Paleo-bathymetry of the northern North Atlantic and consequences for the opening of the Fram Strait     

Birte-Marie Ehlers  Wilfried Jokat 《Marine Geophysical Researches》2013,34(1):25-43

In the past decade, the geophysical database in the northern North Atlantic and central Arctic Ocean constantly grew. Though far from being complete, the information from new aeromagnetic and seismic data north of the Jan Mayen Fracture Zone and in the Arctic Ocean, in combination with existing compiled geological and geophysical data, is used to produce paleo-bathymetric maps for several Cenozoic time intervals. This paleo-bathymetric model provides evidence for an initial deep-water exchange through the Fram Strait starting around 17 Ma. Furthermore, the model suggests that crustal rifting prior to initial seafloor spreading might have facilitated an earlier deep-water connection. This confirms that the paleo-topography of the Yermak Plateau played an important role in allowing at least the exchange of shallow water between the northern North Atlantic and the Arctic Ocean before the opening of the deep-water Fram Strait gateway. In the south of the research area the paleo-bathymetric model indicates that the first possibility for a deep-water overflow from the Norwegian-Greenland Sea to the North Atlantic could have been between 15 and 20 Ma.  相似文献   

Control factors on turbidite sedimentation in a deep-sea trench setting. – The example of the Schlieren Flysch (Upper Maastrichtian-Lower Eocene,Central Switzerland)     

Wilfried Winkler 《Geodinamica Acta》2013,26(2):81-102

Abstract

Deep-sea turbidite sedimentation in convergent margin settings generally is controlled by tectonic uplift, climate and eustatic sea-level variations. The rate of tectonic uplift governs the relief of the source area and the position of the base level (coinciding with sea-level), climate influences the rate and style of weathering and continental runoff and eustatic seal-level additionally shifts the base level, functioning with the concurrently working tectonic movements. Thus, these factors primarly determine the availability of sediment (yield and nature of material and the site of intermittent storage) at the basin margin which is unlocked periodically to flow downslope to the basin.

This paper attempts to decipher quantitatively the importance of the individual factors in the Late Maastrichtian to Early Eocene Schieren Flysch Croup. The flysch was deposited in a moderately converging remnant oceanic trench basin. Mean parameters are calculated on the basis of formations and the duration of nannofossil zones comprised in. For transposing these zone into absolute age intervals the problem of inconsistent durations in current time scales had to be solved by a best-fit approach. Frequencies and periodicities of turbidite events, decompacted and compacted sedimentation rates (the latter are considered as apparent denudation rates) are calculated to reveal the dynamics of sedimentation. Climatic evidence is deduced from clay mineralogy. Changing uplift rates in the drainage area are indirectly interpreted from back-stripped tectonic subsisdence rates in the basin.

The obtained data point to an immediate control of sub-duction-Iinked tectonic uplift in the bordering drainage and shelf area on turbidite sedimentation, as frequency and thickness of the turbidite events are closely correlated with the increasing tectonic subsisdence in the basin (assumed to match the rate of subduction and underplating). This general trend is modified by the temporary migration of the oceanic hinge zone towards the trench causing periodically the starvation of outer portions of the basin at the transition from Early to Late Paleocene and Late Paleocene to Eocene. Regional climatic trends additionnaly rule the turbidite facies development and apparent denudation rates. In the upper part of Early Eocene series high rate mud dominated sediments correlate with warm/humid conditions and in Late Paleocene deposits low rate sandy sediments coincide with cool ones. During the Late Paleocene period the global 2nd-order sea-level lowering probably may be responsible for the by-passing of the shelf by the coarse grained sediments.  相似文献   

Erratum to: Atmospheric water vapor transport and recycling in Equatorial Central Africa through NCEP/NCAR reanalysis data     

Wilfried M. Pokam  Lucie A. Tchotchou Djiotang  François K. Mkankam 《Climate Dynamics》2014,42(1-2):553-553

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Laser ablation U/Pb age patterns of detrital zircons in the Schlieren Flysch (Central Switzerland): new evidence on the detrital sources     

Endrio Bütler  Wilfried Winkler  Marcel Guillong 《Swiss Journal of Geoscience》2011,104(2):225-236

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The early interaction between the Caribbean Plateau and the NW South American Plate     

Cristian Vallejo  Richard A. Spikings  Leonard Luzieux  Wilfried Winkler  David Chew  Laurence Page 《地学学报》2006,18(4):264-269

The determination of accurate and precise ages for the timing of collision between oceanic plateaus and continental crust requires an understanding of how the indenting and buttressing plates respond to the collision. We present geochronological, thermochronological, geochemical and isotopic analyses of magmatic rocks from the Ecuadorian Andes, which relate to the collision of the Late Cretaceous Caribbean Plateau and Great Arc sequence with NW South America. The cessation of subduction magmatism during 65–64 Ma beneath the eastern edge of Caribbean Plateau was synchronous with accelerated surface uplift and exhumation within the buttressing continental margin during 75–65 Ma. We interpret this as the collision of the leading edge of the Caribbean Plateau and arc sequence with the South American Plate at 75–65 Ma. A U/Pb (zircon) SHRIMP age of 87.10 ± 1.66 (2σ) Ma, yielded by an accreted fragment of the plateau, precludes previous estimates of collision at 85–80 Ma if the plateau erupted above the Galápagos hotspot. Terra Nova, 18, 264–269, 2006  相似文献   

Periglacial geomorphology—the binghampton symposium in geomorphology. International Series No. 22. Edited by J. C. Dixon and A. D. abrahams. Publisher John Wiley & Sons,Chichester 1992 354 pp.) £79.95 ISBN 0 471 93342 2     

Wilfried Haeberli 《第四纪科学杂志》1995,10(4):401-402

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In memoriam Prof. Dr. Jürgen Schwoerbel (1930–2002)     

Wilfried Schnborn 《Limnologica》2003,33(4):229-230

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Lab and Field Measurements of the Hydraulic Conductivity of Clayey Silts     

Petra Döll  Wilfried Schneider 《Ground water》1995,33(6):884-891

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Preserved landscapes underneath the Antarctic Ice Sheet reveal the geomorphological history of Jutulstraumen Basin     

Steven Franke  Hannes Eisermann  Wilfried Jokat  Graeme Eagles  Jölund Asseng  Heinrich Miller  Daniel Steinhage  Veit Helm  Olaf Eisen  Daniela Jansen 《地球表面变化过程与地形》2021,46(13):2728-2745

The landscape of Antarctica, hidden beneath kilometre-thick ice in most places, has been shaped by the interactions between tectonic and erosional processes. The flow dynamics of the thick ice cover deepened pre-formed topographic depressions by glacial erosion, but also preserved the subglacial landscapes in regions with moderate to slow ice flow. Mapping the spatial variability of these structures provides the basis for reconstruction of the evolution of subglacial morphology. This study focuses on the Jutulstraumen Glacier drainage system in Dronning Maud Land, East Antarctica. The Jutulstraumen Glacier reaches the ocean via the Jutulstraumen Graben, which is the only significant passage for draining the East Antarctic Ice Sheet through the western part of the Dronning Maud Land mountain chain. We acquired new bed topography data during an airborne radar campaign in the region upstream of the Jutulstraumen Graben to characterise the source area of the glacier. The new data show a deep relief to be generally under-represented in available bed topography compilations. Our analysis of the bed topography, valley characteristics and bed roughness leads to the conclusion that much more of the alpine landscape that would have formed prior to the Antarctic Ice Sheet is preserved than previously anticipated. We identify an active and deeply eroded U-shaped valley network next to largely preserved passive fluvial and glacial modified landscapes. Based on the landscape classification, we reconstruct the temporal sequence by which ice flow modified the topography since the beginning of the glaciation of Antarctica.  相似文献   

The nonlinear anomalous lattice elasticity associated with the high-pressure phase transition in spodumene: a high-precision static compression study     

Angela Ullrich  Wilfried Schranz  Ronald Miletich 《Physics and Chemistry of Minerals》2009,36(10):545-555

The high-pressure behavior of the lattice elasticity of spodumene, LiAlSi₂O₆, was studied by static compression in a diamond-anvil cell up to 9.3 GPa. Investigations by means of single-crystal XRD and Raman spectroscopy within the hydrostatic limits of the pressure medium focus on the pressure ranges around ~3.2 and ~7.7 GPa, which have been reported previously to comprise two independent structural phase transitions. While our measurements confirm the well-established first-order C2/c–P2₁/c transformation at 3.19 GPa (with 1.2% volume discontinuity and a hysteresis between 0.02 and 0.06 GPa), both unit-cell dimensions and the spectral changes observed in high-pressure Raman spectra give no evidence for structural changes related to a second phase transition. Monoclinic lattice parameters and unit-cell volumes at in total 59 different pressure points have been used to re-calculate the lattice-related properties of spontaneous strain, volume strain, and the bulk moduli as a function of pressure across the transition. A modified Landau free energy expansion in terms of a one component order parameter has been developed and tested against these experimentally determined data. The Landau solution provides a much better reproduction of the observed anomalies than any equation-of-state fit to data sets truncated below and above P _tr, thus giving Landau parameters of K ₀ = 138.3(2) GPa, K′ = 7.46(5), λ _V  = 33.6(2) GPa, a = 0.486(3), b = −29.4(6) GPa and c = 551(11) GPa.  相似文献