Comparing the evidence relevant to impact and flood basalt at times of major mass extinctions.


:The five major mass extinctions identified in 1982 by Raup and Sepkoski have expanded to six, with the suggestion that the Permian-Triassic extinction was a double event. Is there a general explanation for great mass extinctions, or can they result from different triggers, or even from internal system instabilities? The two most-discussed candidates for a general extinction mechanism are impacts and flood-basalt eruptions. A compilation of evidence for impact at the times of mass extinctions shows that this cause is abundantly confirmed in the case of the Cretaceous-Tertiary extinction and the late Eocene, which is a time of minor and gradual extinction, but little or no evidence connects other major extinctions to impact. On the other hand, there is a remarkable time correlation between flood basalts and four major extinctions, but no other evidence that flood basalts cause mass extinctions. The evidence for an impact-extinction linkage is strikingly different from that for a connection between flood basalts and extinctions. Flood basalts cover larger areas than craters and their associated thick ejecta blankets, which are thus less likely to be found. Impacts distribute proxies globally at instantaneous time horizons, whereas flood-basalt events are extended in time, and no remote proxies have been recognized. Many global killing mechanisms have been proposed in the case of impacts, but few have been suggested for flood basalts. It is possible that flood basalts are triggered by impact, but it is not obvious how impacts could result from anything other than chance. The hypothesis that impacts are the general cause of mass extinctions has not received supporting evidence, but has not been falsified. The hypothesis that flood basalts are the general cause of mass extinctions is supported by evidence from timing, but is not susceptible to falsification. Other candidates for general extinction causes, especially sea-level changes and system instabilities, would require separate treatment. The question is still very much open.






Alvarez W





Has Abstract


2003-04-01 00:00:00












  • The definition of life: a brief history of an elusive scientific endeavor.

    abstract::In spite of the spectacular developments in our understanding of the molecular basis that underlies biological phenomena, we still lack a generally agreed-upon definition of life, but this is not for want of trying. Life is an empirical concept; and, as suggested by the many unsuccessful efforts to define it, this tas...


    pub_type: 历史文章,杂志文章


    authors: Tirard S,Morange M,Lazcano A

    更新日期:2010-12-01 00:00:00

  • Adsorption water-related potential chemical and biological processes in the upper martian surface.

    abstract::Mars Odyssey has given strong evidence for the existence of water in the upper martian surface at equatorial latitudes. The water content, which corresponds to the hydrogen in the soil, can regionally reach values up to about 15%. This water is mainly in the form of structurally and partially irreversibly bound "cryst...


    pub_type: 杂志文章


    authors: Möhlmann D

    更新日期:2005-12-01 00:00:00

  • Fate of prebiotic adenine.

    abstract::Equilibrium adsorption isotherm data for the purine base adenine has been obtained on several prebiotically relevant minerals by frontal analysis using water as a mobile phase. Adenine is far displaced toward adsorption on pyrite (FeS2), quartz (SiO2), and pyrrhotite (FeS), but somewhat less for magnetite (Fe3O4) and ...


    pub_type: 杂志文章


    authors: Cohn CA,Hansson TK,Larsson HS,Sowerby SJ,Holm NG

    更新日期:2001-01-01 00:00:00

  • The Raman-Derived Carbonization Continuum: A Tool to Select the Best Preserved Molecular Structures in Archean Kerogens.

    abstract:UNLABELLED:The search for indisputable traces of life in Archean cherts is of prime importance. However, their great age and metamorphic history pose constraints on the study of molecular biomarkers. We propose a quantitative criterion to document the thermal maturity of organic matter in rocks in general, and Archean ...


    pub_type: 杂志文章


    authors: Delarue F,Rouzaud JN,Derenne S,Bourbin M,Westall F,Kremer B,Sugitani K,Deldicque D,Robert F

    更新日期:2016-06-01 00:00:00

  • A microbial oasis in the hypersaline Atacama subsurface discovered by a life detector chip: implications for the search for life on Mars.

    abstract::The Atacama Desert has long been considered a good Mars analogue for testing instrumentation for planetary exploration, but very few data (if any) have been reported about the geomicrobiology of its salt-rich subsurface. We performed a Mars analogue drilling campaign next to the Salar Grande (Atacama, Chile) in July 2...


    pub_type: 杂志文章


    authors: Parro V,de Diego-Castilla G,Moreno-Paz M,Blanco Y,Cruz-Gil P,Rodríguez-Manfredi JA,Fernández-Remolar D,Gómez F,Gómez MJ,Rivas LA,Demergasso C,Echeverría A,Urtuvia VN,Ruiz-Bermejo M,García-Villadangos M,Postigo M,Sánchez-R

    更新日期:2011-12-01 00:00:00

  • A Possible Role for Stochastic Astrophysical Ionizing Radiation Events in the Systematic Disparity between Molecular and Fossil Dates.

    abstract::Major discrepancies have been noted for some time between fossil ages and molecular divergence dates for a variety of taxa. Recently, systematic trends within avian clades have been uncovered. The trends show that the disparity is much larger for mitochondrial DNA than for nuclear DNA, also that it is larger for crown...


    pub_type: 杂志文章


    authors: Melott AL

    更新日期:2017-01-01 00:00:00

  • Structural and Energetic Compatibility: The Driving Principles of Molecular Evolution.

    abstract::In this work, we provide an answer to the question formulated by Albert Eschenmoser: "How would you envisage the bridge between potentially primordial geochemistry that had been disordered and one that gradually became self-organizing?" Analysis of the free-energy profiles of some of the key reactions leading to forma...


    pub_type: 杂志文章,评审


    authors: Šponer JE,Šponer J,Di Mauro E

    更新日期:2019-09-01 00:00:00

  • The Dynamic Albedo of Neutrons (DAN) experiment for NASA's 2009 Mars Science Laboratory.

    abstract::We present a summary of the physical principles and design of the Dynamic Albedo of Neutrons (DAN) instrument onboard NASA's 2009 Mars Science Laboratory (MSL) mission. The DAN instrument will use the method of neutron-neutron activation analysis in a space application to study the abundance and depth distribution of ...


    pub_type: 杂志文章


    authors: Litvak ML,Mitrofanov IG,Barmakov YN,Behar A,Bitulev A,Bobrovnitsky Y,Bogolubov EP,Boynton WV,Bragin SI,Churin S,Grebennikov AS,Konovalov A,Kozyrev AS,Kurdumov IG,Krylov A,Kuznetsov YP,Malakhov AV,Mokrousov MI,Ryzhkov

    更新日期:2008-06-01 00:00:00

  • Searching for life on Mars: degradation of surfactant solutions used in organic extraction experiments.

    abstract::Life-detection instruments on future Mars missions may use surfactant solutions to extract organic matter from samples of martian rocks. The thermal and radiation environments of space and Mars are capable of degrading these solutions, thereby reducing their ability to dissolve organic species. Successful extraction a...


    pub_type: 杂志文章


    authors: Court RW,Sims MR,Cullen DC,Sephton MA

    更新日期:2014-09-01 00:00:00

  • UV photochemistry of DNA in vitro and in Bacillus subtilis spores at earth-ambient and low atmospheric pressure: implications for spore survival on other planets or moons in the solar system.

    abstract::Two major parameters influencing the survival of Bacillus subtilis spores in space and on bodies within the Solar System are UV radiation and vacuum, both of which induce inactivating damage to DNA. To date, however, spore survival and DNA photochemistry have been explored only at the extremes of Earth-normal atmosphe...


    pub_type: 杂志文章


    authors: Nicholson WL,Setlow B,Setlow P

    更新日期:2002-01-01 00:00:00

  • Microterracettes in Sabkha Oum Dba (Western Sahara, Morocco): Physical and Biological Interactions in the Formation of a Surface Micromorphology.

    abstract::Small-scale terracing (microterracettes) is a surface geomorphic feature that recurs under a range of environmental settings, such as those existing in high to low temperature geothermal springs and evaporitic environments, through the single or combined action of physicochemical agents and microbiological processes. ...


    pub_type: 杂志文章


    authors: Barbieri R,Cavalazzi B

    更新日期:2018-10-01 00:00:00

  • Interstellar Travel and Galactic Colonization: Insights from Percolation Theory and the Yule Process.

    abstract:UNLABELLED:In this paper, percolation theory is employed to place tentative bounds on the probability p of interstellar travel and the emergence of a civilization (or panspermia) that colonizes the entire Galaxy. The ensuing ramifications with regard to the Fermi paradox are also explored. In particular, it is suggeste...


    pub_type: 杂志文章


    authors: Lingam M

    更新日期:2016-06-01 00:00:00

  • Terahertz circular dichroism spectroscopy: a potential approach to the in situ detection of life's metabolic and genetic machinery.

    abstract::We propose a terahertz (far-infrared) circular dichroism-based life-detection technology that may provide a universal and unequivocal spectroscopic signature of living systems regardless of their genesis. We argue that, irrespective of the specifics of their chemistry, all life forms will employ well-structured, chira...


    pub_type: 杂志文章


    authors: Xu J,Ramian GJ,Galan JF,Savvidis PG,Scopatz AM,Birge RR,Allen SJ,Plaxco KW

    更新日期:2003-10-01 00:00:00

  • Common freshwater cyanobacteria grow in 100% CO2.

    abstract::Cyanobacteria and similar organisms produced most of the oxygen found in Earth's atmosphere, which implies that early photosynthetic organisms would have lived in an atmosphere that was rich in CO2 and poor in O2. We investigated the tolerance of several cyanobacteria to very high (>20 kPa) concentrations of atmospher...


    pub_type: 杂志文章


    authors: Thomas DJ,Sullivan SL,Price AL,Zimmerman SM

    更新日期:2005-02-01 00:00:00

  • Identification and Characterization of Early Mission Phase Microorganisms Residing on the Mars Science Laboratory and Assessment of Their Potential to Survive Mars-like Conditions.

    abstract::Planetary protection is governed by the Outer Space Treaty and includes the practice of protecting planetary bodies from contamination by Earth life. Although studies are constantly expanding our knowledge about life in extreme environments, it is still unclear what the probability is for terrestrial organisms to surv...


    pub_type: 杂志文章


    authors: Smith SA,Benardini JN 3rd,Anderl D,Ford M,Wear E,Schrader M,Schubert W,DeVeaux L,Paszczynski A,Childers SE

    更新日期:2017-03-01 00:00:00

  • Phosphine as a Biosignature Gas in Exoplanet Atmospheres.

    abstract::A long-term goal of exoplanet studies is the identification and detection of biosignature gases. Beyond the most discussed biosignature gas O2, only a handful of gases have been considered in detail. In this study, we evaluate phosphine (PH3). On Earth, PH3 is associated with anaerobic ecosystems, and as such, it is a...


    pub_type: 杂志文章


    authors: Sousa-Silva C,Seager S,Ranjan S,Petkowski JJ,Zhan Z,Hu R,Bains W

    更新日期:2020-02-01 00:00:00

  • Growth, Viability, and Death of Planktonic and Biofilm Sphingomonas desiccabilis in Simulated Martian Brines.

    abstract::Aqueous solutions on Mars are theorized to contain very different ion compositions than those on Earth. To determine the effect of such solutions on typical environmental micro-organisms, which could be released from robotic spacecraft or human exploration activity, we investigated the resistance of Sphingomonas desic...


    pub_type: 杂志文章


    authors: Stevens AH,Childers D,Fox-Powell M,Nicholson N,Jhoti E,Cockell CS

    更新日期:2019-01-01 00:00:00

  • A possible prebiotic origin on volcanic islands of oligopyrrole-type photopigments and electron transfer cofactors.

    abstract::Tetrapyrroles are essential to basic biochemical processes such as electron transfer and photosynthesis. However, it is not known whether these evolutionary old molecules have a prebiotic origin. We have serendipitously obtained pyrroles, which are the corresponding monomers, in laboratory experiments that simulated t...


    pub_type: 杂志文章


    authors: Fox S,Strasdeit H

    更新日期:2013-06-01 00:00:00

  • Extreme water loss and abiotic O2 buildup on planets throughout the habitable zones of M dwarfs.

    abstract::We show that terrestrial planets in the habitable zones of M dwarfs older than ∼1 Gyr could have been in runaway greenhouses for several hundred million years following their formation due to the star's extended pre-main sequence phase, provided they form with abundant surface water. Such prolonged runaway greenhouses...


    pub_type: 杂志文章


    authors: Luger R,Barnes R

    更新日期:2015-02-01 00:00:00

  • The NASA Astrobiology Roadmap.

    abstract::The NASA Astrobiology Roadmap provides guidance for research and technology development across the NASA enterprises that encompass the space, Earth, and biological sciences. The ongoing development of astrobiology roadmaps embodies the contributions of diverse scientists and technologists from government, universities...


    pub_type: 杂志文章


    authors: Des Marais DJ,Allamandola LJ,Benner SA,Boss AP,Deamer D,Falkowski PG,Farmer JD,Hedges SB,Jakosky BM,Knoll AH,Liskowsky DR,Meadows VS,Meyer MA,Pilcher CB,Nealson KH,Spormann AM,Trent JD,Turner WW,Woolf NJ,Yorke HW

    更新日期:2003-07-01 00:00:00

  • Raman hyperspectral imaging of microfossils: potential pitfalls.

    abstract::Initially, Raman spectroscopy was a specialized technique used by vibrational spectroscopists; however, due to rapid advancements in instrumentation and imaging techniques over the last few decades, Raman spectrometers are widely available at many institutions, allowing Raman spectroscopy to become a widespread analyt...


    pub_type: 杂志文章


    authors: Marshall CP,Olcott Marshall A

    更新日期:2013-10-01 00:00:00

  • Experimental Constraints on Abiotic Formation of Tubules and Other Proposed Biological Structures in Subsurface Volcanic Glass.

    abstract::Formation of microtubules in volcanic glass from subsurface environments has been widely attributed to in situ activity of micro-organisms, but evidence directly linking those structures to biological processes remains lacking. Investigations into the alternative possibility of abiotic tubule formation have been limit...


    pub_type: 杂志文章


    authors: McCollom TM,Donaldson C

    更新日期:2019-01-01 00:00:00

  • Calibration of carbonate composition using micro-Raman analysis: application to planetary surface exploration.

    abstract::Stromatolite structures in Early Archean carbonate deposits form an important clue for the existence of life in the earliest part of Earth's history. Since Mars is thought to have had similar environmental conditions early in its history, the question arises as to whether such stromatolite structures also evolved ther...


    pub_type: 杂志文章


    authors: Rividi N,van Zuilen M,Philippot P,Ménez B,Godard G,Poidatz E

    更新日期:2010-04-01 00:00:00

  • Detection and Degradation of Adenosine Monophosphate in Perchlorate-Spiked Martian Regolith Analogue, by Deep-Ultraviolet Spectroscopy.

    abstract::The search for organic biosignatures on Mars will depend on finding material protected from the destructive ambient radiation. Solar ultraviolet can induce photochemical degradation of organic compounds, but certain clays have been shown to preserve organic material. We examine how the SHERLOC instrument on the upcomi...


    pub_type: 杂志文章


    authors: Razzell Hollis J,Fornaro T,Rapin W,Wade J,Vicente-Retortillo Á,Steele A,Bhartia R,Beegle LW

    更新日期:2021-01-25 00:00:00

  • Introducing Vibrio natriegens as a Microbial Model Organism for Microgravity Research.

    abstract::Microbial contamination of human-tended spacecraft is unavoidable, making the study of microbial growth under space conditions essential for the preservation of astronauts' health and equipment integrity. Previous studies suggested that spaceflight conditions, such as microgravity, cause a range of physiological micro...


    pub_type: 杂志文章


    authors: Garschagen LS,Mancinelli RL,Moeller R

    更新日期:2019-10-01 00:00:00

  • Assessing antibody microarrays for space missions: effect of long-term storage, gamma radiation, and temperature shifts on printed and fluorescently labeled antibodies.

    abstract::Antibody microarrays are becoming frequently used tools for analytical purposes. A key factor for optimal performance is the stability of the immobilized (capturing) antibodies as well as those that have been fluorescently labeled to achieve the immunological test (tracers). This is especially critical for long-distan...


    pub_type: 杂志文章


    authors: de Diego-Castilla G,Cruz-Gil P,Mateo-Martí E,Fernández-Calvo P,Rivas LA,Parro V

    更新日期:2011-10-01 00:00:00

  • Lessons learned from the microbial analysis of the Herschel spacecraft during assembly, integration, and test operations.

    abstract::Understanding microbial diversity in spacecraft assembly clean rooms is of major interest with respect to planetary protection considerations. A coordinated screening of different clean rooms in Europe and South America by three German institutes [Deutsches Zentrum für Luft- und Raumfahrt (DLR), Leibniz-Institut DSMZ-...


    pub_type: 杂志文章,评审


    authors: Moissl-Eichinger C,Pukall R,Probst AJ,Stieglmeier M,Schwendner P,Mora M,Barczyk S,Bohmeier M,Rettberg P

    更新日期:2013-12-01 00:00:00

  • Impact of the Arizona NExSS Winter School on Astrobiology Knowledge and Attitudes.

    abstract::Astrobiology is an inherently interdisciplinary area of study, demanding communication across multiple fields: astronomy, geochemistry, planetary science, and so on. Successful communication requires that researchers be aware of the basic findings, open questions, and tools and techniques of allied fields and possess ...


    pub_type: 杂志文章


    authors: Burnam-Fink M,Desch SJ,Scalice D,Davis H,Huff CJ,Apai D

    更新日期:2018-03-01 00:00:00

  • Meteorites and the RNA World: A Thermodynamic Model of Nucleobase Synthesis within Planetesimals.

    abstract::The possible meteorite parent body origin of Earth's pregenetic nucleobases is substantiated by the guanine (G), adenine (A), and uracil (U) measured in various meteorites. Cytosine (C) and thymine (T), however, are absent in meteorites, making the emergence of an RNA and later RNA/DNA/protein world problematic. We in...


    pub_type: 杂志文章


    authors: Pearce BK,Pudritz RE

    更新日期:2016-11-01 00:00:00

  • Astrobiology outreach and the nature of science: the role of creativity.

    abstract::There is concern in many developed countries that school students are turning away from science. However, students may be choosing not to study science and dismissing the possibility of a scientific career because, in the junior secondary years, they gain a false view of science and the work of scientists. There is a ...


    pub_type: 杂志文章,评审


    authors: Fergusson J,Oliver C,Walter MR

    更新日期:2012-12-01 00:00:00