Fragmentation processes and xenolith transport in a Proterozoic minette dyke,Grenville Province,Québec     

D. Morin  Louise Corriveau 《Contributions to Mineralogy and Petrology》1996,125(4):319-331

 The Mesoproterozoic Rivard minette dyke provides a case example of dyke-parallel fracturing induced by propagation of low-viscosity melts at deep crustal levels. The dyke constitutes a xenolith-choked intrusion breccia and provides samples of an extensive section of the lithosphere underlying the southwestern Grenville Province of Québec at 1.08 Ga. The xenoliths occupy approximately 50% of the volume of the breccia. They are extremely diverse and include pyroxenites and mafic granulites from the upper mantle and lower crust, and Grenvillian gabbroids, gneisses and quartzites. Wall-rock fragments are detached to various extents along dyke-parallel fractures and apophyses. The host lamprophyre magma has a calculated viscosity of ca. 40 Pa·s. Rapid ascent of magma and turbulence are suggested by the presence of large dense fragments and the brittle-to-ductile deformation at the margins of some xenoliths. A minimum ascent velocity of ca. 50 cm·s^–1 is estimated from the settling velocity of a 40 cm long pyroxenite xenolith. The progressive addition of xenoliths increased the effective viscosity of the liquid-solid mixture to 10³ Pa·s during emplacement. This favoured Bingham behaviour and laminar flow of the magma, and xenolith suspension. Field evidence suggests that xenoliths were formed through (1) early fracturing of wall rock by inelastic deformation during dyke propagation, and (2) continuous delamination of wall rock by intrusion of magma along the dyke-parallel fractures. This led to removal of chilled margins, and to fluid infiltration, partial melting and microbrecciation in the wall rock. Pre-existing discontinuities played a minor role in the fracturing process. Xenoliths may thus be abundant in alkaline magmas not only because these magmas ascend rapidly and can transport xenoliths, but possibly also, because their low viscosities promote intense fracturing of wall rock. Received: 10 June 1995 / Accepted: 10 February 1996  相似文献   

A Statistical Evaluation of Formation Disturbance Produced by Well-Casing Installation Methods   总被引：1，自引：0，他引：1  

Roger H. Morin  Denis R. LeBlanc  Warren E. Teasdale 《Ground water》1988,26(2):207-217

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Determining the Distribution of Hydraulic Conductivity in a Fractured Limestone Aquifer by Simultaneous Injection and Geophysical Logging   总被引：2，自引：0，他引：2  

Roger H. Morin  Alfred E. Hess  Frederick L. Paillet 《Ground water》1988,26(5):587-595

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Linking frequency of rainstorms,runoff generation and sediment transport across hyperarid talus-pediment slopes     

Yuval Shmilovitz  Efrat Morin  Yair Rinat  Itai Haviv  Genadi Carmi  Amit Mushkin  Yehouda Enzel 《地球表面变化过程与地形》2020,45(7):1644-1659

Documenting hillslope response to hydroclimatic forcing is crucial to our understanding of landscape evolution. The evolution of talus-pediment sequences (talus flatirons) in arid areas was often linked to climatic cycles, although the physical processes that may account for such a link remain obscure. Our approach is to integrate field measurements, remote sensing of rainfall and modeling to link between storm frequency, runoff, erosion and sediment transport. We present a quantitative hydrometeorological analysis of rainstorms, their geomorphic impact and their potential role in the evolution of hyperarid talus-pediment slopes in the Negev desert, Israel. Rainstorm properties were defined based on intensity–duration–frequency curves and using a rainfall simulator, artificial rainstorms were executed in the field. Then, the obtained measured experimental results were up-scaled to the entire slope length using a fully distributed hydrological model. In addition, natural storms and their hydro-geomorphic impacts were monitored using X-band radar and time-lapse cameras. These integrated analyses constrain the rainfall threshold for local runoff generation at rain intensity of 14 to 22 mm h^-1 for a duration of five minutes and provide a high-resolution characterization of small-scale runoff-generating rain cells. The current frequency of such runoff-producing rainstorms is ~1–3 per year. However, extending this local value into the full extent of hillslope runoff indicates that it occurs only under rainstorms with ≥ 100-years return interval, or 1% annual exceedance probability. Sheetwash efficiency rises with downslope distance; beyond a threshold distance of ~100 m, runoff during rainstorms with such annual exceedance probability are capable of transporting surface clasts. The erosion efficiency of these discrete rare events highlights their potential importance in shaping the landscape of arid regions. Our results support the hypothesis that a shift in the properties and frequency of extreme events can trigger significant geomorphic transitions in areas that remained hyperarid during the entire Quaternary. © 2020 John Wiley & Sons, Ltd.  相似文献   

Sinuosity evolution along an incising channel: New insights from the Jordan River response to the Dead Sea level fall     

Elad Dente  Nadav G. Lensky  Efrat Morin  Thomas Dunne  Yehouda Enzel 《地球表面变化过程与地形》2019,44(3):781-795

The geomorphic evolution of the Jordan River in recent decades indicates that interaction between incision and high-magnitude floods controls sinuosity changes under increasing mouth gradients during base-level fall. The evolution of the river was analyzed based on digital elevation models, remotely sensed imagery, hydrometric data, and a hydraulic model. The response varies along the river. Near the river mouth, where incision rate is high and a deep channel forms, overbank flooding is less likely. There, large floods exert high shear stress within the confined channel, increasing sinuosity. Upstream, near the migrating knickzone channel gradients also increase, incision is more moderate and floods continue to overtop the banks, favoring meander chute cutoffs. The resulting channel has a downstream well-confined meandering segment and an upstream low-sinuosity segment. These new insights regarding spatial differences along an incising channel can improve interpretations of the evolution of ancient planforms and floodplains that responded to base-level decline. © 2018 John Wiley & Sons, Ltd.  相似文献   

Model complexity and data requirements in snow hydrology: seeking a balance in practical applications          下载免费PDF全文

Francesco Avanzi  Carlo De Michele  Samuel Morin  Carlo Maria Carmagnola  Antonio Ghezzi  Yves Lejeune 《水文研究》2016,30(13):2106-2118

We investigate the problem of balancing model complexity and input data requirements in snow hydrology. For this purpose, we analyze the performance of two models of different complexity in estimating variables of interest in snow hydrology applications. These are snow depth, bulk snow density, snow water equivalent and snowmelt run‐off. We quantify the differences between data and model prediction using 18 years of measurements from an experimental site in the French Alps (Col de Porte, 1325 m AMSL). The models involved in this comparison are a one‐layer temperature‐index model (HyS) and a multilayer model (Crocus). Results show that the expected loss in performance in the one‐layer temperature‐index model with respect to the multilayer model is low when considering snow depth, snow water equivalent and bulk snow density. As for run‐off, the comparison returns less clear indications for identification of a balance. In particular, differences between the models' prediction and data with an hourly resolution are higher when considering the Crocus model than the HyS model. However, Crocus is better at reproducing sub‐daily cycles in this variable. In terms of daily run‐off, the multilayer physically based model seems to be a better choice, while results in terms of cumulative run‐off are comparable. The better reproduction of daily and sub‐daily variability of run‐off suggests that use of the multilayer model may be preferable for this purpose. Variation in performance is discussed as a function of both the calibration solution chosen and the time of year. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献