Exogenous carbonaceous microstructures in Early Archaean cherts and BIFs from the Isua Greenstone Belt: implications for the search for life in ancient rocks
The microstructure of HF-etched samples of Early Archaean banded iron formations (BIFs) and cherts from the >3.7 b.y.-old Isua Greenstone Belt (southwestern Greenland) was investigated using high resolution scanning electron microscopy equipped with an electron diffraction system, capable of anal...
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ftunitours:oai:HAL:hal-00088213v1 2024-05-12T08:04:40+00:00 Exogenous carbonaceous microstructures in Early Archaean cherts and BIFs from the Isua Greenstone Belt: implications for the search for life in ancient rocks Westall, F. R.L., Folk Centre de biophysique moléculaire (CBM) Université d'Orléans (UO)-Université de Tours (UT)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Institut de Chimie - CNRS Chimie (INC-CNRS)-Centre National de la Recherche Scientifique (CNRS) 2003 https://hal.science/hal-00088213 https://doi.org/10.1016/S0301-9268(03)00102-5 en eng HAL CCSD Elsevier info:eu-repo/semantics/altIdentifier/doi/10.1016/S0301-9268(03)00102-5 hal-00088213 https://hal.science/hal-00088213 doi:10.1016/S0301-9268(03)00102-5 ISSN: 0301-9268 Precambrian Research https://hal.science/hal-00088213 Precambrian Research, 2003, 126, pp.313-330. ⟨10.1016/S0301-9268(03)00102-5⟩ Isua Chert BIF Graphite Endoliths Contamination info:eu-repo/semantics/article Journal articles 2003 ftunitours https://doi.org/10.1016/S0301-9268(03)00102-5 2024-04-18T00:08:17Z The microstructure of HF-etched samples of Early Archaean banded iron formations (BIFs) and cherts from the >3.7 b.y.-old Isua Greenstone Belt (southwestern Greenland) was investigated using high resolution scanning electron microscopy equipped with an electron diffraction system, capable of analysing light elements. The rocks contain both endogenous (of internal origin) and exogenous (of external origin) carbonaceous microstructures. The former consist of inclusions of graphite and, possibly, small, amorphous carbonaceous particles, both embedded in metacherts (however, further in situ TEM studies are needed to verify the endogeneity of the amorphous particles). Moreover, these rocks also contain endolithic microorganisms (i.e. inhabiting cracks in rocks), as well as undifferentiated carbonaceous matter, that occur in fractures and cracks between grains. The microorganisms include cyanobacteria, filamentous microorganisms such as fungal hyphae and possibly bacteria, as well as large, unidentified cells or spores. Most of the microorganisms appear to have been fossilised. The endoliths are evidently younger than the host rock, but must have infiltrated at different periods, most likely after the Inland Ice retreated (~8000 years ago).The presence of endolithic carbonaceous matter in cracks and microfissures in these rocks will affect any analyses of bulk samples, such as carbon isotopes and chemical biomarkers, as well as analyses of acid-macerated residues. Thus, previous isotope measurements made on BIFs and cherts from Isua may reflect younger contamination rather than an endogenous (original) signal. Likewise, some of the previously described Isuan microorganisms probably represent recent, endolithic contamination. Article in Journal/Newspaper Greenland Université François-Rabelais de Tours: HAL Greenland Precambrian Research 126 3-4 313 330 |
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Open Polar |
collection |
Université François-Rabelais de Tours: HAL |
op_collection_id |
ftunitours |
language |
English |
topic |
Isua Chert BIF Graphite Endoliths Contamination |
spellingShingle |
Isua Chert BIF Graphite Endoliths Contamination Westall, F. R.L., Folk Exogenous carbonaceous microstructures in Early Archaean cherts and BIFs from the Isua Greenstone Belt: implications for the search for life in ancient rocks |
topic_facet |
Isua Chert BIF Graphite Endoliths Contamination |
description |
The microstructure of HF-etched samples of Early Archaean banded iron formations (BIFs) and cherts from the >3.7 b.y.-old Isua Greenstone Belt (southwestern Greenland) was investigated using high resolution scanning electron microscopy equipped with an electron diffraction system, capable of analysing light elements. The rocks contain both endogenous (of internal origin) and exogenous (of external origin) carbonaceous microstructures. The former consist of inclusions of graphite and, possibly, small, amorphous carbonaceous particles, both embedded in metacherts (however, further in situ TEM studies are needed to verify the endogeneity of the amorphous particles). Moreover, these rocks also contain endolithic microorganisms (i.e. inhabiting cracks in rocks), as well as undifferentiated carbonaceous matter, that occur in fractures and cracks between grains. The microorganisms include cyanobacteria, filamentous microorganisms such as fungal hyphae and possibly bacteria, as well as large, unidentified cells or spores. Most of the microorganisms appear to have been fossilised. The endoliths are evidently younger than the host rock, but must have infiltrated at different periods, most likely after the Inland Ice retreated (~8000 years ago).The presence of endolithic carbonaceous matter in cracks and microfissures in these rocks will affect any analyses of bulk samples, such as carbon isotopes and chemical biomarkers, as well as analyses of acid-macerated residues. Thus, previous isotope measurements made on BIFs and cherts from Isua may reflect younger contamination rather than an endogenous (original) signal. Likewise, some of the previously described Isuan microorganisms probably represent recent, endolithic contamination. |
author2 |
Centre de biophysique moléculaire (CBM) Université d'Orléans (UO)-Université de Tours (UT)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Institut de Chimie - CNRS Chimie (INC-CNRS)-Centre National de la Recherche Scientifique (CNRS) |
format |
Article in Journal/Newspaper |
author |
Westall, F. R.L., Folk |
author_facet |
Westall, F. R.L., Folk |
author_sort |
Westall, F. |
title |
Exogenous carbonaceous microstructures in Early Archaean cherts and BIFs from the Isua Greenstone Belt: implications for the search for life in ancient rocks |
title_short |
Exogenous carbonaceous microstructures in Early Archaean cherts and BIFs from the Isua Greenstone Belt: implications for the search for life in ancient rocks |
title_full |
Exogenous carbonaceous microstructures in Early Archaean cherts and BIFs from the Isua Greenstone Belt: implications for the search for life in ancient rocks |
title_fullStr |
Exogenous carbonaceous microstructures in Early Archaean cherts and BIFs from the Isua Greenstone Belt: implications for the search for life in ancient rocks |
title_full_unstemmed |
Exogenous carbonaceous microstructures in Early Archaean cherts and BIFs from the Isua Greenstone Belt: implications for the search for life in ancient rocks |
title_sort |
exogenous carbonaceous microstructures in early archaean cherts and bifs from the isua greenstone belt: implications for the search for life in ancient rocks |
publisher |
HAL CCSD |
publishDate |
2003 |
url |
https://hal.science/hal-00088213 https://doi.org/10.1016/S0301-9268(03)00102-5 |
geographic |
Greenland |
geographic_facet |
Greenland |
genre |
Greenland |
genre_facet |
Greenland |
op_source |
ISSN: 0301-9268 Precambrian Research https://hal.science/hal-00088213 Precambrian Research, 2003, 126, pp.313-330. ⟨10.1016/S0301-9268(03)00102-5⟩ |
op_relation |
info:eu-repo/semantics/altIdentifier/doi/10.1016/S0301-9268(03)00102-5 hal-00088213 https://hal.science/hal-00088213 doi:10.1016/S0301-9268(03)00102-5 |
op_doi |
https://doi.org/10.1016/S0301-9268(03)00102-5 |
container_title |
Precambrian Research |
container_volume |
126 |
container_issue |
3-4 |
container_start_page |
313 |
op_container_end_page |
330 |
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1798846892478562304 |