3D surface‐wave estimation and separation using a closed‐loop approach          下载免费PDF全文

T. Ishiyama  G. Blacquière  D.J. Verschuur  W. Mulder 《Geophysical Prospecting》2016,64(6):1413-1427

Surface waves in seismic data are often dominant in a land or shallow‐water environment. Separating them from primaries is of great importance either for removing them as noise for reservoir imaging and characterization or for extracting them as signal for near‐surface characterization. However, their complex properties make the surface‐wave separation significantly challenging in seismic processing. To address the challenges, we propose a method of three‐dimensional surface‐wave estimation and separation using an iterative closed‐loop approach. The closed loop contains a relatively simple forward model of surface waves and adaptive subtraction of the forward‐modelled surface waves from the observed surface waves, making it possible to evaluate the residual between them. In this approach, the surface‐wave model is parameterized by the frequency‐dependent slowness and source properties for each surface‐wave mode. The optimal parameters are estimated in such a way that the residual is minimized and, consequently, this approach solves the inverse problem. Through real data examples, we demonstrate that the proposed method successfully estimates the surface waves and separates them out from the seismic data. In addition, it is demonstrated that our method can also be applied to undersampled, irregularly sampled, and blended seismic data.  相似文献   

Historical and future development of the tidally averaged transport of sandy sediments in the Scheldt estuary: a 2D exploratory model     

Boelens  Thomas  Schuttelaars  Henk  Plancke  Yves  De Mulder  Tom 《Ocean Dynamics》2020,70(4):481-504

Ocean Dynamics - To investigate the historical development of the tidally averaged transport of sandy sediments in the main branch of the Scheldt estuary over the last decades (1950–2013), a...  相似文献   

The structure and metamorphism of the Red Point Metamorphic Complex—A newly discovered high-pressure metamorphic complex from the south coast of Tasmania     

J. A. Mulder  R. F. Berry  R. J. Scott 《Australian Journal of Earth Sciences》2013,60(8):969-983

This study presents new data on the deformational and metamorphic history of previously unstudied Cambrian high-pressure metamorphic rocks exposed on the remote south coast of Tasmania. The Red Point Metamorphic Complex consists of two blocks of high-pressure, medium-grade metamorphic rocks including pelitic schist and minor garnet-bearing amphibolite, which are faulted against a sequence of low-grade phyllite and quartzite. The Red Point Metamorphic Complex records five phases of deformation, all of which except the first are expressed at a mesoscopic scale in both the medium- and low-grade rocks. Peak metamorphic conditions in the high-pressure epidote–amphibolite facies is recorded by medium-grade schist and amphibolite and was synchronous with the second major deformation event, which produced a pervasive schistosity and mesoscale isoclinal folds. The juxtaposition of the low- and medium-grade rocks is interpreted to have first occurred prior to the development of upright, opening folding associated with the third deformation. However, the present contacts between the two contrasting metamorphic sequences formed during widespread faulting and ductile-shear zone development associated with the fourth and fifth deformation events. The new data from the Red Point Metamorphic Complex provide insights into the structural and metamorphic history experienced by the medium-grade rocks of Tasmania during the Cambrian Tyennan Orogeny. This study demonstrates that Cambrian medium-grade metamorphic rocks are more widespread throughout Tasmania than previously realised, which represents an important step towards understanding the large-scale architecture of the Tyennan Orogen.  相似文献   

Were the 2.1-Gyr fossil colonial organisms discovered in the Francevillian basin (Palaeoproterozoic,Gabon) buried by turbidites?     

Olivier Parize  Jean-Louis Feybesse  François Guillocheau  Thierry Mulder 《Comptes Rendus Geoscience》2013,345(2):101-110

The Francevillian series (Gabon) in which the Earth's oldest large colonial organisms were recently discovered (El Albani et al., 2010) were deposited 2 Gyr ago. These series are usually interpreted as a fining-upward basin-fill sequence composed by five superimposed lithological terms noted FA to FE. New studies initiated by AREVA, allowed new data to be collected on the southwestern edge of the Francevillian basin, particularly on newly excavated outcrops. Facies interpretations show that the Poubara sandstones and associated shales and black shales (upper part of FB,FB2a), correspond to turbidites deposited on an upper slope rather than one a shelf, submitted to tidal currents or storm wave action. These new interpretations based on facies association, sedimentary geometries, and basin evolution show that the depositional environment could be a turbidite lobe set at a palaeobathymetry deeper than 200 m.  相似文献   

Inferring denudation variations from the sediment record; an example of the last glacial cycle record of the Golo Basin and watershed,East Corsica,western Mediterranean sea     

G. Calvès  S. Toucanne  G. Jouet  S. Charrier  E. Thereau  J. Etoubleau  T. Marsset  L. Droz  M. Bez  V. Abreu  S. Jorry  T. Mulder  G. Lericolais 《Basin Research》2013,25(2):197-218

Geophysical data and sampling of the Golo Basin (East Corsica margin) provide the opportunity to study mass balance in a single drainage system over the last 130 kyr, by comparing deposited sediments in the sink and the maximum eroded volume in the source using total denudation proxies. Evaluation of the solid sediments deposited offshore and careful integration of uncertainties from the age model and physical properties allow us to constrain three periods of sedimentation during the last climatic cycle. The peak of sedimentation initiated during Marine Isotopic Stage (MIS) 3 (ca. 45 ka) and lasted until late in MIS 2 (ca. 18 ka). This correlates with Mediterranean Sea palaeoclimatic records and the glaciation in high altitude Corsica. The yield of solid sediment into the Golo Basin drops in the observed present day Mediterranean basins (gauging stations), whereas the palaeo‐denudation estimate derived from the sediments over the last glacial period is one to ten times higher than that predicted using cosmogenic or thermochronometer estimates of exhumation. The catchment‐wide denudation rate calculated from deposited solid sediment ranges from 47 to 219 mm kyr^?1, which is higher than the estimate from palaeosurface ablation in the proximal part of the source (9–140 mm kyr^?1) and lower than the distal, narrow, incised channel of the Golo River (160–475 mm kyr^?1). This mismatch raises questions about the investigation of denudation at millennial‐time scale (kyr) and at higher integrating times (Myr) as a reliable tool for determining the effect of climate change on mountain building and on sedimentary basin models.  相似文献   

Nile floods recorded in deep Mediterranean sediments     

Emmanuelle Ducassou  Thierry Mulder  Sbastien Migeon  Eliane Gonthier  Anne Murat  Marie Revel  Lucilla Capotondi  Stefano M. Bernasconi  Jean Mascle  Sbastien Zaragosi 《Quaternary Research》2008,70(3):382-391

Clastic mud beds rich in continental organic matter are observed recurrently in the Nile deep-sea turbidite system. They formed during flooding periods of the river similar to those that induce sapropel formation and occurred during periods of increased density stratification of the eastern Mediterranean. The very fine-grained flood deposits are intercalated within pelagic sediments, sapropels and Bouma-type turbidites. These flood deposits form by the successive reconcentrations of surface (hypopycnal) plumes by convective sedimentation, which in turn generate a fine-grained low-energy hyperpycnal flow. Sea-level high stands seem also to favor hypopycnal plume formation and increase clastic mud bed formation. Consequently, these muddy clastic beds provide a direct link between deep-marine sedimentary records and continental climatic change through flood frequency and magnitude.  相似文献   

Sediment failures and flows in the Gulf of Cadiz (eastern Atlantic)     

T. Mulder  E. Gonthier  P. Lecroart  V. Hanquiez  E. Marches  M. Voisset 《Marine and Petroleum Geology》2009,26(5):660-672

Several types of sediment failures in the Gulf of Cadiz were observed using multibeam bathymetry, acoustic imagery and high-resolution seismic. These instabilities are mainly sediment failures and flows. Their width and length vary from 1 to more than 10 km. The failures are mainly related to high sedimentation rates, particularly in places where the Mediterranean Outflow Water (MOW) spills over, such as channel bends and the outer side of the giant contourite levee. Steep slopes are also a trigger for failure at the continental shelf-slope transition, on valley sides, on canyon flanks, and on the sides of bathymetric highs. Other mass movements are related to fluid escape (mud volcanoes) and earthquakes. In areas where the MOW flows along the seafloor, the constant shearing and related erosion can add to the overall stresses. The frequency of failures can be estimated using the deposits resulting of their distal transformations into turbidites.  相似文献   

Niek Rengers, Editor, Engineering geology of quaternary sediments, A.A. Balkema, Rotterdam (1994)US$ 49 (excl. VAT), hard cover.     

E.F.J. de Mulder 《Engineering Geology》1996,42(4):301-302

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The western part of the Gulf of Cadiz: contour currents and turbidity currents interactions   总被引：2，自引：0，他引：2  

T. Mulder  P. Lecroart  V. Hanquiez  E. Marches  E. Gonthier  J.-C. Guedes  E. Thiébot  B. Jaaidi  N. Kenyon  M. Voisset  C. Perez  M. Sayago  Y. Fuchey  S. Bujan 《Geo-Marine Letters》2006,26(1):31-41

Recent multibeam bathymetry and acoustic imagery data provide a new understanding of the morphology of the western part of the Gulf of Cadiz. The gulf is under the influence of a strong current, the Mediterranean Outflow Water (MOW). This current is at the origin of the construction of the giant Contourite Depositional System. Canyons and valleys with erosive flanks are observed. Only the Portimao Canyon is presently connected to the continental shelf. Channels occur on the continental shelf but are presently disconnected from the deeper network of channels and valleys. Slumps are localized in steep slope areas. They are caused by oversteepening and overloading, sometimes probably associated with earthquake activity. Slumps transform sharply into turbidity currents, depositing turbidites on the floor of deep valleys. Interaction of the MOW and gravity currents is suggested by the filling of the incisions located on the drifts below the present seafloor, the shifting of valleys and canyons in the direction of the MOW flow inducing an unusual phenomenon of capture of submarine valleys.  相似文献   

A few months-old storm-generated turbidite deposited in the Capbreton Canyon (Bay of Biscay, SW France)   总被引：1，自引：1，他引：1  

T. Mulder  O. Weber  P. Anschutz  F. Jorissen  J.-M. Jouanneau 《Geo-Marine Letters》2001,21(3):149-156

A gravity core taken in the canyon of Capbreton shows a succession of sedimentary facies which can be interpreted as three superimposed Bouma sequences. The turbiditic sequences are covered by an oxidised layer which contains live benthic foraminiferal faunas indicating a reprisal of hemipelagic deposition. Activities of ²³⁴Th and ²¹⁰Pb suggest that the most recent turbidite was deposited between early December 1999 and mid-January 2000. During this period, the most probable natural event able to trigger a turbidity current was the violent storm which affected the French Atlantic coast on 27 December 1999. The turbidity current could have been caused by a sediment failure due to an excess in pore pressure generated by the storm waves, an increase of the littoral drift, or the dissipation of the along-coast water bulge through the canyon. This sub-recent turbidite shows that the canyon experiences modern gravity processes, despite the lack of a direct connection with a major sediment source.  相似文献