An abiotic origin for hydrocarbons in the Allan Hills 84001 martian meteorite through cooling of magmatic and impact‐generated gases

Abstract— Thermodynamic calculations of metastable equilibria were used to evaluate the potential for abiotic synthesis of aliphatic and polycyclic aromatic hydrocarbons (PAHs) in the martian meteorite Allan Hills (ALH) 84001. The calculations show that PAHs and normal alkanes could form metastably from CO, CO², and H² below approximately 250–300°C during rapid cooling of trapped magmatic or impact‐generated gases. Depending on temperature, bulk composition, and oxidation‐reduction conditions, PAHs and normal alkanes can form simultaneously or separately. Moreover, PAHs can form at lower H/C ratios, higher CO/CO² ratios, and higher temperatures than normal alkanes. Dry conditions with H/C ratios less than approximately 0.01–0.001 together with high CO/CO² ratios also favor the formation of unalkylated PAHs. The observed abundance of PAHs, their low alkylation, and a variable but high aromatic to aliphatic ratio in ALH 84001 all correspond to low H/C and high CO/CO² ratios in magmatic and impact gases and can be used to deduce spatial variations of these ratios. Some hydrocarbons could have been formed from trapped magmatic gases, especially if the cooling was fast enough to prevent reequilibration. We propose that subsequent impact heating(s) in ALH 84001 could have led to dissociation of ferrous carbonates to yield fine‐grain magnetite, formation of a CO‐rich local gas phase, reduction of water vapor to H², reequilibration of the trapped magmatic gases, aromatization of hydrocarbons formed previously, and overprinting of the synthesis from magmatic gases, if any. Rapid cooling and high‐temperature quenching of CO‐, H²‐rich impact gases could have led to magnetite‐catalyzed hydrocarbon synthesis     

The impact of glaciation, river-discharge and sea-level change on Late Quaternary environments in the southwestern Kara Sea

Sedimentary records from the southwestern Kara Sea were investigated to better understand the extent of the last glaciation on the Eurasian Arctic shelf, sea-level change, and history of the Ob' and Yenisey river discharge. Sediment-core and seismic-reflection data indicate that the Quaternary depositional sequence in the southwestern Kara Sea consists of glacial, glaciomarine, and marine sedimentary units. Glaciogenic sediments in the deep Novaya Zemlya Trough are presumably related to the Last Glacial Maximum (LGM), whereas further east they may represent an earlier glaciation. Thus, it is inferred that the southeastern margin of the LGM Barents-Kara ice sheet was contained in the southwestern Kara Sea east of the Novaya Zemlya Trough. Changes in mineralogical, foraminiferal, and stable-isotopic composition of sediment cores indicate that riverine discharge strongly influenced sedimentary and biotic environments in the study area during the Late Weichselian and early Holocene until ca. 9 ka, consistent with lowered sea levels. Subsequent proxy records reflect minor changes in the Holocene hydrographic regime, generally characterized by reduced riverine inputs.     

Improvements of drilling fluid processing for cable-suspended electromechanical drills

Deep ice drilling in Polar Regions plays a key role in paleo-climate, microbiological and glaciological researches. For deep ice and subglacial coring the special purpose-built electromechanical cable-suspended drills with bottom-hole circulation are designed and explored. Used at present drilling fluid circulation systems are specified by very high fluid wastes during processing. Measurements in deep drilling projects in Antarctic and Greenland ice sheets showed that 25%-40% of the drilling fluid, pumped into the hole, is retrieved to the surface with cable and drill, and up to 45% of retrieved fluid goes to waste. This leads not only to increasing of the fluid consumption and cost of the project in general but also to severe contamination of air, surface and near-surface snow-firn layers at the drilling site. In order to reduce wastes and environmental impact, it is proposed to modify drilling fluid processing system by avoiding of evaporation and leakages of fluid as far as practicable. Drilling fluid is prepared and pumped into the hole according to predetermined program on semiautomatic mode, and volume and density of blended and pumped into the hole drilling fluid are measured continuously. Components of the drilling fluid are stored and mixed in the special closed containers equipped by pressure relief valves. Separation of drilling fluid from ice cuttings is carried out by two steps: firstly, fluid is separated with hydro extractor and then with thermal separator. To reduce the amount of removed drilling fluid with cable special squeezing collar is installed on the borehole mouth. All these arrangements are able to decrease drilling fluid wastes in many times.     

The oxidation state of hydrothermal systems on early Enceladus

The discovery of CO₂, CH₄, and N₂ in a plume at Enceladus provides useful clues about the chemistry and evolution of this moon of Saturn. Here, we use chemical equilibrium and kinetic calculations to estimate the oxidation state of hydrothermal systems on early Enceladus, with the assumption that the plume's composition was inherited from early hydrothermal fluids. Chemical equilibrium calculations are performed using the CO₂/CH₄ ratio in the plume, and kinetic calculations are conducted using equations from fluid dynamics and chemical kinetics. Our results suggest that chemical equilibrium between CO₂ and CH₄ would have been reachable at temperatures above ∼200 °C in hydrothermal systems. The oxidation state of the hydrothermal systems would have been close to the pyrrhotite-pyrite-magnetite (PPM) or fayalite-magnetite-quartz (FMQ) redox buffer (i.e., terrestrial-like) if the plume's CO₂ and CH₄ equilibrated in hydrothermal systems long ago. As for minerals, we suggest that iron metal would have been oxidized to magnetite by the escape of H₂ from the early satellite. Our calculations also indicate that, assuming CO₂ and CH₄ reached chemical equilibrium, magnetite would not have been oxidized to hematite in hydrothermal systems, perhaps due to insufficient H₂ escape. It is shown that, if Enceladus accreted as much NH₃ as comets contain, the presence of N₂ and deficiency of NH₃ in the plume can be understood in the context of chemical equilibrium in the C-N-O-H system. We conclude by proposing an evolutionary hypothesis in which the fairly oxidized nature of the plume can be explained by a brief episode of oxidation caused by short-lived radioactivity. These suggestions can be rigorously tested by acquiring gravity and isotopic data in the future.     

Monochromatic intensity measurements of selected areas of lunar surface for possible investigations

Absolute photoelectric intensity measurements of 104 selected lunar regions are given in five interference filters 4035 Å, 4765 Å, 5538 Å, 6692 Å and 7922 Å. Among these regions, eighteen lunar regions have been measured repeatedly for several phase angles between +86° and ?43°. They include observations made very close to the full Moon. A catalogue has been compiled to serve as a basin for possible investigations of colour contrasts of lunar grounds, variation of the ratio of reflectivity with wavelengths and phase angles for morphological studies. The study can be extended for the brightness phase variation, opposition effect and radiance factors at zero phase in five colours.     

Orbital forcing of continental climate during the Pleistocene: a complete astronomically tuned climatic record from Lake Baikal, SE Siberia

A new composite BDP-96 biogenic silica record over the entire Pleistocene was generated by splicing BDP-96-1 and BDP-96-2 drill cores from Lake Baikal, crosschecked against a similar record from a nearby BDP-98 drill core. A new astronomically tuned age model is proposed based on correlating peak biogenic silica responses with the timing of September perihelia. This target is derived from analysis of regional climate proxy responses during the Holocene, the last interglacial and around paleomagnetic reversals. By resolving virtually every precessional cycle during the Pleistocene, the new age model represents a major improvement compared with previously reported Lake Baikal timescales. The astronomically tuned ages of the Pleistocene paleomagnetic reversals are consistent with published dates. The minimal tuning approach we used (precession only) has also aligned high signal power in a narrow obliquity band, confirming the strong presence of orbital forcing. There are also strong ca 100-ka scale cycles, but these are not aligned with the orbital eccentricity.Despite the location of Lake Baikal in a continental interior that is highly sensitive to insolation forcing, the tuned biogenic silica record reveals a consistent phase difference of −32° (ca 4 ka) relative to insolation in the obliquity band. An inherent lag embedded in a continental proxy record, not driven by global ice volume, is an intriguing finding. Another new observation is that long-term changes in sedimentation rates in Lake Baikal appear to be related to the amplitude of orbital forcing; both amplitudes and sedimentation rates undergo significant changes during MIS 24-MIS 19 interval corresponding to the Middle Pleistocene Transition. With potential for linking continental and marine climato-stratigraphies, the new Baikal record serves a new benchmark correlation target in continental Eurasia, as an alternative to June 65°N insolation and ODP-correlated timescales.     

Space Physics Interactive Data Resource—SPIDR

SPIDR (Space Physics Interactive Data Resource) is a standard data source for solar-terrestrial physics, functioning within the framework of the ICSU World Data Centers. It is a distributed database and application server network, built to select, visualize and model historical space weather data distributed across the Internet. SPIDR can work as a fully-functional web-application (portal) or as a grid of web-services, providing functions for other applications to access its data holdings.

Paleomagnetic implications on the evolution of the tethys belt from the atlantic ocean to the pamirs since the triassic

We first re-examined the apparent polar wander curves for stable Eurasia and Africa since the Triassic. These curves were then combined together with curves of North and South America according to the kinematics of the Atlantic ocean and a synthetic polar wander curve was given. Then, most of the paleomagnetic results from the Tethys mobile belt, from the Atlantic to the Pamirs, were analysed.Several groups of plates, microplates and blocks can be seen. First, relatively stable regions like Maghreb and Sicily, which have not moved much. Then we have a group formed by Iberia, Sardinia, Italy and, to a lesser extent, Corsica and the Western and Central Alps. For these blocks, movements are anticlockwise rotations chiefly driven by the anticlockwise rotation of Africa, but they are sometimes stronger.To the east, a major change takes place. The north of the Aegean Sea and the Ionian zone are clockwise rotated and these rotations are recent: Oligocene-Miocene for the first part, Pliocene to the present for the second part.A major problem arises in Turkey, Caucasus and Iran. Paleomagnetic results indicate a position far to the south of Eurasia, and, at the same time, geological evidence is in favour of a position close to Eurasia. We discuss these discrepancies.