Crustal memory and basin evolution in the Central European Basin System—new insights from a 3D structural model   总被引：1，自引：2，他引：1  

Magdalena Scheck-Wenderoth  Juliette Lamarche   《Tectonophysics》2005,397(1-2):143

The Central European Basin System (CEBS) is composed of a series of subbasins, the largest of which are (1) the Norwegian–Danish Basin (2), the North German Basin extending westward into the southern North Sea and (3) the Polish Basin. A 3D structural model of the CEBS is presented, which integrates the thickness of the crust below the Permian and five layers representing the Permian–Cenozoic sediments. Structural interpretations derived from the 3D model and from backstripping are discussed with respect to published seismic data. The analysis of structural relationships across the CEBS suggests that basin evolution was controlled to a large degree by the presence of major zones of crustal weakness. The NW–SE-striking Tornquist Zone, the Ringkøbing-Fyn High (RFH) and the Elbe Fault System (EFS) provided the borders for the large Permo–Mesozoic basins, which developed along axes parallel to these fault systems. The Tornquist Zone, as the most prominent of these zones, limited the area affected by Permian–Cenozoic subsidence to the north. Movements along the Tornquist Zone, the margins of the Ringkøbing-Fyn High and the Elbe Fault System could have influenced basin initiation. Thermal destabilization of the crust between the major NW–SE-striking fault systems, however, was a second factor controlling the initiation and subsidence in the Permo–Mesozoic basins. In the Triassic, a change of the regional stress field caused the formation of large grabens (Central Graben, Horn Graben, Glückstadt Graben) perpendicular to the Tornquist Zone, the Ringkøbing-Fyn High and the Elbe Fault System. The resulting subsidence pattern can be explained by a superposition of declining thermal subsidence and regional extension. This led to a dissection of the Ringkøbing-Fyn High, resulting in offsets of the older NW–SE elements by the younger N–S elements. In the Late Cretaceous, the NW–SE elements were reactivated during compression, the direction of which was such that it did not favour inversion of N–S elements. A distinct change in subsidence controlling factors led to a shift of the main depocentre to the central North Sea in the Cenozoic. In this last phase, N–S-striking structures in the North Sea and NW–SE-striking structures in The Netherlands are reactivated as subsidence areas which are in line with the direction of present maximum compression. The Moho topography below the CEBS varies over a wide range. Below the N–S-trending Cenozoic depocentre in the North Sea, the crust is only 20 km thick compared to about 30 km below the largest part of the CEBS. The crust is up to 40 km thick below the Ringkøbing-Fyn High and up to 45 km along the Teisseyre–Tornquist Zone. Crustal thickness gradients are present across the Tornquist Zone and across the borders of the Ringkøbing-Fyn High but not across the Elbe Fault System. The N–S-striking structural elements are generally underlain by a thinner crust than the other parts of the CEBS.The main fault systems in the Permian to Cenozoic sediment fill of the CEBS are located above zones in the deeper crust across which a change in geophysical properties as P-wave velocities or gravimetric response is observed. This indicates that these structures served as templates in the crustal memory and that the prerift configuration of the continental crust is a major controlling factor for the subsequent basin evolution.  相似文献   

3D structural model of the Polish Basin     

Juliette Lamarche  Magdalena Scheck-Wenderoth 《Tectonophysics》2005,397(1-2):73

A 3D structural modelling of the Permian–Mesozoic Polish Basin was performed in order to understand its structural and sedimentary evolution, which led to basin maturation (Permian–Cretaceous) and its tectonic inversion (Late Cretaceous–Paleogene). The model is built on the present-day structure of the basin and comprises 13 horizons within the Permian to Quaternary rocks. The analysis is based on 3D depth views and thickness maps. The results image the basin-scale symmetry, the perennial localization of the NW–SE-oriented basin axis, the salt movements due to tectonics and/or burial, and the transverse segmentation of the Polish Basin. From these observations, we deduce that salt structures are correlated to the main faults and tectonic events. From the model analysis, we interpret the stress conditions, the timing, and the geometry of the tectonic inversion of the Polish Basin into a NW–SE-oriented central horst (Mid-Polish Swell) bordered by two lateral troughs. Emphasis is placed on the Zechstein salt, considering its movements during the Mesozoic sedimentation and its decoupling effect during the tectonic inversion. Moreover, we point to the structural control of the Paleozoic basement and the crustal architecture (Teisseyre–Tornquist Zone) on the geometry of the Polish Basin and the Mid-Polish Swell.  相似文献   

Assessment of the frequency domain decomposition technique by forced‐vibration tests of a full‐scale structure     

C. P. Lamarche  P. Paultre  J. Proulx  S. Mousseau 《地震工程与结构动力学》2008,37(3):487-494

Dynamic characteristics of buildings are of utmost importance in earthquake engineering. The vibration periods are required to determine design loads, and damping is necessary in time‐history analysis. These parameters are generally obtained through forced‐vibration tests (FVTs) or after a seismic event in the case of permanently instrumented structures. However, for large civil engineering structures, FVTs are often too costly or practically difficult, and ambient or output‐only methods are used. This paper describes a comparison between ambient and FVTs carried out on a two‐story building. Results from both testing methods are compared and discussed in order to assess the vibration properties estimates obtained with the frequency domain decomposition technique. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

Introduction to the Special Issue “Seafloor backscatter data from swath mapping echosounders: from technological development to novel applications”     

Geoffroy Lamarche  Xavier Lurton 《Marine Geophysical Researches》2018,39(1-2):1-3

  相似文献   

Unsupervised fuzzy classification and object-based image analysis of multibeam data to map deep water substrates, Cook Strait, New Zealand   总被引：1，自引：0，他引：1  

Vanessa Lucieer  Geoffroy Lamarche 《Continental Shelf Research》2011,31(11):1236-1247

A comprehensive 32 kHz multibeam bathymetry and backscatter survey of Cook Strait, New Zealand (∼8500 km²), is used to generate a regional substrate classification map over a wide range of water depths, seafloor substrates and geological landforms using an automated mapping method based on the textural image analysis of backscatter data. Full processing of the backscatter is required in order to obtain an image with a strongly attenuated specular reflection. Image segmentation of the merged backscatter and bathymetry layers is constrained using shape, compactness, and texture measures. The number of classes and their spatial distribution are statistically identified by employing an unsupervised fuzzy-c-means (FCM) clustering algorithm to sediment samples, independent of the backscatter data. Classification is achieved from the overlay of the FCM result onto a segmented image and attributing segments with the FCM class. Four classes are identified and uncertainty in class attribution is quantified by a confusion index layer. Validation of the classification map is done by comparing the results with the sediment and structural maps. Backscatter (BS) strength angular profiles are used to show acoustic class separation. The method takes us one step further in combining multibeam data with physical seabed data in a complementary analysis to seek correlations between datasets using object-based image analysis and unsupervised classification. Texture within these identified classes is then examined for correlation with typical backscatter angular responses for mud, sand and gravel. The results show a first order correlation between each of the classes and both the sedimentary properties and the geomorphological map.  相似文献   

Estimating baselines for climate change for less developed countries: the case of the Sahel     

Mohammed H.I. Dore  Jean François Lamarche 《Climate Policy》2013,13(2):231-240

Abstract

The UN Framework Convention on Climate Change (UNFCCC) and the Kyoto Protocol provide mechanisms for assisting less developed countries that are adversely affected by climate change. Such assistance would need a baseline, which ideally would set a precise date for specific impacts of climate change. This article presents the results of statistical tests that we carried out and, for the African region of the Sahel, finds that for precipitation (affecting food supply), impacts due to climate change can be ‘dated’ to the year 1967, when precipitation fell drastically, affecting the local food supply. Such a statistically robust benchmark would be useful to the Subsidiary Body for Scientific and Technological Advice (SBSTA) of the UNFCCC. The method illustrates how other baselines may be established for the important work of the SBSTA.  相似文献   

The Côte d’Ivoire–Ghana transform margin: sedimentary and tectonic structure from multichannel seismic data     

G. Lamarche  C. Basile  J. Mascle  Franc¸oise Sage 《Geo-Marine Letters》1997,17(1):62-69

We present multi channel seismic data recorded at the transition between the Ivorian (rifted) basin and the Côte d’Ivoire–Ghana marginal ridge (formed in a Cretaceous transform margin). The ridge is made of sedimentary sequences continuous with the synrift sediments of the Ivorian basin. Clinoformal structures suggest synrift progradational sedimentation originating from the Brazilian craton, which was located to the south during the Cretaceous. Subsequent to rifting, southward migration of the transform motion isolated the ridge from the Brazilian shelf. In the western part of the marginal ridge, crustal half-grabens are buried by postrifting progradational sedimentation, suggesting important posttransform subsidence.  相似文献   

Structure of a hypovolcanic acid complex inferred from magnetic susceptibility anisotropy measurements: the Western Red Hills granites (Skye,Scotland, Thulean Igneous Province)     

Geoffroy  Laurent  Olivier  Philippe  Rochette  Pierre 《Bulletin of Volcanology》1997,59(2):147-159

 The geochemistry and the injection mechanism of hypovolcanic ring dykes have been extensively studied, but such is not the case for their internal fabric. The Tertiary Western Red Hills epigranites of the Isle of Skye are a classic example of such intrusions. Using anisotropy of magnetic susceptibility measurements, we present the first structural data of their internal magmatic fabric. The magnetic foliations, equated with the magmatic flow planes, have strikes which roughly follow the walls of the different intrusions. They dip steeply toward the convex wall of each intrusion. The lineations, or maximal magnetic susceptibility axes, generally have shallow plunges, except in the latest granite intrusion. These structures appear to be related to the compressional deformation of each intrusion toward the end of its crystallization. This shortening would be a consequence of a radial and compressive stress field acting after each injection of magma. This radial stress field is interpreted as the effect of high magma pressures originating from the acid magma chamber underlying the ring-dyke complex at a shallow depth. Received: 10 October 1995 / Accepted: 4 June 1997  相似文献   

Did Yemeni Tertiary granites intrude neck zones of a stretched continental upper crust?     

L. Geoffroy  P. Huchon  & K. Khanbari 《地学学报》1998,10(4):196-200

We demonstrate that the Miocene alkali granites of Yemen which emplaced along the Great Escarpment are contemporaneous with the stretching of the southern Red Sea continental crust. There is a gradient of Miocene extension towards the granites as well as a change of the geometry of tilted blocks around them. Geometrically, most of these granites seem to be emplaced passively in the necked areas of a stretched continental crust. These necked areas correspond to previous syn-plume Oligocene NNW–SSE to N–S trending areas of localized extension marked by basaltic dyke swarms. These early extensional areas were associated with the emplacement of the flood basalt volcanic pile and were probably localized over large basement discontinuities.  相似文献   

La fabrique magnétique du flysch dauphinois (Alpes francaises) : origine et application quantitative     

Geoffroy Lamarche  Pierre Rochette 《Geodinamica Acta》2013,26(2):103-112

Résumé

Les propriétés magnétiques des schistes, grès et calcaires du flysch eocène de la zone dauphinoise ont été étudiées en relation avec la minéralogie et la structure de ces roches. La susceptibilité magnétique en champ faible est principalement due au paramagnétisme des phyllosilicates (illite et chlorite).

L’anisotropie de susceptibilité correspond à un ellipsoïde aplati qui présente les caractéristiques suivantes : un axe minimal perpendiculaire à la schistosité et un axe maximal parallèle soit à une linéation d’intersection soit à la direction d’étirement maximal.

On présente un modèle mathématique simple permettant d’utiliser le taux d’anisotropie magnétique pour quantifier l’orientation préférentielle des phyllosilicates. Ce modèle testé sur les niveaux les plus phylliteux du flysch donne des résultats en bon accord avec ceux de la goniometrie de texture. Les possibilités et les avantages de cette méthode structure-logique quantitative sont discutés.  相似文献