Upper Miocene and Pliocene geomagnetic secular variation in the Borgarfjördur area of Western Iceland     

Norman D. Watkins  Ian McDougall  Leo Kristjansson 《Geophysical Journal International》1977,49(3):609-632

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Petroleum hydrocarbons, polycyclic aromatic hydrocarbons, organochlorine pesticides and polychlorinated biphenyls in tissues of Indo-Pacific humpback dolphins from south China waters     

Leung CC  Jefferson TA  Hung SK  Zheng GJ  Yeung LW  Richardson BJ  Lam PK 《Marine pollution bulletin》2005,50(12):33-1719

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Tektonische Untersuchungen an der Basis der Silvretta-Decke im Val Tuoi (Unterengadin)     

Leo M. Krasser 《International Journal of Earth Sciences》1940,31(3-4):163-187

Ohne Zusammenfassung  相似文献   

Der Ural im Lichte der neuesten russischen Forschung     

Leo von zur Mühlen 《International Journal of Earth Sciences》1940,31(7-8):594-633

Ohne Zusammenfassung  相似文献   

Über Sedimentation und atektonische Verformung der Deckschicht auf Eiskegeln abschmelzender Gletscher     

Leo M. Krasser 《International Journal of Earth Sciences》1939,30(6):665-669

Ohne Zusammenfassung  相似文献   

A geophysical survey of the Spitsbergen Margin and surrounding areas     

Dmitry Baturin  Tatiana Fedukhina  Leo Savostin  Artem Yunov 《Marine Geophysical Researches》1994,16(6):463-484

New geophysical information including multichannel seismic profiling data obtained by the PGO Sevmorgeologia Ministry of Geology of the former USSR, Murmansk during 1984–1988 is discussed and interpreted in this study. The deep structure, sedimentary cover and stratigraphy of the Spitsbergen Continental Margin, considered to be a passive margin, i.e. divergent in the northern part and strike-slip in the western part, is described.Two genetically different types of plateaus on the continental margin, Yermak in the north and Spitsbergen (Vestnesa) in the west, have been identified.The entire extent of the continental slope of the northern part of the Spitsbergen Continental Margin in the Eurasia Basin is underlain by attenuated continental crust, while at the base of the Southwest Continental Margin, the oceanic crust along almost the entire extent is observed. The sedimentary cover, up to 10 km thick within the West Spitsbergen Continental Margin, is likewise observed. Within the North Spitsbergen Margin, however, it does not exceed 3.5 km in thickness.The extension and deposition within the West Spitsbergen Margin began in early Oligocene, while the rifting with accompanying sedimentation within the North Spitsbergen Continental Margin started probably in Early Cretaceous.  相似文献   

Rural and urban livelihoods,social exclusion and social protection in sub-Saharan Africa     

Leo de Haan 《Geografisk tidskrift / udgivet af Bestyrelsen for Det Kongelige danske geografiske selskab》2017,117(2):130-141

Abstract

This paper shows that with the decline of overall poverty, the concern for rising or persisting inequalities and the need for a transformative social protection, the capacity of countering social exclusion and promoting social justice also becomes increasingly relevant to urbanizing sub-Saharan Africa. It is argued that several parts of sub-Saharan Africa are likely to move towards pro-poor urbanization and show emerging changes in rural and urban livelihoods. Then, the practice of social protection programmes along the rural–urban continuum in sub-Saharan Africa is examined extensively in order to determine whether these practices align with emerging changes in livelihoods and tackle social exclusion in a transformative way. It is found that the livelihoods of the poor are enhanced and that social inclusion has increased. However, social protection’s adaptation to emerging changes in rural and urban livelihoods is still poor, and so is social protection’s capacity to tackle social exclusion in a transformative way. It is concluded that transformative social protection would require more structural interventions through empowering pressure on the state and innovative decentralization from the top.  相似文献   

Spatial and temporal variations in minibasin geometry and evolution in salt tectonic provinces: Lower Congo Basin,offshore Angola     

Zhiyuan Ge  Rob L. Gawthorpe  Leo Zijerveld  Ayodeji P. Oluboyo 《Basin Research》2021,33(1):594-611

In passive margin salt basins, the distinct kinematic domains of thin‐skinned extension, translation and contraction exert important controls on minibasin evolution. However, the relationship between various salt minibasin geometries and kinematic domain evolution is not clear. In this study, we use a semi‐regional 3D seismic reflection dataset from the Lower Congo Basin, offshore Angola, to investigate the evolution of a network of minibasins and intervening salt walls during thin‐skinned, gravity‐driven salt flow. Widespread thin‐skinned extension occurred during the Cenomanian to Coniacian, accommodated by numerous distributed normal faults that are typically 5–10 km long and spaced 1–4 km across strike within the supra‐salt cover. Subsequently, during the Santonian–Paleocene, multiple, 10–25 km long, 5–7 km wide depocentres progressively grew and linked along strike to form elongate minibasins separated by salt walls of comparable lengths. Simultaneous with the development of the minibasins, thin‐skinned contractional deformation occurred in the southwestern downslope part of the study area, forming folds and thrusts that are up to 20 km long and have a wavelength of 2–4 km. The elongate minibasins evolved into turtle structures during the Eocene to Oligocene. From the Miocene onwards, contraction of the supra‐salt cover caused squeezing and uplift of the salt walls, further confining the minibasin depocentres. We find kinematic domains of extension, translation and contraction control the minibasin initiation and subsequent evolution. However, we also observe variations in minibasin geometries associated with along‐strike growth and linkage of depocentres. Neighbouring minibasins may have different subsidence rates and maturity leading to marked variations in their geometry. Additionally, migration of the contractional domain upslope and multiple phases of thin‐skinned salt tectonics further complicates the spatial variations in minibasin geometry and evolution. This study suggests that minibasin growth is more variable and complex than existing domain‐controlled models would suggest.  相似文献   

Dynamic torsional response of an end bearing pile in saturated poroelastic medium   总被引：1，自引：0，他引：1  

Kuihua Wang  Zhiqing Zhang  Chin Jian Leo  Kanghe Xie 《Computers and Geotechnics》2008,35(3):450-458

A comprehensive analytical solution is developed in this paper to investigate the torsional vibration of an end bearing pile embedded in a homogeneous poroelastic medium and subjected to a time-harmonic torsional loading. The poroelastic medium is modeled using Biot’s two-phased linear theory and the pile using one-dimensional elastic theory. By using the separation of variables technique, the torsional response of the soil layer is solved first. Then based on perfect contact between the pile and soil, the dynamic response of the pile is obtained in a closed form. Numerical results for torsional impedance of the soil layer are presented first to portray the influence of wave modes, slenderness ratio, pile–soil modulus ratio and poroelastic properties. A comparison with the plane strain theory is performed. The selected numerical results are obtained to analyze the influence of the major parameters on the torsional impedance at the level of the pile head. Finally, the dynamic torsional impedance of this study is compared with that for floating pile in elastic soil.  相似文献   

Seismic source mechanism inversion from a linear array of receivers reveals non-double-couple seismic events induced by hydraulic fracturing in sedimentary formation     

Zuzana Jechumtlov  Leo Eisner 《Tectonophysics》2008,460(1-4):124-133

We developed a new method to invert source mechanisms of seismic events observed from a single (vertical or near vertical) array of receivers. This method was tested on a synthetic dataset and applied to a seismic dataset acquired during hydraulic fracturing of a sedimentary formation. We show that a crack-opening seismic event recorded on a single vertical array can be inverted as a pure shear seismic event, indicating that the best fitting shear mechanisms inverted from seismic data acquired along a vertical borehole provide misleading information. We found that the majority of the analyzed source mechanisms of the induced events are not consistent with pure shear faulting as previously thought. The non-shear source mechanisms are required even when seismic noise, location uncertainty, and uncertainty in the attenuation structural model are considered.  相似文献