Ages,rare-earth element enrichment,and petrogenesis of tholeiitic and alkalic basalts from Kahoolawe Island,Hawaii

Kahoolawe Island, Hawaii (18×11 km), is a basaltic shield volcano with caldera-filling lavas, seven identified postshield vents, and at least two occurrences of apparent rejuvenated-stage eruptive. We examined 42 samples that represent all stages of Kahoolawe volcano stratigraphy for their petrography, whole-rock major-and trace-element contents, mineral compositions, and K–Ar ages. The two oldest shield samples have an average age of 1.34±0.08 Ma, and four postshield samples (3 are alkalic) average 1.15±0.03 Ma; ages of 1.08 and 0.99 Ma for two additional tholeiitic samples probably are minimum ages. Whole-rock major- and trace-element and mineral compositions of Kahoolawe shield and caldera-fill laves are generally similar to the lavas forming Kilauea and Mauna Loa tholeiitic shields, but in detail, Kahoolawe shield lavas have distinctive compositions. An unusual aspect of many postshield Ka-hoolawe lavas is anomalously high REE and Y abundances (up to 200 ppm La and 175 ppm Y) and negative Ce anomalies. These enrichments reflect surficial processes, where weathering and soil development promoted REE-Y transport at the weathering front. Major element abundances (MgO, 10–6 wt.%) for shield and caldera-fill basalts are consistent with fractionation of ol+px+pl in frequently replenished magma reservoirs. In general, tholeiitic basalts erupted from late vents are higher in SiO₂ than the shield lavas, and temporal differences in parental magma compositions are the likely explanation. Alkalic basalts that erupted from vents are comparable in composition to those at other Hawaiian volcanoes. Trace-element abundance ratios indicate that alkalic basalts represent either relatively lower degrees of melting of the shield source or a distinct source. Apparent rejuvenated-stage basalts (i.e., emplaced after substantial Kahoolawe erosion) are tholeiitic, unlike the rejuvenated-stages at other Hawaiian volcanoes (alkalic). Kahoolawe, like several other Hawaiian volcanoes, has intercalated tholeiitic and alkalic basalts in the postshield stage, but it is the only volcano that appears to have produced tholeiitic rejuvenated-stage lavas.     

Sources of Uncertainty in Shear Stress and Roughness Length Estimates Derived from Velocity Profiles*

Shear stress is a fundamental parameter in many sediment transport expressions. It is commonly estimated from information contained in the velocity profile, specifically, shear velocity, u_*, and roughness length, z₀ Under ideal conditions, the functional relationship between elevation above the bed and flow velocity is log-linear, as expressed by the “law of the wall.” Unless the field data conform exactly to this ideal relationship, there is uncertainty in estimates of u_* and z₀. derived from velocity profiles. This uncertainty depends on the degree of scatter or deviation from the assumed log-linear model. Expressions are presented to quantify the error and to correct for it. Guidelines are suggested to minimize potential uncertainty, especially with regard to instrument deployment and velocity profile analysis. Calculation of confidence intervals around estimates of u_* and z₀, as proposed by Wilkinson (1984), is necessary and recommended.     

Sequence architecture and carbonate platform configuration (Late Cenomanian–Santonian), Sinai, Egypt

Abstract Relative sea‐level changes on the mixed carbonate–siliciclastic platform of Sinai are manifested in shifts of distinct facies belts (deep‐water facies, high‐energy subtidal, shallow subtidal, lagoon, shallow shoreface siliciclastics, supratidal) and are interpreted in terms of sequence stratigraphy. Eight sedimentary sequences are recognized for the Upper Cenomanian to Santonian. Their correlation along a north–south transect reveals distinct changes in lithofacies and progradation/retrogradation patterns within the individual systems tracts. The number and stratigraphy of the sequence boundaries of Sinai correlate well with those from adjacent areas. Patterns of increased subsidence are documented for the Central Sinai Basin since the Late Cenomanian by increased thickness of the stratal packages (post‐CeSin 7 HST, post‐TuSin 1 LST and HST, post‐TuSin 2 LST) and are balanced by varying accumulation rates. Based on new sedimentological and biostratigraphic data, large‐scale palaeogeographic maps and cross‐sections show the: (1) temporal and spatial evolution of the Central Sinai Basin, e.g. its latest Cenomanian initial formation, Lower Turonian deep‐water facies, Middle Turonian to Coniacian synsedimentary subsidence; (2) drowning of the Cenomanian platform coinciding with the latest Cenomanian to Early Turonian relative sea‐level rise; (3) re‐establishment of the platform in Middle–Late Turonian times; and (4) a Coniacian basin and swell morphology.     

On the Importance of Reliable Background Concentrations of Ozone for Regional Scale Photochemical Modelling

Ozone throughout the troposphere is subject of significant temporal and spatial variability due to photochemical production in the planetary boundary layer and free troposphere, stratospheric intrusions, convective events and long range transport. However, high resolving observations of ozone in the troposphere are generally rare today. That is of special disadvantage for limited area models, which represent mathematically a differential equation system with an initial and boundary problem. As ozone concentrations usually increase from the earth surface to the stratosphere, a proper choice of the background ozone concentrations is necessary to reproduce or even predict the amount and distribution of ozone in a specific region of interest.In this paper the impact of background concentrations of ozone on regional scale model results is analysed during a summer smog episode over Europe. For this purpose ozone is artificially partitioned into individual categories. For each category, transport and chemical transformation is calculated separately. Initial and boundary concentrations of ozone dominate total ozone concentrations increasingly with height. But also in the planetary boundary layer they contribute with more than 30% to thetotal ozone changes and are therefore far from being negligible. Moderately modified assumptions of background ozone concentrations reveal an uncertainty of near surface ozone concentrations of 5–15%depending on the weather situation.     

Die Zählung von Protozoen und kleinen Metazoen im Belebtschlamm

Summary: A method for the estimation of the abundance of protozoa and small metazoa in activated sludge is described. 5 × 10 μl of activated sludge are counted in vivo microscopically using a Thoma-Counting-Chamber and a magnification of 100: 1. The efficiency of this counting method was tested by “recovery” experiments. 46–100% of the ciliates (mean 85 %, n = 165 countings) were recovered. A positive correlation between body size and percentage of recovery could be found. Preliminary experiments showed that the method is suitable for nematodes (recovery 95 %, n = 10), rotators (recovery 84 %, n = 10) and testate amoebae (recovery 78 %, n = 10), too. The described method is independent of the sludge-structure, is easy to handle and is an acceptable compromise between time spent and necessary degree of accuracy.     

Climate forcing due to the 8200 cal yr BP event observed at Early Neolithic sites in the eastern Mediterranean

We explore the hypothesis that the abrupt drainage of Laurentide lakes and associated rapid switch of the North Atlantic thermohaline circulation 8200 yr ago had a catastrophic influence on Neolithic civilisation in large parts of southeastern Europe, Anatolia, Cyprus, and the Near East. The event at 8200 cal yr BP is observed in a large number of high-resolution climate proxies in the Northern Hemisphere, and in many cases corresponds to markedly cold and arid conditions. We identify the relevant archaeological levels of major Neolithic settlements in Central Anatolia, Cyprus, Greece and Bulgaria, and examine published stratigraphic, architectural, cultural and geoarchaeological studies for these sites. The specific archaeological events and processes we observe at a number of these sites during the study interval 8400–8000 cal yr BP lead us to refine some previously established Neolithisation models. The introduction of farming to South-East Europe occurs in all study regions (Thrace, Macedonia, Thessaly, Bulgaria) near 8200 cal yr BP. We observe major disruptions of Neolithic cultures in the Levant, North Syria, South-East Anatolia, Central Anatolia and Cyprus, at the same time. We conclude that the 8200 cal yr BP aridity event triggered the spread of early farmers, by different routes, out of West Asia and the Near East into Greece and Bulgaria.     

Field-aligned electric currents and their measurement by the incoherent backscatter technique

Field-aligned electric currents flow in the magnetosphere in many situations of fundamental geophysical interest. It is shown here that the incoherent backscatter technique can be used to measure these currents when the plasma line can be observed. To our knowledge this has not been proposed before. The technique provides a ground-based means of measuring these currents which complements the rocket and satellite ones.     

Geckos from the middle Miocene of Devínska Nová Ves (Slovakia): new material and a review of the previous record

New species of a gecko of the genus Euleptes is described here—E. klembarai. The material comes from the middle Miocene (Astaracian, MN 6) of Slovakia, more precisely from the well-known locality called Zapfe`s fissure fillings (Devínska Nová Ves, Bratislava). The fossil material consists of isolated left maxilla, right dentary, right pterygoid and cervical and dorsal vertebrae. The currently known fossil record suggests that isolation of environment of the Zapfe`s fissure site, created a refugium for the genus Euleptes in Central Europe (today, this taxon still inhabits southern part of Europe and North Africa—E. europea), probably resulting from the island geography of this area during the middle Miocene. The isolation of this territory might have facilitated allopatric speciation.     

Geophysical greenfield exploration in the permo‐carboniferous Saar–Nahe basin—The Wiesbaden Geothermal Project,Germany

Structurally bound upwelling and outflowing hot fluids in the city of Wiesbaden suggest an interesting geothermal potential at the northern margin of the permo‐carboniferous Saar–Nahe basin, Germany. The Saar–Nahe basin in the Wiesbaden area was previously not a target for intensive geophysical prospecting of the deep underground. We present an exploration concept to investigate potential geothermal reservoirs near Wiesbaden for heat and power production. The acquired geophysical exploration data give new insights into the local geometry and internal structure of the Saar–Nahe basin. The exploration combines a wide range of methods, including the analysis of data, a dense grid gravity survey, as well as two‐dimensional and three‐dimensional seismic surveys. The resulting data, which for the first time reveal the deep structure of the Mainz and Saar–Nahe basins near Wiesbaden down to a depth of c. 4,000 m, show that the Saar–Nahe basin is strongly segmented and contains deep‐reaching active faults. Combining these information with numerical models of the stresses in the fault system and of the temperature distribution in the exploration area, a promising drilling target has been identified, which promise high permeability at a low risk of induced or triggered seismicity.     

Cumulative spatial impact layers: A novel multivariate spatio‐temporal analytical summarization tool

Scientific inquiry often requires analysis of multiple spatio‐temporal datasets, ranging in type and size, using complex multi‐step processes demanding an understanding of GIS theory and software. Cumulative spatial impact layers (CSIL) is a GIS‐based tool that summarizes spatio‐temporal datasets based on overlapping features and attributes. Leveraging a recursive quadtree method, and applying multiple additive frameworks, the CSIL tool allows users to analyze raster and vector datasets by calculating data, record, or attribute density. Providing an efficient and robust method for summarizing disparate, multi‐format, multi‐source geospatial data, CSIL addresses the need for a new integration approach and resulting geospatial product. The built‐in flexibility of the CSIL tool allows users to answer a range of spatially driven questions. Example applications are provided in this article to illustrate the versatility and variety of uses for this CSIL tool and method. Use cases include addressing regulatory decision‐making needs, economic modeling, and resource management. Performance reviews for each use case are also presented, demonstrating how CSIL provides a more efficient and robust approach to assess a range of multivariate spatial data for a variety of uses.