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The scenes of violent shaking in dense urban Mexico City from the new Sept 19 earthquake are genuinely horrifying. Buildings twist, collide, crumble, buckle, and collapse before your eyes like some scene out of a movie; trees thrash wildly as boatmen on the Xochimilco Canals struggle for balance on a river being thrown violently from its banks; inside, furniture flies across rooms and ceilings cave in while desperate residents and officeworkers …

Tracking driftwood gives researchers insight into past Arctic Ocean changes

Wood from trees that fell into Arctic-draining rivers thousands of years ago is giving scientists a detailed look at how Arctic Ocean circulation has changed over the past 12,000 years. In a new study, researchers used nearly 1,000 pieces of driftwood collected from Arctic shorelines since the 1950s to track Arctic sea ice extent and ocean circulation since the start of the Holocene.

Controls of basin margin tectonics on the morphology of alluvial fans in the western Ganga foreland basin’s piedmont zone, India

Six distinct alluvial fans have developed in the western Ganga basin’s piedmont zone between the Ganga (aka Ganges) River in the west and the Sarda River in the east. The basin margin is demarked by the active Himalayan Frontal Thrust along which the Siwalik ranges are uplifted and placed over the alluvia of the Ganga basin. The 6 alluvial fans show marked morphological variances, but their morphometric parameters exhibit proportionality relationships with the “mountain‐front sinuosity index (Smf),” “stream‐gradient index (SL),” and “valley‐floor width to height ratio (Vf)” of the adjoining mountain‐front segments. Correlation and regression analyses reveal that these relationships are statistically significant. The size of the fan is directly proportional to the magnitude of Smf and inversely proportional to the magnitude of SL, whereas the fan gradient is inversely proportional to Smf. The higher the Smf and the lower the SL values, the larger and gentler is the alluvial fan. Given that the studied alluvial fans have developed in the same climatic zone and their drainage basins have similar physiographic, geologic, and climatic conditions, the morphological diversities among the alluvial fans are attributed to the tectonics of the basin margin. Moreover, statistical analyses further rule out any significant relationships of the fan size with area, or drainage density of the drainage basin. The lower values of Smf and Vf and higher values of SL indicate a more active nature and, thus, greater/faster uplift of the mountain‐front and expected deepening of the accommodation space in the adjoining basin, which favoured vertical aggradation and development of smaller and steeper alluvial fans. Conversely, the higher values of Smf and Vf and lower values of SL indicate a less active nature and, thus, relatively lower/slower uplift of the mountain‐front and thus creation of shallower accommodation space in the adjoining basin, favouring the development of larger and gentler alluvial fans.

Influence on the oil‐gas accumulation potential of the laminated algal micritic dolomite in Jixian system from Mesozoic magmatic activities at the south‐western margin of the Ordos Basin, China

The Mesoproterozoic Jixian System is widely distributed at the south‐western margin of the Ordos Basin. It is mainly dominated by siliceous laminated algal micritic dolomite that is a set of potential carbonate source rocks. The magmatic activities at the south‐western margin of the Ordos Basin were frequent and intensive, and the Tongcheng intrusion exposed in this area has an intrusive contact relationship with the Jixian System. This paper uses geochemical methods to study the influence of magmatism to lithology, physical properties, hydrocarbon generating property, and geochemistry of the Jixian System. Analysis data reveal that, with the increasing distance to the intrusion, the porosity, permeability, and content of dolomite, trace elements, and rare earth elements in surrounding rock decrease while the density and silica content increase gradually. In addition, the parameters have a weakening trend about adsorbed hydrocarbon (S1), pyrolysis hydrocarbon (S2), hydrocarbon generating potential (S1 + S2), and pyrolysis peak temperature (Tmax). The results suggest that the magmatic hydrothermalism and the thermal effect of magmatic intrusion changed the physical and geochemical characteristics of the surrounding rock and promoted the hydrocarbon generation of organic matter. However, these characteristics reflect that the magmatic activities only have a relatively small effect on the laminated algal micritic dolomite in Jixian System without a destructive effect at the south‐western margin of the Ordos Basin. The petroleum potential of the Jixian System is worthy to be further explored.

Researchers take on atmospheric effects of Arctic snowmelt

Researchers at the University of Alaska Fairbanks’ Geophysical Institute are exploring the changing chemistry of the Arctic’s atmosphere to help answer the question of what happens as snow and ice begin to melt. The research is concerned with the Arctic’s reactive bromine season, the period of time when bromine is consuming ozone, producing bromine monoxide and oxidizing mercury.