Palaeoenvironment of mid- to late Holocene loess deposit of the southern margin of the Tarim Basin,NW China

Holocene environmental history in the Tarim Basin and the Taklimakan Desert is known mainly from isolated eolian and lacustrine deposits and remain puzzling. Here we present an adequately preserved loess section, covering the past 5000 years, at a highland (2,850 m a.s.l) on the northern slope of Kunlun Mountains. Pollen preserved in the section reveal a drying trend with significant moisture fluctuations around 3000–2600 cal yr BP and 1800 cal yr BP at the study site. Comparing the pollen, grain size from the same section provides a different scene occurred in the Tarim basin and the Taklimakan desert. Comparison of grain size to A/C ration of pollen suggests that active sand southward shifting in south margin of the desert is coincident with increasing moisture condition at the section locality, implying a casual link. This moisture pattern occurred at the upper and lower elevation of the slope is best explained by the vertical variation of local precipitation along the slope.     

Petroleum system analysis of the Khatatba Formation in the Shoushan Basin,north Western Desert,Egypt

The Middle Jurassic Khatatba Formation is an attractive petroleum exploration target in the Shoushan Basin, north Western Desert, Egypt. However, the Khatatba petroleum system with its essential elements and processes has not been assigned yet. This study throws the lights on the complete Khatatba petroleum system in the Shoushan Basin which has been evaluated and collectively named the Khatatba-Khatatba (!) petroleum system. To evaluate the remaining hydrocarbon potential of the Khatatba system, its essential elements were studied, in order to determine the timing of hydrocarbon generation, migration and accumulation. Systematic analysis of the petroleum system of the Khatatba Formation has identified that coaly shales and organic-rich shales are the most important source rocks. These sediments are characterised by high total organic matter content and have good to excellent hydrocarbon generative potential. Kerogen is predominantly types II–III with type III kerogen. The Khatatba source rocks are mature and, at the present time, are within the peak of the oil window with vitrinite reflectance values in the range of 0.81 to 1.08 % Ro. The remaining hydrocarbon potential is anticipated to exist mainly in stratigraphic traps in the Khatatba sandstones which are characterised by fine to coarse grain size, moderate to well sorted. It has good quality reservoir with relatively high porosity and permeability values ranging from 1 to 17 % and 0.05–1,000 mD, respectively. Modelling results indicated that hydrocarbon generation from the Khatatba source rocks began in the Late Cretaceous time and peak of hydrocarbon generation occurred during the end Tertiary time (Neogene). Hydrocarbon primarily migrated from the source rock via fractured pathways created by abnormally high pore pressures resulting from hydrocarbon generation. Hydrocarbon secondarily migrated from active Khatatba source rocks to traps side via vertical migration pathways through faults resulting from Tertiary tectonics during period from end Oligocene to Middle Miocene times.     

Integrated geoelectrical survey for groundwater and shallow subsurface evaluation: case study at Siliyin spring, El-Fayoum, Egypt

Siliyin spring is one of the many natural fresh water springs in the Western Desert of Egypt. It is located at the central part of El-Fayoum Delta, which is a potential place for urban developments and touristic activities. Integrated geoelectrical survey was conducted to facilitate mapping the groundwater resources and the shallow subsurface structures in the area. Twenty-eight transient electromagnetic (TEM) soundings, three vertical electrical soundings (VES) and three electrical resistivity tomography (ERT) profiles were carried out around the Siliyin spring location. The dense cultivation, the rugged topography and the existence of infra structure in the area hindered acquiring more data. The TEM data were inverted jointly with the VES and ERT, and constrained by available geological information. Based on the inversion results, a set of geoelectrical cross-sections have been constructed. The shallow sand to sandy clay layer that forms the shallow aquifer has been completely mapped underneath and around the spring area. Flowing of water from the Siliyin spring is interconnected with the lateral lithological changes from clay to sand soil. Exploration of the extension of Siliyin spring zone is recommended. The interpretation emphasizes the importance of integrating the geoelectrical survey with the available geological information to obtain useful, cheap and fast lithological and structural subsurface information.     

Tectonometamorphic Evolution of Jutulsessen,Gjelsvikfjella, cDML,East Antarctica

The Jutulsessen area, can provide a vital clue to the supercontinent assembly of Gondwana Land as it is situated within the Circum East Antarctic Mobile Belt just east of the Penksockett rift marking the divide between the central Dronning Maud Land from the Western Dronning Maud Land. This landmass is dominated by migmatitic quartzo-feldspathic rocks intruded by syn to post-tectonic granites. The work highlights the data from western part cDML area with a view to arrive at a more comprehensive model for the cDML and subsequently to the super continent assembly. Granitic and migmatitic gneisses comprising of amphibolitic and biotite rich enclaves. The gneisses show variations from quartzo-felspathic gneiss to amphibolitic gneiss. The area has witnessed complex geological history involving at different deformational episodes with concomitant metamorphism. The pervasive dominant foliation trends NW-SE with shallow to medium dips towards SW. In the Stabben area, a nonfoliated intrusive syenite-gabbro pluton limits the gneissic exposures. Compositionally, the orthogneisses plot in the monzogranitegranodiorite field where as the mafic dykes/enclaves plot in the basalt-andesite-rhyodacite field. The bulk geochemical characteristics suggest significant crustal contamination. Garnet-biotite Fe-Mg exchange thermometry gives peak metamorphic temperature of 483° C for the gneisses and 628° C for the dioritic enclave within gneisses. A peak metamorphic grade of upper amphibolite to granulite facies is deduced from the mineral assemblages. Widespread anatexis has led to extensive occurrence of migmatites in the area. Recent geochronological studies assign an age of 1170 Ma to 970 Ma for the migmatites/gneisses and an emplacement age of 501 Ma for the Stabben gabbro and syenite. The discriminant plots of the Jutulsessen rocks indicate diverse origin ranging from pre-plate collision to post-collision orogenic tectonic setting. The mafic enclaves/dykes show ocean island arc to MORB affinities. Voluminous addition of juvenile crust during the Pan-African orogeny strongly overprints earlier structures.     

Satellite altimetry for measuring river stages in remote regions

The advent in satellite altimetry with the most accurate satellite radar altimeter since 1992 and its successive missions have enabled the routine global monitoring of water-level (or stage) for surface waters and changes in the quantities of dammed water reservoirs. However, satellite altimeter measurements typically have spatial resolution capable of observing only large water bodies, such as major lakes and rivers. This paper addresses the challenges of how to investigate water levels in medium (~?1 km in width) to small (~?100 m and narrower) rivers. Comparisons between the ENVISAT altimetry ICE-1 waveform retracking height and standard water-level measurements for multiple sections of Ohio River, Columbia River, and Red River of the North in the United States (US) reveals that the satellite altimetry measured water levels agree well with those observed at nearby US Geological Survey gaging stations over the 10-year period starting from 2002. The significant results include those obtained at Thompson, North Dakota (ND, correlation coefficient or R value of 0.76 between satellite and in situ water-level measurements) and Fargo, ND (R?=?0.74), where the stream channels of Red River are merely?~?50 m and ~?40 m wide, respectively, under normal climatic conditions. In addition, demonstrations of the approach over largely inaccessible portions of Tigris–Euphrates Rivers and Helmand River in the Middle East aided in understanding hydrology in these systems. This study demonstrates the ability of satellite radar altimetry to characterize rivers in these study regions which are much narrower than 100 m in width.     

Neo-rural populations and their relations with local decision makers in rural Québec: collaboration or conflict?

The socio-demographic recomposition of the countryside is affecting local interactions and power relations. Understanding these relationships remains a challenge, as the studies to date are often limited to conflicts between neo-rural populations (newcomers) and long-time country residents over partial issues, without including decision makers. To go beyond this conflictual and fragmentary perspective, the objective of this article is to present an overall picture of both cooperative and oppositional relations between four groups, namely, newcomers, long-time rural residents, leaders of local organizations and municipal officials, in regard to all the issues that concern them. The data are based on interviews with these various actors in two contrasting rural areas of Québec (Canada). After looking at the newcomers’ mixed assessment of their participation in community life, we concentrate on areas of collaboration and/or conflict between all the actors regarding demographic, economic, sociocultural, political, environmental and agricultural issues. Three main trends emerge, revealing unexpected ways of interacting, complex power relations and antagonistic conceptions of rural spaces and their future development.     

Review of comparative studies on market mechanisms for carbon emission reduction: a bibliometric analysis

This study uses the bibliometric method to analyze the comparative studies on different market mechanisms applied to carbon reduction between 1970 and 2016 based on the online databases of Science Citation Index Expanded (1970–2016) and Social Science Citation Index (2002–2016). We found by observing the characteristics of publications that such studies belong to a multidisciplinary field that has been continuously developing since the 1990s. The USA and the UK have maintained their leading research strengths in the field, whereas China entered late but has developed rapidly. The most productive journal, institution, and author in this field are Energy Policy, Resources for the Future, and Pizer from the USA, respectively. The auctorial and institutional cooperation degrees are growing and still have a broad collaboration space, but the cooperation among countries is fluctuating at a lower level. Nonetheless, the USA keeps its significant international cooperation ties. The bibliographic coupling and co-citation analysis reveals that articles in this field are closely related to one another. The basic literature in the field was written by Weitzman and published in 1974, and the article by Nordhaus published in Science in 1992 is the most cited in the field. The analysis of keywords and abstract shows that the hot spots include policy choice, price-versus-quantity analysis, and mechanism design.     

Control of climate and Tethyan legacy on distribution of Paleocene–Eocene gastropods and establishment of the Northern Tropical Realm

Palaeobiogeographical distribution of gastropod genera from the Paleocene and the Eocene has been analysed. Based on this distribution, formal palaeobiogeographical provinces have been established and their relationships are sought. It has been found that the provinces were largely restricted to the palaeo-tropics and subtropics mainly of the northern hemisphere and they share a large proportion of their generic composition. The Northern Tropical Realm has been established to include these provinces. The distribution evinces presence of ocean surface currents in the tropics across longitudes. The possible currents moved through the relict Tethys Ocean, across the Atlantic Ocean and perhaps also across the Pacific. However, planktotrophic larvae of these benthic molluscs could not cross the deep ocean barrier that lay between the Northern Tropical Realm and the Austro-New Zealand Province of the southern hemisphere. The gastropod fauna in the latter province evolved independently. Distribution of all the provinces within palaeo-tropics and subtropics indicates strong control of temperature over it. Paleocene–Eocene Thermal Maximum appears to be responsible for extinction and range contraction of high latitude faunas. Low latitude faunas also suffered significant extinction. However, large diversification in the Eocene was a response to widespread transgression that coincided with the thermal event.