Sulfur Metabolism

MTB would also take part in the sulfur cycle. In nature, sulfur is mainly found under three forms compounds of the sulfate ion (SO42-), compounds of the sulfide ion (S2-) and elemental sulfur (S0). Sulfates are very abundant on Mars and some MTB can reduce the sulfate ion to sulfide. This biochemical process would form sulfydric acid and sulfides. Other bacterial species, such as strain MC-1, can oxidize sulfides and thiosulfates and producing elemental sulfur. The sulfide ion can be used by...

Barberton Microbial Mats And Microfossils

Climbing the stratigraphy slightly, there are reports from the Buck Reef Chert (K1 in Fig. 3b) of putative microbial mat remains in a sedimentary setting (Tice and Lowe, 2004, 2006). This contrasts with many recent studies of Archean cherts that have been interpreted as formed from either hydrothermal exhalites or injections, or as hydrothermally modified sediments (e.g. Hofmann and Bolhar, 2007 Van Kranendonk, 2006 Brasier et al., 2005). In the case of the Buck Reef Chert, however, Tice and...

Iv

Gibson NANOSIMS OPENS A NEW WINDOW FOR DECIPHERING ORGANIC MATTER IN TERRESTRIAL AND EXTRATERRESTRIAL SAMPLES* DOROTHY Z. OEHLER1, FRAN OIS ROBERT2, SMAIL MOSTEFAOUI2, ANDERS MEIBOM2, MADELEINE SELO2, DAVID S. MCKAY1 AND EVERETT K. GIBSON1 'Astromaterials Research and Exploration Science Directorate, NASA-Johnson Space Center, Houston, Texas 2Laboratoire d'Etude de la Mati re Extraterrestre, Mus um National d'Histoire Naturelle, Paris, France Recognition of the...

Magnetotactic Bacteria And Exobiology

The chemical and microscopic analyses of Martian meteorite ALH 84001 caused a great surprise to the scientific community because it contains magnetite crystals whose origins, either biotic or abiotic, remain an open question (Barber and Scott, 2002 Buseck et al., 2001 Taylor et al., 2001 Thomas-Keprta et al., 2002 McKay et al., 2003 Weiss et al., 2004). McKay et al. (2003) also suggested that more studies of ALH84001, extensive laboratory simulations of non-biological magnetite formation, as...

Irradiation of Cometary Ices in Laboratory Experiments

Ample lists of authors have devoted their efforts since the early 60s, when cometary simulation experiments began, to understand the processes and the evolution that comets experience. A Russian group did pioneering work their samples (of sand and water) were deposited onto a cold finger, and then exposed to a strong light (see Kochan et al., 1998 for references). In 1961, Oro proposed that comets could have been carriers of organic material then, with experimental data, he reinforced the...

Life Forms Bridging Up the Gap Between Life and Nonlife

Now we make a further step in exploring cosmic life forms by asking whether life can be continuous with the apparently inanimate world, as many scientists suggested (e.g. Nature, Editorial, 2007). We all know that highly organized life can be manifest only when suitable conditions are present. Yet there are strong arguments telling that there is no sharp boundary between life and non-life. For example, quanta in the double-slit experiment are able to orientate themselves according to the...

Nunzia Stivaletta And Roberto Barbieri

Dipartimento di Scienze della Terra e Geologico-Ambientali, Universit di Bologna, Via Zamboni 67, 40126 Bologna, Italy Abstract Microbial life in hot and cold desert environments inhabits endolithic niches. The endolithic microorganisms include bacteria, fungi and lichens. To protect themselves from the inhospitable conditions, such as high UV radiation, dryness, and rapid temperature variations, microorganisms migrate into fractures or in pore spaces where the necessary nutrient, moisture, and...

Info

Walsh (eds.), From Fossils to Astrobiology, 211-229. Springer Science + Business Media B. V. 2009 DECIPHERING FOSSIL EVIDENCE FOR THE ORIGIN OF LIFE AND THE ORIGIN OF ANIMALS Common Challenges in Different Worlds JONATHAN ANTCLIFFE1 AND NICOLA MCLOUGHLIN2 'Department of Earth Sciences, University of Oxford, Parks Road, Oxford, OX' 3PR, UK 2Department of Earth Sciences and Centre for Excellence in Geobiology, the University of Bergen, Allegaten 4', N-5007, Bergen, Norway...

Geology Of The Makgabeng Formation

The generally mature, fine- to medium-grained quart arenites (and lesser finer rocks as well as pebbly sandstones) of the Makgabeng Formation are interpreted as eolian dune, playa, saline pan and interdune facies within an overall desert setting. The eolian facies (inversely-graded wind ripple strata unequivocally support such an origin) is predominant, both stratigraphically and geographically, with contained cross-bedding patterns suggesting either barchanoid or straight-crested dune bedforms...

Jessica C Goin And Sherry L Cady

Department of Geology, Portland State University, Portland, OR 97201, USA Abstract Though the majority of microorganisms in hot spring ecosystems fail to be preserved as bona fide (carbonaceous) microfossils, the presence of microbial biofilms on accretionary surfaces of hot spring sinters can influence the development of sinter fabrics. The extent of biological influence on a primary sinter fabric depends upon the behavior of the microbial community at the time the sinter accretes as well as...

Mineralogy Of Mars And The Problem Of Carbonates

The question of the type of elements and minerals comprising the surface of Mars is of extreme interest for the reconstruction of the geological evolution of the planet (Baker, 2006). The mineral composition of the Martian surface may provide clues to deciphering the question of possible life on Mars. The recent missions of the NASA's exploration rovers Spirit and Opportunity and ESA's Mars Express have produced a wealth of new data about its surface composition by using a variety of...

If Not Impacts What Causes Mass Extinctions

In recent years, scientists have moved beyond naive and simplistic impact scenarios, and looked at the detailed records of several mass extinctions to test new hypotheses of their causes. One of the most popular alternatives is the volcanic hypothesis (Rampino and Stothers, 1988 Courtillot, 1999 Courtillot and Renne, 2003). Indeed, the Permian extinction is associated with the huge Siberian trap eruptions, the largest in earth history, and the late Triassic extinctions seem to be associated...

The Common Frontier of Astronomy and Astrobiology

Both astronomy and astrobiology share a common frontier. Vertiginous progress in instrumentation such as novel microanalytical tools to study extraterrestrial materials, including those collected in space return missions, and availability of long ice cores and other fossil archives providing detailed records of the past terrestrial environment, can give deeper insights into the origin and history of life on Earth. The early stage of the Sun and other space-palaeoclimate conditions are relevant...

Microbial Mat Related Features In The Makgabeng Interdune Deposits

In addition to the normal sedimentary structures (e.g., cross-bedding, planar bedding, ripple marks, evaporite crystal imprints etc. - see Eriksson et al., 2000 Simpson et al., 2004) identified within the interdune facies at Makgabeng, four main groups of inferred microbial mat-related features were also observed 2. Sand cracks - from simple to complex-curved forms (Fig. 4) 3. Sand chips and desiccated larger fragments (Fig. 5) 4. Roll-ups (from simple to complex) (Fig. 6) These features were...

The Big Bang At Time Zero

PRAVDO2 'Bahn Biotechnology Co., 10415 E. Boyd Rd., Mt. Vernon, IL 62864, USA 2Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91106, USA Abstract The cosmic background radiation left over from the Big Bang approximately 14 billion years ago is the oldest of all fossils. The Big Bang at time zero is the most important of all boundary conditions for the very possibility of life in the Universe. In the Big Bang singularity, space and time...

Pilbara Microfossils

Perhaps the most well known report of microfossil evidence for earliest life comes from the 3,460 Ma 'Apex chert'. These Apex 'microfossils' (e.g., Fig. 2f) were described in detail in a series of high profile papers (Schopf and Packer, 1987 Schopf, 1992a, b, 1993 Schopf et al., 2002) and became the benchmark for bona fide early Archean 'microfossils', the only ones to gain wide acceptance by the scientific community during the 1980s and 1990s (e.g., Buick, 1990 Knoll and Walter, 1996...

Barberton Sulfur Isotopes

A similar sulfur isotope story to that in the Pilbara emerges in the Barberton area from the work of Ohmoto et al. (1993). These authors sampled a shale and three black cherts from the uppermost Onverwacht Group (-3,300 Ma Mendon Formation) in the Barberton and used high resolution laser ablation mass spectroscopy to analyse individual pyrite grains. The range of 534S values (up to 12 o variation) from these pyrites was argued to be greater than that expected if they had formed from purely...

Magnetotactic Bacteria And Their Potential For Terraformation

ARDELEAN12, CRISTINA MOISESCU1 AND DAN RAZVAN POPOVICIU2 'Center of Microbiology, Institute of Biology 060031 Bucharest, Romania 2Ovidius University Faculty of Natural Sciences Constantza, Romania This paper is focused on magnetotactic bacteria and their possible contributions to the terraformation of Mars or other planets. The potential for terraformation is mainly based on their ability to carry out aerobic or anaerobic respiration with either nitrate or ferric iron, to fix carbon...

Carbonate Globules

ALH84001 contains secondary carbonate minerals in the form of globules from 1 to 250 m across, that have radiogenic Rb-Sr ages of 3.9 0.04 billion years (Borg et al., 1999) (Fig. 1). This is a distinct feature of ALH84001, since other Figure 1. Evidence of Martian life suggested by McKay et al. (1996). Center ALH84001 after removal of some samples (Photo Credit NASA JSC). Top left carbonate globules (examples marked by arrows) in the meteorite. Scale bar is 200 m (Photo Credit Jacek Wierzchos...

Looking Through Windows Onto The Earliest History Of Life On Earth And Mars

DAVID WACEY1, NICOLA MCLOUGHLIN12 AND MARTIN D. BRASIER1 'Department of Earth Sciences, University of Oxford, Parks Road, Oxford, OX' 3PR, UK 2Department of Earth Sciences and Centre for Geobiology, Allegaten 4', Bergen-5007, Norway Abstract We know that planet Earth is about 4.5 billion years old but what is less clear is when it first became home to life. Locating the first evidence for life on Earth is a question of considerable complexity and controversy. Biogeochemical signals or examples...

Universal Magnetic Assay For Biogenicity

As mentioned above, Thomas-Keprta et al. (2002) proposed a MAB, including six distinctive properties displayed by bacterial magnetosomes, that allow to distinguish them from inorganic magnetic particles, including defect-free crystals, consistent shapes and aspect ratios, elongated crystal morphologies and chemical purity. Yet some magnetite-producing bacteria synthesize magnetosomes with crystallographic defects similar to that of synthetic magnetite crystals (Devouard et al., 1998 Taylor et...

Complex Organic Compounds

Polycyclic aromatic hydrocarbons (PAHs) were detected in the interior of ALH84001 at concentration in the parts per million range (McKay et al., 1996). PAHs are complex organic compounds with two or more fused aromatic rings (Fig. 1). On Earth, PAHs form as a result of the incomplete combustion of organic materials during industrial and other human activities, and also through diagenesis of organic compounds. McKay et al. (1996) only found a few different types of PAHs in the meteorite, in...

Preservation Potential And Some Ancient Analogues

As most of the organic matter produced by the cyanobacteria is soon decomposed and mineralized so that organic components or even carbon are rarely preserved in the ancient siliciclastic record, preservation of mat-related structures is largely dependent on the volume of inorganic material present in the mat or trapped by the structure. A major process to introduce silt- to sand-sized sediment grains into the mat is 'trapping and binding' as described before. In the same way, clay minerals may...

Obq

A Field photo of Zavarzin Pool. B Filamentous cyanobacteria positive for chlorophyll-a autofluorescence . C Mineral grains 1 bound by biological material 2 . Figure 5. A Field photo of Zavarzin Pool. B Filamentous cyanobacteria positive for chlorophyll-a autofluorescence . C Mineral grains 1 bound by biological material 2 . photo-trophic mats have developed along the floor of the outflow channel, and their silicification preserves several distinct sinter fabrics along the length of...

Microbial Communities Of Stromatolites

WALTER AND BRETT A. NEILAN Australian Centre for Astrobiology, School of Biotechnology and Biomolecular Sciences and the University of New South Wales, 2052 Australia One of the major challenges in science is to identify modern living systems that present unique opportunities to address fundamental questions in fields ranging from microbial ecology, evolution, chemical biology, functional genomics, and biotechnology. Stromatolites represent such a system. One of the...

Amino Alcohols

After reviewing the work of Azrak and Angell Azrak and Angell, 1973 , which suggested that amino alcohols may covalently bond more readily with silicates than regular alcohols, it was only logical to investigate amino alcohols in addition Table 2. Summary of the interactions of various organic compounds with sodium silicate. Class of organic molecule Notes Amino acids AA Mechanism Catalysis. Entombment possible in trace amounts low levels of organics detected in some cases. Biological AA Gel...

Discussion and Concluding Remarks

The main thesis that we have maintained in this work is that solar activity, space climate and astrobiology should be brought within a unified framework that would include contributions from other disciplines relevant to the past of environments in the solar system. This approach naturally leads us to the suggestion of exploiting instruments and methods from somewhat dissimilar sciences astronomy and astrobiology with a unified objective Messerotti and Chela-Flores, 2007a, b . We have attempted...

Foreword

From Fossils to Astrobiology Records of Life on Earth and Search for Extraterrestrial Biosignatures Astrobiology, the study of life in the universe, draws on many traditional areas of scientific study, including astronomy, chemistry and planetary science. This volume, number 12 in the Cellular Origin, Life in Extreme Habitats and Astrobiology series published by Springer focuses on the study of the record of life on planet Earth, which is critical in guiding investigations in the rest of the...

Wladyslaw Altermann

Department of Earth- and Environmental Sciences, Ludwig-Maximilians-University amp GeoBioCenterLMU, Luisenstr. 37, D-80333 Munich, Germany Joseph Seckbach, the editor of the present book series, invited me to write the introduction to From Fossils to Astrobiology during his 3 months visit to my Institute at the Ludwig-Maximilians-University under the fellowship of DAAD German Academic Exchange Foundation in 2006. Of course I felt honoured by his choice, but being sceptical towards the youngest...

Pilbara Stromatoloids

Apex Chert Fossils

Stromatolites are laminated sedimentary structures that provide a controversial candidate signature for early life. In the following discussion, we therefore adopt the non-genetic term 'stromatoloid', thus making no assumptions about their biogenicity cf. Buick et al., 1981 . A stromatoloid can be defined non-genetically as an attached, laminated, lithified sedimentary growth structure, accretionary away from a point or limited surface of initiation Semikhatov et al., 1979 , and in outcrop are...

Division Of

The Schwarzeneggerization of Life. A muscle-bound man stands as the end product of a linear progression - the Great Chain of Being - a ladder of life that leads to male Caucasian weight lifters. One can create such an apparent linear trend out of the crooked phylogenetic branch of any species. Looking back from any particular species we will find the evolution of the traits of that particular species. However, precisely because we can construct such a figure from the lineage of any...

Endolithic Life In Cold Deserts

In spite of their limited water availability, cold temperature, strong winds, and large variations in solar radiation input, cold deserts harbour endolithic microorganisms. Antarctica is characterized by extreme climatic conditions, with low humidity and precipitation during the winter lt 10 RH relative humidity Horowitz et al., 1972 , which make the continent relatively inhospitable for the development of biological communities. In proper niches, however, microbial life can thrive and...

Haloarchaea From Salt Sediments

Halococcus Dombrowskii

The huge salt sediments on Earth, which were deposited during evaporation of sea water or continental brines, are the origin of evaporitic rocks. Similarly as for other natural environments, progress in methodology has increased greatly the knowledge of microbial diversity. As recently as 1981, Larsen 1981 described mined rock salts as free from bacteria, although isolations of halophilic microorganisms from ancient salt sediments had occasionally been reported since the early decades of the...

Dna And Silicification

Mechanism Entombment or covalent bonding are possible. Organics were observed in IR spectra. Si-O-C IR bands were observed in some cases. Gel formation and appearance Immediately formed hard, white gels. Needed a very small volume to form gel compared to an alcohol of similar molecular weights. Gels were partially water-soluble. Dried gels consist of hard, rubbery, opaque chunks. Sol-gel-sol transformation Some transformations were seen related to water-solubility. Other One of the rare cases...

Eh Environmental Parameters

Theoretical representation of preservation windows A-C displayed in a three-dimensional space defined by essential environmental parameters for preservation of biological information such as temperature, Eh and ion concentration named as S in mg L-1 . A represents ion-enriched medium temperature and high Eh conditions compatible for acidic to neutral environments where paleobiological structures are preserved under a fast mineralization. Same S and Eh records changing to high...

Are There Possible Traces of Catastrophic Space Climate Events in the Hominid Fossil Record

The role of cataclysmic events in the evolution of life on Earth has been discussed in recent times. Tobias has suggested the possible causal connection between large impacts such as the Vredefot impact structure in the Free State it is the latest World Heritage Site to be listed in South Africa . Its reconstructed diameter of 250-300 km was made by a projectile estimated at 10-15 km in diameter, which collided with the Earth at 2.1 Ga Tobias, 2005 . This impact coincided with two significant...

Quantitative Evaluation

To quantify the crystal aspect variability, we conducted detailed imaging and statistical analyses on high resolution scanning electron micrographs of the four crystal morphologies described above. For each crystal type, the dimensions of length and width were measured. The raw results are presented in Fig. 12A. The figure also shows the length and width of granule aggregates red color . A total of 1,075 randomly chosen crystals specifically 350 perpendicularly oriented prismatic apatite...

References

Altwegg, K., Ehrenfreund, P., Geiss, J., Huebner, W.F. and Levasseur-Regourd A.C. 1999 . Cometary materials Progress toward understanding the composition in the outer solar nebula. Space Sci. Rev. 90 373-389. Amici, S., Piccioni, G., Coradini A. and Solazzo, S. 2000 . VIRTIS-M laboratory spectral measurements of analogues cometary samples. Planet. Space Sci. 48 401-410. Bahr, D.F., Fama, M., Vidal, R.A. and Baragiola, R.A. 2001 . Radiolysis of water ice in the outer Solar System Sputtering and...

Mineralized

Based on our analyses and a comparison of our findings with modern hyperthermophilic biofilm remnants, we propose that the threads and curved films are the mineralized remains of microbial biofilms. We have also found that this Figure 11. Examples of remnants of modern hyperthermophilic biofilms collected from near-boiling hot springs, Yellowstone National Park, USA. The biofilm remnants consist primarily of extracellular polymeric substances EPS that give enough coherency and flexibility to...

Y

Limits of extremophiles Sedimentary rocks or not Taphonomic modification A hollow tube is not evidence of life Nature of branching, size changes, directionality, fractal Could this indicate Eukarya. How could a prokaryote do this Taphonomic difficulties, geochemical corollary - is it a nucleus or a black blob Population dynamics Prokarya large populations of similar forms. Eukarya more diversity and potentially recognisable developmental systems Single celled Eukarya can be as small as Prokarya...

Xiao Shuhai

DEPARTMENT OF GEOSCIENCES, VIRGINIA POLYTECHNIC INSTITUTE AND STATE UNIVERSITY, BLACKSBURG, VA 24061, USA. Biodata of Dorothy Z. Oehler, author with Fran ois Robert, Smail Mostefaoui, Anders Meibom, Madeleine Selo, David S. McKay, and Everett K. Gibson of NanoSIMS Opens a New Window for Deciphering Organic Matter in Terrestrial and Extraterrestrial Samples Dr. Dorothy Z. Oehler is a NASA Senior Fellow at Johnson Space Center in Houston. She obtained her Ph.D. at the University of California at...

Endolithic Life In Hot Deserts

Cryptoendolithic algae from hot, semiarid lands and deserts were first described from the Negev Desert Friedmann et al., 1967 . Cryptoendoliths of hot desert were then documented in North America Friedmann, 1972 Bell et al., 1983, 1986 and South Africa Critchley et al., 1987 . The most common substrate are porous, crystalline sandstone and, less often, limestone. The first report of hot desert cryptoendoliths identified the coccoid cyanobacteria Chroococcidiopsis and Gleocapsa Friedmann, 1971,...

Type C

This specimen of sponge is in the form of a cylinder with a large opening on the top of its body interpreted here as osculum Fig. 3, Plate 1, Fig. 3 . There are numerous small pores or ostia in the wall of the cylinder and inside the cylinder is a body cavity large central cavity or spongocoel Paragastrc cavity . Ostia open in this spongocoel and permit entry of water in this cavity, which exits through osculum. The present specimens show radial symmetry and simplest type of Ascon types canal...

Preservation In Thin Films Covering Rocks

The water history of Mars suggests that rock coatings, desert varnishes and weathering rinds should be present in any sedimentary deposit or embedded inside alteration materials derived from ancient and recent aqueous activity. Spirit MER has indeed provided direct evidences of rock coatings of unequivocal aqueous alteration Haskin et al., 2005 . In this sense, location and analysis of rock coatings of several ages can be essential to trace back the climatic and environmental history Dorn and...

Shark Bay Stromatolites

Lyngbya Hieronymusii

The stromatolites of Hamelin Pool at Shark Bay Australia are well recognised as the best examples of actively lithifying marine stromatolites Fig. 4 . Hamelin Pool is the innermost basin of Shark Bay, a shallow hypersaline bay on the western coast of Australia. Across the mouth of Hamelin Pool is a sea-grass covered sandbank that restricts water flow into Hamelin Pool. Combined with the high evaporation rates, low rainfall, and the lack of freshwater input from the extremely arid land...

Shuhai Xiao And James D Schiffbauer

Department of Geosciences, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, USA One of the major tasks of astrobiology is to critically examine evidence of past or present ecosystems beyond our planet. As Earth is the only planet that is known to have hosted life, perhaps as early as 3.8-3.5 billion years ago or Ga, Giga anna as illustrated by biologically-meaningful carbon isotopic signatures and prokaryotic microfossils Mojzsis et al., 1996 Schopf, 2006 but see...

Vera M Kolb And Patrick J Liesch

Department of Chemistry, University of Wisconsin-Parkside, Kenosha, WI53141-2000, USA Abstract Silicates are abundant on both Earth and Mars, and hold great potential for harboring biosignatures. Biosignatures are signs of past or present life and may be either organic or inorganic in nature. Our most recent work, which we review here, is a survey of how different classes of organic compounds interact with highly basic sodium silicate solution to model the formation of biosignatures in nature....

Roberto Barbieri And Barbara Cavalazzi

Fossil Microbe Silice

Dipartimento di Scienze della Terra e Geologico-Ambientali, Universit di Bologna, Via Zamboni 67, I-40126 Bologna, Italy Abstract The recent detection of methane in the martian atmosphere has stimulated a debate on its source, including speculations on a possible biological origin as in the Earth's atmosphere, where methane is present as a trace gas and is mostly produced by life. Large amounts of methane seepage flows from the subsurface are documented on Earth since the lower Paleozoic by the...

Preservation Windows For Paleobiological Traces In The Mars Geological Record

FERN NDEZ-REMOLAR1, OLGA PRIETO-BALLESTEROS1, C SAR MENOR-SALV N1, MARTA RU Z-BERMEJO1, FELIPE G MEZ1, DAVID G MEZ-ORTIZ2 AND RICARDO AMILS13 1Centro de Astrobiolog a, INTA-CSIC, Ctra Ajalvir km. Torrej n de Ardoz, Spain 2 rea de Geolog a, Universidad Rey Juan Carlos, C Tulip n s n, Madrid, Spain 3Unidad de Microbiolog a, Centro de Biolog a Molecular, Universidad Aut noma de Madrid, Spain Keywords Mars, astrobiology, preservation windows, paleobiological traces 1. Introduction A New...

Formulation of the Bauer Principle in Elementary Sentences

Regular compensation of equilibration processes with uphill ones requires a systematic work on the internal structure of the organism. In order to initiate uphill processes, regenerating nonequilibrium structures, gradients and potentials, living organisms must be able to work continuously against the thermodynamic equilibrium that otherwise ultimately would be reached given the actual instantaneous state of the organism on the basis of physical laws. This simplified chain of thoughts points...

Attila Grandpierre

Konkoly Observatory of the Hungarian Academy of Sciences H-1525 Budapest, P.O. Box 67, Hungary Abstract We propose that the first principle of biology is a useful guide in exploring cosmic life forms. Moreover, it determines the basic prerequisites of life in material-independent form. Starting from the Bauer principle BP , we made explicit its content, and found that the Bauer principle is mediated by virtual interaction VI which generates biological couplings BC opening up an enormous realm...

Pilbara Sulfur Isotopes

Sulfur isotopes are a promising additional tool in our armoury for investigating the early biosphere given that primitive bacteria which metabolize sulfur compounds are one of the most deeply rooted groups in the Tree of Life e.g. Mojzsis, 2007, Figs. 7.5-12 . Sulfur isotopes have also been utilized as a hotly debated tracer for the rise of atmospheric oxygen, an application that we will not discuss further here see instead Kasting, 2006 Mojzsis, 2007 . The analysis of sulfur isotopes preserved...

To Hydrthermal Activity

Hydrothermal activity has been present on Mars since early Noachian to recent times. Such a process has been recognized through the volcanism Fig. 3A that affected the crust water mobilization in the form of lacustrine and fluvial systems Cabrol and Grin, 2001 Varnes et al., 2003 Schulze-Makuch et al., 2007 , as well Figure 2. Noachian deltaic deposits Grant et al., 2007 infilling the Holden Crater in Mars A-C and preserved microbial mat structures in Archean deltaic materials D-E at Barberton...

Vinod Chandra Tewari

Classification Himalaya India Map

Wadia Institute of Himalayan Geology, Dehra Dun 248 001, Uttarakhand, India and International Centre for Theoretical Physics, Miramare 34100 Trieste, Italy A comparative study of possible genesis of life on planet Earth and Mars reveals that similar conditions would have been present on Mars supporting a probable occurrence of unicellular Martian microfossils and stromatolites. The genetic aspect of eukaryotes or eukaryogenesis, eukaryotic evolution and probable geological and recent...

Summary

To summarize, we recognize several different phosphatic textures, probably indicating different phosphatization processes responsible for the preservation of Doushantuo microfossils. Phosphatic encrustation by micrometric, perpendicularly oriented crystals is most pervasive in the Doushantuo Formation. It occurs as bot-ryoidal and isopachous cements on a variety of substrates, including animal egg embryo cell surfaces, egg embryonic envelopes, algal cell walls, organic filaments, as well as...