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This article explores the origin and cycling of volatile compounds, such as water, carbon dioxide, and nitrogen, and their significance in the habitability of planets. The text includes four perspective papers, three comprehensive reviews, and an interview with Professor Charles H. Langmuir. The topics covered range from the origin of water on the Moon to the evidence of water on Mars, as well as the behavior of volatiles in Earth's mantle and the coevolution of atmospheric oxygen and carbon dioxide levels. The article emphasizes the importance of understanding volatile processes in unraveling the mysteries of planetary habitability and the potential for life beyond Earth. [Extracted from the article]

The neutron flux monitor is a critical part of the process of 40Ar/39Ar dating. Sanidine in tuffaceous rocks is the best choice for this role, but the currently used standards are mainly cenozoic due to the difficulty in preserving the tuff. Here, we report a new protocol to prepare a neutron flux monitor from the sanidine contained within obsidian, a rock which has undergone rapid eruption and cooling on the surface. The results show that the sanidine in Yunshan obsidian has a homogenous K (7.95 ± 0.18 wt%) and Ca (0.15 ± 0.01 wt%) content, and has no significant intragrain differences in the major elements. The 40Ar/39Ar ages range from 93.29 ± 0.46 Ma (2 se) to 93.49 ± 0.29 Ma (2 se) calculated from the step heating method and are 93.74 ± 0.31 Ma (2 sd) at the single grain level. The variations in zircon SIMS U–Pb ages (93.80 ± 0.58 Ma, 2 sd) and the sanidine 40Ar/39Ar ages did not exceed analytical uncertainties. We propose the development of older (>∼65 Ma) neutron flux monitor standards from obsidian instead of tuff, as it is readily available in the field and a large amount of neutron flux monitor can be prepared from it for daily use. [ABSTRACT FROM AUTHOR]

The [sup.40]Ar-[sup.39]Ar dating reveals three episodes of basaltic volcanism in eastern Guangdong of SE China since the late Eocene (i.e., 35.5, ~20 and 6.6 Ma). The Miocene alkali olivine basalts [...]

New sensitive high-resolution ion microprobe (SHRIMP) U-Pb zircon ages, geochemical data, and a synthesis of existing stratigraphic, geochronologic, and geochemical results from the Tarim block and the Central Asian orogenic belt in northwestern China suggest the presence of a Permian (ca. 275 Ma) large igneous province (the Bachu large igneous province). The large igneous province consists predominantly of coevalmatic rocks (basalts and mafic-ultramafic intrusions) having an aerial coverage of more than 600,000 [km.sup.2], and its formation was accompanied by voluminous emplacement of A-type granites. This large igneous province, interpreted to be of mantle plume origin, is ~15 m.y. older than the ca. 260 Ma Emeishan large igneous province in southwestern China and ~25 m.y. older than the 251 Ma Siberian Trap in Russia. Such a sudden flair up of plume activity in the Permian may represent the early stage of the Pangean superplume event. The Permian plumes likely played a role in late Paleozoic rapid continental crustal growth in the Central Asian orogenic belt. In addition, there appear to be two types of mantle geochemical provinces (domains) in the region, a long-term enriched Tarim province and a subduction-metasomatized and depleted Central Asian orogenic belt province. doi: 10.1130/B30007.1

Prevolcanic kilometer-scale lithospheric doming in the Emeishan large igneous province, southwest China, allows us to evaluate the spatial and temporal consequences of uplift on the paleogeography, geology, geochemistry, and geophysics of the region. Systematic spatial variations are observed across the domal structure in the distribution and thickness of elastic and carbonate sediments, the extent of erosion, thickness, and chemistry of volcanic rocks, and the crust-mantle structure. These features, which are best explained by a mantle plume, may be used to track older plume sites in the geologic record. Keywords: paleogeography, geochemistry, geophysics, plumelithosphere interaction, Emeishan basalt.