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Journal articles on the topic 'Precambrian cherts'

Author: Grafiati

Published: 4 June 2021

Last updated: 13 February 2022

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1

GarcÍa-Ruiz, Juan Manuel. "Inorganic self-organisation in precambrian cherts." Origins of Life and Evolution of the Biosphere 24, no. 6 (1994): 451–67. http://dx.doi.org/10.1007/bf01582030.

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2

Perry, E. C., and L. Lefticariu. "The oxygen isotopic composition of Precambrian cherts." Geochimica et Cosmochimica Acta 70, no. 18 (2006): A483. http://dx.doi.org/10.1016/j.gca.2006.06.1429.

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3

Robert, François. "Carbon and oxygen isotope variations in precambrian cherts." Geochimica et Cosmochimica Acta 52, no. 6 (1988): 1473–78. http://dx.doi.org/10.1016/0016-7037(88)90218-9.

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4

Golovenok, V. K. "PRECAMBRIAN MICROFOSSILS IN CHERTS AND THEIR BIOSTRATIGRAPHIC SIGNIFICANCE." International Geology Review 31, no. 10 (1989): 1018–24. http://dx.doi.org/10.1080/00206818909465955.

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5

Schwartzman, David, and Charles H. Lineweaver. "Precambrian Surface Temperatures and Molecular Phylogeny." Symposium - International Astronomical Union 213 (2004): 355–58. http://dx.doi.org/10.1017/s0074180900193532.

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The timing of emergence of major organismal groups is consistent with the climatic temperature being equal to their upper temperature limit of growth (Tmax), implying a temperature constraint on the evolution of each group, with the climatic temperature inferred from the oxygen isotope record of marine cherts. Support for this constraint comes from the correlation of Tmax with the rRNA molecular phylogenetic distance from the last common ancestor (LCA) for both thermophilic Archaea and Bacteria. In particular, this correlation for hyperthermophilic Archaea suggests a climatic temperature of ab

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6

Robert, François, and Marc Chaussidon. "A palaeotemperature curve for the Precambrian oceans based on silicon isotopes in cherts." Nature 443, no. 7114 (2006): 969–72. http://dx.doi.org/10.1038/nature05239.

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7

Marin-Carbonne, J., F. Robert, and M. Chaussidon. "The silicon and oxygen isotope compositions of Precambrian cherts: A record of oceanic paleo-temperatures?" Precambrian Research 247 (July 2014): 223–34. http://dx.doi.org/10.1016/j.precamres.2014.03.016.

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8

Beaumont, V., and F. Robert. "Nitrogen isotope ratios of kerogens in Precambrian cherts: a record of the evolution of atmosphere chemistry?" Precambrian Research 96, no. 1-2 (1999): 63–82. http://dx.doi.org/10.1016/s0301-9268(99)00005-4.

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9

Nagasawa, Hiroshi, and Kanenori Suwa. "Rare-earth concentrations in 3.5-billion-year-old Onverwacht cherts: An indicator for early Precambrian crustal environments." GEOCHEMICAL JOURNAL 20, no. 5 (1986): 253–60. http://dx.doi.org/10.2343/geochemj.20.253.

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Nagasawa, Hiroshi, and Kanenori Suwa. "Rare-earth concentrations in 3.5-billion-year-old Onverwacht cherts : An indicator for early Precambrian crustal environments." GEOCHEMICAL JOURNAL 20, no. 5 (1986): 255–60. http://dx.doi.org/10.2343/geochemj.20.255.

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11

Schopf, J. William, Anatoliy B. Kudryavtsev, Malcolm R. Walter, et al. "Sulfur-cycling fossil bacteria from the 1.8-Ga Duck Creek Formation provide promising evidence of evolution's null hypothesis." Proceedings of the National Academy of Sciences 112, no. 7 (2015): 2087–92. http://dx.doi.org/10.1073/pnas.1419241112.

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The recent discovery of a deep-water sulfur-cycling microbial biota in the ∼2.3-Ga Western Australian Turee Creek Group opened a new window to life's early history. We now report a second such subseafloor-inhabiting community from the Western Australian ∼1.8-Ga Duck Creek Formation. Permineralized in cherts formed during and soon after the 2.4- to 2.2-Ga “Great Oxidation Event,” these two biotas may evidence an opportunistic response to the mid-Precambrian increase of environmental oxygen that resulted in increased production of metabolically useable sulfate and nitrate. The marked similarity

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Qingyu, Wu, Liu Zhili, and Zhu Haoran. "Biogeochemical Model and Simulation of the Effect of Precambrian Algae on the Formation Process of Certain Laminated Cherts." Acta Geologica Sinica-English 60, no. 4 (2009): 67–81. http://dx.doi.org/10.1111/j.1755-6724.1986.mp60004007.x.

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13

Chick, Jonathan, Sydney E. McKim, Adriana Potra, Walter L. Manger, and John R. Samuelsen. "Radiogenic Pb Enrichment of Mississippi Valley-Type Metallic Ore Deposits, Southern Ozarks: Constraints Based on Geochemical Studies of Source Rocks and Their Diagenetic History." Geosciences 11, no. 4 (2021): 172. http://dx.doi.org/10.3390/geosciences11040172.

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Southern Ozark Mississippi Valley-type ores are enriched in radiogenic Pb, with isotopic signatures suggesting that metals were supplied by two end-member components. While the less radiogenic component appears to be derived from various shale and sandstone units, the source of the more radiogenic component has not yet been identified. Analyses of cherts from the Early Ordovician Cotter Dolomite and tripolitic chert from the Early Mississippian Boone Formation contain highly radiogenic Pb, with isotopic ratios comparable to those of ores. However, most samples have lower 208Pb/204Pb and 207Pb/

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14

Zakharov, D. O., J. Marin-Carbonne, J. Alleon, and I. N. Bindeman. "Triple Oxygen Isotope Trend Recorded by Precambrian Cherts: A Perspective from Combined Bulk and in situ Secondary Ion Probe Measurements." Reviews in Mineralogy and Geochemistry 86, no. 1 (2021): 323–65. http://dx.doi.org/10.2138/rmg.2021.86.10.

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15

Sergeev, Vladimir N., and J. William Schopf. "Taxonomy, paleoecology and biostratigraphy of the late Neoproterozoic Chichkan microbiota of South Kazakhstan: the marine biosphere on the eve of metazoan radiation." Journal of Paleontology 84, no. 3 (2010): 363–401. http://dx.doi.org/10.1666/09-133.1.

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Carbonaceous bedded cherts of the late Neoproterozoic (Cryogenian) ∼800 to 750 Ma old Chichkan Formation of South Kazakhstan contain an abundant, diverse assemblage of exquisitely preserved microorganisms. Like many Proterozoic microbiotas, the Chichkan assemblage is dominated by prokaryotic cyanobacteria, both filamentous (oscillatorialeans and nostocaleans, represented primarily by cellular trichomes and empty sheaths) and coccoidal (chroococcaleans and pleurocapsaleans, including solitary, colonial, and stalk-forming specimens). However, unlike Proterozoic microbiotas reported from peritida

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16

Premovic, Pavle, Goran Nikolic, Miroslav Premovic, and Ivana Tonsa. "Fourier transform infrared and electron spin resonance examinations of kerogen from the gunflint stromatolitic cherts (Middle Precambrian, Ontario, Canada) and related materials." Journal of the Serbian Chemical Society 65, no. 4 (2000): 229–44. http://dx.doi.org/10.2298/jsc0004229p.

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Kerogen occurrences in stromatolitic cherts from the Middle Precambrian Gunflint Formation and related rocks have been investigated by the use of elemental analysis, Fourier transform infrared and electron spin resonance spectroscopies. Particular attention was paid to the structural properties of the Schreiber kerogen to allow comparison with biologically controlled kerogens from Paleozoic carbonaceous rocks. The low atomic H/C ratios (0.5) of the Schreiber kerogen indicates that this material has reached a high level of maturity. The Fourier transform infrared/electron spin resonance examina

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Schopf, J. William, Anatoliy B. Kudryavtsev, and Vladimir N. Sergeev. "Confocal laser scanning microscopy and Raman imagery of the late Neoproterozoic Chichkan microbiota of South Kazakhstan." Journal of Paleontology 84, no. 3 (2010): 402–16. http://dx.doi.org/10.1666/09-134.1.

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Precambrian microbiotas, such as that permineralized in bedded and stromatolitic cherts of the late Neoproterozoic, 750- to 800-Ma-old, Chichkan Formation of South Kazakhstan, have traditionally been studied by optical microscopy only. Such studies, however, are incapable of documenting accurately either the three-dimensional morphology of such fossils or their chemical composition and that of their embedding minerals. As shown here by analyses of fossils of the Chichkan Lagerstätte, the solution to these long-standing problems is provided by two techniques recently introduced to paleontology:

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18

Marin-Carbonne, Johanna, François Faure, Marc Chaussidon, Damien Jacob, and François Robert. "A petrographic and isotopic criterion of the state of preservation of Precambrian cherts based on the characterization of the quartz veins." Precambrian Research 231 (July 2013): 290–300. http://dx.doi.org/10.1016/j.precamres.2013.03.019.

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19

Marin-Carbonne, Johanna, Marc Chaussidon, and François Robert. "Micrometer-scale chemical and isotopic criteria (O and Si) on the origin and history of Precambrian cherts: Implications for paleo-temperature reconstructions." Geochimica et Cosmochimica Acta 92 (September 2012): 129–47. http://dx.doi.org/10.1016/j.gca.2012.05.040.

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20

Horodyski, Robert J., Kathleen B. Dudek, Gerald M. Ross, and J. Allan Donaldson. "Microfossils from the Early Proterozoic Hornby Bay Group, District of Mackenzie, Northwest Territories, Canada." Canadian Journal of Earth Sciences 22, no. 5 (1985): 758–67. http://dx.doi.org/10.1139/e85-080.

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Spheroidal and filamentous organic-walled microfossils have been detected in ca. 1.7 Ga old cherts of the Hornby Bay Group, Northwest Territories, Canada. The majority of the spheroidal forms range from 1 to 4 μm in diameter, are referable to the genus Sphaerophycus, and probably represent the preserved sheaths of chroococcacean cyanophytes. A single, robust-walled, 27 μm diameter, spheroidal microfossil of undetermined affinity is also present. The filamentous forms are tubular, unbranched, and range from 1 to 8 μm in diameter. They appear to represent the preserved sheaths of nostocalean cya

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21

Herwartz, Daniel, Andreas Pack, and Thorsten J. Nagel. "A CO2 greenhouse efficiently warmed the early Earth and decreased seawater 18O/16O before the onset of plate tectonics." Proceedings of the National Academy of Sciences 118, no. 23 (2021): e2023617118. http://dx.doi.org/10.1073/pnas.2023617118.

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The low 18O/16O stable isotope ratios (δ18O) of ancient chemical sediments imply ∼70 °C Archean oceans if the oxygen isotopic composition of seawater (sw) was similar to modern values. Models suggesting lower δ18Osw of Archean seawater due to intense continental weathering and/or low degrees of hydrothermal alteration are inconsistent with the triple oxygen isotope composition (Δ’17O) of Precambrian cherts. We show that high CO2 sequestration fluxes into the oceanic crust, associated with extensive silicification, lowered the δ18Osw of seawater on the early Earth without affecting the Δ’17O. H

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22

Liljestrand, Frasier L., Andrew H. Knoll, Nicholas J. Tosca, et al. "The triple oxygen isotope composition of Precambrian chert." Earth and Planetary Science Letters 537 (May 2020): 116167. http://dx.doi.org/10.1016/j.epsl.2020.116167.

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23

Akai, Junji, Shun Ito, Nozomu Sekiguchi, and Munetomo Nedachi. "Mineralogy of microbial fossil-like textures in the Precambrian Marble Bar chert and Gunflint chert." Materials Science and Engineering: C 26, no. 4 (2006): 613–16. http://dx.doi.org/10.1016/j.msec.2005.06.057.

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24

Maliva, Robert G., Andrew H. Knoll, and Bruce M. Simonson. "Secular change in the Precambrian silica cycle: Insights from chert petrology." Geological Society of America Bulletin 117, no. 7 (2005): 835. http://dx.doi.org/10.1130/b25555.1.

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25

Brasier, M. D., and P. Singh. "Microfossils and Precambrian–Cambrian boundary stratigraphy at Maldeota, Lesser Himalaya." Geological Magazine 124, no. 4 (1987): 323–45. http://dx.doi.org/10.1017/s0016756800016666.

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AbstractAn assemblage of problematical microfossils of Precambrian–Cambrian boundary age is redescribed from the Chert–Phosphorite Member, at the base of the Lower Tal Formation of Maldeota in the Lesser Himalaya of India. This assemblage has previously been ascribed to various ages, from Precambrian to Cretaceous, but is held by us to contain:Maldeotaia bandalica, Protohertzina anabaricagroup, trumpet-shaped elements, acicular elements A & B, ?Conothecasp.,Ovalithecacf.multicostata, allathecid sp. A,Barbitositheca ansata, Hexangulaconulariacf.formosa, Coleoloidesaff.typicalis, Hyolithellu

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26

Kumar, Gopendra, D. K. Bhatt, and B. K. Raina. "Skeletal microfauna of Meishucunian and Qiongzhusian (Precambrian–Cambrian boundary) age from the Ganga Valley, Lesser Himalaya, India." Geological Magazine 124, no. 2 (1987): 167–71. http://dx.doi.org/10.1017/s0016756800015995.

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AbstractThe earliest skeletal microfauna of Precambrian-Cambrian age recovered from the ‘Lower Tal’ sequence (Chert-Phosphorite to Calcareous members) of the Tal Formation, exposed in the Ganga Valley, Lesser Himalaya, Uttar Pradesh, India, has been grouped into three assemblages. In ascending order these are: assemblage I, containing Anabarites trisulcatus Missarzhevsky, Tiksitheca korobovi (Miss.). Circotheca sp., Turcutheca sp., Spirellus columnorus Jiang and Olivooides alveus Qian; assemblage II, yielding Allonia erromenosa Jiang, A. sp. cf. A. erromenosa Jiang, Dimidia simpleca Jiang, D.

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27

Rasmussen, Birger, and Janet R. Muhling. "Organic-rich microfossils produced by oil infiltration of hollow silicified bacteria: Evidence from the ca. 340 Ma Red Dog Zn-Pb deposit, Alaska." Geology 47, no. 12 (2019): 1107–11. http://dx.doi.org/10.1130/g46346.1.

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Abstract The remarkable preservation of carbonaceous microfossils in Precambrian chert has been attributed to rapid silica precipitation enclosing original cellular carbon. However, while silicification of bacteria can preserve cellular morphology, in modern silicifying environments, organic molecules are rapidly destroyed after death, raising questions about the origin of carbon in ancient microfossils. Here, we show that carbonaceous matter in filamentous microfossils in chert from the Carboniferous Red Dog Zn-Pb deposit, northern Alaska, represents relicts of migrated oil. Black, carbonaceo

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Tiwari, Meera. "Organic-walled microfossils from the Chert–phosphorite Member, Tal Formation, Precambrian–Cambrian Boundary, India." Precambrian Research 97, no. 1-2 (1999): 99–113. http://dx.doi.org/10.1016/s0301-9268(99)00023-6.

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29

Simonson, Bruce M., and A. D. T. Goode. "First discovery of ferruginous chert arenites in the early Precambrian Hamersley Group of Western Australia." Geology 17, no. 3 (1989): 269. http://dx.doi.org/10.1130/0091-7613(1989)017<0269:fdofca>2.3.co;2.

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30

Ryazantsev, A. V., L. A. Novikov, and A. A. Razumovskij. "Carboniferous continental margin mafic-ultramafic sheeted dyke complex in the West Magnitogorsk zone (Southern Urals)." Proceedings of higher educational establishments. Geology and Exploration, no. 3 (June 28, 2019): 42–50. http://dx.doi.org/10.32454/0016-7762-2019-3-42-50.

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In the West of the aHochthon of Magnitogorsk zone thrusted onto the Precambrian complexes of the Uraltau zone, the Devonian island-arc complexes overlap stratigraphicalry the Ordovician and Silurian chert-basalt sequences and serpentine melange. Melange and Ordovician strata are intruded by dyke swarms and sheeted dykes («dyke in dyke») which are composed of mafic and ultramafic rocks. The dykes, composed by gabbro-dolerite, amphibole K-feldspar gabbro, hornblendite, picrite and lamprophyre, predominate. The composition of the ultramafic rocks corresponds to the composition of picrite and koma

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31

Waggoner, Benjamin M. "Fossil actinomycete in Eocene-Oligocene Dominican amber." Journal of Paleontology 68, no. 2 (1994): 398–401. http://dx.doi.org/10.1017/s0022336000022964.

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Actinomycetes are Gram-positive prokaryotes that tend to form branching and fragmenting filaments, which in some groups form a sizable mycelium. They make up a large and important part of modern terrestrial microfloras but are not known extensively as fossils, although they have a long fossil history. Actinomycete-like fossils appear several times in the Precambrian: in the middle Precambrian Gowganda Formation of Ontario (Jackson, 1967), in the 2.0 Ga Gunflint Chert of Ontario (Lanier, 1987), and possibly in a lichen-like symbiosis in the 2.8 Ga Witwatersrand rocks of South Africa (Hallbauer

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32

Osterhout, Jeffrey T., Andrew D. Czaja, Julie K. Bartley, and Philip W. Fralick. "Preservation of carbon isotopes in kerogen from thermally altered Mesoproterozoic lacustrine microbialites." Canadian Journal of Earth Sciences 56, no. 10 (2019): 1017–26. http://dx.doi.org/10.1139/cjes-2018-0309.

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Stable carbon isotope geochemistry is a well-established and reliable tool for studying metabolisms of microbial communities in the Precambrian record; however, the isotopic effects of high-temperature alteration from igneous intrusions (i.e., contact metamorphism) have not been thoroughly explored. The Mesoproterozoic (∼1.4 Ga) Middlebrun Bay Member of the Rossport Formation, Sibley Group, in Ontario, Canada, is composed of carbonaceous stromatolites and microbial laminites preserved in an evaporitic, lacustrine chert–carbonate deposit and is cross-cut by an intrusive mafic sill at the studie

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Burgess, Ray, Sarah L. Goldsmith, Hirochika Sumino, et al. "Archean to Paleoproterozoic seawater halogen ratios recorded by fluid inclusions in chert and hydrothermal quartz." American Mineralogist 105, no. 9 (2020): 1317–25. http://dx.doi.org/10.2138/am-2020-7238.

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Abstract Past changes in the halogen composition of seawater are anticipated based on the differing behavior of chlorine and bromine that are strongly partitioned into seawater, relative to iodine, which is extremely depleted in modern seawater and enriched in marine sediments due to biological uptake. Here we assess the use of chert, a chemical sediment that precipitated throughout the Precambrian, as a proxy for halide ratios in ancient seawater. We determine a set of criteria that can be used to assess the primary nature of halogens and show that ancient seawater Br/Cl and I/Cl ratios can b

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34

Gupta, A. K., and A. K. Singh. "Geochemical and biostratigraphic constraints on the genesis of mafic intrusive in the Buxa Dolomite (Neoproterozoic), Panging area of the Arunachal Lesser Himalaya, north east India." Journal of Nepal Geological Society 40 (December 1, 2010): 1–12. http://dx.doi.org/10.3126/jngs.v40i0.23591.

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Mafic intrusive within Neoproterozoic carbonates of Miri-Buxa Group in the Panging area of the Arunachal Lesser Himalaya, NE India has been reported for the first time. These mafic rocks have affinity to subalkaline-Mg-tholeiites and identified as low-Ti gabbro. Geochemically they are characterized by enrichment in LILE and LREE, depleted in HFSE with minor REE fractionated nature [(La/Yb)N = 2.70-3.29)] and positive Eu anomalies (Eu/Eu* = 1.00-1.30). These rocks have the influence of a within plate signature which were intruded in a continental rift tectonic environment. Petrogenetic modeling

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35

Natal’in, Boris A., Gürsel Sunal, Erkan Gün, Bo Wang, and Yang Zhiqing. "Precambrian to Early Cretaceous rocks of the Strandja Massif (northwestern Turkey): evolution of a long lasting magmatic arc." Canadian Journal of Earth Sciences 53, no. 11 (2016): 1312–35. http://dx.doi.org/10.1139/cjes-2016-0026.

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The Strandja Massif, northwestern Turkey, forms a link between the Balkan Zone of Bulgaria, which is correlated with the Variscan orogen in Europe, and the Pontides, where Cimmerian structures are prominent. Five fault-bounded tectonic units form the massif structure. (1) The Kırklareli Unit consists of the Paleozoic basement intruded by the Carboniferous to Triassic Kırklareli metagranites. It is unconformably overlain by Permian and Triassic metasediments. (2) The Vize Unit that is made of Neoproterozoic metasediments, which are intruded by Cambrian metagranites, and overlain by the pre-Ordo

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36

Nelson, JoAnne L. "The Sylvester Allochthon: upper Paleozoic marginal-basin and island-arc terranes in northern British Columbia." Canadian Journal of Earth Sciences 30, no. 3 (1993): 631–43. http://dx.doi.org/10.1139/e93-048.

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The Sylvester Allochthon is a composite klippe of upper Paleozoic ophiolitic, island-arc, and pericratonic assemblages, which rests directly on the Cassiar terrane, a displaced sliver of Ancestral North America. Each tectonic assemblage occurs at a distinct and consistent structural level within the allochthon. They are assigned, respectively, to the Slide Mountain, Harper Ranch, and Yukon–Tanana terranes. The Sylvester Allochthon provides a view of the structural relationships between these terranes prior to Early Cretaceous – early Tertiary strike-slip dismemberment, as well as possible sedi

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Hajná, Jaroslava, Jiří Žák, Lukáš Ackerman, Martin Svojtka, and Jan Pašava. "A giant late Precambrian chert-bearing olistostrome discovered in the Bohemian Massif: A record of Ocean Plate Stratigraphy (OPS) disrupted by mass-wasting along an outer trench slope." Gondwana Research 74 (October 2019): 173–88. http://dx.doi.org/10.1016/j.gr.2018.10.010.

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38

Nelson, JoAnne, and George Gehrels. "Detrital zircon geochronology and provenance of the southeastern Yukon–Tanana terrane." Canadian Journal of Earth Sciences 44, no. 3 (2007): 297–316. http://dx.doi.org/10.1139/e06-105.

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Two samples of late Paleozoic grit and Late Mississippian quartzite–chert conglomerate collected from southeastern Yukon–Tanana terrane (YTT) — a composite thrust sheet resting structurally above North American parautochthonous strata and intervening imbricate sheets of the late Paleozoic oceanic Slide Mountain terrane — yielded, respectively, 89 and 74 concordant or nearly concordant (<20% discordant) U–Pb ages on single detrital zircons. They provide constraints on the provenance of this allochthonous pericratonic terrane. Zircons in the grit range from 1770 to 2854 Ma, with a well-define

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Dai, Yanpei, Yudi Zhu, Lianchang Zhang, and Mingtian Zhu. "Meso- and Neoarchean Banded Iron Formations and Genesis of High-Grade Magnetite Ores in the Anshan-Benxi Area, North China Craton." Economic Geology 112, no. 7 (2017): 1629–51. http://dx.doi.org/10.5382/econgeo.2017.4524.

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Abstract The Anshan-Benxi area in the North China craton has numerous occurrences of Algoma-type banded iron formations (BIFs) with subordinate high-grade magnetite ores. These ores provide insight into iron metallogenesis and early evolution of the North China craton. In this paper, we present Sm-Nd-Fe-O isotope, mineralogical, and structural data for four BIF-type iron deposits to place constraints on their depositional ages and formation mechanism. Previous SIMS and LA-ICP-MS zircon U-Pb dating results indicated a Mesoarchean age (ca. 3.10 Ga) for the Dagushan BIF and a Neoarchean age (ca.

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Nims, Christine, Julia Lafond, Julien Alleon, Alexis S. Templeton, and Julie Cosmidis. "Organic biomorphs may be better preserved than microorganisms in early Earth sediments." Geology, January 28, 2021. http://dx.doi.org/10.1130/g48152.1.

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The Precambrian rock record contains numerous examples of microscopic organic filaments and spheres, commonly interpreted as fossil microorganisms. Microfossils are among the oldest traces of life on Earth, making their correct identification crucial to our understanding of early evolution. Yet, spherical and filamentous microscopic objects composed of organic carbon and sulfur can form in the abiogenic reaction of sulfide with organic compounds. Termed organic biomorphs, these objects form under geochemical conditions relevant to the sulfidic environments of early Earth. Furthermore, they ado

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41

Schopf, J. William. "Precambrian Paleobiology: Precedents, Progress, and Prospects." Frontiers in Ecology and Evolution 9 (August 27, 2021). http://dx.doi.org/10.3389/fevo.2021.707072.

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In 1859, C. R. Darwin highlighted the “inexplicable” absence of evidence of life prior to the beginning of the Cambrian. Given this lack of evidence and the natural rather than theological unfolding of life’s development Darwin espoused, over the following 50 years his newly minted theory was disputed. At the turn of the 19th century, beginning with the discoveries of C. D. Walcott, glimmerings of the previously “unknown and unknowable” early fossil record came to light – but Walcott’s Precambrian finds were also discounted. It was not until the breakthrough advances of the 1950’s and the iden

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Lukmanov, Rustam A., Andreas Riedo, David Wacey, et al. "On Topological Analysis of fs-LIMS Data. Implications for in Situ Planetary Mass Spectrometry." Frontiers in Artificial Intelligence 4 (August 23, 2021). http://dx.doi.org/10.3389/frai.2021.668163.

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In this contribution, we present results of non-linear dimensionality reduction and classification of the fs laser ablation ionization mass spectrometry (LIMS) imaging dataset acquired from the Precambrian Gunflint chert (1.88 Ga) using a miniature time-of-flight mass spectrometer developed for in situ space applications. We discuss the data generation, processing, and analysis pipeline for the classification of the recorded fs-LIMS mass spectra. Further, we define topological biosignatures identified for Precambrian Gunflint microfossils by projecting the recorded fs-LIMS intensity space into

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"Concluding remarks." Philosophical Transactions of the Royal Society of London. B, Biological Sciences 311, no. 1148 (1985): 187–92. http://dx.doi.org/10.1098/rstb.1985.0151.

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Abstract:

Charles Walcott’s discovery of the Burgess Shale was by no means the first exceptional fossil locality with soft-part preservation to be unearthed, but in many ways his publications (spanning 1910-1931) provide a landmark in the history of the documentation of soft-bodied fossil biotas. Over the last 50 years the record and interpretation of exceptional preservation has grown dramatically. Milestones include the recognition of the exquisitely preserved microbiotas of the Precambrian Gunflint Chert (Barghoorn & Tyler 1965) and Bitter Springs Chert (Schopf 1968) (see also Knoll, this symposi

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