نتایج جستجو برای: microfossils

تعداد نتایج: 531  

Journal: :Proceedings of the National Academy of Sciences of the United States of America 1976
L A Nagy J E Zumberge

Microfossils, probably representing members of Precambrian photosynthetic communities of bacteria and blue-green algae, have been found in the approximately 2800-2500 million-year-old Bulawayan stromatolites from Rhodesia. Several populations of coccoid and elongate microfossils have been observed in the dark, carbon-rich stromatolite laminae. Some of these elongate forms are morphologically si...

2017
Frédéric Delarue François Robert Kenichiro Sugitani Romain Tartèse Rémi Duhamel Sylvie Derenne

Observations of Archean organic-walled microfossils suggest that their fossilization took place through both encapsulation and permineralization. In this study, we investigated microfossils from the ca. 3.0 Ga Farrel Quartzite (Pilbara, Western Australia) using transmitted light microscopy, scanning electron microscopy, Raman microspectrometry, and nanoscale secondary ion mass spectrometry (Nan...

2000
Cristina Simonetti Thomas R. Fairchild

Compressed organic-walled microfossils attributable to five filamentous taxa, and ten coccoidal eight, (taxa originally spheroidal forms and two originally ellipsoidal, colonial forms), all having long time-ranges in the Proterozoic, have been identified in fine-grained siliciclastic sediments in cores from four bore holes cutting subsurface equivalents of the Mesoproterozoic Conselheiro Mata G...

Journal: :نشریه دانشکده فنی 0
عباس کیمیائی

the study of plant microfossils (palynology) has increased in past ten years. this paper reviews briefly the importance of these microscopic particles, the geo logic occurrence, methods of preparation, factors affecting observation and study, identification and classification , and finally the interpretation of palynological results plant microfossils include any type of fossil plant of microsc...

2013
Célia H. C. Boyadjian Sabine Eggers Karl J. Reinhard Célia Helena C. Boyadjian Karl Reinhard

A variety of microfossils, originating from plant foods, become trapped in the dental calculus matrix. Processing of dental calculus allows extraction of these microfossils. The resulting data can be used to reconstruct diet at the individual and population levels as the identification of microfossils like starch grains and phytoliths to the generic level, and sometimes to the species level, is...

2016
Julien Alleon Sylvain Bernard Corentin Le Guillou Johanna Marin-Carbonne Sylvain Pont Olivier Beyssac Kevin D. McKeegan François Robert

The significant degradation that fossilized biomolecules may experience during burial makes it challenging to assess the biogenicity of organic microstructures in ancient rocks. Here we investigate the molecular signatures of 1.88 Ga Gunflint organic microfossils as a function of their diagenetic history. Synchrotron-based XANES data collected in situ on individual microfossils, at the submicro...

2002
S. M. AWRAMIK

Some time ago Buick (1984) cast doubt on both the biogenicity and the age of the objects we described as Early Archean bacterial microfossils in a previous paper (Awramik et al., 1983). He presented new evidence significant to the interpretation of these objects, but his report also contains statements that may be misleading. We wish to comment on his new evidence and to correct the misleading ...

2008
Laurence Lemelle Philippe Labrot Murielle Salomé Alexandre Simionovici Michel Viso Frances Westall

The study of very ancient microfossils has recently raised contentious issues regarding interpretation of the biogenicity of the structures. In situ investigation of certain elements such as sulfur within potential microfossils is a powerful complement to other methods of investigation that can provide valuable information on biogenicity. We present here a first such study on Precambrian microf...

Journal: :Anais da Academia Brasileira de Ciencias 2012
Giselle Utida Setembrino Petri Emiliano C Oliveira Paulo C Boggiani

Microfossils present in Quaternary micrites from Serra da Bodoquena, Mato Grosso do Sul State, Brazil, are here described for the first time. The studied taxa are: a) ostracods: Candona sp., Candonopsis sp., Cyclocypris sp., Cypria sp., Cypridopsis sp., Notodromas sp., Ilyocypris sp., Cyprideis sp., Wolburgiopsis cf. chinamuertensis (Musacchio 1970), Darwinula sp. and 5 morphotypes; b) microgas...

Journal: :Geological Magazine 1962

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