Outward transport of CAIs during FU‐Orionis events

Abstract— Evidence from meteorites shows that the first solids to form in the solar system, calcium‐aluminum‐rich inclusions (CAIs), were transported outward from the Sun by several AU in the early solar system. We introduce a new concept of levitation and outward transport of CAIs at the surface of protoplanetary disks. Thermal radiation from the disk and the Sun can cause particles to levitate above the disk and drift outward through a process known as photophoresis. During normal conditions this process only works for dust‐sized particles but during high luminosity events like FU‐Orionis outbursts, the process can provide an efficient lift and transport of CAIs from within the inner 1 AU to a distance of several AU from the Sun. This might explain why CAIs, believed to have formed close to the Sun, are common in meteorites believed to come from the outer asteroid belt but are rare or absent in samples from the inner solar system. Since the process only works during the FU‐Orionis event and only for particles up to cm‐size, it may also explain why the CAIs we find in meteorites appear to have formed within a short period of time and why they rarely exceed cm size.     

The Swedish Deep Drilling Program: the quest for the Earth's inner secrets

The Swedish Deep Drilling Program (SDDP) has been initiated to study fundamental problems of the dynamic Earth system, its natural history and evolution. Many key scientific questions can be addressed through in situ investigations only, requiring deep continental drilling. Some are unique to Scandinavia, most are of international interest and significance. At present, five core projects ( Fig. 1 ) with international teams are integrating scientific problems with societal and industrial applications. If SDDP succeeds to attract the funding required, Sweden will have a number of world‐class boreholes at key locations by 2020.

Figure 1 Open in figure viewer PowerPoint Locations of SDDP drilling project proposals. PFDP—Postglacial Fault Drilling Project; PaMVAS—Palaeoproterozoic mineralized volcanic arc systems: the Skellefte District; COSC—Collisional Orogeny in the Scandinavian Caledonides; DRL—The Dellen Impact Crater, a geoscientific deep rock laboratory; SELHO—Svecofennian accretion, an example of the early structural evolution in a large hot orogen; CISP—Concentric Impact Structures in the Palaeozoic: the Lockne and Siljan craters. Background and inset image from Blue Marble Next Generation data set (NASA Earth Observatory, http://earthobservatory.nasa.gov/Features/BlueMarble/ ).     

Modeling the 2.7?km in Diameter, Shallow Marine Ritland Impact Structure

The newly discovered Ritland impact structure (2.7?km in diameter) has been modeled by numerical simulation, based on detailed field information input. The numerical model applies the SOVA multi-material hydrocode, which uses the ANEOS equation of state for granite, describing thermodynamical properties of target and projectile material. The model displays crater formation and possible ejecta distribution that strongly supports a 100?m or less water depth at the time of impact. According to the simulations resurge processes and basinal syn- and postimpact sedimentation are highly dependent on water depth; in more than 100?m of water depth, much more powerful resurge processes are generated than at water depths shallower than 100?m (the Ritland case). In Ritland the 100?m high (modeled) crater rim formed a barrier and severely reduced the resurge processes. In the case of deeper water, powerful resurge processes, tsunami wave generations and related currents could have triggered even more violent crater fill sedimentation. The presented model demonstrates the importance of understanding the interactions between water layer and both syn-impact crater fill and ejecta distribution. According to the presented simulations ejecta blocks up to 10?m in diameter could be transported up to about 5?km outside the crater rim.     

Bayesian Inversion in Hidden Markov Models with Varying Marginal Proportions

Mathematical Geosciences - Knowledge of the sub-surface characteristics is crucial in many engineering activities. Sub-surface soil classes must, for example, be predicted from indirect...     

Alaska in den Jahren 1909 und 1910

Ohne Zusammenfassung     

Meeresschutzgebiete für den Nordost-Atlantik und die ostsee im Rahmen der Oslo-Paris-und der Helsinki-Übereinkommen

Ocean Dynamics - Seit Jahrzehnten, besonders intensiv jedoch seit Verabschiedung der “Konvention zum Schutz der Biologischen Vielfalt” in Rio (1992), werden Meeresgebiete unter Schutz...     

Lead isotopes of the carbonate-hosted Kabwe, Tsumeb, and Kipushi Pb-Zn-Cu sulphide deposits in relation to Pan African orogenesis in the Damaran-Lufilian Fold Belt of Central Africa

Lead isotope ratios of galena from the carbonate-hosted massive sulphide deposits of Kabwe (Pb-Zn) and Tsumeb (Pb-Zn-Cu) in Zambia and Namibia, respectively, have been measured and found to be homogeneous and characteristic of upper crustal source rocks. Kabwe galena has average isotope ratios of ^206/204Pb = 17.997 ± 0.007, ^207/204Pb = 15.713 ± 0.010 and ^208/204Pb = 38.410 ± 0.033. Tsumeb galena has slightly higher ^206/204Pb (18.112 ± 0.035) and slightly lower ^207/204Pb (15.674 ± 0.016) and ^208/204Pb (38.276 ± 0.073) ratios than Kabwe galena. The isotopic differences are attributed to local differences in the age and composition of the respective source rocks for Kabwe and Tsumeb. The homogeneity of the ore lead in the two epigenetic deposits suggests lead sources of uniform isotopic composition or, alternatively, thorough mixing of lead derived from sources with relatively similar isotopic compositions. Both deposits have relatively high ²³⁸U/²⁰⁴Pb ratios of 10.31 and 10.09 for Kabwe and Tsumeb galenas, respectively. These isotope ratios are considered to be typical of the upper continental crust in the Damaran-Lufilian orogenic belt, as also indicated by basement rocks and Cu-Co sulphides in stratiform Katangan metasediments which have a mean μ-value of 10.25 ± 0.12 in the Copperbelt region of Zambia and the Democratic Republic of Congo (formerly Zaire). The ²³²Th/²⁰⁴Pb isotope ratios of 43.08 and 40.42 for Kabwe and Tsumeb suggest Th-enriched source regions with ²³²Th/²³⁵U (κ-values) of 4.18 and 4.01, respectively. Model isotopic ages determined for the Kabwe (680 Ma) and Tsumeb (530 Ma) deposits indicate that the timing of the mineralisation was probably related to phases of orogenic activity associated with the Pan-African Lufilian and Damaran orogenies, respectively. Galena from the carbonate-hosted Kipushi Cu-Pb-Zn massive sulphide deposit in the Congo also has homogeneous lead isotope ratios, but its isotopic composition is comparable to that of the average global lead evolution curve for conformable massive sulphide deposits. The μ (9.84) and κ (3.69) values indicate a significant mantle component, and the isotopic age of the Kipushi deposit (456 Ma) suggests that the emplacement of the mineralisation was related to a post-tectonic phase of igneous activity in the Lufilian belt. The isotope ratios (^206/204Pb, ^207/204Pb, ^208/204Pb) of the three deposits are markedly different from the heterogeneous lead ratios of the Katangan Cu-Co stratiform mineralisation of the Copperbelt as well as those of the volcanogenic Nampundwe massive pyrite deposit in the Zambezi belt which typically define radiogenic linear trends on lead-lead plots. The host-rock dolomite of the Kabwe deposit also has homogeneous lead isotope ratios identical to the ore galena. This observation indicates contamination of the Kabwe Dolomite Formation with ore lead during mineralisation. Received: 8 September 1997 / Accepted: 21 August 1998     

Phase Composition of Flood Sediments of the German-Polish Odra River Immediately after the Flood Event in 1997

Immediately after the flood event in summer 1997 at the Odra river, samples of flood sediments were taken for a complex phase analysis. The realized investigations show that the sampled flood sediments are very inhomogeneous. The main reasons for this substantial condition are surely different states of flow during the flood event. It is possible to characterize the investigated material as middle to fine sands with variable phase compositions. The mineral content of the fraction <2 μm shows a complex composition of amorphous matter, quartz, feldspars, and a different composed clay mineral matter. A high distribution of several mixed layers in the clay mineral phase is detectable. Within the scope of the taken analyses the following minerals were detected: kaolinite (disordered), kaolinite/smectite-mixed layer, chlorite/smectite-mixed layer, montmorillonite, illite/smectite-mixed layer, celadonite. The investigation of the heavy fraction shows heavy minerals and heavy particles of different geneses. Mainly these are geogenic, transparent heavy minerals like zircon, amphibole, garnet, pyroxene, apatite, rutile, and epidote. Furthermore there were analysed geogenic, opaque heavy minerals (magnetite and ilmenite), anthropogenic, opaque heavy particles (fly ashes and slags), and biogenic components (pyrite framboids). The substantial character of the investigated flood sediments (e.g. content of organic matter, content of clay minerals) shows that this material is able to act as a fixation medium of contaminants.     

Petroleum-related hydrocarbons in deep and subsurface sediments from South-Western Barents Sea

Subsurface sediments from a pockmark area in South-Western Barents Sea have been earlier found to contain elevated levels of petroleum-related polycyclic aromatic hydrocarbons. This work describes a comprehensive analysis of various biomarkers, including the highly source-specific hopanes, in a 4.5?m long gravity core from the same area, together with subsurface sediment samples from other areas in the region without pockmarks present ("background samples"). A clear difference between the pockmark gravity core and the background sediment cores was found, both with regard to genesis and the level of transformation of organic matter. A number of indicator parameters, such as methylphenanthrene index (MPI-1), point towards a significantly higher maturity of hydrocarbons in the pockmark core throughout its length as compared to the other sampled locations. Higher contents of microbial hopanoids (hopenes) may indicate the former presence of petroleum. These findings confirm the hypothesis of a natural hydrocarbon source in the deeper strata present in the studied location with pockmarks.