Diese Webseite setzt Cookies für folgende Funktionen ein: Anmeldung, Suche, personalisierte Inhalte, Seitenanalyse, Facebook likes.

Auf Wunsch der EU muss explizit darauf hingewiesen werden. Durch Nutzung unserer Website erklären Sie sich damit einverstanden.

Ancient microbial activity recorded in fracture fillings from granitic rocks (Äspö Hard Rock Laboratory, Sweden)

Hits: 888
Year:
2012
Type of Publication:
Artikel
Autoren:
HEIM, C.; LAUSMAA, J.; SJÖVALL, P.; TOPORSKI, J.; DIEING, T.; Simon, Klaus; HANSEN, B. T.; Kronz, Andreas; ARP, G.; REITNER, J.; THIEL, V.
Journal:
Geobiology
Volume:
10
Nummer:
4
Seiten:
280-297
ISSN:
1472-4669
BibTex:
Kurzzusammenfassung:
Fracture minerals within the 1.8-Ga-old Äspö Diorite (Sweden) were investigated for fossil traces of subterranean microbial activity. To track the potential organic and inorganic biosignatures, an approach combining complementary analytical techniques of high lateral resolution was applied to drill core material obtained at −450 m depth in the Äspö Hard Rock Laboratory. This approach included polarization microscopy, time-of-flight secondary ion mass spectrometry (ToF-SIMS), confocal Raman microscopy, electron microprobe (EMP) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). The fracture mineral succession, consisting of fluorite and low-temperature calcite, showed a thin (20–100 μm), dark amorphous layer lining the boundary between the two phases. Microscopic investigations of the amorphous layer revealed corrosion marks and, in places, branched tubular structures within the fluorite. Geochemical analysis showed significant accumulations of Si, Al, Mg, Fe and the light rare earth elements (REE) in the amorphous layer. In the same area, ToF-SIMS imaging revealed abundant, partly functionalized organic moieties, for example, CxHy+, CxHyN+, CxHyO+. The presence of such functionalized organic compounds was corroborated by Raman imaging showing bands characteristic of C-C, C-N and C-O bonds. According to its organic nature and the abundance of relatively unstable N- and O- heterocompounds, the organic-rich amorphous layer is interpreted to represent the remains of a microbial biofilm that established much later than the initial cooling of the Precambrian host rock. Indeed, δ13C, δ18O and 87Sr/86Sr isotope data of the fracture minerals and the host rock point to an association with a fracture reactivation event in the most recent geological past.
Free business joomla templates