekins Foundation* Byrl D. Carey, Jr. David A. Stephenson* Larry S. Bowlds Unrestricted—GSA Garry D. McKenzie Norman Bayne Cranford Frank A. Campini Brian G. Anderson IEE John Montagne John F. Jefferson-Squibb Foundation* Darinka Zigic Briggs Thomas C. Davenport Jon Olsen John A. Larson William W. Craig Laurel Pringle Goodell Anthony H. Fleming Orrin H. Pilkey Eric A. Lauha Charles C. Daniel III Alan D. Hoagland David A. Stephenson* Prentice Hall* John N. Louie Gordon P. Eaton* Louis S. Hochman Charles Marsh Christopher Anne Suczek V. Standish Mallory Swapan S. Ghosh Lloyd W. Staples Woodruff, Jr. Peter K. Matthews Harold T. Stearns Manuel Tello-B* Philip Oxley* Fellowship Award Dean G. Wilder *Century Plus Roster (gifts of $150 or more) Dominic A. Perruccio Harmon Craig*

Meteorite continued from p. 6 Morowitz, H. J., 1996, Technical comment: Science, Valley, J. W., Eiler, J. M., Graham, C. M., Gibson, v. 273, p. 1639–1640. E. K. Jr., Romanek, C. S., and Stolper, E. S., 1997, Low- temperature carbonate concretions in the martian Knoll, A. H., and Walter, M. R., 1996, Evolution of Romanek, C. S., Grady, M. M., Wright, I. P., Mittle- meteorite, ALH84001: Evidence from stable isotopes hydrothermal ecosystems on Earth (and Mars?): Chich- fehldt, D. W., Socki, R. A., Pillinger, C. T., and Gibson, and mineralogy: Science, v. 275, p. 1633–1637. ester, UK, Wiley, p. 198–213. E. K., Jr., 1994, Record of fluid-rock interactions on Mars from the meteorite ALH84001: Nature, v. 372, Vali, H., Zhang, C., Sears, S. K., Lin, S., Phelps, T. J., Leshin, L. A., McKeegan, K. D., and Harvey, R. P., 1997, p. 655–657. Cole, D., Onstott, T. C., Kirschvink, J. L., Williams- Oxygen isotopic constraints on the genesis of carbon- , A. E., and McKay, D. S., 1997, Formation of mag- ates from martian meteorite ALH84001 (abs.): Lunar Scott, E. R. D., Yamaguchi, A., and Krot, A. N., 1997, netite and Fe-rich carbonates by thermophilic bacteria and Planetary Science, v. 28, p. 805–806. Shock melting of carbonate, plagioclase, and silica in from deep terrestrial subsurface: A possible mechanism the martian meteorite ALH84001 (abs.): Lunar and McDonald, G. D., and Bada, J. L., 1995, A search for for biomineralization in ALH84001 (abs.): Lunar and Planetary Science, v. 28, p. 1271–1272. endogenous amino acids in the martian meteorite Planetary Science, v. 28, p. 1473–1474. EETA79001: Geochimica et Cosmochimica Acta, v. 59, Shearer, C. K., Layne, G. D., Papike, J. J., and Spilde, Wright, I. P., Grady, M. M., and Pillinger, C. T., 1989, p. 1179–1184. M. N., 1996, Sulfur isotopic systematics in alteration Organic materials in a martian meteorite: Nature, assemblages in martian meteorite Allan Hills 84001: McKay, D. S., Gibson, E. K., Thomas-Keprta, K. L., v. 340, p. 220–222. Geochimica et Cosmochimica Acta, v. 60, Vali, H., Romanek, C. S., Clemett, S. J., Chillier, X. D. F., p. 2921–2926. Wright, I. P., Grady, M. M., and Pillinger, C. T., 1997a, Maechling, C. R., and Zare, R. N., 1996, Search for past Evidence relative to the life on Mars debate. (2) Amino life on Mars: Possible relic biogenic activity in martian Steele, A., Goddard, D. T., Stapleton, D., , J., acid results (abs.): Lunar and Planetary Science, v. 28, meteorite ALH84001: Science, v. 273, p. 924–930. Tapper, R., Grady, M., McKay, D. S., Gibson, E. K., Jr., p. 1587–1588. Thomas-Keprta, K. L., and Beech, I. B., 1997, Atomic McKay, D. S., Gibson, E. K., Thomas-Keprta K., force microscopy imaging of ALH84001 fragments Wright, I. P., Grady, M. M., and Pillinger, C. T., 1997b, Romanek, C. S., and Allen, C. C., 1997, Possible (abs.): Lunar and Planetary Science, v. 28, p. 1369–1370. Isotopically light carbon in ALH84001: Martian biofilms in ALH84001 (abs.): Lunar and Planetary or Teflon contamination? (abs.): Lunar Science, v. 28, p. 919–920. Stolz, J. F., Lovley, D. R., and Haggerty, S. E., 1990, Bio- and Planetary Science, v. 28, p. 1591–1592. genic magnetite and the magnetization of sediments: McKay, G. A., and Lofgren, G. E., 1997, Carbonates in Journal of Geophysical Research, v. 95, p. 4335–4361. Zenobi, R., Philippoz, J.-M., Buseck, P. R., and Zare, ALH84001: Evidence for kinetically controlled growth R. N., 1989, Spatially resolved organic analysis of the (abs.): Lunar and Planetary Science, v. 28, p. 921–922. Thomas-Keprta, K. L., Romanek, C., Wentworth, S. J., : Science, v. 246, p. 1026–1029. McKay, D. S., Fisler, D., Golden, D. C., and Gibson, McSween, H. Y., Jr., 1994, What we have learned E. K., 1997, TEM analyses of fine-grained minerals in Received April 4, 1997; revision received April 23, 1997; about Mars from SNC meteorites: Meteoritics, v. 29, the carbonate globules of martian meteorite ALH84001 accepted April 28, 1997 ■ p. 757–779. (abs.): Lunar and Planetary Science, v. 28, p. 1433–1434. Mittlefehldt, D. W., 1994, ALH84001, a cumulate Treiman, A. H., 1997, Chemical disequilibrium in car- orthopyroxenite member of the martian meteorite clan: bonate minerals in martian meteorite ALH84001: Meteoritics, v. 29, p. 214–221. Inconsistent with high formation temperature (abs.): Lunar and Planetary Science, v. 28, p. 1445–1446.

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