Results 61 to 70 of about 32,483 (245)
Examining Archean methanotrophy [PDF]
Earth and Planetary Science Letters, 2016 The carbon isotope ratios preserved in sedimentary rocks can be used to fingerprint ancient metabolisms. Organic carbon in Late Archean samples stands out from that of other intervals with unusually low δ^(13)C values (∼−45 to −60‰). It was hypothesized that these light compositions record ecosystem-wide methane cycling and methanotrophy, either of the
Slotznick, Sarah P. +1 more
openaire +2 more sources
The Medicine Hat Block and the Early Paleoproterozoic Assembly of Western Laurentia
Geosciences, 2020 The accretion of the Wyoming, Hearne, and Superior Provinces to form the Archean core of western Laurentia occurred rapidly in the Paleoproterozoic. Missing from Hoffman’s (1988) original rapid aggregation model was the Medicine Hat block (MHB).
Jennifer N. Gifford +2 more
doaj +1 more source
An orbital window into the ancient Sun's mass [PDF]
, 2018 Models of the Sun's long-term evolution suggest that its luminosity was substantially reduced 2-4 billion years ago, which is inconsistent with substantial evidence for warm and wet conditions in the geological records of both ancient Earth and Mars ...
Fischer, Woodward W. +2 more
core +3 more sources
Microbial Endolithic Community at Meteor Crater
Meteoritics &Planetary Science, EarlyView.Abstract Postimpact recovery and evolution in response to climate changes produced a modern ecosystem at Meteor Crater dominated by a grassland and woodland of piñon and juniper, which has been used to evaluate floral and megafaunal consequences of impact cratering during the Phanerozoic Eon of complex life.
David A. Kring, Charles S. Cockell
wiley +1 more source
Учёные записки Казанского университета: Серия Естественные наукиGiant mafic dykes are the key markers of the Earth’s evolution in the Precambrian and have been the subject of extensive research. This article presents the results of the paleomagnetic, rock-magnetic, and paleointensity Banc studies of the Great Dyke of
V. V. Shcherbakova +6 more
doaj +1 more source
Meteoritics &Planetary Science, EarlyView.Abstract A core drilled through shocked and faulted Archean granitoid gneisses and dolerites in the eroded peak ring of the 70–80 km diameter Morokweng impact structure intersects multiple centimeter‐ to meter‐wide clastic‐matrix breccias containing a polymict clast population of lithic and mineral clasts and altered, millimeter‐ to centimeter ‐size ...
Roger L. Gibson +3 more
wiley +1 more source
Mountain‐top spherules: Criteria to identify natural and synthetic particles
Meteoritics &Planetary Science, EarlyView.Abstract Natural microspherules are important tracers of geologic and environmental processes in modern and ancient deposits. However, anthropogenic contamination can dilute natural collections by releasing synthetic microspherules into the environment.
M. R. Boyd, M. J. Genge
wiley +1 more source
Journal of the Geological Survey of BrazilGamma-ray spectrometry, as well as magnetic and gravity data, are used to investigate the geophysical signatures of the Archean nuclei of the Borborema Province.
Roberto Gusmão de Oliveira +6 more
doaj +1 more source
Photosynthetic primary production in the Mesoproterozoic
New Phytologist, EarlyView.Summary The Mesoproterozoic atmosphere had more CO2 and less O2 than at present. While the upper ocean was oxygenated, the deeper ocean was euxinic or ferruginous. Primary production was performed by Chlorobia, Cyanobacteria, Proteobacteria, and Archaeplastida.
Patricia Sánchez‐Baracaldo +1 more
wiley +1 more source
UV radiation limited the expansion of cyanobacteria in early marine photic environments
Nature Communications, 2018 The means by which planktonic cyanobacteria were able to persist through the Archean despite high fluxes of UV radiation are unclear. Here, the authors show that Fe(III)-Si rich precipitates in the Archean photic zone could have provided early planktonic
Aleksandra M. Mloszewska +6 more
doaj +1 more source