Late Cretaceous tectonic switch from a Western Pacific‐ to an Andean‐Type continental margin evolution in East Asia,and a foreland basin development in NE China

The early Cretaceous structure of NE China was a result of slab‐rollback‐driven extensional tectonics, characteristic of Western Pacific‐type continental margins. Oblique docking of a microcontinent along the Asian active margin in the early Late Cretaceous induced a compressional stress regime that brought about an Andean‐type continental margin development. Partitioning of contractional–transpressional strain across NE China produced a retroarc foreland basin system, comprising, from east to west, an orogenic wedge, a foredeep (Songliao basin), a forebulge (Great Xing'an Range) and a back‐bulge depozone (Hailar and Erlian basins). A sub‐circular lacustrine depozone in the pre‐existing Songliao basin evolved into a NNE‐trending depocentre near the forebulge and acquired a westward flowing fluvial–deltaic drainage system during the Campanian. Development of this retroarc foreland basin system signals a significant tectonic switch from a Western Pacific‐type to an Andean‐type continental margin evolution in the geological history of East Asia.     

Variations in basaltic geochemistry along a propagating rift of the late Ordovician marginal basin of the West Norwegian Caledonides

The late Ordovician Solund-Stavfjord ophiolite complex in the western Norwegian Caledonides records a multi stage seafloor spreading history of an Iapetus marginal basin and contains three structural domains with distinctive tectonomagmatic evolutionary paths. The NNE-trending Domain 1 consisting of high-level gabbro, sheeted dykes and extrusive rocks is interpreted to represent fossil oceanic crust developed along a spreading centre that propagated northwards into pre-existing oceanic crust in the marginal basin. Dyke swarms at the head of this inferred propagating rift range from primitive, high-MgO basalts to highly fractionated quartz-diorites. Southwards along-strike of Domain 1, the abundance of primitive basalts decreases and the proportion of FeTi-basalts increases to become predominant furthest behind the tip of the propagating rift. This geochemical evolution is comparable to that of the basalts of modern propagating rifts at the East Pacific Rise and the Galapagos spreading ridge. We suggest that the chemical variations of the metabasalts reflect changes in magma supply rates and in the increasing size of magma chamber(s) along-strike of the spreading centres.     

VGDI – Advancing the Concept: Volunteered Geo‐Dynamic Information and its Benefits for Population Dynamics Modeling

The concept of Volunteered Geographic Information (VGI) has progressed from being an exotic prospect to making a profound impact on GIScience and geography in general, as initially anticipated. However, while massive and manifold data is continuously produced voluntarily and applications are built for information and knowledge extraction, the initially introduced concept of VGI lacks certain methodological perspectives in this regard which have not been fully elaborated. In this article we highlight and discuss an important gap in this concept, i.e. the lack of formal acknowledgment of temporal aspects. By coining the proposed advanced framework ‘Volunteered Geo‐Dynamic Information’ (VGDI), we attempt to lay the ground for full conceptual and applied spatio‐temporal integration. To illustrate that integrative approach of VGDI and its benefits, we describe the potential impact on the field of dynamic population distribution modeling. While traditional approaches in that domain rely on survey‐based data and statistics as well as static geographic information, the use of VGDI enables a dynamic setup. Foursquare venue and user check‐in data are presented for a test site in Lisbon, Portugal. Two core modules of spatio‐temporal population assessment are thereby addressed, namely time use profiling and target zone characterization, motivated by the potential integration in existing population dynamics frameworks such as the DynaPop model.     

Remote sensing and GIS-based landslide susceptibility mapping using frequency ratio and analytical hierarchy methods in Rize province (NE Turkey)

The northeast part of Turkey is prone to landslides because of the climatic conditions, as well as geologic and geomorphologic characteristics of the region. Especially, frequent landslides in the Rize province often result in significant damage to people and property. Therefore, in order to mitigate the damage from landslides and help the planners in selecting suitable locations for implementing development projects, especially in large areas, it is necessary to scientifically assess susceptible areas. In this study, the frequency ratio method and the analytical hierarchy process (AHP) were used to produce susceptibility maps. Especially, AHP gives best results because of allowing better structuring of various components, including both objective and subjective aspects and comparing them by a logical and thorough method, which involves a matrix-based pairwise comparison of the contribution of different factors for landslide. For this purpose, lithology, slope angle, slope aspect, land cover, distance to stream, drainage density, and distance to road were considered as landslide causal factors for the study area. The processing of multi-geodata sets was carried out in a raster GIS environment. Lithology was derived from the geological database and additional field studies; slope angle, slope aspect, distance to stream, distance to road and drainage density were invented from digital elevation models; land cover was produced from remote sensing imagery. In the end of study, the results of the analysis were verified using actual landslide location data. The validation results showed satisfactory agreement between the susceptibility map and the existing data on landslide locations.     

Development of Polymeric and Polymer‐Based Hybrid Adsorbents for Chromium Removal from Aqueous Solution

Ferric oxide‐loaded hybrid sorbents are environmentally benign and exhibit sorption behaviors for chromium removal from waters. In the current study, glycidyl methacrylate‐based polymer (GMD) and nanosized ferric oxide loaded glycidyl methacrylate‐based polymer (GMDFe) were prepared and assayed to examine the effect of ferric oxide loading on chromium sorption from aqueous solution for the first time from the equilibrium and kinetic points of view. The experimental equilibrium data, suitably fitted by the Langmuir and Freundlich isotherms, have shown that ferric oxide loaded hybrid sorbent exhibits higher adsorption capacity than glycidyl methacrylate‐based polymer (GMD). The Langmuir isotherm model was found to be the most suitable one for the Cr(VI) adsorption. The maximum adsorption capacities of GMD and GMDFe sorbents were determined at pH 4 as 109.54 and 157.52 mg/g, respectively. A series of column experiments was carried out to determine the breakthrough curves. The column was regenerated by eluting Cr(VI) using NaOH (10% w/v) solution after adsorption studies.     

Community structure of epiphytic algae on three different macrophytes at Acarlar floodplain forest （northern Turkey）

The aim of this study was to determine the species composition, biodiversity and, relative abundance of epiphytic algae and their relationship with environmental variables on three different macrophytes( Nymphaea alba, Ceratophyllum demersum, Typha latifolia) at Acarlar Floodplain Forest(AFF). Epiphytic algae were gathered monthly by collecting aquatic plants between November 2011 and October 2012, except in winter when there were no plants. In this study, 67 taxa on N. alba, 66 taxa on C. demersum and 66 taxa on T. latifolia were identified as epiphytic algae. The mean value of species richness was 17, that of diversity was 1.5 and that of evenness was 0.54 for epiphytic algae on N. alba, 17, 1.1, and 0.39 on C. demersum, and 18, 1.64, and 0.56 on T. latifolia, respectively. Oscillatoria sp. and Komvophoron crassum(Vozzen) Anagnostidis and Komárek were the most abundant and consistent epiphytic algal species, occurring in high abundance on all macrophytes. Results show that species composition of epiphytic algae was different, but diversity values were similar on all the macrophytes. The hydrological pulse is one of the most important factors determining the physical and chemical environment of the epiphytic algal community. However, substrate type also affected the colonization by F. capucina, O. sancta, P. catenata, and L. truncicola more than the epiphytic algal seasonality.     

Weight matrices and spatial autocorrelation statistics using a topological vector data model

Abstract

This paper reports on software to construct alternative weight matrices and to compute spatial autocorrelation statistics, namely the Moran coefficient and the Geary coefficient using Arc/Info’s data structure. As such it is an addition to recent efforts in linking GIS with exploratory spatial data analysis. The software is interfaced with Arc/Info via the Arc Macro Language (AML) so that it can be run in the ARC environment. This allows the user to perform exploratory analysis within GIS which may provide insights in subsequent spatial analysis and modelling.     

Tectonic control of bioalteration in modern and ancient oceanic crust as evidenced by carbon isotopes

Abstract We review the carbon‐isotope data for finely disseminated carbonates from bioaltered, glassy pillow rims of basaltic lava flows from in situ slow‐ and intermediate‐spreading oceanic crust of the central Atlantic Ocean (CAO) and the Costa Rica Rift (CRR). The δ¹³C values of the bioaltered glassy samples from the CAO show a large range, between ?17 and +3‰ (Vienna Peedee belemnite standard), whereas those from the CRR define a much narrower range, between ?17‰ and ?7‰. This variation can be interpreted as the product of different microbial metabolisms during microbial alteration of the glass. In the present study, the generally low δ¹³C values (less than ?7‰) are attributed to carbonate precipitated from microbially produced CO₂ during oxidation of organic matter. Positive δ¹³C values >0‰ likely result from lithotrophic utilization of CO₂ by methanogenic Archaea that produce CH₄ from H₂ and CO₂. High production of H₂ at the slow‐spreading CAO crust may be a consequence of fault‐bounded, high‐level serpentinized peridotites near or on the sea floor, in contrast to the CRR crust, which exhibits a layer‐cake pseudostratigraphy with much less faulting and supposedly less H₂ production. A comparison of the δ¹³C data from glassy pillow margins in two ophiolites interpreted to have formed at different spreading rates supports this interpretation. The Jurassic Mirdita ophiolite complex in Albania shows a structural architecture similar to that of the slow‐spreading CAO crust, with a similar range in δ¹³C values of biogenic carbonates. The Late Ordvician Solund–Stavfjord ophiolite complex in western Norway exhibits structural and geochemical evidence for evolution at an intermediate‐spreading mid‐ocean ridge and displays δ¹³C signatures in biogenic carbonates similar to those of the CRR. Based on the results of this comparative study, it is tentatively concluded that the spreading rate‐dependent tectonic evolution of oceanic lithosphere has a significant control on the evolution of microbial life and hence on the δ¹³C biosignatures preserved in disseminated biogenic carbonates in glassy, bioaltered lavas.     

Effect of heavy metal and alkali contamination on the swelling properties of kaolinite

One of the most important factors that determine engineering properties of soils are the type and the amount of clay present in soil. Kaolinite being a very common and non-swelling clay mineral in soil was chosen as the medium, and significance of the change in swelling property of kaolinite due to contaminant-clay interaction was investigated. The amount of change in swelling percentages of the kaolinite due to contamination with 10,000 ppm solutions of Pb(NO₃)₂ and Zn(NO₃)₂ was determined using oedometers. For uncontaminated kaolinite, the amount of swell was determined as 2.2%. For Pb-contaminated and Zn-contaminated kaolinite, these values reached to 5.8 and 5.3%, respectively. Besides heavy metals, kaolinite was also contaminated with 4 N NaOH. The biggest change in the amount of swelling was obtained from NaOH-contaminated kaolinite which is 13.9%. In addition to swelling percentages, swelling pressures were also determined. The swelling pressure of the uncontaminated kaolinite was found as 1.06 N/cm². For Zn and Pb-contaminated kaolinite, this value reached up to 2.0 and 2.6 N/cm². The NaOH-contaminated kaolinite has the greatest swelling pressure which was 230 N/cm².