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Evidence for life on Earth before 3,800 million years ago
IT is unknown when life first appeared on Earth. The earliest known microfossils (˜3,500 Myr before present) are structurally complex, and if it is assumed that the associated organisms required aExpand
Methane-Consuming Archaea Revealed by Directly Coupled Isotopic and Phylogenetic Analysis
These results demonstrate the feasibility of simultaneous determination of the identity and the metabolic activity of naturally occurring microorganisms and indicate assimilation of isotopically light methane into specific archaeal cells. Expand
Multiple archaeal groups mediate methane oxidation in anoxic cold seep sediments
The results provide direct evidence for the involvement of at least two distinct archaeal groups (ANME-1 and ANME-2) in AOM at methane seeps and indicate that the microbial species and biotic interactions mediating anaerobic methanotrophy are diverse and complex. Expand
Prolonged residence times for the youngest rhyolites associated with Long Valley Caldera:230Th—238U ion microprobe dating of young zircons
Abstract We describe a new ion microprobe method for dating magmatic zircon growth that is based on in situ measurement of the magnitude of238U—230Th disequilibrium. Our results support independentExpand
Origin and episodic emplacement of the Manaslu Intrusive Complex
decompression to achieve the same result appear to require extreme The Manaslu granite is the most studied of the dozen or so plutons conditions not permitted by available geological constraints.Expand
Detection of inherited monazite in the Manaslu leucogranite by 208Pb232Th ion microprobe dating: Crystallization age and tectonic implications
Abstract Although leucogranites are among the least petrologically variable of all igneous rocks, ironically they are among the most difficult to reliably date. The High Himalayan leucogranites haveExpand
Mass-Independent Sulfur of Inclusions in Diamond and Sulfur Recycling on Early Earth
Populations of sulfide inclusions in diamonds from the Orapa kimberlite pipe in the Kaapvaal-Zimbabwe craton, Botswana, preserve mass-independent sulfur isotope fractionations. The data indicate thatExpand
The Chlorine Isotope Composition of the Moon and Implications for an Anhydrous Mantle
The chlorine isotope content of lunar samples returned by the Apollo missions is found to be 25-fold greater than for rocks and minerals that have been measured from Earth and meteorites, implying that the Moon’s water content is much lower than suggested by recent studies. Expand
Mass-independent isotope effects in Archean (2.5 to 3.8 Ga) sedimentary sulfides determined by ion microprobe analysis
We report sulfur isotope anomalies with 33 S, the deviation from a mass-dependent fractionation line for the three-isotope system ( 34 S/ 32 S vs. 33 S/ 32 S), ranging up to 2‰ within individualExpand
Initial 26Al/27Al in carbonaceous-chondrite chondrules: too little 26Al to melt asteroids
We report 26Mg excesses correlated with Al/Mg ratios in five chondrules from the primitive CO3.0 chondrite Yamato 81020 that yield a mean initial 26Al/27Al ratio of only (3.8 ± 0.7) × 10−6, aboutExpand