Thermochronology of allochthonous terranes in Ecuador: Unravelling the accretionary and post-accretionary history of the Northern Andes     

R.A. Spikings  W. Winkler  R.A. Hughes  R. Handler 《Tectonophysics》2005,399(1-4):195

The western cordilleras of the Northern Andes (north of 5°S) are constructed from allochthonous terranes floored by oceanic crust. We present ⁴⁰Ar/³⁹Ar and fission-track data from the Cordillera Occidental and Amotape Complex of Ecuador that probably constrain the time of terrane collision and post-accretionary tectonism in the western Andes. The data record cooling rates of 80–2 °C/my from temperatures of 540 °C, during 85 to 60 Ma, in a highly tectonised mélange (Pujilí unit) at the continent–ocean suture and in the northern Amotape Complex. The rates were highest during 85–80 Ma and decelerated towards 60 Ma. Cooling was a consequence of exhumation of the continental margin, which probably occurred in response to the accretion of the presently juxtaposing Pallatanga Terrane. The northern Amotape Complex and the Pujilí unit may have formed part of a single, regional scale, tectonic mélange that started to develop at ~85 Ma, part of which currently comprises the basement of the Interandean Depression. Cooling and rotation in the allochthonous, continental, Amotape Complex and along parts of the continent–ocean suture during 43–29 Ma, record the second accretionary phase, during which the Macuchi Island Arc system collided with the Pallatanga Terrane. Distinct periods of regional scale cooling in the Cordillera Occidental at 13 and 9 Ma were synchronous with exhumation in the Cordillera Real and were probably driven by the collision of the Carnegie Ridge with the Ecuador Trench. Finally, late Miocene–Pliocene reactivation of the Chimbo–Toachi Shear Zone was coincident with the formation of the oldest basins in the Interandean Depression and probably formed part of a transcurrent or thrust system that was responsible for the inception and subsequent growth of the valley since 6 Ma.  相似文献   

Interferometric study of the dolomite dissolution: a new conceptual model for mineral dissolution     

A Lttge  U Winkler  A.C Lasaga 《Geochimica et cosmochimica acta》2003,67(6):1099-1116

The dissolution rate and mechanism of three different cleavage faces of a dolomite crystal from Navarra (near Pamplona), Spain, were studied in detail by vertical scanning interferometry techniques. A total of 37 different regions (each about 124 × 156 μm in size) on the three sample surfaces were monitored as a function of time during dissolution at 25°C and pH 3. Dissolution produced shallow etch pits with widths reaching 20 μm during 8 h of dissolution. Depth development as a function of time was remarkably similar for all etch pits on a given dolomite surface.On the basis of etch pit distribution and volume as a function of time, the calculated dissolution rate increases from near zero to 4 × 10⁻¹¹ mol cm⁻² s⁻¹ over 5 h. The time variation is different for each of the three cleavage surfaces studied. In addition, the absolute dissolution rates of different parts of the dolomite crystal surface can be computed by using a reference surface. The different surfaces yield an “average” rate of 1.08 × 10⁻¹¹ mol cm⁻² s⁻¹ with a standard deviation of 0.3 × 10⁻¹¹ mol cm⁻² s⁻¹ based on about 60 analyses. The mean absolute rate of the dolomite surface is about 10 times slower than the rate calculated from etch pit dissolution alone. On the other hand, earlier batch rate data that used BET surface areas yield rates that are at least 30 to 60 times faster than our directly measured mean dissolution rate for the same pH and temperature.A conceptual model for mineral dissolution has been inferred from the surface topography obtained by the interferometry investigations. In this model, mineral dissolution is not dominated by etch pit formation itself but rather by extensive dissolution stepwaves that originate at the outskirts of the etch pits. These stepwaves control the overall dissolution as well as the dependence on temperature and saturation state.  相似文献   

Book reviews     

William L. Halvorson  Marjorie Green Winkler  Thomas M. Soniat  R. Eugene Turner  Warren S. Wooster 《Estuaries and Coasts》1997,20(1):249-252

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Clay mineral sedimentation in high northern latitude deep-sea basins since the Middle Miocene (ODP Leg 151, NAAG)   总被引：10，自引：0，他引：10  

A. Winkler  T. Wolf-Welling  K. Stattegger  J. Thiede 《International Journal of Earth Sciences》2002,91(1):133-148

High-resolution clay mineralogical investigations and their comparison with other sedimentological data from ODP Sites 908 and 909 (central Fram Strait) were used to reconstruct the paleoclimate and paleoceanography in the high northern latitudes since the Middle Miocene. Ice rafting has probably occurred since 15 Ma. The comparison of sand-sized components and clay mineral distribution demonstrate that both were not delivered by the same transport process. The input of the clay fraction is related to transport through sea ice and/or oceanic currents. A provenance change at 11.2 Ma is indicated by variations within clay mineral distribution and increased accumulation rates. This is interpreted as a result of an increase in water mass exchange through the Fram Strait. Decreases of the smectite to illite and chlorite ratio at Site 909 suggest a Middle Miocene cooling phase between 14.8 and 14.6 Ma, and a further cooling phase between 10 and 9 Ma. The intensification of glaciation in the Northern Hemisphere is documented by an increase of illite and chlorite from 3.4 to 3.3 Ma, which is synchronous to the onset of major Northern Hemisphere glaciation as indicated by oxygen isotope data.  相似文献   

Magnetic mineralogy changes in the Pleistocene marine sequence of Montalto di Castro (central Italy) and influences on the magnetic anisotropy     

Benot Lehman  Leonardo Sagnotti †  Aldo Winkler †  Claudia Lo Cascio 《Geophysical Journal International》1996,127(2):529-541

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The influence of pressure on the structure and dynamics of hydrogen bonds in zoisite and clinozoisite     

Björn Winkler  Julian D. Gale  Keith Refson  Dan J. Wilson  Victor Milman 《Physics and Chemistry of Minerals》2008,35(1):25-35

Density functional theory calculations have been used to study the pressure-induced changes of the hydrogen bond of Fe-free orthozoisite and clinozoisite and the concomitant shifts of the OH-stretching frequencies. Two independent parameter-free lattice dynamical calculations have been employed. One was based on a plane-wave basis set in conjunction with norm-conserving pseudopotentials and a density functional perturbation theory approach, while the other used a localised basis set and a finite displacement algorithm for the lattice dynamical calculations. Both models confirm the unusually large pressure-induced red-shift found experimentally (−33.89 cm⁻¹/GPa) in orthozoisite, while the pressure-induced shifts in clinozoisite are much smaller (−5 to −9 cm⁻¹/GPa). The atomistic model calculations show that in orthozoisite the nearly linear O–H⋯O arrangement is compressed by about 8% on a pressure increase to 10 GPa, while concomitantly the O–H distance is significantly elongated (by 2.5% at 10 GPa). In clinozoisite, the O–H⋯O arrangement is kinked at ambient conditions and remains kinked at high pressures, while the O-H distance is elongated by only 0.5% at 10 GPa. The current calculations confirm that correlations between the distances and dynamics of hydrogen bonds, which have been established at ambient conditions, cannot be used to infer hydrogen positions at high pressures.  相似文献   

Zur geomorphologischen und geologischen Entwicklungsgeschichte der Ostabdachung der Zentralalpen in der MiozÄnzeit     

A. Winkler 《International Journal of Earth Sciences》1926,17(5):384-384

Ohne Zusammenfassung  相似文献   

Zur geomorphologischen und geologischen Entwicklungsgeschichte der Ostabdachung der Zentralalpen in der Miozänzeit     

Artur Winkler 《International Journal of Earth Sciences》1926,17(4):291-310

Ohne Zusammenfassung  相似文献   

Old landscapes,new eyes: Revisiting geomorphological research in the Southern Alps of New Zealand          下载免费PDF全文

David W. Hedding  Martin S. Brook  Stefan Winkler 《New Zealand geographer》2018,74(2):109-112

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Late Glacial – Holocene Glacier Fluctuations and Climatic Implications in Sub-arctic Northern Norway     

Eric Leonard  Stefan Winkler 《Norsk geografisk tidsskrift. Norwegian journal of geography》2018,72(2):127-128

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