The North Crimean–Caucasian Marginal Flexure–Rupture Zone

Doklady Earth Sciences - The North Crimean–Caucasian flexure–rupture zone is a boundary structure at the junction of the newest Crimean–Caucasian orogenic range and the...     

Special Issue Devoted to Petroleum Geology in Marginal Sea Deepwater Settings—Take the South China Sea as an Example

1 Deepwater Settings of Marginal Seas一the Frontier of Oil and Gas Exploration From the perspective of geographical environment,the areas of global oil and gas exploration can be divided into land,shallow water and deep water areas.The timespan of oil and gas discovery in each field is different.Oil and gas have been discovered on land since ancient tinies,but the application of modern technology to discover oil and gas began in 1859 in Pennsylvania,USA(Hua,1984).Largescale oil and gas exploration began in the 1920s,and the reserve discovery reached its peak in the 1960s and 1970s.     

The Hydrothermal Na—Ca Alteration at the Marginal Part of the Florina Granite and the Associated Magnetite—Hematite Bands With Thorium and Uranium Mineralization

The Oxia mineralized granite is the product of differentiation in the external parts of the Florina magmatic mass. Acidic hydrothermal solutions either of magmatic or of meteoric origin reacted with the upper tectonically fractured parts of the Florina granite and became enriched in iron, thorium, uranium, zircon and rare-earth elements. The most abundant alteration minerals are sericite and quartz, while the minerals of the mineralization bands include magnetite, hematite, thorite, monazite and zircon. The outer parts of the Oxia granite made it easy the percolation of hydrothermal solutions from the deeper heater to the upper cooler parts of the granite which acted as a hot spot.     

Special Issue Devoted to Petroleum Geology in Marginal Sea Deepwater Settings—Take the South China Sea as an Example Preface

1 Deepwater Settings of Marginal Seas—the Frontier of Oil and Gas Exploration From the perspective of geographical environment, the areas of global oil and gas ...     

Special Issue Devoted to Petroleum Geology in Marginal Sea Deepwater Settings—Take the South China Sea as an Example Preface

High‐resolution tomographic images of the belt crossing the Japan Trench‐Changbai Mountains‐Dong Ujimqin Qi are represented in this paper, revealing the shape of a subducted slab in the western Pacific region and characteristics of the lithospheric structures under the Changbai Mountains and the Da Hinggan Mountains. Studies of the spatial distribution, subduction time and the time‐lag between the subduction and magmatism, combined with petrology and isotope geochemistry of the Late Mesozoic volcano‐plutonic rocks from the Da Hinggan Mountains‐Yanshan Mountains have further proved the independence of magmatic activities from the subduction of the Pacific plate. The Mesozoic tectono‐thermal evolutionary history and structural characteristics of the lithosphere in the Da Hinggan Mountains and North China suggest that the formation and evolution of magma have probably a close relationship with the delamination and thinning of the continental lithosphere and the underplating resulting from the consequent upwelling of the asthenosphere. On the other hand, the large‐scale strike‐slip fault system, resulting from sinistral shearing of the Pacific plate relative to the Asian continent in the Mesozoic, is responsible for the formation and emplacement of magma on the continental margin. It was the intense crust‐mantle interaction, together with structural deformation at the shallower levels that led to the large tectono‐magmatic belt in the East Asian continental margin.     

Indebted to Fair Trade? Coffee and crisis in Nicaragua

This paper explores the following general question: Why are Fair Trade coffee farmers in Nicaragua burdened by debt? Nearly five years from “the end” of the coffee crisis, peasant farming households committed to Fair Trade standards continue to struggle with a legacy of indebtedness caused by years of low farm-gate prices and declining productivity between 2000 and 2004. Through ethnographic observation and interviews with peasant farmers in Nicaragua, I explore how farmers experience a simple reproduction squeeze that hinders them from “bootstrapping” their own economic development. I argue that the effort to raise the Fair Trade minimum price and premium for coffee through Fair Trade Labelling Organizations International (FLO) in 2008 demonstrated a good first step toward improving farm-gate prices, however, these gains must be understood in the context of long-term indebtedness as well as rising production costs and household consumption costs.     

Variegated capitalism,the Greek crisis and SYRIZA’s counter-neoliberalisation challenge

The objective of this critical review is twofold. Firstly, we intend to tackle a number of assumptions that view the Greek crisis as the result of a marked resistance to (neoliberal) structural reforms and the failure to engage constructively with the challenges of globalisation. Instead, we argue that Greece was set on a neoliberal trajectory much before the crisis erupted, and that it is precisely this sustained neoliberalisation process – rather than its absence – that lays behind much of Greece’s current troubles. Secondly, we attempt an assessment of the prospect that SYRIZA’s victory may be signalling the start of a counter-neoliberal mobilisation. Drawing on the work of Brenner and others, we identify four alternative scenarios – capitulation, divorce, compromise, transformation – and discuss their implications for Greece and the Eurozone.     

Rural settlements in transition – agricultural and countryside crisis in the Central-Eastern Europe

The paper presents a synthesis of French and Bulgarian researches on the transition in villages in Central Eastern Europe. The main points focus on three questions, the rural unemployment and the crisis of small towns, the demographical deterioration, the new relations between villages and towns. A generalization of the rural central places' visual change and metaphors is proposed, completed by a typology of rural settlements. The question of the rural administrative divisions is discussed, with its implication for the future. As a whole the paper gives a contribution to the problematic of the likely development in the rural evolution pattern throughout Europe. This revised version was published online in July 2006 with corrections to the Cover Date.     

Crisis? What crisis? Displacing the spatial imaginary of the fiscal state

This paper argues that there is an immanent and evolving relationship between the prevailing form of taxation and the economic geographies of the state. Despite this, the geographic significance of taxation has been obscured by the language in which its historic transformation tends to be couched. Prevailing fiscal systems tend to be presented as essentially static – institutionally and spatially fixed and routinely inscribed within the fixed boundaries and territories of the ‘sovereign’ fiscal state. Any threat to, or change in the nature or geography of the fiscal state tends to be couched in terms of ‘crisis’ – of negative and discontinuous change. This paper contends that these related and essentially conservative discourses of fiscal geography mask the degree to which fiscal spaces are both multiple and continuously evolving. More importantly, it argues, this fluidity and multiplicity does not threaten the stability and viability of state form, but it is an essential process in its maintenance and reproduction. Running counter to the prevailing discourse of the ‘national economy’, the practice of fiscal geography is an under-analysed but key aspect of the historical evolution and transformation of the imagined geographies of economies.     

An overview of US state drought plans: crisis or risk management?

Natural Hazards - Recent severe drought events across the nation have raised our concerns over society’s changing and increasing vulnerability to droughts. All levels of governments have...     

Volgian–Early Berriasian Marginal Filter in the West Siberian Marine Basin and Its Influence on Sediment Distribution

Lithology and Mineral Resources - The West Siberian marine basin of the Volgian–initial Berriasian ages is described. It is shown that a marginal filter (according to A.P. Lisitsyn)...     

Primary production and fluxes of organic carbon to the seabed in the Eurasian arctic seas, 2003–2012

The primary production and fluxes of organic matter to the seabed and their variations were estimated in the Greenland, Barents, Kara, Laptev, East Siberian, and Chukchi seas in 2003–2012 on the basis of satellite and in situ data. When counting the open water area with the assumptions made for the assessment of the primary production in the sea areas hidden under clouds, an increase in primary production was recorded in all these seas, the total production (phytoplankton and ice algae) has grown from 250 × 10⁶ to 400 × 10⁶ t of C per year over the last ten years. The calculation of the OM flux to the seabed showed growth for certain seas from 4 to 12% per year.     

Geochemistry and petrogenesis of the Late Mesozoic–Early Cenozoic volcanic rocks of the Okhotsk and Japan marginal seas

The results of ICP-MS trace-element (LILE, HFSE, REE) study of the Late Mesozoic–Early Cenozoic volcanic rocks of the Okhotsk and Japan seas and geochronological K-Ar dating of the Eocene volcanic rocks are presented. Specifics of volcanism developed on submarine rises of these seas was characterized for the first time, and magma sources and geodynamic settings of the volcanic complexes predating the formation of the deep-water basins were determined. It is established that the Late Mesozoic magmas were formed in a subduction setting from spinel peridotites of suprasubduction mantle wedge, which was metasomatically reworked by aqueous fluids that were released by dehydration of sedimentary layer of subducting oceanic plate. This follows from the elevated concentrations of H₂O, alkalis, potassium, LILE and LREE, and lowered HFSE (including Ta-Nb minimum) and HREE contents, at lowered Sm/Yb, Nb/Ta, Nb/Y and elevated La/Nb, Ba/La, and Zr/Y ratios. Eocene adakite-like volcanic rocks were identified for the first time in the Sea of Okhotsk. They vary from andesitic to more felsic compositions with elevated MgO (>4%) and elevated La/Yb (>14) and Sr/Y (50–60) ratios. Identification of adakite-like volcanic rocks serves as evidence in support of the transform continental-margin (or plate sliding) setting, which is characterized by breaking apart of subduction slab and formation of slab “windows” acting as pathways for the transfer of asthenospheric mantle into continental lithosphere. New geochemical data on the Late Mesozoic–Early Cenozoic volcanic rocks of the Okhotsk and Japan seas and analysis of literature data were used to distinguish two geodynamic settings within these seas: subduction and transform margin. Similar settings operated at that time in the adjacent continental- margin volcanic belts (Akinin and Miller, 2011; Martynov and Khanchuk, 2013; et al.).     

Glacial–interglacial records of the reflectance of sediments from the Norwegian–Greenland–Iceland Sea (Nordic seas)

 The reflectance of sediments (gray level) were measured on 11 sediment cores from the Norwegian–Greenland–Iceland Sea (Nordic seas). The analyzed time interval covers the past five glacial–interglacial cycles. Although the results demonstrate that the gray-level method has a potential for stratigraphic purposes, it is indicated that gray-level changes in the Nordic seas are not necessarily driven by variations in the content of biogenic calcite. A detailed comparison of gray-level values with contents of total CaCO₃ (carbonate) and total organic carbon (TOC) reveals no overall causal link between these proxies. However, specific glacial core sections with layers containing organic-rich sediment clasts as a consequence of iceberg-rafting seem to correlate well with law gray-level values. Of those cores which show relatively high and comparable carbonate values in the last three main interglacial intervals (stages 11, 5.5, and 1), stage 11 is always marked by the highest gray-level values. A close inspection of the surface structure of the foraminiferal tests as well as the conduction of reflectance measurements on these tests leads to the conclusion that enhanced carbonate corrosion occurred during stage 11. The test corrosion not only affected the reflectance of the tests by making them appear whiter, it also seems responsible for the comparatively high gray-level values of the total sediment in stage 11. In contrast, the relatively low gray-level values found in stages 5.5, and 1 are not associated with enhanced test corrosion. This observation implies that variable degrees of carbonate corrosion can have a profound effect on total sediment reflectance. Received: 6 September 1998 / Accepted: 4 April 1999     

An empirical study on Twitter’s use and crisis retweeting dynamics amid Covid-19

Natural Hazards - This study conducts an analysis on topics of the most diffused tweets and retweeting dynamics of crisis information amid Covid-19 to provide insights into how Twitter is used by...     

The Frasnian–Famennian biotic crisis: How many (if any) bolide impacts?

The prime causation of the mid-Late Devonian mass extinction near the Frasnian–Famennian (F–F) boundary remains uncertain. Nevertheless, geochemical evidence has been presented recently as decisive evidence of a giant bolide impact occurring precisely at the F–F boundary, which promoted the global mortality episode. Palaeobiological data, however, imply a gradual global change, which is otherwise seen as a record of either multiple extraterrestrial catastrophes or of impact-triggered Earth-bound mechanisms. Sedimentological (mega-tsunami), physical (craters, microtektites), and geochemical records remain either elusive in many aspects, or incompatible with the predicted impact crisis pattern. Biotic succession across the F–F horizon is still poorly known, especially in continental domains, to evidence a synchronous ("bedding-plane") killing event at the close of the crisis. Instead, the commonly documented stepwise loss of biomass and an unproved distinctive "dead zone" are hard to explain simply as sampling artifacts. The assumed mass mortality precisely at the F–F boundary may be limited mainly to the pelagic realm. The underestimated role of early Variscan tectonism and associated volcanic-hydrothermal processes, resulting in thermal and nutrient pulses, as possible prime controls of the F–F crisis is suggested, as well as resemblances to the superplume-conditioned eventful mid-Cretaceous interval, exemplified in the Cenomanian-Turonian mass extinction. Additional shocks, generated by minor cometary strikes, are not excluded but may have affected some F–F biotas or areas. Received: 9 June 1998 / Accepted: 2 November 1998