TY - JOUR
T1 - An examination of spherulitic dubiomicrofossils in Precambrian banded iron formations using the transmission electron microscope
AU - Heaney, Peter J.
AU - Veblen, David R.
N1 - Funding Information:
Heartfelt gratitude goes to Ken Livi, who operated the electron microprobe. In addition, Jeff Post kindly allowed us to use his automated powder diffractometer. We also thank Profs. LaBerge and Mancuso for generously providing the specimens used in this study. Bruce Simonson, Andy Knoll, Laurie Hardie, and Michael Beer provided invaluable discussions, and helpful observations also were made by George Guthrie, Jill Banfield, and Gene Smelik. This research was supported by NSF Grants EAR86-09277 and EAR89-03630. Electron microscopy was performed in the Johns Hopkins HRTEM laboratory, which was established with partial support from NSF Grant EAR83-00365.
PY - 1991/2
Y1 - 1991/2
N2 - The discovery of microfossils from the banded iron-formations of southern Ontario (Tyler and Barghoorn, 1954) has spurred many researchers to attribute a biogenic origin to a great variety of unusual structures in Precambrian BIFs. In particular, LaBerge (1973) has argued that jaspery and sideritic spherulites common to all major BIF deposits represent the fossilized remains of a unicellular blue-green algae of the Early Proterozoic, Eosphaera tyleri. Oehler (1976b), on the other hand, regards such structures as crystallization products of a viscous and impure silica gel. Examination of these 30-μm spherulites with a transmission electron microscope sheds doubt on both interpretations. Our analysis suggests that the jaspery spheres formed from the local recrystallization of the chert-hematite matrix after contact with an infiltrating fluid; thus, these structures are best viewed as diagenetic features. On the other hand, we discovered that the sideritic spheres contain cores of apatite; consequently, these spheres may have a biogenic origin, though the abundance of phosphate would indicate that they are not fossils of individual cells.
AB - The discovery of microfossils from the banded iron-formations of southern Ontario (Tyler and Barghoorn, 1954) has spurred many researchers to attribute a biogenic origin to a great variety of unusual structures in Precambrian BIFs. In particular, LaBerge (1973) has argued that jaspery and sideritic spherulites common to all major BIF deposits represent the fossilized remains of a unicellular blue-green algae of the Early Proterozoic, Eosphaera tyleri. Oehler (1976b), on the other hand, regards such structures as crystallization products of a viscous and impure silica gel. Examination of these 30-μm spherulites with a transmission electron microscope sheds doubt on both interpretations. Our analysis suggests that the jaspery spheres formed from the local recrystallization of the chert-hematite matrix after contact with an infiltrating fluid; thus, these structures are best viewed as diagenetic features. On the other hand, we discovered that the sideritic spheres contain cores of apatite; consequently, these spheres may have a biogenic origin, though the abundance of phosphate would indicate that they are not fossils of individual cells.
UR - http://www.scopus.com/inward/record.url?scp=0026021650&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0026021650&partnerID=8YFLogxK
U2 - 10.1016/0301-9268(91)90041-8
DO - 10.1016/0301-9268(91)90041-8
M3 - Article
AN - SCOPUS:0026021650
SN - 0301-9268
VL - 49
SP - 355
EP - 372
JO - Precambrian Research
JF - Precambrian Research
IS - 3-4
ER -