TY - JOUR
T1 - (Micro)morphological, inorganic-organic isotope geochemisty and microbial populations in endostromatolites (cf. fissure calcretes), Haughton impact structure, Devon Island, Canada
T2 - The influence of geochemical pathways on the preservation of isotope biomarkers
AU - Lacelle, Denis
AU - Pellerin, André
AU - Clark, Ian D.
AU - Lauriol, Bernard
AU - Fortin, Danielle
N1 - Funding Information:
This work was supported by a Canadian Space Agency internal research fund to DL, and Natural Sciences and Engineering Research Council of Canada (NSERC) and Canadian Space Agency (CSA–CARN) grants to IDC, BL and DF. Logistical support from Northern Scientific Training to AP is also greatly appreciated. We would like to thank C. Hillaire-Marcel for leading us to the site, and all those involved in the Haughton–Mars Project, especially P. Lee and J. Schwartz, for their assistance during the 2006–07 field seasons. The manuscript was improved by the constructive comments provided by 2 anonymous reviewers.
PY - 2009/5/15
Y1 - 2009/5/15
N2 - Endostromatolites (cf. fissure calcretes), which possess microbial evidence for a biogenic origin, are also thought to preserve isotopic biosignatures. In this study, a multi-proxy approach combining (micro)morphological, geochemical and isotopic analyses of middle Holocene age endostromatolites within sub-horizontal fissures in dolomitic limestone outcrops in the Haughton impact crater region (Devon Island, NU) was used to determine their origin (abiotic versus biogenic) and to identify potential isotope biosignatures. The micro-morphologies of the endostromatolites revealed some structures typical of a physico-chemical origin, whereas the presence of rod-shape particles and filamentous structures was more reminiscent of biologically-induced forms. The endostromatolites have δ13C and δ18O compositions reaching maximum values of 7.2‰ and - 11.2‰, respectively. Positive relations between the elemental (Mg, Sr) and isotopic (δ18O and δ13C) composition of the endostromatolites are indicative of an evaporative enrichment process of the meteoric water infiltrating the fissures prior to calcite precipitation. However, the positive δ13CTOC-δ13CCaCO3 relation in the endostromatolites is strongly indicative that they were microbially-mediated. In support of a microbial origin, mostly aerobic heterotrophic bacteria that have been linked to both carbonate dissolution and mineralization were observed in the microbial diversity of the endostromatolites. However, the results are inconclusive to attribute the formation of the endostromatolites solely to a biologically-induced mineralization, but instead, favor a more complex origin that involved abiotic (evaporation), and to some extent, biological processes prior to and during calcite precipitation. Considering that the endostromatolites result from microbially-influenced mineralization, the effects of physico-chemical processes on the geochemical and isotopic composition of the endostromatolites were much greater than the effect of the biological processes. Thus, it seems that preservation of isotopic biosignatures in secondary carbonate precipitates is dependent on the sequence of processes generating chemical and isotopic modifications of the solution prior to calcite precipitation, the mechanism and condition (equilibrium or kinetic) of formation and post-fossilization alteration processes. Crown
AB - Endostromatolites (cf. fissure calcretes), which possess microbial evidence for a biogenic origin, are also thought to preserve isotopic biosignatures. In this study, a multi-proxy approach combining (micro)morphological, geochemical and isotopic analyses of middle Holocene age endostromatolites within sub-horizontal fissures in dolomitic limestone outcrops in the Haughton impact crater region (Devon Island, NU) was used to determine their origin (abiotic versus biogenic) and to identify potential isotope biosignatures. The micro-morphologies of the endostromatolites revealed some structures typical of a physico-chemical origin, whereas the presence of rod-shape particles and filamentous structures was more reminiscent of biologically-induced forms. The endostromatolites have δ13C and δ18O compositions reaching maximum values of 7.2‰ and - 11.2‰, respectively. Positive relations between the elemental (Mg, Sr) and isotopic (δ18O and δ13C) composition of the endostromatolites are indicative of an evaporative enrichment process of the meteoric water infiltrating the fissures prior to calcite precipitation. However, the positive δ13CTOC-δ13CCaCO3 relation in the endostromatolites is strongly indicative that they were microbially-mediated. In support of a microbial origin, mostly aerobic heterotrophic bacteria that have been linked to both carbonate dissolution and mineralization were observed in the microbial diversity of the endostromatolites. However, the results are inconclusive to attribute the formation of the endostromatolites solely to a biologically-induced mineralization, but instead, favor a more complex origin that involved abiotic (evaporation), and to some extent, biological processes prior to and during calcite precipitation. Considering that the endostromatolites result from microbially-influenced mineralization, the effects of physico-chemical processes on the geochemical and isotopic composition of the endostromatolites were much greater than the effect of the biological processes. Thus, it seems that preservation of isotopic biosignatures in secondary carbonate precipitates is dependent on the sequence of processes generating chemical and isotopic modifications of the solution prior to calcite precipitation, the mechanism and condition (equilibrium or kinetic) of formation and post-fossilization alteration processes. Crown
KW - Arctic
KW - Devon Island
KW - biomineralization
KW - cold-climate carbonates
KW - endostromatolites
UR - http://www.scopus.com/inward/record.url?scp=64549116273&partnerID=8YFLogxK
U2 - 10.1016/j.epsl.2009.02.022
DO - 10.1016/j.epsl.2009.02.022
M3 - Article
AN - SCOPUS:64549116273
SN - 0012-821X
VL - 281
SP - 202
EP - 214
JO - Earth and Planetary Science Letters
JF - Earth and Planetary Science Letters
IS - 3-4
ER -