Micro Raman spectroscopy of carbonaceous material in microfossils and meteorites: improving a method for life detection.

The identification of biosignatures in Earth's ancient rock record and detection of extraplanetary life is one of the primary goals in astrobiology. Intrinsic to this goal is the improvement of analytical techniques and protocols used to identify an unambiguous signal of life. Micro Raman spectroscopy is a nondestructive method that allows for in situ identification of a wide range of minerals and compounds. The use of D (∼1350 cm(-1)) and G (∼1580 cm(-1)) band parameters to infer the biogenicity of carbonaceous materials in fossils has become a commonly used analytical tool, but carbonaceous compounds from different sources often share the same spectroscopic characteristics. Microfossil studies do not always take into consideration a nonbiological source for the carbon in their samples and therefore still rely on morphology as the primary mode of identification. Comprehensive studies that consider all carbon sources are typically done on metasediments, coals, or meteorites, and the results are not clearly applicable to microfossil identification. In this study, microfossils from a suite of sedimentary rock samples of various ages were analyzed with micro Raman spectroscopy to investigate the nature and provenance of carbonaceous material. To further constrain D- and G-band carbon characteristics, micro Raman analyses were also performed on well-characterized meteorite samples as abiological controls. The results appear to show a correlation of precursor carbonaceous material with D-band parameters and thermal history with G-band parameters. This systematic study lays the groundwork for improving the use of the G- and D-band trends as useful indicators of the origin of carbon in microfossils. Before unambiguous biosignatures can be established, further work characterizing the carbonaceous material in microfossils of different ages, thermal histories, and host rock compositions is needed.

[1]  W. F. Cannon,et al.  The Penokean orogeny in the Lake Superior region , 2007 .

[2]  A. Knoll,et al.  New Microorganisms from the Aphebian Gunflint Iron Formation, Ontario , 1978 .

[3]  M. Brasier,et al.  Microfossils and Precambrian–Cambrian boundary stratigraphy at Maldeota, Lesser Himalaya , 1987, Geological Magazine.

[4]  F. Pirajno,et al.  Geochemistry of metabasalts and hydrothermal alteration zones associated with c. 3.45 Ga chert and barite deposits: implications for the geological setting of the Warrawoona Group, Pilbara Craton, Australia , 2004, Geochemistry: Exploration, Environment, Analysis.

[5]  Wei Wang,et al.  U-Pb Ages from the Neoproterozoic Doushantuo Formation, China , 2005, Science.

[6]  J. Robertson,et al.  Interpretation of Raman spectra of disordered and amorphous carbon , 2000 .

[7]  Jean-Noël Rouzaud,et al.  Characterization of carbonaceous materials by correlated electron and optical microscopy and Raman microspectroscopy , 1985 .

[8]  K. Konhauser.  Diversity of bacterial iron mineralization , 1998 .

[9]  D. Rowley,et al.  Late Precambrian through Early Paleozoic stratigraphic and tectonic evolution of the Nanling region, Hunan province, South China , 1997 .

[10]  Andrew Steele,et al.  Raman Spectroscopy and Confocal Raman Imaging in Mineralogy and Petrography , 2010 .

[11]  P. Cloud.  Significance of the Gunflint (Precambrian) Microflora , 1965, Science.

[12]  H. Edwards,et al.  Understanding the application of Raman spectroscopy to the detection of traces of life. , 2010, Astrobiology.

[13]  Raymond E. Smith,et al.  Burial metamorphism in the Hamersley Basin, Western Australia , 1982 .

[14]  R. Murray,et al.  Diagenesis of Metals Chemically Complexed to Bacteria: Laboratory Formation of Metal Phosphates, Sulfides, and Organic Condensates in Artificial Sediments , 1983, Applied and environmental microbiology.

[15]  J. Pasteris,et al.  Necessary, but not sufficient: Raman identification of disordered carbon as a signature of ancient life. , 2003, Astrobiology.

[16]  S. Awramik,et al.  The relationship between morphology, microstructure, and microbiota in three vertically intergrading stromatolites from the Gunflint Iron Formation , 1979 .

[17]  A. Guedes,et al.  Characterisation of dispersed organic matter from lower Palaeozoic metasedimentary rocks by organic petrography, X-ray diffraction and micro-Raman spectroscopy analyses , 2005 .

[18]  A. Knoll,et al.  Secular change in the Precambrian silica cycle: Insights from chert petrology , 2005 .

[19]  A. Steele,et al.  Graphite Whiskers in CV3 Meteorites , 2008, Science.

[20]  M. Perraki,et al.  Raman micro-spectroscopy on diamond, graphite and other carbon polymorphs from the ultrahigh-pressure metamorphic Kimi Complex of the Rhodope Metamorphic Province, NE Greece , 2006 .

[21]  A. Knoll,et al.  PHOSPHATIZED ANIMAL EMBRYOS FROM THE NEOPROTEROZOIC DOUSHANTUO FORMATION AT WENG'AN, GUIZHOU, SOUTH CHINA , 2000 .

[22]  L. P. Knauth,et al.  Stable isotope geochemistry of cherts and carbonates from the 2.0 Ga gunflint iron formation: implications for the depositional setting, and the effects of diagenesis and metamorphism , 1992 .

[23]  D. Houseknecht,et al.  Kerogen maturation and incipient graphitization of hydrocarbon source rocks in the Arkoma Basin, Oklahoma and Arkansas: a combined petrographic and Raman spectrometric study , 1998 .

[24]  D. Sears,et al.  Overview and classification of meteorites. , 1988 .

[25]  Larry R. Nittler,et al.  Characterization of insoluble organic matter in primitive meteorites by microRaman spectroscopy , 2007 .

[26]  N. Trewin,et al.  Geological setting of the Early Devonian Rhynie cherts, Aberdeenshire, Scotland: an early terrestrial hot spring system , 2002, Journal of the Geological Society.

[27]  J. Pasteris,et al.  Raman spectra of graphite as indicators of degree of metamorphism , 1991 .

[28]  T. Taylor,et al.  A filamentous cyanobacterium showing structured colonial growth from the Early Devonian Rhynie chert , 2007 .

[29]  R. Clayton,et al.  The oxygen isotope record in Murchison and other carbonaceous chondrites , 1984 .

[30]  Gordon E. Brown,et al.  Microbially influenced formation of 2,724-million-year-old stromatolites , 2008 .

[31]  J. Rouzaud,et al.  Raman spectra of carbonaceous material in metasediments: a new geothermometer , 2002 .

[32]  J. Schopf,et al.  Microfossils of the Early Archean Apex Chert: New Evidence of the Antiquity of Life , 1993, Science.

[33]  J. Schopf,et al.  Early Archean (3.3-billion to 3.5-billion-year-old) microfossils from Warrawoona Group, Australia. , 1987, Science.

[34]  J. Rouzaud,et al.  Graphitization in a high-pressure, low-temperature metamorphic gradient: a Raman microspectroscopy and HRTEM study , 2002 .

[35]  Michael H. Engel,et al.  The stereochemistry of amino acids in the Murchison meteorite , 2001 .

[36]  F. Guyot,et al.  Exceptional preservation of fossil plant spores in high-pressure metamorphic rocks , 2007 .

[37]  T. Wdowiak,et al.  In situ laser-Raman imagery of precambrian microscopic fossils. , 2001, Proceedings of the National Academy of Sciences of the United States of America.

[38]  R. McCreery,et al.  Raman Spectroscopy of Carbon Materials: Structural Basis of Observed Spectra , 1990 .

[39]  M. Brandon,et al.  Raman spectroscopic carbonaceous material thermometry of low-grade metamorphic rocks: Calibration and application to tectonic exhumation in Crete, Greece [rapid communication] , 2005 .

[40]  W. Lanier.  Interstitial and peloid microfossils from the 2.0 Ga Gunflint Formation: Implications for the paleoecology of the Gunflint Stromatolites , 1989 .

[41]  D. Davis,et al.  The age of the Gunflint Formation, Ontario, Canada: single zircon U-Pb age determinations from reworked volcanic ash , 2002 .

[42]  A. Knoll,et al.  MACROSCOPIC CARBONACEOUS COMPRESSIONS IN A TERMINAL PROTEROZOIC SHALE: A SYSTEMATIC REASSESSMENT OF THE MIAOHE BIOTA, SOUTH CHINA , 2002, Journal of Paleontology.

[43]  J. Jehlička,et al.  Raman spectroscopy of carbon and solid bitumens in sedimentary and metamorphic rocks. , 2003, Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy.

[44]  A. Knoll,et al.  Chemical Evidence for Cell Wall Lignification and the Evolution of Tracheids in Early Devonian Plants , 2003, International Journal of Plant Sciences.

[45]  P. Sheldonr,et al.  Ancient Marine Phosphorites , 1981 .

[46]  F. J. Luque.  Natural fluid-deposited graphite: Mineralogical characteristics and mechanisms of formation , 1998 .

[47]  A. Knoll,et al.  New Lu–Hf and Pb–Pb age constraints on the earliest animal fossils , 2002 .

[48]  M. V. Kranendonk,et al.  Geology and Tectonic Evolution of the Archean North Pilbara Terrain,Pilbara Craton, Western Australia , 2002 .

[49]  A. Steele,et al.  The problem of deep carbon—An Archean paradox , 2005 .

[50]  B. Kwieciǹska,et al.  Raman spectroscopy of selected carbonaceous samples , 2010 .

[51]  J. Schopf,et al.  Confocal laser scanning microscopy and Raman imagery of ancient microscopic fossils , 2009 .

[52]  M. Maurel,et al.  The micro-distribution of carbonaceous matter in the Murchison meteorite as investigated by Raman imaging. , 2005, Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy.

[53]  J. Rouzaud,et al.  High resolution TEM of chondritic carbonaceous matter: Metamorphic evolution and heterogeneity , 2012 .

[54]  P. Cloud,et al.  Reproductive structures and taxonomic affinities of some nannofossils from the gunflint iron formation. , 1968, Proceedings of the National Academy of Sciences of the United States of America.

[55]  G. Libourel,et al.  Type C Ca, Al-rich inclusions from Allende: Evidence for multistage formation , 2007 .

[56]  Makoto Ito,et al.  Facies architecture and sequence-stratigraphic features of the Tumbiana Formation in the Pilbara Craton, northwestern Australia: Implications for depositional environments of oxygenic stromatolites during the Late Archean , 2005 .

[57]  F. Tuinstra,et al.  Raman Spectrum of Graphite , 1970 .

[58]  M. V. Kranendonk,et al.  Evidence for Mesoarchean (∼3.2 Ga) rifting of the Pilbara Craton: The missing link in an early Precambrian Wilson cycle , 2010 .

[59]  V. Clément,et al.  Hydrothermal alteration and microfossil artefacts of the 3,465-million-year-old Apex chert , 2009 .

[60]  Abigail C. Allwood,et al.  Raman spectroscopy reveals thermal palaeoenvironments of c.3.5 billion-year-old organic matter , 2006 .

[61]  N. Trewin,et al.  Subaqueous silicification of the contents of small ponds in an Early Devonian hot-spring complex, Rhynie, Scotland , 2003 .

[62]  K. Konhauser,et al.  Bacterial clay authigenesis: a common biogeochemical process , 1999 .

[63]  A. Steele,et al.  Critical testing of Earth's oldest putative fossil assemblage from the ∼3.5Ga Apex chert, Chinaman Creek, Western Australia , 2005 .

[64]  J. Pasteris,et al.  Structural characterization of kerogens to granulite-facies graphite; applicability of Raman microprobe spectroscopy , 1993 .

[65]  Pasteris.  Causes of the uniformly high crystallinity of graphite in large epigenetic deposits , 1999 .

[66]  C. Marshall,et al.  Haematite pseudomicrofossils present in the 3.5-billion-year-old Apex Chert , 2011 .

[67]  A. Knoll,et al.  Three-dimensional preservation of algae and animal embryos in a Neoproterozoic phosphorite , 1998, Nature.

[68]  M. V. Kranendonk,et al.  Early traces of life investigations in drilling Archean hydrothermal and sedimentary rocks of the Pilbara Craton, Western Australia and Barberton Greenstone Belt, South Africa , 2009 .

[69]  D. Darby.  Reproductive Modes of Huroniospora microreticulata from Cherts of the Precambrian Gunflint Iron-Formation , 1974 .

[70]  J. Rouzaud,et al.  Precursor and metamorphic condition effects on Raman spectra of poorly ordered carbonaceous matter in chondrites and coals , 2009 .

[71]  D. Bower.  Micro‐Raman spectroscopic investigations of mineral assemblages in parallel to bedding laminae in 2.9 Ga sandstones of the Pongola Supergroup, South Africa , 2011 .

[72]  J. Jehlička,et al.  Application of Raman microspectrometry in the study of structural changes in precambrian kerogens during regional metamorphism , 1992 .

[73]  J. Miller,et al.  Reproductive Structures and Strategies of Turtles , 2007 .

[74]  J William Schopf,et al.  Raman imagery: a new approach to assess the geochemical maturity and biogenicity of permineralized precambrian fossils. , 2005, Astrobiology.