Galileiite: A new meteoritic phosphate minera

Abstract— A new mineral named galileiite, NaFe₄(PO₄)₃, has been found within troilite nodules in iron meteorites of the IIIA and IIIB groups. the mineral is optically positive (ω = 1.72, ω = 1.75), colorless in transmitted light and pale amber in reflected light. Grains of galileiite are very small, generally 10 μm or less; rarely, grains are up to 30 μm. It is associated with Ca-free graftonite (or Ca-free sarcopside), chromite and, occasionally, schreibersite. Johnsomervilleite may occur within troilite nodules in the same meteorite as galileiite, but they have never been observed together in the same troilite nodule. Because of the small sample size, single crystal x-ray work was not successful; however, Gandolfi diffraction measurements were made. The three strongest diffraction peaks are 2.71 Å, 3.01 Å and 4.13 Å. On the basis of its composition and similar diffraction pattern, it is considered to be related to johnsomervilleite, fillowite and chladniite, all of which are rhombohedral and isostructural. Galileiite may also be rhombohedral, but that is yet to be demonstrated.     

Sedimentation and Organic Carbon Burial in the Yangtze River and Hudson River Estuaries: Implications for the Global Carbon Budget

One of the most important challenges in global climate change research is balancing the carbon budget within the global carbon cycle. Carbon burial in sediments at the land–ocean interface has been difficult to quantify and model because it represents non-steady-state boundary conditions that are also affected by human activities. In this study, we document carbon burial rates in the Yangtze River (1.6–4.9 × 10¹² gC year^?1) and Hudson River (1.8–3.6 × 10¹⁰ gC year^?1) estuaries and integrate our results with carbon burial rates determined by others in the world’s 25 largest river-estuarine systems (6–11 × 10¹³ gC year^?1). Our results indicate that carbon burial in estuaries, bays, coves, lagoons, mud flats, marshes, mangroves, and other highly productive or protected low-energy areas at the land–ocean interface along the entirety of the world’s coastlines may serve as an unrecognized sink within the global carbon budget.     

The depositional architecture and facies variability of shelf deltas in the Eocene Battfjellet Formation,Nathorst Land,Spitsbergen

Deltas are commonly classified according to their plan‐view morphology as either river‐dominated, tide‐dominated or wave‐dominated. However, most deltas form under the mixed influence of these processes, commonly with laterally varying process regimes. It has also become clear that there is a mismatch between the plan‐view morphology and internal facies composition in some deltas. Combined outcrop and subsurface data from the Eocene Battfjellet Formation, Spitsbergen, provide an example of ancient shelf deltas that formed under mixed influence. Internally, these shelf deltas are characterized by wave‐dominated facies that are normally associated with strike‐extensive, nearly linear shoreline sandstones. However, the formation comprises partially overlapping sandstone bodies of limited lateral extent (<20 km in any direction). This stacking pattern is attributed to frequent autogenic lobe switching that caused localized and rapid transgressions. Such processes typify fluvial‐dominated deltas and occur less commonly in wave‐dominated ones. Thus, there is an apparent mismatch between inferred plan‐view morphology and internal facies composition. It is argued that the Battfjellet deltas were flood‐dominated and prograded mainly during periods of high fluvial discharge. However, reworking of the fluvial‐flood facies by fair‐weather and storm waves, as well as longshore currents, resulted in a wave‐dominated facies character. Delta lobes undergoing auto‐retreat were particularly prone to reworking by basinal processes, including tidal currents. It is suggested that repeated delta progradation from inner shelf settings towards the outer shelf and shelf edge was aided by high sediment supply rather than relative falls in sea‐level as previously suggested. This interpretation is supported by: (i) the lack of major facies dislocations and extensive sub‐aerial unconformities; and (ii) an overall relative rise in sea‐level as evidenced by an overall low‐angle (0·8 to 1·2°) ascending shoreline trajectory. The latter results from the combined effect of basin subsidence, eustatic highstand and sediment compaction.     

Radiocarbon Dating of Interdune Paleo‐Wetland Deposits to Constrain the Age of Mid‐to‐Late Holocene Microlithic Artifacts from the Zhongba site,Southwestern Qinghai‐Tibet Plateau

Microlithic artifacts, some found in situ, are abundant in the Zhongba archaeological site in southwestern Tibet. The site environment consists of extant wetlands and paleo‐wetland deposits found in depressions between sand dunes derived from the Yarlung Tsangpo floodplain. Constraining ¹⁴C dates from wetland vegetation and shell from one site fall between ca. 6600–2600 cal. yr B.P., while a second site is dated 3400–1200 cal. yr B.P. A significant and variable ¹⁴C reservoir effect—up to 1400 ¹⁴C yr—limits these ranges to terminus post quem constraints. The in situ artifacts are supplemented by surface collections fully characterizing raw material and typological variability for each site. Raw material found at Zhongba is chert and chalcedony likely sourced from Cretaceous bedrock near the site. Typologically, microblades are nongeometric and are derived from conical and wedge‐shaped cores similar to those identified in the Qinghai Lake Basin and the Chang Tang Nature Reserve of similar or greater age. The later occupation period at Zhongba is broadly contemporaneous with sites on the Qinghai‐Tibet Plateau containing bronze and iron artifacts, indicating microlithic technology remained an important tool‐making strategy in western Tibet late into the protohistoric period.     

Energy coefficients for a propeller series

The efficiency for a propeller is calculated by energy coefficients. These coefficients are related to four types of losses, i.e. the axial, the rotational, the frictional, and the finite blade number loss, and one gain, i.e. the axial gain. The energy coefficients are derived by use of the potential theory with the propeller modelled as an actuator disk. The efficiency based on the energy coefficients is calculated for a propeller series. The results show a good agreement between the efficiency based on the energy coefficients and the efficiency obtained by a vortex-lattice method.     

Farside explorer: unique science from a mission to the farside of the moon

Farside Explorer is a proposed Cosmic Vision medium-size mission to the farside of the Moon consisting of two landers and an instrumented relay satellite. The farside of the Moon is a unique scientific platform in that it is shielded from terrestrial radio-frequency interference, it recorded the primary differentiation and evolution of the Moon, it can be continuously monitored from the Earth–Moon L2 Lagrange point, and there is a complete lack of reflected solar illumination from the Earth. Farside Explorer will exploit these properties and make the first radio-astronomy measurements from the most radio-quiet region of near-Earth space, determine the internal structure and thermal evolution of the Moon, from crust to core, and quantify impact hazards in near-Earth space by the measurement of flashes generated by impact events. The Farside Explorer flight system includes two identical solar-powered landers and a science/telecommunications relay satellite to be placed in a halo orbit about the Earth–Moon L2 Lagrange point. One lander would explore the largest and oldest recognized impact basin in the Solar System— the South Pole–Aitken basin—and the other would investigate the primordial highlands crust. Radio astronomy, geophysical, and geochemical instruments would be deployed on the surface, and the relay satellite would continuously monitor the surface for impact events.     

Analyse af den morfologiske udvikling på strandplanet nord for indsejlingen til Torsminde havn 1947–85

Olsen, H.A.: Analyse af den morfologiske udvikling på strandplanet nord for indsejlingen til Torsminde havn 1947–85. Geografisk Tidsskrift 86: 31–45. København, juni 1986.

Abstract

Movement of bars on the off-shore by Torsminde harbour on the west coast of Jutland, Denmark is described and connected with structures of moles and sedimentation in the port entrance.     

Clay mineralogy, grain size distribution and their correlations with trace metals in the salt marsh sediments of the Skallingen barrier spit, Danish Wadden Sea

To understand the behavior of trace metals in the salt marsh at Skallingen, Danish Wadden Sea, we investigated a profile from surface to 25?cm depth of the salt marsh sediment, focusing primarily on clay mineralogy and grain size distribution of the sediments and their relationship with trace metals. The clay assembly of the sediment consists of illite, kaolinite and much less chlorite and smectite. The major clay minerals of illite, kaolinite as well as chlorite correlate very poorly with all the trace metals investigated, due probably to the weak competing strength of these clays compared with the other adsorbents and to low availability of the mobile trace metals in the system. Correlation between trace metals and clay minerals may therefore be used as an indicator in environmental assessment. Fine grain fractions of the sediment increased markedly after salt marsh invasion in about 1931 but decreased after 1964. This increase was contributed mainly by the grains finer than 20???m while the fraction of 40?C63???m actually decreased soon after the invasion. The relation between most of the trace metals and grain size distributions is close in general but far from linear. The drastic turning point is observed at about 30???m, around where the correlation coefficient r drops from 0.8 to 0.1. Adsorption is the controlling mechanism for the behavior of trace metals in the salt marsh. Fe/Mn (hydr)oxides and organic matter play the key role.     

Late Occupation of the High‐Elevation Northern Tibetan Plateau Based on Cosmogenic,Luminescence, and Radiocarbon Ages

¹⁰Be‐²⁶Al cosmogenic surface exposure, optically stimulated luminescence, and radiocarbon dates from the site of Xidatan 2 (∼4300 m above sea level [asl] in the Kunlun Pass, northern Tibetan Plateau) suggest the site was intermittently and briefly occupied approximately 9200–6400 yr B.P. This age is substantially younger than expected given the late Upper Paleolithic character of the lithic assemblage, which is dominated by microlithic and unique discoidal prepared core technologies. Comparisons between Xidatan 2 and known surface lithic assemblages in the Kekexili and Chang Tang regions of the central high Plateau show not only that the latter are technologically similar to Xidatan 2, but also that they are demonstrably connected to Xidatan 2 through utilization of the same stone raw materials, which includes a chemically distinctive obsidian. Contrary to most accounts of Tibetan Plateau colonization, our results suggest that the earliest substantial occupations on the interior Tibetan Plateau above 4000 m asl may date to the Pleistocene/Holocene transition.